Nicholas Giori MD, PhD

All Publications

• CORR Insights®: Does the SORG Machine-learning Algorithm for Extremity Metastases Generalize to a Contemporary Cohort of Patients? Temporal Validation From 2016 to 2020. Clinical orthopaedics and related research Giori, N. J. 2023

  View details for DOI 10.1097/CORR.0000000000002735

  View details for PubMedID 37335238

• "I Often Feel Conflicted in Denying Surgery": Perspectives of Orthopaedic Surgeons on Body Mass Index Thresholds for Total Joint Arthroplasty: A Qualitative Study. The Journal of bone and joint surgery. American volume Godziuk, K., Reeson, E. A., Harris, A. H., Giori, N. J. 2023

  Abstract

  Use of a patient body mass index (BMI) eligibility threshold for total joint arthroplasty (TJA) is controversial. A strict BMI criterion may reduce surgical complication rates, but over-restrict access to effective osteoarthritis (OA) treatment. Factors that influence orthopaedic surgeons' use of BMI thresholds are unknown. We aimed to identify and explore orthopaedic surgeons' perspectives regarding patient BMI eligibility thresholds for TJA.A cross-sectional, online qualitative survey was distributed to orthopaedic surgeons who conduct hip and/or knee TJA in the United States. Survey questions were open-ended, and responses were collected anonymously. Survey data were coded and analyzed in an iterative, systematic process to identify predominant themes.Forty-five surveys were completed. Respondents were 54.3 ± 12.4 years old (range, 34 to 75 years), practiced in 22 states, and had 21.2 ± 13.3 years (range, 2 to 44 years) of surgical experience. Twelve factors influencing BMI threshold use by orthopaedic surgeons were identified: (1) evidence interpretation, (2) personal experiences, (3) difficulty of surgery, (4) professional ramifications, (5) ethics and biases, (6) health-system policies and performance metrics, (7) surgical capacity and resources, (8) patient body fat distribution, (9) patient self-advocacy, (10) control of decision-making in the clinical encounter, (11) expectations for demonstrated weight loss, and (12) research and innovation gaps.Multilevel, complex factors underlie BMI threshold use for TJA eligibility. Addressing identified factors at the patient, surgeon, and health-system levels should be considered to optimally balance complication avoidance with improving access to life-enhancing surgery.This study may influence how orthopaedic surgeons think about their own practices and how they approach patients and consider surgical eligibility.

  View details for DOI 10.2106/JBJS.22.01312

  View details for PubMedID 37071729

• CORR Insights: What Are Orthopaedic Patients' and Clinical Team Members' Perspectives Regarding Whether and How to Address Mental Health in the Orthopaedic Care Setting? A Qualitative Investigation of Patients With Neck or Back Pain. Clinical orthopaedics and related research Giori, N. J. 2023

  View details for DOI 10.1097/CORR.0000000000002550

  View details for PubMedID 36607738

• Large Surgical Databases with Direct Data Abstraction: VASQIP and ACS-NSQIP. The Journal of bone and joint surgery. American volume Habermann, E. B., Harris, A. H., Giori, N. J. 2022; 104 (Suppl 3): 9-14

  Abstract

  ABSTRACT: Direct data abstraction from a patient's chart by experienced medical professional data abstractors has been the historical gold standard for quality and accuracy in clinical medical research. The limiting challenge to population-wide studies for quality and public health purposes is the high personnel costs associated with very large-scale efforts of this type. Two historically related programs that are at least partially able to successfully circumvent this problem and provide high-quality data relating to surgical procedures and the early postoperative period are reviewed in this article. Both utilize similar data abstraction efforts by specially trained and qualified medical abstractors of a sample subset of the total procedures performed at participating hospitals.The Veterans Affairs Surgical Quality Improvement Program (VASQIP), detailed by Nicholas J. Giori, MD, PhD, in the first section of this article, makes use of trained abstractors and has undergone recent additions and updates, including the development of an associated total hip registry for the VA system. The data elements and data integrity provided by both of these programs establish important benchmarks for other "big data" efforts, which often attempt to use alternative less-expensive methods of data collection in order to achieve more widespread or even nationwide data collection.In the second section, Elizabeth B. Habermann, PhD, MPH, provides a detailed review of the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP), the data elements collected, and examples of the range of quality improvement and outcomes studies in orthopaedic surgery that it has made possible, along with information on data that have not been collected and the resulting limitations. The ACS NSQIP was actually modeled after the very similar earlier effort started by the United States Department of Veterans Affairs (VA).

  View details for DOI 10.2106/JBJS.22.00596

  View details for PubMedID 36260037

• Association of Quality of Care With Where Veterans Choose to Get Knee Replacement Surgery. JAMA network open Giori, N. J., Beilstein-Wedel, E. E., Shwartz, M., Harris, A. H., Vanneman, M. E., Wagner, T. H., Rosen, A. K. 2022; 5 (9): e2233259

  Abstract

  Recent legislation expanded veterans' access to Veterans Health Administration (VA)-purchased care. Quality should be considered when choosing where to get total knee arthroplasty (TKA), but currently available quality metrics provide little guidance.To determine whether an association exists between the proportion of TKAs performed (vs purchased) at each VA facility and the quality of care provided (as measured by short-term complication rates).This 3-year cohort study used VA and community care data (fiscal year 2017 to fiscal year 2019) from the VA's Corporate Data Warehouse. Complications were defined following the Centers for Medicare and Medicaid Services' methodology. The setting included 140 VA health care facilities performing or purchasing TKAs. Participants included veterans who had 43 371 primary TKA procedures that were either VA-performed or VA-purchased during the study period.Of the 43 371 primary TKA procedures, 18 964 (43.7%) were VA-purchased.The primary outcome was risk-standardized short-term complication rates of VA-performed or VA-purchased TKAs. The association between the proportion of TKAs performed at each VA facility and quality of VA-performed and VA-purchased care was examined using a regression model. Subgroups were also identified for facilities that had complication rates above or below the overall mean complication rate and for facilities that performed more or less than half of the facility's TKAs.Among the study sample's 41 775 veterans who underwent 43 371 TKAs, 38 725 (89.3%) were male, 6406 (14.8%) were Black, 33 211 (76.6%) were White, and 1367 (3.2%) had other race or ethnicity (including American Indian or Alaska Native, Asian, and Native Hawaiian or other Pacific Islander); mean (SD) age was 66.9 (8.5) years. VA-performed and VA-purchased TKAs had a mean (SD) raw overall short-term complication rate of 2.97% (0.08%). There was no association between the proportion of TKAs performed in VA facilities and risk-standardized complication rates for VA-performed TKAs, and no association for VA-purchased TKAs.In this cohort study, surgical quality did not have an association with where veterans had TKA, possibly because meaningful comparative data are lacking. Reporting local and community risk-standardized complication rates may inform veterans' decisions and improve care. Combining these data with the proportion of TKAs performed at each site could facilitate administrative decisions on where resources should be allocated to improve care.

  View details for DOI 10.1001/jamanetworkopen.2022.33259

  View details for PubMedID 36178687

• A Tool to Estimate Risk of 30-day Mortality and Complications After Hip Fracture Surgery: Accurate Enough for Some but Not All Purposes? A Study From the ACS-NSQIP Database. Clinical orthopaedics and related research Harris, A. H., Trickey, A. W., Eddington, H. S., Seib, C. D., Kamal, R. N., Kuo, A. C., Ding, Q., Giori, N. J. 2022

  Abstract

  Surgical repair of hip fracture carries substantial short-term risks of mortality and complications. The risk-reward calculus for most patients with hip fractures favors surgical repair. However, some patients have low prefracture functioning, frailty, and/or very high risk of postoperative mortality, making the choice between surgical and nonsurgical management more difficult. The importance of high-quality informed consent and shared decision-making for frail patients with hip fracture has recently been demonstrated. A tool to accurately estimate patient-specific risks of surgery could improve these processes.With this study, we sought (1) to develop, validate, and estimate the overall accuracy (C-index) of risk prediction models for 30-day mortality and complications after hip fracture surgery; (2) to evaluate the accuracy (sensitivity, specificity, and false discovery rates) of risk prediction thresholds for identifying very high-risk patients; and (3) to implement the models in an accessible web calculator.In this comparative study, preoperative demographics, comorbidities, and preoperatively known operative variables were extracted for all 82,168 patients aged 18 years and older undergoing surgery for hip fracture in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) between 2011 and 2017. Eighty-two percent (66,994 of 82,168) of patients were at least 70 years old, 21% (17,007 of 82,168) were at least 90 years old, 70% (57,260 of 82,168) were female, and 79% (65,301 of 82,168) were White. A total of 5% (4260 of 82,168) of patients died within 30 days of surgery, and 8% (6786 of 82,168) experienced a major complication. The ACS-NSQIP database was chosen for its clinically abstracted and reliable data from more than 600 hospitals on important surgical outcomes, as well as rich characterization of preoperative demographic and clinical predictors for demographically diverse patients. Using all the preoperative variables in the ACS-NSQIP dataset, least absolute shrinkage and selection operator (LASSO) logistic regression, a type of machine learning that selects variables to optimize accuracy and parsimony, was used to develop and validate models to predict two primary outcomes: 30-day postoperative mortality and any 30-day major complications. Major complications were defined by the occurrence of ACS-NSQIP complications including: on a ventilator longer than 48 hours, intraoperative or postoperative unplanned intubation, septic shock, deep incisional surgical site infection (SSI), organ/space SSI, wound disruption, sepsis, intraoperative or postoperative myocardial infarction, intraoperative or postoperative cardiac arrest requiring cardiopulmonary resuscitation, acute renal failure needing dialysis, pulmonary embolism, stroke/cerebral vascular accident, and return to the operating room. Secondary outcomes were six clusters of complications recently developed and increasingly used for the development of surgical risk models, namely: (1) pulmonary complications, (2) infectious complications, (3) cardiac events, (4) renal complications, (5) venous thromboembolic events, and (6) neurological events. Tenfold cross-validation was used to assess overall model accuracy with C-indexes, a measure of how well models discriminate patients who experience an outcome from those who do not. Using the models, the predicted risk of outcomes for each patient were used to estimate the accuracy (sensitivity, specificity, and false discovery rates) of a wide range of predicted risk thresholds. We then implemented the prediction models into a web-accessible risk calculator.The 30-day mortality and major complication models had good to fair discrimination (C-indexes of 0.76 and 0.64, respectively) and good calibration throughout the range of predicted risk. Thresholds of predicted risk to identify patients at very high risk of 30-day mortality had high specificity but also high false discovery rates. For example, a 30-day mortality predicted risk threshold of 15% resulted in 97% specificity, meaning 97% of patients who lived longer than 30 days were below that risk threshold. However, this threshold had a false discovery rate of 78%, meaning 78% of patients above that threshold survived longer than 30 days and might have benefitted from surgery. The tool is available here: https://s-spire-clintools.shinyapps.io/hip_deploy/.The models of mortality and complications we developed may be accurate enough for some uses, especially personalizing informed consent and shared decision-making with patient-specific risk estimates. However, the high false discovery rate suggests the models should not be used to restrict access to surgery for high-risk patients. Deciding which measures of accuracy to prioritize and what is "accurate enough" depends on the clinical question and use of the predictions. Discrimination and calibration are commonly used measures of overall model accuracy but may be poorly suited to certain clinical questions and applications. Clinically, overall accuracy may not be as important as knowing how accurate and useful specific values of predicted risk are for specific purposes.Level of Evidence Level III, therapeutic study.

  View details for DOI 10.1097/CORR.0000000000002294

  View details for PubMedID 35901441

• Survival of hydroxyapatite-coated vs. non hydroxyapatite coated total hip arthroplasty implants in a veteran population. The Journal of arthroplasty Tyagi, V., Harris, A. H., Giori, N. J. 2022

  Abstract

  BACKGROUND: Hydroxyapatite (HA) coatings were introduced to improve uncemented implant osteointegration and to prevent loosening and osteolysis. However, data regarding these implants have been inconsistent. We studied the effect of HA coating of femoral stems and acetabular cups on component revision after primary THA in the veteran population.METHODS: We identified patients who underwent uncemented primary THA at any Veterans Health Administration (VHA) hospital from 2000 to 2017 and who had implants that were available as either HA-coated or non-HA-coated models. Endpoint was removal of the component of interest for any reason. For each individual stem and shell, unadjusted and adjusted (for age and BMI) Cox proportional hazards models were used to estimate hazard ratios for risk of explantation between the HA-coated and non-HA-coated implants of the same type.RESULTS: A total of 262 HA-coated cups, 4580 non-HA-coated cups, 4767 HA-coated stems, and 9397 non-HA-coated stems were available for analysis. Mean follow-up time was 9.01 years (43,627 total implant-years) for cups and 7.13 years (101,004 total implant-years) for stems. One of two shells reviewed had significantly lower survivorship and an elevated hazard ratio for explantation with HA coating. Among the five implant pairs of stems, and the other shell, implant survival and hazard ratios for explantation that were not affected by HA coating.CONCLUSION: HA coating did not improve THA implant survival in our veteran population. As HA-coated versions of hip implants tend to be more costly than their non-coated counterparts, these results do not support their general use.

  View details for DOI 10.1016/j.arth.2022.02.067

  View details for PubMedID 35219818

• CORR Insights: Small Random Angular Variations in Pelvic Tilt and Lower Extremity Can Cause Error In Static Image-based Preoperative Hip Arthroplasty Planning: A Computer Modeling Study. Clinical orthopaedics and related research Giori, N. J. 2022

  View details for DOI 10.1097/CORR.0000000000002141

  View details for PubMedID 35133303

• Comparing Postoperative Readmission Rates Between Veterans Receiving Total Knee Arthroplasty in the Veterans Health Administration Versus Community Care. Medical care Rosen, A. K., Beilstein-Wedel, E. E., Harris, A. H., Shwartz, M., Vanneman, M. E., Wagner, T. H., Giori, N. J. 1800; 60 (2): 178-186

  Abstract

  BACKGROUND: There are growing concerns that Veterans' increased use of Veterans Health Administration (VA)-purchased care in the community may lead to lower quality of care.OBJECTIVE: We compared rates of hospital readmissions following elective total knee arthroplasties (TKAs) that were either performed in VA or purchased by VA through community care (CC) at both the national and facility levels.METHODS: Three-year cohort study using VA and CC administrative data from the VA's Corporate Data Warehouse (October 1, 2016-September 30, 2019). We obtained Medicare data to capture readmissions that were paid by Medicare. We used the Centers for Medicare and Medicaid Services (CMS) methods to identify unplanned, 30-day, all-cause readmissions. A secondary outcome, TKA-related readmissions, identified readmissions resulting from complications of the index surgery. We ran mixed-effects logistic regression models to compare the risk-adjusted odds of all-cause and TKA-related readmissions between TKAs performed in VA versus CC, adjusting for patients' sociodemographic and clinical characteristics.PRINCIPAL FINDINGS: Nationally, the odds of experiencing an all-cause or TKA-related readmission were significantly lower for TKAs performed in VA versus CC (eg, the odds of experiencing an all-cause readmission in VA were 35% of those in CC. At the facility level, most VA facilities performed similarly to their corresponding CC providers, although there were 3 VA facilities that performed worse than their corresponding CC providers.CONCLUSIONS: Given VA's history in providing high-quality surgical care to Veterans, it is important to closely monitor and track whether the shift to CC for surgical care will impact quality in both settings over time.

  View details for DOI 10.1097/MLR.0000000000001678

  View details for PubMedID 35030566

• CORR Insights: High Risk of Neck-liner Impingement and Notching Observed with Thick Femoral Neck Implants in Ceramic-on-ceramic THA. Clinical orthopaedics and related research Giori, N. J. 2021

  View details for DOI 10.1097/CORR.0000000000002067

  View details for PubMedID 34870952

• A Simple Device and Biplanar Technique to Improve Precision When Templating for Total Joint Arthroplasty TECHNIQUES IN ORTHOPAEDICS Chen, F., Giori, N. 2021; 36 (3): 295-297

  View details for DOI 10.1097/BTO.0000000000000447

  View details for Web of Science ID 000690997600018

• Assessment of Extractability and Accuracy of Electronic Health Record Data for Joint Implant Registries. JAMA network open Giori, N. J., Radin, J., Callahan, A., Fries, J. A., Halilaj, E., Re, C., Delp, S. L., Shah, N. H., Harris, A. H. 2021; 4 (3): e211728

  Abstract

  Importance: Implant registries provide valuable information on the performance of implants in a real-world setting, yet they have traditionally been expensive to establish and maintain. Electronic health records (EHRs) are widely used and may include the information needed to generate clinically meaningful reports similar to a formal implant registry.Objectives: To quantify the extractability and accuracy of registry-relevant data from the EHR and to assess the ability of these data to track trends in implant use and the durability of implants (hereafter referred to as implant survivorship), using data stored since 2000 in the EHR of the largest integrated health care system in the United States.Design, Setting, and Participants: Retrospective cohort study of a large EHR of veterans who had 45 351 total hip arthroplasty procedures in Veterans Health Administration hospitals from 2000 to 2017. Data analysis was performed from January 1, 2000, to December 31, 2017.Exposures: Total hip arthroplasty.Main Outcomes and Measures: Number of total hip arthroplasty procedures extracted from the EHR, trends in implant use, and relative survivorship of implants.Results: A total of 45 351 total hip arthroplasty procedures were identified from 2000 to 2017 with 192 805 implant parts. Data completeness improved over the time. After 2014, 85% of prosthetic heads, 91% of shells, 81% of stems, and 85% of liners used in the Veterans Health Administration health care system were identified by part number. Revision burden and trends in metal vs ceramic prosthetic femoral head use were found to reflect data from the American Joint Replacement Registry. Recalled implants were obvious negative outliers in implant survivorship using Kaplan-Meier curves.Conclusions and Relevance: Although loss to follow-up remains a challenge that requires additional attention to improve the quantitative nature of calculated implant survivorship, we conclude that data collected during routine clinical care and stored in the EHR of a large health system over 18 years were sufficient to provide clinically meaningful data on trends in implant use and to identify poor implants that were subsequently recalled. This automated approach was low cost and had no reporting burden. This low-cost, low-overhead method to assess implant use and performance within a large health care setting may be useful to internal quality assurance programs and, on a larger scale, to postmarket surveillance of implant performance.

  View details for DOI 10.1001/jamanetworkopen.2021.1728

  View details for PubMedID 33720372

• CORR Insights®: Custom Implants in TKA Provide No Substantial Benefit in Terms of Outcome Scores, Reoperation Risk, or Mean Alignment: A Systematic Review. Clinical orthopaedics and related research Giori, N. J. 2021

  View details for DOI 10.1097/CORR.0000000000001703

  View details for PubMedID 33929998

• Diagnosing Acute Periprosthetic Infection: An Important Advance: Commentary on an article by Kamolsak Sukhonthamarn, MD, et al.: "Determining Diagnostic Thresholds for Acute Postoperative Periprosthetic Joint Infection". The Journal of bone and joint surgery. American volume Giori, N. J. 2020; 102 (23): e132

  View details for DOI 10.2106/JBJS.20.01644

  View details for PubMedID 33264219

• Prevalence of Hepatitis C Virus Infection in the Veteran Population Undergoing Total Joint Arthroplasty: An Update. The Journal of arthroplasty Shapiro, C. B., Cheung, R. C., Giori, N. J. 2020

  Abstract

  BACKGROUND: In 2012, we reported on the prevalence of hepatitis C virus (HCV) infection in Veterans Affairs (VA) patients undergoing total joint arthroplasty (TJA) at our center. In this patient population, 8.4% were antibody positive and 4.5% were viremic with HCV. In 2014, the first all-oral direct-acting antiviral treatment for hepatitis C became available. The Department of Veterans Affairs then underwent an aggressive program to eradicate hepatitis C from the veteran population. The purpose of this report is to provide updated information on the prevalence of HCV viremia among patients undergoing primary TJA at the same center.METHODS: A retrospective review was performed of all patients undergoing primary TJA at a single VA medical center in 2019. Anti-HCV antibody and HCV viremia prevalence were calculated. Comparisons were made to data from a previously reported cohort of patients who had undergone TJA at the same center from 2007 to2009.RESULTS: Thirty-three (11.6%) of 285 patients screened preoperatively were positive for the hepatitis C antibody. Only one of the 33 anti-HCV-positive patients was viremic at the time of screening for an overall viremic prevalence of 0.4%. We found no statistically significant difference in the birth year, or anti-HCV antibody-positive rate from the prior cohort, but the prevalence of HCV viremia decreased significantly.CONCLUSION: Because direct-acting antiviral HCV treatment has become available, HCV viremia among VA patients undergoing TJA has been reduced from 4.5% to 0.4%. Surgeons are still advised to minimize the risk of sharps injury.

  View details for DOI 10.1016/j.arth.2020.08.023

  View details for PubMedID 32900563

• Resection of hip heterotrophic ossification leads to resolution of autonomic nervous system dysfunction in a patient with spinal Charcot arthropathy: a case report. Spinal cord series and cases Fatemi, P., Prolo, L. M., Giori, N. J., Tharin, S. 2020; 6 (1): 41

  Abstract

  INTRODUCTION: Patients with complete spinal cord injury (SCI) may develop concurrent sequalae that interact and share symptoms; thus, a careful approach to diagnosis and management of new symptoms is crucial.CASE PRESENTATION: A patient with prior T4 complete SCI presented with progressive autonomic nervous system (ANS) dysfunction. The initial differential diagnosis included syringomyelia and lumbar Charcot arthropathy. He had comorbid heterotopic ossification (HO) of the left hip. Surprisingly, his autonomic symptoms resolved following resection of the HO. In hindsight, loss of motion through the hip caused by HO may have led to hinging through a previously asymptomatic lumbar Charcot joint, causing dysautonomia.DISCUSSION: ANS dysfunction is a disabling sequela of complete SCI and has a broad differential diagnosis. Hip immobility may be an indirect and overlooked cause due to the mechanical relationship between the hip and the lumbar spine.

  View details for DOI 10.1038/s41394-020-0286-5

  View details for PubMedID 32404876

• Social Determinants of Health and Patient-Reported Outcomes Following Total Hip and Knee Arthroplasty in Veterans. The Journal of arthroplasty Rubenstein, W. J., Harris, A. H., Hwang, K. M., Giori, N. J., Kuo, A. C. 2020

  Abstract

  BACKGROUND: Social determinants of health (SDOH) are the conditions in which people are born, grow, live, work, and age. They are associated with disparities in outcomes following total joint arthroplasty (TJA). These disparities occur even in equal-access healthcare systems such as the Veterans Health Administration (VHA). Our goal was to determine whether SDOH affect patient-reported outcome measures (PROMs) following TJA in VHA patients.METHODS: Patients scheduled to undergo total hip or knee arthroplasty at VHA Hospitals in Minneapolis, MN, Palo Alto, CA, and San Francisco, CA, prospectively completed PROMs before and 1 year after surgery. PROMs included the Hip disability and Osteoarthritis Outcome Score, the Knee injury and Osteoarthritis Outcome Score, and their Joint Replacement subscores. SDOH included race, ethnicity, marital status, education, and employment status. The level of poverty in each patient's neighborhood was determined. Medical comorbidities were recorded. Univariate and multivariate analyses were performed to determine whether SDOH were significantly associated with PROM improvement after surgery.RESULTS: On multivariate analysis, black race was significantly negatively correlated with knee PROM improvement and Hispanic ethnicity was significantly negatively correlated with hip PROM improvement compared to whites. Higher baseline PROM scores and lower age were significantly associated with lower PROM improvement. Significant associations were also found based on education, gender, comorbidities, and neighborhood poverty.CONCLUSION: Minority VHA patients have lower improvement in PROM scores after TJA than white patients. Further research is required to identify the reasons for these disparities and to design interventions to reduce them.

  View details for DOI 10.1016/j.arth.2020.04.095

  View details for PubMedID 32498969

• CORR Insights: The Impingement-free, Prosthesis-specific and Anatomy-adjusted Combined Target Zone for Component Positioning in THA Depends on Design and Implantation Parameters of both Components. Clinical orthopaedics and related research Giori, N. J. 2020

  View details for DOI 10.1097/CORR.0000000000001299

  View details for PubMedID 32379140

• Editorial Commentary: Augmenting Suture Anchor Fixation: Why Has It Not Caught on? Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association Truntzer, J. N., Giori, N. J., Saleh, J. R. 2020; 36 (4): 1009–10

  Abstract

  Biomechanical studies with reliable clinical applicability are challenging to carry out. The results can be heavily dependent on the materials being tested (condition and ages of specimens), environmental conditions (temperature, moisture), magnitude and direction of loading, loading characteristics (static, dynamic), loading cycles and frequency, and how one measures and defines failure. The interested reader gains more confidence in the results and recommendations of a biomechanics study if the methodology reasonably models real-world scenarios and multiple studies from different labs all come to the same general conclusion.

  View details for DOI 10.1016/j.arthro.2020.02.010

  View details for PubMedID 32247400

• CORR Insights®: The Impingement-free, Prosthesis-specific, and Anatomy-adjusted Combined Target Zone for Component Positioning in THA Depends on Design and Implantation Parameters of both Components. Clinical orthopaedics and related research Giori, N. J. 2020; 478 (8): 1919–21

  View details for DOI 10.1097/CORR.0000000000001299

  View details for PubMedID 32732576

• Cannabinoid and Opioid Use Among Total Joint Arthroplasty Patients: A 6-Year, Single-Institution Study. Orthopedics Denduluri, S. K., Woolson, S. T., Indelli, P. F., Mariano, E. R., Harris, A. H., Giori, N. J. 2020: 1–6

  Abstract

  Evidence is limited regarding cannabinoid use among total joint arthroplasty (TJA) patients, despite increased availability and popularity for treating chronic pain. The authors hypothesized that preoperative cannabinoid use increased and opioid use decreased during a 6-year interval in total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients, and also asked whether complications were associated with use of these substances. This retrospective, single-institution study reviewed electronic medical records and the Veterans Affairs Surgical Quality Improvement Program (VASQIP) database for TJA cases from 2012 through 2017. Primary outcomes were the prevalence and trends of active cannabinoid and opioid use, as determined by routine preoperative urine toxicology screening. Multivariable regression analyses were conducted to investigate a secondary outcome, whether there was an association between cannabinoid or opioid use and postoperative complications. A total of 1778 operations (1161 TKAs and 617 THAs) performed on 1519 patients were reviewed. The overall prevalence of pre-operative cannabinoid and opioid use was 11% and 23%, respectively. Comparing 2012 with 2017, cannabinoid use increased from 9% to 15% (P=.049), and opioid use decreased from 24% to 17% (P=.040). Cannabinoid users were more likely to be taking opioids than nonusers (P=.002). Controlling for age, sex, surgery type, and American Society of Anesthesiologists score, cannabinoid use was not associated with 90-day readmission, infection, reoperation, or other VASQIP-captured complications. Laboratory testing indicated a much higher prevalence of cannabinoid use among TJA patients than previously reported. During a 6-year period, cannabinoid use increased more than 60%, and opioid use decreased approximately 30%. These findings indicate that cannabinoid use did not appear to be associated with perioperative complications. [Orthopedics. 2021;44(x):xx-xx.].

  View details for DOI 10.3928/01477447-20200928-02

  View details for PubMedID 33002174

• Can Machine Learning Methods Produce Accurate and Easy-to-Use Preoperative Prediction Models of One-Year Improvements in Pain and Functioning After Knee Arthroplasty? The Journal of arthroplasty Harris, A. H., Kuo, A. C., Bowe, T. R., Manfredi, L. n., Lalani, N. F., Giori, N. J. 2020

  Abstract

  Approximately 15%-20% of total knee arthroplasty (TKA) patients do not experience clinically meaningful improvements. We sought to compare the accuracy and parsimony of several machine learning strategies for developing predictive models of failing to experience minimal clinically important differences in patient-reported outcome measures (PROMs) 1 year after TKA.Patients (N = 587) in 3 large Veteran Health Administration facilities completed PROMs before and 1 year after TKA (92% follow-up). Preoperative PROMs and electronic health record data were used to develop and validate models to predict failing to experience at least a minimal clinically important difference in Knee Injury and Osteoarthritis Outcome Score (KOOS) Total, KOOS JR, and KOOS subscales (Pain, Symptoms, Activities of Daily Living, Quality of Life, and recreation). Several machine learning strategies were used for model development. Ten-fold cross-validation and bootstrapping were used to produce measures of overall accuracy (C-statistic, Brier Score). The sensitivity and specificity of various predicted probability cut-points were examined.The most accurate models produced were for the Activities of Daily Living, Pain, Symptoms, and Quality of Life subscales of the KOOS (C-statistics 0.76, 0.72, 0.72, and 0.71, respectively). Strategies varied substantially in terms of the numbers of inputs required to achieve similar accuracy, with none being superior for all outcomes.Models produced in this project provide estimates of patient-specific improvements in major outcomes 1 year after TKA. Integrating these models into clinical decision support, informed consent and shared decision making could improve patient selection, education, and satisfaction.Level III, diagnostic study.

  View details for DOI 10.1016/j.arth.2020.07.026

  View details for PubMedID 32798181

• Replacement of Fascia Iliaca Catheters with Continuous Erector Spinae Plane Blocks Within a Clinical Pathway Facilitates Early Ambulation After Total Hip Arthroplasty. Pain medicine (Malden, Mass.) Xu, L. n., Leng, J. C., Elsharkawy, H. n., Hunter, O. O., Harrison, T. K., Vokach-Brodsky, L. n., Kumar, G. n., Funck, N. n., Hill, J. N., Giori, N. J., Indelli, P. F., Kou, A. n., Mariano, E. R. 2020

  Abstract

  The optimal continuous peripheral nerve block (CPNB) technique for total hip arthroplasty (THA) that maximizes both analgesia and mobility is unknown. Continuous erector spinae plane (ESP) blocks were implemented at our institution as a replacement for fascia iliaca (FI) catheters to improve our THA clinical pathway. We designed this study to test the hypothesis that this change will increase early postoperative ambulation for elective primary THA patients.We identified all consecutive primary unilateral THA cases six months before and six months after the clinical pathway change to ESP catheters. All other aspects of the THA clinical pathway and multimodal analgesic regimen including perineural infusion protocol did not change. The primary outcome was total ambulation distance (meters) on postoperative day 1. Other outcomes included total ambulation on postoperative day 2, combined two-day ambulation distance, pain scores, opioid consumption, inpatient length of stay, and minor and major adverse events.Eighty-eight patients comprised the final sample (43 FI and 45 ESP). Postoperative day 1 total ambulation distance was greater for the ESP group compared with the FI group (median [10th-90th percentiles] = 24.4 [0.0-54.9] vs 9.1 [0.7-45.7] meters, respectively, P = 0.036), and two-day ambulation distance was greater for the ESP group compared with the FI group (median [10th-90th percentiles] = 68.6 [9.0-128.0] vs 46.6 [3.7-104.2] meters, respectively, P = 0.038). There were no differences in pain scores, opioid use, or other outcomes.Replacing FI catheters with continuous ESP blocks within a clinical pathway results in increased early ambulation by elective primary THA patients.

  View details for DOI 10.1093/pm/pnaa243

  View details for PubMedID 32869079

• An ultrasound-guided fascia iliaca catheter technique does not impair ambulatory ability within a clinical pathway for total hip arthroplasty. Korean journal of anesthesiology Mudumbai, S. C., Kim, T. E., Howard, S. K., Giori, N. J., Woolson, S. n., Ganaway, T. n., Kou, A. n., King, R. n., Mariano, E. R. 2020; 73 (3): 267

  View details for DOI 10.4097/kjae.2016.69.4.368.e1

  View details for PubMedID 32506897

• Clinical Faceoff: Should Orthopaedic Surgeons Have Strict BMI Cutoffs for Performing Primary TKA and THA? Clinical orthopaedics and related research Ricciardi, B. F., Giori, N. J., Fehring, T. K. 2019; 477 (12): 2629-2634

  View details for DOI 10.1097/CORR.0000000000001017

  View details for PubMedID 31764323

• Clinical Faceoff: Should Orthopaedic Surgeons Have Strict BMI Cutoffs for Performing Primary TKA and THA? Clinical orthopaedics and related research Ricciardi, B. F., Giori, N. J., Fehring, T. K. 2019

  View details for DOI 10.1097/CORR.0000000000001017

  View details for PubMedID 31688134

• Debridement, antibiotic pearls, and retention of the implant (DAPRI): A modified technique for implant retention in total knee arthroplasty PJI treatment. Journal of orthopaedic surgery (Hong Kong) Calanna, F., Chen, F., Risitano, S., Vorhies, J. S., Franceschini, M., Giori, N. J., Indelli, P. F. 2019; 27 (3): 2309499019874413

  Abstract

  We describe a modified surgical technique developed to enhance the classical irrigation and debridement procedure to improve the possibilities of retaining an infected total knee arthroplasty. This technique, debridement antibiotic pearls and retention of the implant (DAPRI), aims to remove the intra-articular biofilm allowing a higher and prolonged local antibiotic concentration using calcium sulfate beads. The combination of three different surgical techniques (methylene blue staining, argon beam electrical stimulation, and chlorhexidine gluconate brushing) might enhance the identification, disruption, and finally removal of the bacterial biofilm, which is the main responsible of antibiotics and antibodies resistance. The DAPRI technique might represent a safe and more conservative treatment for acute and early hematogenous periprosthetic joint infection.

  View details for DOI 10.1177/2309499019874413

  View details for PubMedID 31554470

• Trunnion Corrosion in Total Hip Arthroplasty-Basic Concepts. The Orthopedic clinics of North America Urish, K. L., Giori, N. J., Lemons, J. E., Mihalko, W. M., Hallab, N. 2019; 50 (3): 281–88

  Abstract

  There has been increased interest in the role of corrosion in early implant failures and adverse local tissue reaction in total hip arthroplasty. We review the relationship between the different types of corrosion in orthopaedic surgery including uniform, pitting, crevice, and fretting or mechanically assisted crevice corrosion (MACC). Passive layer dynamics serves a critical role in each of these processes. The femoral head-neck trunnion creates an optimal environment for corrosion to occur because of the limited fluid diffusion, acidic environment, and increased bending moment.

  View details for PubMedID 31084829

• Trunnion Corrosion in Total Hip Arthroplasty - Basic Concepts ORTHOPEDIC CLINICS OF NORTH AMERICA Urish, K. L., Giori, N., Lemons, J. E., Mihalko, W. M., Hallab, N. 2019; 50 (3): 281-+

  View details for DOI 10.1016/j.ocl.2019.02.001

  View details for Web of Science ID 000471742100003

• CORR Insights: Is Parkinson's Disease Associated with Increased Mortality, Poorer Outcomes Scores, and Revision Risk After THA? Findings from the Swedish Hip Arthroplasty Register. Clinical orthopaedics and related research Giori, N. J. 2019; 477 (6): 1356–57

  View details for DOI 10.1097/CORR.0000000000000716

  View details for PubMedID 31136434

• IgE-mediated mast cell activation promotes inflammation and cartilage destruction in osteoarthritis ELIFE Wang, Q., Lepus, C. M., Raghu, H., Reber, L. L., Tsai, M. M., Wong, H. H., von Kaeppler, E., Lingampalli, N., Bloom, M. S., Hu, N., Elliott, E. E., Oliviero, F., Punzi, L., Giori, N. J., Goodman, S. B., Chu, C. R., Sokolove, J., Fukuoka, Y., Schwartz, L. B., Galli, S. J., Robinson, W. H. 2019; 8

  View details for DOI 10.7554/eLife.39905

  View details for Web of Science ID 000467895900001

• Role of the acetabular labrum on articular cartilage consolidation patterns BIOMECHANICS AND MODELING IN MECHANOBIOLOGY Kim, Y., Giori, N. J., Lee, D., Ahn, K., Kang, C., Shin, C. S., Song, Y. 2019; 18 (2): 479-489

  View details for DOI 10.1007/s10237-018-1097-5

  View details for Web of Science ID 000461323600016

• Can Machine Learning Methods Produce Accurate and Easy-to-use Prediction Models of 30-day Complications and Mortality After Knee or Hip Arthroplasty? CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Harris, A. S., Kuo, A. C., Weng, Y., Trickey, A. W., Bowe, T., Giori, N. J. 2019; 477 (2): 452–60

  View details for DOI 10.1097/CORR.0000000000000601

  View details for Web of Science ID 000472544900035

• Can Machine Learning Methods Produce Accurate and Easy-to-use Prediction Models of 30-day Complications and Mortality After Knee or Hip Arthroplasty? Clinical orthopaedics and related research Harris, A. H., Kuo, A. C., Weng, Y., Trickey, A. W., Bowe, T., Giori, N. J. 2019

  Abstract

  BACKGROUND: Existing universal and procedure-specific surgical risk prediction models of death and major complications after elective total joint arthroplasty (TJA) have limitations including poor transparency, poor to modest accuracy, and insufficient validation to establish performance across diverse settings. Thus, the need remains for accurate and validated prediction models for use in preoperative management, informed consent, shared decision-making, and risk adjustment for reimbursement.QUESTIONS/PURPOSES: The purpose of this study was to use machine learning methods and large national databases to develop and validate (both internally and externally) parsimonious risk-prediction models for mortality and complications after TJA.METHODS: Preoperative demographic and clinical variables from all 107,792 nonemergent primary THAs and TKAs in the 2013 to 2014 American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) were evaluated as predictors of 30-day death and major complications. The NSQIP database was chosen for its high-quality data on important outcomes and rich characterization of preoperative demographic and clinical predictors for demographically and geographically diverse patients. Least absolute shrinkage and selection operator (LASSO) regression, a type of machine learning that optimizes accuracy and parsimony, was used for model development. Tenfold validation was used to produce C-statistics, a measure of how well models discriminate patients who experience an outcome from those who do not. External validation, which evaluates the generalizability of the models to new data sources and patient groups, was accomplished using data from the Veterans Affairs Surgical Quality Improvement Program (VASQIP). Models previously developed from VASQIP data were also externally validated using NSQIP data to examine the generalizability of their performance with a different group of patients outside the VASQIP context.RESULTS: The models, developed using LASSO regression with diverse clinical (for example, American Society of Anesthesiologists classification, comorbidities) and demographic (for example, age, gender) inputs, had good accuracy in terms of discriminating the likelihood a patient would experience, within 30 days of arthroplasty, a renal complication (C-statistic, 0.78; 95% confidence interval [CI], 0.76-0.80), death (0.73; 95% CI, 0.70-0.76), or a cardiac complication (0.73; 95% CI, 0.71-0.75) from one who would not. By contrast, the models demonstrated poor accuracy for venous thromboembolism (C-statistic, 0.61; 95% CI, 0.60-0.62) and any complication (C-statistic, 0.64; 95% CI, 0.63-0.65). External validation of the NSQIP- derived models using VASQIP data found them to be robust in terms of predictions about mortality and cardiac complications, but not for predicting renal complications. Models previously developed with VASQIP data had poor accuracy when externally validated with NSQIP data, suggesting they should not be used outside the context of the Veterans Health Administration.CONCLUSIONS: Moderately accurate predictive models of 30-day mortality and cardiac complications after elective primary TJA were developed as well as internally and externally validated. To our knowledge, these are the most accurate and rigorously validated TJA-specific prediction models currently available (http://med.stanford.edu/s-spire/Resources/clinical-tools-.html). Methods to improve these models, including the addition of nonstandard inputs such as natural language processing of preoperative clinical progress notes or radiographs, should be pursued as should the development and validation of models to predict longer term improvements in pain and function.LEVEL OF EVIDENCE: Level III, diagnostic study.

  View details for PubMedID 30624314

• Are Case Volume and Facility Complexity Level Associated With Postoperative Complications After Hip Fracture Surgery in the Veterans Affairs Healthcare System? CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Wong, J. K., Kim, T., Mudumbai, S. C., Memtsoudis, S. G., Giori, N. J., Howard, S. K., Oka, R. K., King, R., Mariano, E. R. 2019; 477 (1): 177–90

  View details for DOI 10.1097/CORR.0000000000000460

  View details for Web of Science ID 000472543100031

• A Multidisciplinary Patient-Specific Opioid Prescribing and Tapering Protocol Is Associated with a Decrease in Total Opioid Dose Prescribed for Six Weeks After Total Hip Arthroplasty. Pain medicine (Malden, Mass.) Tamboli, M. n., Mariano, E. R., Gustafson, K. E., Briones, B. L., Hunter, O. O., Wang, R. R., Harrison, T. K., Kou, A. n., Mudumbai, S. C., Kim, T. E., Indelli, P. F., Giori, N. J. 2019

  Abstract

  This retrospective cohort study tested the hypothesis that implementing a multidisciplinary patient-specific discharge protocol for prescribing and tapering opioids after total hip arthroplasty (THA) will decrease the morphine milligram equivalent (MME) dose of opioids prescribed.With institutional review board approval, we analyzed a Perioperative Surgical Home database and prescription data for all primary THA patients three months before (PRE) and three months after (POST) implementation of this new discharge opioid protocol based on patients' prior 24-hour inpatient opioid consumption. The primary outcome was total opioid dosage in MME prescribed and opioid refills for six weeks after surgery. Secondary outcomes included the number of tablets and MME prescribed at discharge, in-hospital opioid consumption, length of stay, and postoperative complications.Forty-nine cases (25 PRE and 24 POST) were included. Total median (10th-90th percentiles) MME for six weeks postoperatively was 900 (57-2082) MME PRE vs 295 (69-741) MME POST (mean difference = 721, 95% confidence interval [CI] = 127-1316, P = 0.007, Mann-Whitney U test). Refill rates did not differ. The median (10th-90th percentiles) initial discharge prescription in MME was 675 (57-1035) PRE vs 180 (18-534) POST (mean difference = 387, 95% CI = 156-618, P = 0.003, Mann-Whitney U test) MME. There were no differences in other outcomes.Implementation of a patient-specific prescribing and tapering protocol decreases the mean six-week dosage of opioid prescribed by 63% after THA without increasing the refill rate.

  View details for DOI 10.1093/pm/pnz260

  View details for PubMedID 31710680

• Medical device surveillance with electronic health records. NPJ digital medicine Callahan, A. n., Fries, J. A., Ré, C. n., Huddleston, J. I., Giori, N. J., Delp, S. n., Shah, N. H. 2019; 2: 94

  Abstract

  Post-market medical device surveillance is a challenge facing manufacturers, regulatory agencies, and health care providers. Electronic health records are valuable sources of real-world evidence for assessing device safety and tracking device-related patient outcomes over time. However, distilling this evidence remains challenging, as information is fractured across clinical notes and structured records. Modern machine learning methods for machine reading promise to unlock increasingly complex information from text, but face barriers due to their reliance on large and expensive hand-labeled training sets. To address these challenges, we developed and validated state-of-the-art deep learning methods that identify patient outcomes from clinical notes without requiring hand-labeled training data. Using hip replacements-one of the most common implantable devices-as a test case, our methods accurately extracted implant details and reports of complications and pain from electronic health records with up to 96.3% precision, 98.5% recall, and 97.4% F1, improved classification performance by 12.8-53.9% over rule-based methods, and detected over six times as many complication events compared to using structured data alone. Using these additional events to assess complication-free survivorship of different implant systems, we found significant variation between implants, including for risk of revision surgery, which could not be detected using coded data alone. Patients with revision surgeries had more hip pain mentions in the post-hip replacement, pre-revision period compared to patients with no evidence of revision surgery (mean hip pain mentions 4.97 vs. 3.23; t = 5.14; p < 0.001). Some implant models were associated with higher or lower rates of hip pain mentions. Our methods complement existing surveillance mechanisms by requiring orders of magnitude less hand-labeled training data, offering a scalable solution for national medical device surveillance using electronic health records.

  View details for DOI 10.1038/s41746-019-0168-z

  View details for PubMedID 31583282

  View details for PubMedCentralID PMC6761113

• Dysregulated integrin αVβ3 and CD47 signaling promotes joint inflammation, cartilage breakdown, and progression of osteoarthritis. JCI insight Wang, Q. n., Onuma, K. n., Liu, C. n., Wong, H. n., Bloom, M. S., Elliott, E. E., Cao, R. R., Hu, N. n., Lingampalli, N. n., Sharpe, O. n., Zhao, X. n., Sohn, D. H., Lepus, C. M., Sokolove, J. n., Mao, R. n., Cisar, C. T., Raghu, H. n., Chu, C. R., Giori, N. J., Willingham, S. B., Prohaska, S. S., Cheng, Z. n., Weissman, I. L., Robinson, W. H. 2019; 4 (18)

  Abstract

  Osteoarthritis (OA) is the leading cause of joint failure, yet the underlying mechanisms remain elusive, and no approved therapies that slow progression exist. Dysregulated integrin function was previously implicated in OA pathogenesis. However, the roles of integrin αVβ3 and the integrin-associated receptor CD47 in OA remain largely unknown. Here, transcriptomic and proteomic analyses of human and murine osteoarthritic tissues revealed dysregulated expression of αVβ3, CD47, and their ligands. Using genetically deficient mice and pharmacologic inhibitors, we showed that αVβ3, CD47, and the downstream signaling molecules Fyn and FAK are crucial to OA pathogenesis. MicroPET/CT imaging of a mouse model showed elevated ligand-binding capacities of integrin αVβ3 and CD47 in osteoarthritic joints. Further, our in vitro studies demonstrated that chondrocyte breakdown products, derived from articular cartilage of individuals with OA, induced αVβ3/CD47-dependent expression of inflammatory and degradative mediators, and revealed the downstream signaling network. Our findings identify a central role for dysregulated αVβ3 and CD47 signaling in OA pathogenesis and suggest that activation of αVβ3 and CD47 signaling in many articular cell types contributes to inflammation and joint destruction in OA. Thus, the data presented here provide a rationale for targeting αVβ3, CD47, and their signaling pathways as a disease-modifying therapy.

  View details for DOI 10.1172/jci.insight.128616

  View details for PubMedID 31534047

• IgE-mediated mast cell activation promotes inflammation and cartilage destruction in osteoarthritis. eLife Wang, Q. n., Lepus, C. M., Raghu, H. n., Reber, L. L., Tsai, M. M., Wong, H. H., von Kaeppler, E. n., Lingampalli, N. n., Bloom, M. S., Hu, N. n., Elliott, E. E., Oliviero, F. n., Punzi, L. n., Giori, N. J., Goodman, S. B., Chu, C. R., Sokolove, J. n., Fukuoka, Y. n., Schwartz, L. B., Galli, S. J., Robinson, W. H. 2019; 8

  Abstract

  Osteoarthritis is characterized by articular cartilage breakdown, and emerging evidence suggests that dysregulated innate immunity is likely involved. Here, we performed proteomic, transcriptomic, and electron microscopic analyses to demonstrate that mast cells are aberrantly activated in human and murine osteoarthritic joint tissues. Using genetic models of mast cell deficiency, we demonstrate that lack of mast cells attenuates osteoarthritis in mice. Using genetic and pharmacologic approaches, we show that the IgE/FcεRI/Syk signaling axis is critical for the development of osteoarthritis. We find that mast cell-derived tryptase induces inflammation, chondrocyte apoptosis, and cartilage breakdown. Our findings demonstrate a central role for IgE-dependent mast cell activation in the pathogenesis of osteoarthritis, suggesting that targeting mast cells could provide therapeutic benefit in human osteoarthritis.This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (see decision letter).

  View details for PubMedID 31084709

• Perioperative Opioid Prescribing Patterns and Readmissions After Total Knee Arthroplasty in a National Cohort of Veterans Health Administration Patients. Pain medicine (Malden, Mass.) Mudumbai, S. C., Chung, P. n., Nguyen, N. n., Harris, B. n., Clark, J. D., Wagner, T. H., Giori, N. J., Stafford, R. S., Mariano, E. R. 2019

  Abstract

  Among Veterans Health Administration (VHA) patients who undergo total knee arthroplasty (TKA) nationally, what are the underlying readmission rates and associations with perioperative opioid use, and are there associations with other factors such as preoperative health care utilization?We retrospectively examined the records of 5,514 TKA patients (primary N = 4,955, 89.9%; revision N = 559, 10.1%) over one fiscal year (October 1, 2010-September 30, 2011) across VHA hospitals nationwide. Opioid use was classified into no opioids, tramadol only, short-acting only, or any long-acting. We measured readmission within 30 days and the number of days to readmission within 30 days. Extended Cox regression models were developed.The overall 30-day hospital readmission rate was 9.6% (N = 531; primary 9.5%, revision 11.1%). Both readmitted patients and the overall sample were similar on types of preoperative opioid use. Relative to patients without opioids, patients in the short-acting opioids only tier had the highest risk for 30-day hospital readmission (hazard ratio = 1.38, 95% confidence interval = 1.14-1.67). Preoperative opioid status was not associated with 30-day readmission. Other risk factors for 30-day readmission included older age (≥66 years), higher comorbidity and diagnosis-related group weights, greater preoperative health care utilization, an urban location, and use of preoperative anticonvulsants.Given the current opioid epidemic, the routine prescribing of short-acting opioids after surgery should be carefully considered to avoid increasing risks of 30-day hospital readmissions and other negative outcomes, particularly in the context of other predisposing factors.

  View details for DOI 10.1093/pm/pnz154

  View details for PubMedID 31309970

• Role of the acetabular labrum on articular cartilage consolidation patterns. Biomechanics and modeling in mechanobiology Kim, Y., Giori, N. J., Lee, D., Ahn, K., Kang, C. H., Shin, C. S., Song, Y. 2018

  Abstract

  Damage to the acetabular labrum has been associated with cartilage degeneration. Because conventional pressure measurement devices were unable to examine the sealing function of the acetabular labrum on cartilage contact mechanics, we used an image-based computational method to examine how labrectomy affects articular cartilage contact area and strain patterns in porcine hips. Cyclically loaded hip samples were continuously imaged in a CT scanner every 3min to trace the positions of the femur and acetabulum. Image-based displacement-controlled finite element analysis was used to calculate articular cartilage contact area and nominal strain at different time points. No changes in cartilage contact area were found after labrectomy. Compared to the labrum intact condition, average nominal strain in labrectomized hips was elevated at early time points after load application. The areas of 'high' strain in labrectomized hips were found to be increased by approximately 7% after 30min of cyclic loading, while the changes in the areas of 'low' strain were minimal. Our result showed that changes in articular cartilage strain following labrectomy were concentrated on locally overloaded areas where the degenerative process of articular cartilage may be initiated.

  View details for PubMedID 30474763

• Is There a Role for Surface Replacement Arthroplasty in Today's Orthopaedic Practice?: Commentary on an article by Marcus C. Ford, MD, et al.: "Five to Ten-Year Results of the Birmingham Hip Resurfacing Implant in the U.S. A Single Institution's Experience". The Journal of bone and joint surgery. American volume Giori, N. J. 2018; 100 (21): e142

  View details for PubMedID 30399089

• Is There a Role for Surface Replacement Arthroplasty in Today's Orthopaedic Practice? JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Giori, N. J. 2018; 100 (21)

  View details for DOI 10.2106/JBJS.18.00813

  View details for Web of Science ID 000449435200005

• American Joint Replacement Registry Risk Calculator Does Not Predict 90-day Mortality in Veterans Undergoing Total Joint Replacement. Clinical orthopaedics and related research Harris, A. H., Kuo, A. C., Bozic, K. J., Lau, E., Bowe, T., Gupta, S., Giori, N. J. 2018; 476 (9): 1869–75

  Abstract

  BACKGROUND: The American Joint Replacement Registry (AJRR) Total Joint Risk Calculator uses demographic and clinical parameters to provide risk estimates for 90-day mortality and 2-year periprosthetic joint infection (PJI). The tool is intended to help surgeons counsel their Medicare-eligible patients about their risk of death and PJI after total joint arthroplasty (TJA). However, for a predictive risk model to be useful, it must be accurate when applied to new patients; this has yet to be established for this calculator.QUESTIONS/PURPOSES: To produce accuracy metrics (ie, discrimination, calibration) for the AJRR mortality calculator using data from Medicare-eligible patients undergoing TJA in the Veterans Health Administration (VHA), the largest integrated healthcare system in the United States, where more than 10,000 TJAs are performed annually.METHODS: We used the AJRR calculator to predict risk of death within 90 days of surgery among 31,214 VHA patients older than 64 years of age who underwent primary TJA; data was drawn from the Veterans Affairs Surgical Quality Improvement Project (VASQIP) and VA Corporate Data Warehouse (CDW). We then used VHA mortality data to evaluate the extent to which the AJRR calculator estimates distinguished individuals who died compared with those who did not (C-statistic), and graphically depicted the relationship between estimated risk and observed mortality (calibration). As a secondary evaluation of the calculator, a sample of 39,300 patients younger than 65 years old was assigned to the youngest age group available to the user (65-69 years) as might be done in real-world practice.RESULTS: C-statistics for 90-day mortality for the older samples were 0.62 (95% CI, 0.60-0.64) and for the younger samples they were 0.46 (95% CI, 0.43-0.49), suggesting poor discrimination. Calibration analysis revealed poor correspondence between deciles of predicted risk and observed mortality rates. Poor discrimination and calibration mean that patients who died will frequently have a lower estimated risk of death than surviving patients.CONCLUSIONS: For Medicare-eligible patients receiving TJA in the VA, the AJRR risk calculator had a poor performance in the prediction of 90-day mortality. There are several possible reasons for the model's poor performance. Veterans Health Administration patients, 97% of whom were men, represent only a subset of the broader Medicare population. However, applying the calculator to a subset of the target population should not affect its accuracy. Other reasons for poor performance include a lack of an underlying statistical model in the calculator's implementation and simply the challenge of predicting rare events. External validation in a more representative sample of Medicare patients should be conducted to before assuming this tool is accurate for its intended use.LEVEL OF EVIDENCE: Level I, diagnostic study.

  View details for PubMedID 30113939

• American Joint Replacement Registry Risk Calculator Does Not Predict 90-day Mortality in Veterans Undergoing Total Joint Replacement CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Harris, A. S., Kuo, A. C., Bozic, K. J., Lau, E., Bowe, T., Gupta, S., Giori, N. J. 2018; 476 (9): 1869-1875

  View details for DOI 10.1097/CORR.0000000000000377

  View details for Web of Science ID 000452513200032

• Are Case Volume and Facility Complexity Level Associated With Postoperative Complications After Hip Fracture Surgery in the Veterans Affairs Healthcare System? Clinical orthopaedics and related research Wong, J. K., Kim, T. E., Mudumbai, S. C., Memtsoudis, S. G., Giori, N. J., Howard, S. K., Oka, R. K., King, R., Mariano, E. R. 2018

  Abstract

  BACKGROUND: Hospital-related factors associated with mortality and morbidity after hip fracture surgery are not completely understood. The Veterans Health Administration (VHA) is the largest single-payer, networked healthcare system in the country serving a relatively homogenous patient population with facilities that vary in size and resource availability. These characteristics provide some degree of financial and patient-level controls to explore the association, if any, between surgical volume and facility resource availability and hospital performance regarding postoperative complications after hip fracture surgery.QUESTIONS/PURPOSES: (1) Do VHA facilities with the highest complexity level designation (Level 1a) have a disproportionate number of better-than-expected performance outliers for major postoperative complications compared with lower-complexity level facilities? (2) Do VHA facilities with higher hip fracture surgical volume have a disproportionate number of better-than-expected performance outliers for major postoperative complications compared with lower-volume facilities?METHODS: We explored the Veterans Affairs Surgical Quality Improvement Project (VASQIP) database from October 2001 to September 2012 for records of hip fracture surgery performed. Data reliability of the VASQIP database has been previously validated. We excluded nine of the 98 VHA facilities for contributing fewer than 30 records. The remaining 89 VHA facilities provided 23,029 records. The VHA designates a complexity level to each facility based on multiple criteria. We labeled facilities with a complexity Level 1a (38 facilities)-the highest achievable VHA designated complexity level-as high complexity; we labeled all other complexity level designations as low complexity (51 facilities). Facility volume was divided into tertiles: high (> 277 hip fracture procedures during the sampling frame), medium (204 to 277 procedures), and low (< 204 procedures). The patient population treated by low-complexity facilities was older, had a higher prevalence of severe chronic obstructive pulmonary disease (26% versus 22%, p < 0.001), and had a higher percentage of patients having surgery within 2 days of hospital admission (83% versus 76%, p < 0.001). High-complexity facilities treated more patients with recent congestive heart failure exacerbation (4% versus 3%, p < 0.001). We defined major postoperative complications as having at least one of the following: death within 30 days of surgery, cardiac arrest requiring cardiopulmonary resuscitation, new q-wave myocardial infarction, deep vein thrombosis and/or pulmonary embolism, ventilator dependence for at least 48 hours after surgery, reintubation for respiratory or cardiac failure, acute renal failure requiring renal replacement therapy, progressive renal insufficiency with a rise in serum creatinine of at least 2 mg/dL from preoperative value, pneumonia, or surgical site infection. We used the observed-to-expected ratio (O/E ratio)-a risk-adjusted metric to classify facility performance-for major postoperative complications to assess the performance of VHA facilities. Outlier facilities with 95% confidence intervals (95% CI) for O/E ratio completely less than 1.0 were labeled "exceed expectation;" those that were completely greater than 1.0 were labeled "below expectation." We compared differences in the distribution of outlier facilities between high and low-complexity facilities, and between high-, medium-, and low-volume facilities using Fisher's exact test.RESULTS: We observed no association between facility complexity level and the distribution of outlier facilities (high-complexity: 5% exceeded expectation, 5% below expectation; low-complexity: 8% exceeded expectation, 2% below expectation; p = 0.742). Compared with high-complexity facilities, the adjusted odds ratio for major postoperative complications for low-complexity facilities was 0.85 (95% CI, 0.67-1.09; p = 0.108).We observed no association between facility volume and the distribution of outlier facilities: 3% exceeded expectation and 3% below expectation for high-volume; 10% exceeded expectation and 3% below expectation for medium-volume; and 7% exceeded expectation and 3% below expectation for low-volume; p = 0.890). The adjusted odds ratios for major postoperative complications were 0.87 (95% CI, 0.73-1.05) for low- versus high-volume facilities and 0.89 (95% CI, 0.79-1.02] for medium- versus high-volume facilities (p = 0.155).CONCLUSIONS: These results do not support restricting facilities from treating hip fracture patients based on historical surgical volume or facility resource availability. Identification of consistent performance outliers may help health care organizations with multiple facilities determine allocation of services and identify characteristics and processes that determine outlier status in the interest of continued quality improvement.LEVEL OF EVIDENCE: Level III, therapeutic study.

  View details for PubMedID 30179946

• CORR Insights: Do Stem Design and Surgical Approach Influence Early Aseptic Loosening in Cementless THA? Clinical orthopaedics and related research Giori, N. J. 2018; 476 (6): 1221–22

  View details for PubMedID 29470244

• CORR Insights (R): Do Stem Design and Surgical Approach Influence Early Aseptic Loosening in Cementless THA? CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Giori, N. J. 2018; 476 (6): 1221-1222

  View details for DOI 10.1007/s11999.0000000000000250

  View details for Web of Science ID 000438531800019

• Letter to the Editor on "Implementation of Preoperative Screening Criteria Lowers Infection and Complication Rates Following Elective Total Hip Arthroplasty and Total Knee Arthroplasty in a Veteran Population" JOURNAL OF ARTHROPLASTY Giori, N. J., Harris, A. S. 2018; 33 (6): 1983–84

  View details for PubMedID 29555493

• Prediction Models for 30-Day Mortality and Complications After Total Knee and Hip Arthroplasties for Veteran Health Administration Patients With Osteoarthritis JOURNAL OF ARTHROPLASTY Harris, A. S., Kuo, A. C., Bowe, T., Gupta, S., Nordin, D., Giori, N. J. 2018; 33 (5): 1539–45

  Abstract

  Statistical models to preoperatively predict patients' risk of death and major complications after total joint arthroplasty (TJA) could improve the quality of preoperative management and informed consent. Although risk models for TJA exist, they have limitations including poor transparency and/or unknown or poor performance. Thus, it is currently impossible to know how well currently available models predict short-term complications after TJA, or if newly developed models are more accurate. We sought to develop and conduct cross-validation of predictive risk models, and report details and performance metrics as benchmarks.Over 90 preoperative variables were used as candidate predictors of death and major complications within 30 days for Veterans Health Administration patients with osteoarthritis who underwent TJA. Data were split into 3 samples-for selection of model tuning parameters, model development, and cross-validation. C-indexes (discrimination) and calibration plots were produced.A total of 70,569 patients diagnosed with osteoarthritis who received primary TJA were included. C-statistics and bootstrapped confidence intervals for the cross-validation of the boosted regression models were highest for cardiac complications (0.75; 0.71-0.79) and 30-day mortality (0.73; 0.66-0.79) and lowest for deep vein thrombosis (0.59; 0.55-0.64) and return to the operating room (0.60; 0.57-0.63).Moderately accurate predictive models of 30-day mortality and cardiac complications after TJA in Veterans Health Administration patients were developed and internally cross-validated. By reporting model coefficients and performance metrics, other model developers can test these models on new samples and have a procedure and indication-specific benchmark to surpass.

  View details for PubMedID 29398261

• Risk Reduction Compared with Access to Care: Quantifying the Trade-Off of Enforcing a Body Mass Index Eligibility Criterion for Joint Replacement JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Giori, N. J., Amanatullah, D. F., Gupta, S., Bowe, T., Harris, A. 2018; 100 (7): 539–45

  Abstract

  Morbidly obese patients with severe osteoarthritis benefit from successful total joint arthroplasty. However, morbid obesity increases the risk of complications. Because of this, some surgeons enforce a body mass index (BMI) eligibility criterion above which total joint arthroplasty is denied. In this study, we investigate the trade-off between avoiding complications and restricting access to care when enforcing BMI-based eligibility criteria for total joint arthroplasty.In this retrospective cohort study, the Veterans Health Administration (VHA) Corporate Data Warehouse (CDW) and Veterans Affairs Surgical Quality Improvement Program (VASQIP) databases were reviewed for patients undergoing total joint arthroplasty from October 2011 through September 2014. We determined, if various BMI eligibility criteria had been enforced over that period of time, how many short-term complications would have been avoided, how many complication-free surgical procedures would have been denied, and the positive predictive value of BMI eligibility criteria as tests for major complications. To provide a frame of reference, we also determined what would have happened if eligibility for total joint arthroplasty were arbitrarily determined by flipping a coin.In this study, 27,671 total joint arthroplasties were reviewed. With a BMI criterion of ≥40 kg/m, 1,148 patients would have been denied a surgical procedure free of major complications, and 83 patients would have avoided a major complication. The positive predictive value of a complication using a BMI of ≥40 kg/m as a test for major complications was 6.74% (95% confidence interval [CI], 5.44% to 8.33%). The positive predictive value of a complication using a BMI criterion of 30 kg/m was 5.33% (95% CI, 4.99% to 5.71%). Flipping a coin had a positive predictive value of 5.05%.A 30 kg/m criterion for total joint arthroplasty eligibility is marginally better than flipping a coin and should not determine surgical eligibility. With a BMI criterion of ≥40 kg/m, the number of patients denied a complication-free surgical procedure is about 14 times larger than those spared a complication. Although the acceptable balance between avoiding complications and providing access to care can be debated, such a quantitative assessment helps to inform decisions regarding the advisability of enforcing a BMI criterion for total joint arthroplasty.Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

  View details for PubMedID 29613922

  View details for PubMedCentralID PMC5895162

• Antiseptics Commonly Used in Total Joint Arthroplasty Interact and May Form Toxic Products JOURNAL OF ARTHROPLASTY Campbell, S. T., Goodnough, L. H., Bennett, C. G., Giori, N. J. 2018; 33 (3): 844–46

  Abstract

  Multiple antiseptics have been described for use in total joint arthroplasty infection, and the use of multiple antiseptic solutions during a single operation has been described. Our clinical experience is that chlorhexidine (CHX) and Dakin's solution (NaOCl) interact and form a precipitate. The purpose of this study is to determine whether this reaction could be replicated in a laboratory setting, and to determine if other commonly used antiseptics also visibly react when mixed.Four percent chlorhexidine gluconate (CHX), 0.5% sodium hypochlorite (NaOCl), 3% hydrogen peroxide (H2O2), and 10% povidone-iodine (BTD) solutions were obtained and all possible combinations were mixed. Any visible reactions were noted and recorded, and a literature search was performed to characterize the reaction and products.CHX and NaOCl, CHX and H2O2, and CHX and BTD reacted instantly, forming a precipitate. NaOCl and H2O2 reacted to produce a gas. NaOCl and BTD reacted and produced a color change. The literature review revealed that at least 2 of the reactions tested (CHX + NaOCl and NaOCl + H2O2) could result in byproducts toxic to humans.Surgeons must be aware of these interactions when using antiseptic solutions during procedures. Caution should be used combining or mixing antiseptics, and we recommend against concomitant introduction in a surgical wound.

  View details for DOI 10.1016/j.arth.2017.10.028

  View details for Web of Science ID 000425893000039

  View details for PubMedID 29137898

• Mobile Compression Reduces Bleeding-related Readmissions and Wound Complications After THA and TKA CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Arsoy, D., Giori, N. J., Woolson, S. T. 2018; 476 (2): 381–87

  Abstract

  The use of chemoprophylaxis to prevent thromboembolic disease after primary THA and TKA can be associated with postoperative bleeding complications. Mechanical prophylaxis has been studied as an alternative to chemoprophylaxis with greater safety in patients undergoing THA, but no data have been published comparing the safety of chemoprophylaxis versus mechanical methods for patients undergoing TKA. The risk of readmission resulting from bleeding and venous thromboembolism (VTE) has also not been determined for patients undergoing THA or TKA when treated with low-molecular-weight heparin (LMWH) alone compared with mechanical prophylaxis plus aspirin (ASA).We sought to answer four questions: For the THA and TKA cohorts, respectively, (1) was the incidence of readmission resulting from VTE and bleeding complications higher with LMWH than mobile compression plus ASA; and (2) was the incidence of wound bleeding complications higher with LMWH than mechanical compression plus ASA? For the TKA cohort specifically, (3) was the frequency of systemic bleeding events and complications related to chemical prophylaxis higher with LMWH compared with mechanical compression plus ASA? (4) Was there a difference in symptomatic VTEs between LMWH and mechanical compression plus ASA?Between November 2008 and April 2011, 632 patients underwent primary THA and TKA. Seventy-two patients (11%) were identified before surgery as being at high risk for VTE (31 patients) or bleeding (41 patients) and were excluded from the study. Five hundred sixty patients (89%) were considered to be at standard risk for VTE and bleeding and comprise the study cohort. Between November 2008 and November 2009, 252 patients (76 THAs, 176 TKAs) underwent THA and TKA and were treated with LMWH (5 mg dalteparin given subcutaneously daily for 14 days) and in-hospital nonmobile mechanical compression. Between November 2009 and April 2011, a total of 308 patients undergoing THA and TKA (108 THAs, 200 TKAs) were treated using a mobile compression device plus oral aspirin once daily for 2 weeks after surgery. All complications and readmissions that occurred within 6 weeks of surgery were noted. There were no differences between the VTE treatment groups with regard to age, sex, or body mass index.For the THA cohort, there was no difference in the frequency of readmission for a bleeding complication (wound or systemic) between the two groups (2.6% for LMWH versus 0.9% for mobile compression; p = 0.57; odds ratio [OR], 2.9). Patients undergoing TKA treated with LMWH had higher readmission rates within 6 weeks of surgery because of a bleeding complication, a wound infection, or the development of a VTE (6.8% for LMWH versus 1.5% for mobile compression; p = 0.015; OR, 4.8). For the THA cohort, there was higher wound bleeding complication frequency with LMWH (9.2% for LMWH versus 0.9% for mechanical compression; p = 0.009; OR, 10.9). Patients undergoing TKA treated with LMWH had a higher frequency of wound bleeding complications or infection (3.9% for LMWH versus 0.5% for mobile compression; p = 0.028; OR, 8.2). Patients undergoing TKA treated with LMWH had higher rates of systemic bleeding or a complication secondary to LMWH administration (2.8% for LMWH versus 0% for mobile compression; p = 0.022; OR, 12.8). No difference was noted in the rate of symptomatic VTEs between either group (for THA: 2.6% for the LMWH group versus 1.9% for the mechanical compression group; p = 1; for TKA: 1.1% versus 0%, respectively; p = 0.22).Based on these results, we advocate for routine use of mobile mechanical compression devices in the prevention of VTEs and complications associated with more potent chemical anticoagulants. However, more focused randomized clinical trials are needed to validate these findings.Level III, therapeutic study.

  View details for PubMedID 29529673

• Joint replacement surgery in homeless veterans. Arthroplasty today Bennett, C. G., Lu, L. Y., Thomas, K. A., Giori, N. J. 2017; 3 (4): 253-256

  Abstract

  Total joint arthroplasty (TJA) in a homeless patient is generally considered contraindicated. Here, we report our known medical and social (housing and employment) results of homeless veterans who had TJA. Thirty-seven TJAs were performed on 33 homeless patients (31 men) at our hospital between November 2000 and March 2014. This was 1.2% of all TJAs. Average age was 54 years. Average hospital stay was 4.1 days. There were no major inpatient complications. Thirty-four cases had at least 1-year follow-up in any clinic within the Veterans Affairs health care system. There were no known surgery-related reoperations or readmissions. At final follow-up, 24 patients had stable housing and 9 were employed. The extensive and coordinated medical and social services that were provided to veterans from the Department of Veterans Affairs contributed to our positive results.

  View details for DOI 10.1016/j.artd.2017.04.001

  View details for PubMedID 29204492

  View details for PubMedCentralID PMC5712036

• CCL2/CCR2, but not CCL5/CCR5, mediates monocyte recruitment, inflammation and cartilage destruction in osteoarthritis ANNALS OF THE RHEUMATIC DISEASES Raghu, H., Lepus, C. M., Wang, Q., Wong, H. H., Lingampalli, N., Oliviero, F., Punzi, L., Giori, N. J., Goodman, S. B., Chu, C. R., Sokolove, J. B., Robinson, W. H. 2017; 76 (5)

  Abstract

  While various monocyte chemokine systems are increased in expression in osteoarthritis (OA), the hierarchy of chemokines and chemokine receptors in mediating monocyte/macrophage recruitment to the OA joint remains poorly defined. Here, we investigated the relative contributions of the CCL2/CCR2 versus CCL5/CCR5 chemokine axes in OA pathogenesis.Ccl2-, Ccr2-, Ccl5- and Ccr5-deficient and control mice were subjected to destabilisation of medial meniscus surgery to induce OA. The pharmacological utility of blocking CCL2/CCR2 signalling in mouse OA was investigated using bindarit, a CCL2 synthesis inhibitor, and RS-504393, a CCR2 antagonist. Levels of monocyte chemoattractants in synovial tissues and fluids from patients with joint injuries without OA and those with established OA were investigated using a combination of microarray analyses, multiplexed cytokine assays and immunostains.Mice lacking CCL2 or CCR2, but not CCL5 or CCR5, were protected against OA with a concomitant reduction in local monocyte/macrophage numbers in their joints. In synovial fluids from patients with OA, levels of CCR2 ligands (CCL2, CCL7 and CCL8) but not CCR5 ligands (CCL3, CCL4 and CCL5) were elevated. We found that CCR2+ cells are abundant in human OA synovium and that CCR2+ macrophages line, invade and are associated with the erosion of OA cartilage. Further, blockade of CCL2/CCR2 signalling markedly attenuated macrophage accumulation, synovitis and cartilage damage in mouse OA.Our findings demonstrate that monocytes recruited via CCL2/CCR2, rather than by CCL5/CCR5, propagate inflammation and tissue damage in OA. Selective targeting of the CCL2/CCR2 system represents a promising therapeutic approach for OA.

  View details for DOI 10.1136/annrheumdis-2016-210426

  View details for Web of Science ID 000398387200022

• Adherence to a Multimodal Analgesic Clinical Pathway: A Within-Group Comparison of Staged Bilateral Knee Arthroplasty Patients. Regional anesthesia and pain medicine Steckelberg, R. C., Funck, N., Kim, T. E., Walters, T. L., Lochbaum, G. M., Memtsoudis, S. G., Giori, N. J., Indelli, P. F., Graham, L. J., Mariano, E. R. 2017

  Abstract

  Multimodal analgesic clinical pathways for joint replacement patients often include perineural catheters, but long-term adherence to these pathways has not yet been investigated. Our primary aim was to determine adherence rate to a knee arthroplasty clinical pathway for patients undergoing staged bilateral procedures.This study was performed at a hospital with a Perioperative Surgical Home program and knee arthroplasty clinical pathway using multimodal analgesia and adductor canal catheters. Data were examined for all orthopedic surgery patients over a 4-year period. We included patients who had staged bilateral knee arthroplasty electively scheduled on 2 separate dates. The primary outcome was rate of adductor canal catheter utilization as a measure of adherence to the clinical pathway. Other outcomes included rates of neuraxial anesthesia and minor and major perioperative complications.We analyzed data for 103 unique patients. The interval between surgeries was a median of 261 days (10th-90th percentile, 138-534 days). All 103 patients had adductor canal catheters for both the first and second surgeries (P > 0.999). Forty-one percent of patients had the same surgeon for both surgeries, but only 2% had the same anesthesiologist (P < 0.001). From the first to the second surgery, utilization of neuraxial anesthesia increased from 51% to 68%, respectively (P = 0.005). There were no differences in minor or major complications.For staged bilateral knee arthroplasty patients, 100% clinical pathway adherence including perineural catheters and multimodal analgesia is feasible despite multiple variables. We believe that patient-centered acute pain management requires consistent and reliable delivery of care.

  View details for DOI 10.1097/AAP.0000000000000588

  View details for PubMedID 28267070

• Uncemented Metal-Backed Tantalum Patellar Components in Total Knee Arthroplasty Have a High Fracture Rate at Midterm Follow-Up. journal of arthroplasty Chan, J. Y., Giori, N. J. 2017

  Abstract

  There is interest in uncemented total knee arthroplasty due to the hope for long-term biologic fixation, but limited data are available regarding uncemented tantalum patellar components. The purpose of this study was to evaluate the radiographic outcomes of uncemented tantalum patellar implants at midterm follow-up.We retrospectively reviewed a consecutive series of 30 knees in 29 patients who underwent cementless total knee arthroplasty with an uncemented metal-backed tantalum patella between September 2006 and April 2009. Patients were required to have a minimum radiographic follow-up of 2 years. Anteroposterior and lateral radiographs of the knee were evaluated for signs of implant fracture or gross loosening. Clinical follow-up was obtained by reviewing each patient's most recent orthopedic record.Thirty knees in 29 patients met inclusion criteria. The mean age of the cohort was 59.1 years with a mean body mass index of 31.9 kg/m(2). Mean postoperative radiographic follow-up time was 5.5 years. Six fractures of the patellar component were noted. This represented a fracture rate of 20% among the entire cohort and 35% among the 17 knees with visible patellae on anteroposterior radiograph. All fractures had a transverse pattern. No gross patellar component loosening was noted. Among patients with component fractures, 2 required revisions for instability and 1 revision was for infection.Our results suggest a minimum 20% rate of component fracture at midterm follow-up. Although many of these patellar component fractures were asymptomatic, they have the potential to impact revision rates in the longer term.

  View details for DOI 10.1016/j.arth.2017.02.062

  View details for PubMedID 28341281

• Femoral Nerve Catheters Improve Home Disposition and Pain in Hip Fracture Patients Treated With Total Hip Arthroplasty. The Journal of arthroplasty Arsoy, D. n., Huddleston, J. I., Amanatullah, D. F., Giori, N. J., Maloney, W. J., Goodman, S. B. 2017

  Abstract

  Opioids have been the mainstay of treatment in the physiologically young geriatric hip fracture patient undergoing total hip arthroplasty (THA). However opioid-related side effects increase morbidity. Regional anesthesia may provide better analgesia, while decreasing opioid-related side effects. The goal of this study was to examine the effect of perioperative continuous femoral nerve blockade with regards to pain scores, opioid-related side effects and posthospital disposition in hip fracture patients undergoing THA.Twenty-nine consecutive geriatric hip fracture patients (22 women/7 men) underwent THA. Average follow-up was 8.3 months (6 weeks-39 months). Fifteen patients were treated with standard analgesia (SA). Fourteen patients received an ultrasound-guided insertion of a femoral nerve catheter after radiographic confirmation of a hip fracture. All complications and readmissions that occurred within 6 weeks of surgery were noted.Continuous femoral nerve catheter (CFNC) patients were discharged home more frequently than SA patients (43% for CFNC vs 7% for SA; P = .023). CFNC patients reported lower average pain scores preoperatively (P < .0001), on postoperative day 1 (P = .005) and postoperative day 2 (P = .037). Preoperatively, CFNC patients required 61% less morphine equivalent (P = .007). CFNC patients had a lower rate of opioid-related side effects compared with SA patients (7% vs 47%; P = .035).CFNC patients were discharged to home more frequently. Use of a CFNC decreased daily average patient-reported pain scores, preoperative opioid usage, and opioid-related side effects after THA for hip fracture. Based on these data, we recommend routine use of perioperative CFNC in hip fracture patients undergoing THA.

  View details for PubMedID 28641968

• Six Month Follow-Up of a Patient With a Retained Fascia Iliaca Catheter: A Case Report. A & A case reports Borg, L. K., Kumar, G. n., Funck, N. n., Tamm-Daniels, I. n., Giori, N. J., Mariano, E. R. 2017

  Abstract

  Retained catheters are a rare but known complication of continuous peripheral nerve block. To date there have been several case reports of retained catheters but none that include longer-term follow-up of the patient experience and outcomes. Here, we present the case of a retained fascia iliaca catheter used for analgesia after total hip arthroplasty that fractured during removal and was ultimately never retrieved. The patient initially experienced paresthesias emanating from the site of continuous peripheral nerve block catheter placement, but these issues resolved completely over several weeks. No infectious or serious sequelae were encountered during 6 months of follow-up.

  View details for DOI 10.1213/XAA.0000000000000642

  View details for PubMedID 28990961

• CCL2/CCR2, but not CCL5/CCR5, mediates monocyte recruitment, inflammation and cartilage destruction in osteoarthritis. Annals of the rheumatic diseases Raghu, H., Lepus, C. M., Wang, Q., Wong, H. H., Lingampalli, N., Oliviero, F., Punzi, L., Giori, N. J., Goodman, S. B., Chu, C. R., Sokolove, J. B., Robinson, W. H. 2016

  Abstract

  While various monocyte chemokine systems are increased in expression in osteoarthritis (OA), the hierarchy of chemokines and chemokine receptors in mediating monocyte/macrophage recruitment to the OA joint remains poorly defined. Here, we investigated the relative contributions of the CCL2/CCR2 versus CCL5/CCR5 chemokine axes in OA pathogenesis.Ccl2-, Ccr2-, Ccl5- and Ccr5-deficient and control mice were subjected to destabilisation of medial meniscus surgery to induce OA. The pharmacological utility of blocking CCL2/CCR2 signalling in mouse OA was investigated using bindarit, a CCL2 synthesis inhibitor, and RS-504393, a CCR2 antagonist. Levels of monocyte chemoattractants in synovial tissues and fluids from patients with joint injuries without OA and those with established OA were investigated using a combination of microarray analyses, multiplexed cytokine assays and immunostains.Mice lacking CCL2 or CCR2, but not CCL5 or CCR5, were protected against OA with a concomitant reduction in local monocyte/macrophage numbers in their joints. In synovial fluids from patients with OA, levels of CCR2 ligands (CCL2, CCL7 and CCL8) but not CCR5 ligands (CCL3, CCL4 and CCL5) were elevated. We found that CCR2+ cells are abundant in human OA synovium and that CCR2+ macrophages line, invade and are associated with the erosion of OA cartilage. Further, blockade of CCL2/CCR2 signalling markedly attenuated macrophage accumulation, synovitis and cartilage damage in mouse OA.Our findings demonstrate that monocytes recruited via CCL2/CCR2, rather than by CCL5/CCR5, propagate inflammation and tissue damage in OA. Selective targeting of the CCL2/CCR2 system represents a promising therapeutic approach for OA.

  View details for DOI 10.1136/annrheumdis-2016-210426

  View details for PubMedID 27965260

• Should Only the Highest-Volume Surgeons and Centers Be Doing Primary Total Knee Arthroplasty? Commentary on an article by Sean Wilson, BA, et al.: "Meaningful Thresholds for the Volume-Outcome Relationship in Total Knee Arthroplasty". journal of bone and joint surgery. American volume Giori, N. J. 2016; 98 (20)

  View details for PubMedID 27869633

• An ultrasound-guided fascia iliaca catheter technique does not impair ambulatory ability within a clinical pathway for total hip arthroplasty. Korean journal of anesthesiology Mudumbai, S. C., Kim, T. E., Howard, S. K., Giori, N. J., Woolson, S., Ganaway, T., Kou, A., King, R., Mariano, E. R. 2016; 69 (4): 368-375

  Abstract

  Both neuraxial and peripheral regional analgesic techniques offer postoperative analgesia for total hip arthroplasty (THA) patients. While no single technique is preferred, quadriceps muscle weakness from peripheral nerve blocks may impede rehabilitation. We designed this study to compare postoperative ambulation outcome in THA patients who were treated with a new ultrasound-guided fascia iliaca catheter (FIC) technique or intrathecal morphine (ITM).We reviewed the electronic health records of a sequential series of primary unilateral THA patients who were part of a standardized clinical pathway; apart from differences in regional analgesic technique, all other aspects of the pathway were the same. Our primary outcome was total ambulation distance (meters) combined for postoperative days 1 and 2. Secondary outcomes included daily opioid consumption (morphine milligram equivalents) and analgesic-related side effects. We examined the association between the primary outcome and analgesic technique by performing crude and adjusted ordinary least-squares linear regression. A P value < 0.05 was considered statistically-significant.The study analyzed the records of 179 patients (fascia iliaca, n = 106; intrathecal, n = 73). The primary outcome (total ambulation distance) did not differ between the groups (P = 0.08). Body mass index (BMI) was the only factor (β = -1.7 [95% CI -0.5 to -2.9], P < 0.01) associated with ambulation distance. Opioid consumption did not differ, while increased pruritus was seen in the intrathecal group (P < 0.01).BMI affects postoperative ambulation outcome after hip arthroplasty, whereas the type of regional analgesic technique used does not. An ultrasound-guided FIC technique offers similar analgesia with fewer side effects when compared with ITM.

  View details for DOI 10.4097/kjae.2016.69.4.368

  View details for PubMedID 27482314

• Osteoarthritis in veterans undergoing bariatric surgery is associated with decreased excess weight loss: 5-year outcomes. Surgery for obesity and related diseases Kubat, E., Giori, N. J., Hwa, K., Eisenberg, D. 2016; 12 (7): 1426-1430

  Abstract

  Obesity exacerbates pre-existing musculoskeletal disease and joint pain. This may limit physical activity in obese individuals.We sought to identify the disease burden and impact of osteoarthritis of the lumbar back, hip, knee, and ankle in veterans undergoing bariatric surgery.Veterans Affairs medical center.Retrospective review of a prospective bariatric database of operations performed at a single Veterans Affairs medical center. Patients with osteoarthritis of the lumbar spine, hip, knee, or ankle were identified and diagnosis confirmed by electronic health record review of prior radiographic reports. Analysis was performed using χ(2) test for continuous variables. Student's t test and one-way analysis of variance were used to compare qualitative variables.Of 254 bariatric surgical patients, 83.9% had preoperative musculoskeletal pain before bariatric surgery and 59.1% had a confirmed diagnosis of osteoarthritis of the lumbar spine, hips, knees, and/or ankles. Follow-up rate was 97.4%, 85.4%, and 82.6% at 1, 3, and 5 years respectively. Of patients with osteoarthritis, 58.6% had knee involvement and 46% had multiple sites involved. In the cohort without osteoarthritis, percent excess body mass index loss was 66.9% at 1 year versus 58.5% in the cohort with osteoarthritis (P = .009), 66.1% versus 51.9% (P = .001) at 3 years, and 64.3% versus 50.1% (P = .002) after 5 years. Percent total weight loss was 28.4% versus 25.2%, 28.0% versus 22.8%, and 27.1% versus 22.4%, respectively, at 1, 3, and 5 years.Osteoarthritis is common among veterans undergoing bariatric surgery. It is associated with significantly less weight loss compared to veterans who do not have osteoarthritis, up to 5 years after bariatric surgery.

  View details for DOI 10.1016/j.soard.2016.02.012

  View details for PubMedID 27260653

• History of Nocturia May Guide Urinary Catheterization for Total Joint Arthroplasty. Orthopedics Rana, S., Woolson, S. T., Giori, N. J. 2016; 39 (4): e749-52

  Abstract

  Urinary tract infection is a common complication after total knee arthroplasty (TKA) and can be related to urethral catheterization. This study attempted to determine whether nocturia could be used as an indicator of risk for postoperative urinary retention to limit the need for prophylactic catheterization in men undergoing TKA. A retrospective study was performed in a consecutive series of men undergoing TKA at a single Veterans Affairs medical center. Patients reporting 0 episodes or 1 episode of nocturia per night were not catheterized prophylactically, and patients reporting 2 or more episodes of nocturia each night were catheterized preoperatively. Of 100 consecutive patients, 51 reported no more than 1 episode of nocturia and did not undergo preoperative catheterization. Of these patients, 10 required 1 postoperative straight catheterization for urinary retention. In the 49 patients who were catheterized prophylactically, all catheters were removed on postoperative day 1. Only 1 of these patients required reinsertion of a catheter. No patient in either group was discharged with a catheter or had a urinary tract infection. Previously, the authors' standard protocol was to use a prophylactic urinary catheter for all men after TKA. In this 100-patient cohort, with this new protocol, 41 patients were not catheterized at all and 10 patients had only 1 straight catheterization. In this study, the frequency of nocturia in men undergoing TKA was an effective screening tool that safely reduced the need for an indwelling catheter in 51% of patients. [Orthopedics. 2016; 39(4):e749-e752.].

  View details for DOI 10.3928/01477447-20160421-06

  View details for PubMedID 27111076

• Can bedside patient-reported numbness predict postoperative ambulation ability for total knee arthroplasty patients with nerve block catheters? Korean journal of anesthesiology Mudumbai, S. C., Ganaway, T., Kim, T. E., Howard, S. K., Giori, N. J., Shum, C., Mariano, E. R. 2016; 69 (1): 32-36

  Abstract

  Adductor canal catheters offer advantages over femoral nerve catheters for knee replacement patients because they produce less quadriceps muscle weakness; however, applying adductor canal catheters in bedside clinical practice remains challenging. There is currently no patient-reported outcome that accurately predicts patients' physical function after knee replacement. The present study evaluates the validity of a relatively new patient-reported outcome, i.e., a numbness score obtained using a numeric rating scale, and assesses its predictive value on postoperative ambulation.We conducted a retrospective cohort study pooling data from two previously-published clinical trials using identical research methodologies. Both studies recruited patients undergoing knee replacement; one studied adductor canal catheters while the other studied femoral nerve catheters. Our primary outcome was patient-reported numbness scores on postoperative day 1. We also examined postoperative day 1 ambulation distance and its association with postoperative numbness using linear regression, adjusting for age, body mass index, and physical status.Data from 94 subjects were included (femoral subjects, n = 46; adductor canal subjects, n = 48). Adductor canal patients reported decreased numbness (median [10(th)-90(th) percentiles]) compared to femoral patients (0 [0-5] vs. 4 [0-10], P = 0.001). Adductor canal patients also ambulated seven times further on postoperative day 1 relative to femoral patients. There was a significant association between postoperative day 1 total ambulation distance and numbness (Beta = -2.6; 95% CI: -4.5, -0.8, P = 0.01) with R(2) = 0.1.Adductor canal catheters facilitate improved early ambulation and produce less patient-reported numbness after knee replacement, but the correlation between these two variables is weak.

  View details for DOI 10.4097/kjae.2016.69.1.32

  View details for PubMedID 26885299

• Arthroscopy for Knee Osteoarthritis Has Not Decreased After a Clinical Trial CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Adelani, M. A., Harris, A. H., Bowe, T. R., Giori, N. J. 2016; 474 (2): 489-494

  Abstract

  Multiple clinical trials have shown that arthroscopy for knee osteoarthritis is not efficacious. It is unclear how these studies have affected orthopaedic practice in the USA.We questioned whether, in the Veterans Health Administration system, rates of knee arthroscopy in patients with osteoarthritis have changed after publication of the initial clinical trial by Moseley et al. in 2002, and whether rates of arthroplasty within 2 years of arthroscopy have changed during the same period.Patients 50 years and older with knee osteoarthritis who underwent arthroscopy between 1998 and 2010 were retrospectively identified and an annual arthroscopy rate was calculated from 1998 through 2002 and from 2006 through 2010. Patients who underwent knee arthroplasty within 2 years of arthroscopy during each period were identified, and a 2-year conversion to arthroplasty rate was calculated.Between 1998 and 2002, the annual arthroscopy rate decreased from 4% to 3%. Of these arthroscopies, 4% were converted to arthroplasty within 2 years. Between 2006 and 2010, the annual arthroscopy rate increased from 3% to 4%. Of these arthroscopies, 5% were converted to arthroplasty within 2 years.Rates of arthroscopy in patients with knee osteoarthritis and conversion to arthroplasty within 2 years have not decreased with time. It may be that evidence alone is not sufficient to alter practice patterns or that arthroscopy rates for arthritis for patients in the Veterans Health Administration system were already so low that the results of the initial clinical trial had no substantial effect.Level III, Retrospective cohort study.

  View details for DOI 10.1007/s11999-015-4514-4

  View details for Web of Science ID 000368021900038

  View details for PubMedCentralID PMC4709284

• CORR Insights (R): High Risk of Failure With Bimodular Femoral Components in THA CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Giori, N. J. 2016; 474 (1): 154-155

  View details for DOI 10.1007/s11999-015-4568-3

  View details for Web of Science ID 000368022600029

  View details for PubMedID 26407701

  View details for PubMedCentralID PMC4686513

• Posterior Glenoid Wear in Total Shoulder Arthroplasty: Eccentric Anterior Reaming Is Superior to Posterior Augment CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Wang, T., Abrams, G. D., Behn, A. W., Lindsey, D., Giori, N., Cheung, E. V. 2015; 473 (12): 3928-3936

  Abstract

  Uncorrected glenoid retroversion during total shoulder arthroplasty may lead to an increased likelihood of glenoid prosthetic loosening. Augmented glenoid components seek to correct retroversion to address posterior glenoid bone loss, but few biomechanical studies have evaluated their performance.We compared the use of augmented glenoid components with eccentric reaming with standard glenoid components in a posterior glenoid wear model. The primary outcome for biomechanical stability in this model was assessed by (1) implant edge displacement in superior and inferior edge loading at intervals up to 100,000 cycles, with secondary outcomes including (2) implant edge load during superior and inferior translation at intervals up to 100,000 cycles, and (3) incidence of glenoid fracture during implant preparation and after cyclic loading.A 12°-posterior glenoid defect was created in 12 composite scapulae, and the specimens were divided in two equal groups. In the posterior augment group, glenoid version was corrected to 8° and an 8°-augmented polyethylene glenoid component was placed. In the eccentric reaming group, anterior glenoid reaming was performed to neutral version and a standard polyethylene glenoid component was placed. Specimens were cyclically loaded in the superoinferior direction to 100,000 cycles. Superior and inferior glenoid edge displacements were recorded.Surviving specimens in the posterior augment group showed greater displacement than the eccentric reaming group of superior (1.01 ± 0.02 [95% CI, 0.89-1.13] versus 0.83 ± 0.10 [95% CI, 0.72-0.94 mm]; mean difference, 0.18 mm; p = 0.025) and inferior markers (1.36 ± 0.05 [95% CI, 1.24-1.48] versus 1.20 ± 0.09 [95% CI, 1.09-1.32 mm]; mean difference, 0.16 mm; p = 0.038) during superior edge loading and greater displacement of the superior marker during inferior edge loading (1.44 ± 0.06 [95% CI, 1.28-1.59] versus 1.16 ± 0.11 [95% CI, 1.02-1.30 mm]; mean difference, 0.28 mm; p = 0.009) at 100,000 cycles. No difference was seen with the inferior marker during inferior edge loading (0.93 ± 0.15 [95% CI, 0.56-1.29] versus 0.78 ± 0.06 [95% CI, 0.70-0.85 mm]; mean difference, 0.15 mm; p = 0.079). No differences in implant edge load were seen during superior and inferior loading. There were no instances of glenoid vault fracture in either group during implant preparation; however, a greater number of specimens in the eccentric reaming group were able to achieve the final 100,000 time without catastrophic fracture than those in the posterior augment group.When addressing posterior glenoid wear in surrogate scapula models, use of angle-backed augmented glenoid components results in accelerated implant loosening compared with neutral-version glenoid after eccentric reaming, as shown by increased implant edge displacement at analogous times.Angle-backed components may introduce shear stress and potentially compromise stability. Additional in vitro and comparative long-term clinical followup studies are needed to further evaluate this component design.

  View details for DOI 10.1007/s11999-015-4482-8

  View details for PubMedID 26242283

• The role of inflammation in the initiation of osteoarthritis after meniscal damage JOURNAL OF BIOMECHANICS Edd, S. N., Giori, N. J., Andriacchi, T. P. 2015; 48 (8): 1420-1426

  Abstract

  Meniscal damage and meniscectomy lead to subsequent osteoarthritis (OA) of the knee joint through multiple and diverse mechanisms, yet the interaction of these mechanisms remains unknown. Therefore, the aim of this review is to suggest the multi-scale, multi-faceted components involved between meniscal injury or meniscectomy and the initiation of OA. There is evidence of structural, mechanical, and biological changes after meniscal damage, all of which can be greatly affected by the presence of local or systemic inflammation. Meniscal damage or resection causes changes in knee mechanics during walking, resulting in altered cartilage loading. Because cartilage is mechanically sensitive, these loading changes can initiate a catabolic effect, culminating in tissue degeneration. The evidence suggests that the addition of elevated inflammation at the time of meniscal damage or meniscectomy results in an accelerated progression toward cartilage degradation. Initial cartilage degradation produces inflammation and pain in conjunction with structural changes to the joint, thus perpetuating the cycle of altered cartilage loading and subsequent degradation. Furthermore, the inflammation secondary to obesity and aging introduces an increased risk of developing OA following meniscal injury. Therefore, an overall route between meniscal damage or resection and OA is presented here in a manner that considers two distinct pathways; these pathways reflect the absence or presence of conditions that cause elevated inflammation.

  View details for DOI 10.1016/j.jbiomech.2015.02.035

  View details for Web of Science ID 000356120000013

  View details for PubMedID 25798759

• Alterations in Knee Kinematics After Partial Medial Meniscectomy Are Activity Dependent AMERICAN JOURNAL OF SPORTS MEDICINE Edd, S. N., Netravali, N. A., Favre, J., Giori, N. J., Andriacchi, T. P. 2015; 43 (6): 1399-1407

  Abstract

  Alterations in knee kinematics after partial meniscectomy have been linked to the increased risk of osteoarthritis in this population. Understanding differences in kinematics during static versus dynamic activities of increased demand can provide important information regarding the possible underlying mechanisms of these alterations.Differences in the following 2 kinematics measures will increase with activity demand: (1) the offset toward external tibial rotation for the meniscectomized limb compared with the contralateral limb during stance and (2) the difference in knee flexion angle at initial foot contact between the meniscectomized and contralateral limbs.Controlled laboratory study.This study compared side-to-side differences in knee flexion and rotation angles during static and dynamic activities. Thirteen patients (2 female) were tested in a motion capture laboratory at 6 ± 2 months after unilateral, arthroscopic, partial medial meniscectomy during a static reference pose and during 3 dynamic activities: walking, stair ascent, and stair descent.The meniscectomized limb demonstrated more external tibial rotation compared with the contralateral limb during dynamic activities, and there was a trend that this offset increased with activity demand (repeated-measures analysis of variance [ANOVA] for activity, P = .07; mean limb difference: static pose, -0.1° ± 3.3°, P = .5; walking, 1.2° ± 3.8°, P = .1; stair ascent, 2.0° ± 3.2°, P = .02; stair descent, 3.0° ± 3.5°, P = .005). Similarly, the meniscectomized knee was more flexed at initial contact than the contralateral limb during dynamic activities (repeated-measures ANOVA for activity P = .006; mean limb difference: reference pose, 1.0° ± 2.5°, P = .09; walking, 2.0° ± 3.9°, P = .05; stair ascent, 5.9° ± 5.3°, P = .009; stair descent, 3.5° ± 4.0°, P = .004).These results suggest both a structural element and a potential muscular element for the differences in kinematics after partial medial meniscectomy and highlight the importance of challenging the knee with activities of increased demands to detect differences in kinematics from the contralateral limb.With further investigation, these findings could help guide clinical rehabilitation of patients with torn meniscus tissue, especially in the context of the patients' increased risk of joint degeneration.

  View details for DOI 10.1177/0363546515577360

  View details for Web of Science ID 000355379200015

  View details for PubMedID 25828080

• A retrospective comparative provider workload analysis for femoral nerve and adductor canal catheters following knee arthroplasty JOURNAL OF ANESTHESIA Rasmussen, M., Kim, E., Kim, T. E., Howard, S. K., Mudumbai, S., Giori, N. J., Woolson, S., Ganaway, T., Mariano, E. R. 2015; 29 (2): 303-307

  Abstract

  Adductor canal catheters preserve quadriceps strength better than femoral nerve catheters and may facilitate postoperative ambulation following total knee arthroplasty. However, the effect of this newer technique on provider workload, if any, is unknown. We conducted a retrospective provider workload analysis comparing these two catheter techniques; all other aspects of the clinical pathway remained the same. The primary outcome was number of interventions recorded per patient postoperatively. Secondary outcomes included infusion duration, ambulation distance, opioid consumption, and hospital length of stay. Adductor canal patients required a median (10-90th percentiles) of 0.0 (0.0-2.6) interventions compared to 1.0 (0.3-3.0) interventions for femoral patients (p < 0.001); 18/23 adductor canal patients (78 %) compared to 2/22 femoral patients (9 %) required no interventions (p < 0.001). Adductor canal catheter infusions lasted 2.0 (1.4-2.0) days compared to 1.5 (1.0-2.7) days in the femoral group (p = 0.016). Adductor canal patients ambulated further [mean (SD)] than femoral patients on postoperative day 1 [24.5 (21.7) vs. 11.9 (14.6) meters, respectively; p = 0.030] and day 2 [44.9 (26.3) vs. 22.0 (22.2) meters, respectively; p = 0.003]. Postoperative opioid consumption and length of stay were similar between groups. We conclude that adductor canal catheters offer both patient and provider benefits when compared to femoral nerve catheters.

  View details for DOI 10.1007/s00540-014-1910-y

  View details for Web of Science ID 000352859100025

  View details for PubMedID 25217117

• A randomized comparison of proximal and distal ultrasound-guided adductor canal catheter insertion sites for knee arthroplasty. Journal of ultrasound in medicine Mariano, E. R., Kim, T. E., Wagner, M. J., Funck, N., Harrison, T. K., Walters, T., Giori, N., Woolson, S., Ganaway, T., Howard, S. K. 2014; 33 (9): 1653-1662

  Abstract

  Proximal and distal (mid-thigh) ultrasound-guided continuous adductor canal block techniques have been described but not yet compared, and infusion benefits or side effects may be determined by catheter location. We hypothesized that proximal placement will result in faster onset of saphenous nerve anesthesia, without additional motor block, compared to a distal technique.Preoperatively, patients receiving an ultrasound-guided nonstimulating adductor canal catheter for knee arthroplasty were randomly assigned to either proximal or distal insertion. A local anesthetic bolus was administered via the catheter after successful placement. The primary outcome was the time to achieve complete sensory anesthesia in the saphenous nerve distribution. Secondary outcomes included procedural time, procedure-related pain and complications, postoperative pain, opioid consumption, and motor weakness.Proximal insertion (n = 23) took a median (10th-90th percentiles) of 12.0 (3.0-21.0) minutes versus 6.0 (3.0-21.0) minutes for distal insertion (n = 21; P= .106) to anesthetize the medial calf. Only 10 of 25 (40%) and 10 of 24 (42%) patients in the proximal and distal groups, respectively, developed anesthesia at both the medial calf and top of the patella (P= .978). Bolus-induced motor weakness occurred in 19 of 25 (76%) and 16 of 24 (67%) patients in the proximal and distal groups (P = .529). Ten of 24 patients (42%) in the distal group required intravenous morphine postoperatively, compared to 2 of 24 (8%) in the proximal group (P = .008), but there were no differences in other secondary outcomes.Continuous adductor canal blocks can be performed reliably at both proximal and distal locations. The proximal approach may offer minor analgesic and logistic advantages without an increase in motor block.

  View details for DOI 10.7863/ultra.33.9.1653

  View details for PubMedID 25154949

• Cartilage Nominal Strain Correlates With Shear Modulus and Glycosaminoglycans Content in Meniscectomized Joints JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME Song, Y., Carter, D. R., Giori, N. J. 2014; 136 (6)

  Abstract

  Postmeniscectomy osteoarthritis (OA) is hypothesized to be the consequence of abnormal mechanical conditions, but the relationship between postsurgical alterations in articular cartilage strain and in vivo biomechanical/biochemical changes in articular cartilage is unclear. We hypothesized that spatial variations in cartilage nominal strain (percentile thickness change) would correlate with previously reported in vivo articular cartilage property changes following meniscectomy. Cadevaric sheep knees were loaded in cyclic compression which was previously developed to mimic normal sheep gait, while a 4.7 T magnetic resonance imaging (MRI) imaged the whole joint. 3D cartilage strain maps were compared with in vivo sheep studies that described postmeniscectomy changes in shear modulus, phase lag, proteoglycan content and collagen organization/content in the articular cartilage. The area of articular cartilage experiencing high (overloaded) and low (underloaded) strain was significantly increased in the meniscectomized tibial compartment by 10% and 25%, respectively, while no significant changes were found in the nonmeniscectomized compartment. The overloaded and underloaded regions of articular cartilage in our in vitro specimens correlated with regions of in vivo shear modulus reduction. Glycosaminoglycans (GAG) content only increased at the underloaded articular cartilage but decreased at the overloaded articular cartilage. No significant correlation was found in phase lag and collagen organization/content changes with the strain variation. Comparisons between postsurgical nominal strain and in vivo cartilage property changes suggest that both overloading and underloading after meniscectomy may directly damage the cartilage matrix stiffness (shear modulus). Disruption of superficial cartilage by overloading might be responsible for the proteoglycan (GAG) loss in the early stage of postmeniscectomy OA.

  View details for DOI 10.1115/1.4027298

  View details for Web of Science ID 000335894800012

  View details for PubMedID 24671447

• Continuous Adductor Canal Blocks Are Superior to Continuous Femoral Nerve Blocks in Promoting Early Ambulation After TKA. Clinical orthopaedics and related research Mudumbai, S. C., Kim, T. E., Howard, S. K., Workman, J. J., Giori, N., Woolson, S., Ganaway, T., King, R., Mariano, E. R. 2014; 472 (5): 1377-1383

  Abstract

  Femoral continuous peripheral nerve blocks (CPNBs) provide effective analgesia after TKA but have been associated with quadriceps weakness and delayed ambulation. A promising alternative is adductor canal CPNB that delivers a primarily sensory blockade; however, the differential effects of these two techniques on functional outcomes after TKA are not well established.We determined whether, after TKA, patients with adductor canal CPNB versus patients with femoral CPNB demonstrated (1) greater total ambulation distance on Postoperative Day (POD) 1 and 2 and (2) decreased daily opioid consumption, pain scores, and hospital length of stay.Between October 2011 and October 2012, 180 patients underwent primary TKA at our practice site, of whom 93% (n = 168) had CPNBs. In this sequential series, the first 102 patients had femoral CPNBs, and the next 66 had adductor canal CPNBs. The change resulted from a modification to our clinical pathway, which involved only a change to the block. An evaluator not involved in the patients' care reviewed their medical records to record the parameters noted above.Ambulation distances were higher in the adductor canal group than in the femoral group on POD 1 (median [10(th)-90(th) percentiles]: 37 m [0-90 m] versus 6 m [0-51 m]; p < 0.001) and POD 2 (60 m [0-120 m] versus 21 m [0-78 m]; p = 0.003). Adjusted linear regression confirmed the association between adductor canal catheter use and ambulation distance on POD 1 (B = 23; 95% CI = 14-33; p < 0.001) and POD 2 (B = 19; 95% CI = 5-33; p = 0.008). Pain scores, daily opioid consumption, and hospital length of stay were similar between groups.Adductor canal CPNB may promote greater early postoperative ambulation compared to femoral CPNB after TKA without a reduction in analgesia. Future randomized studies are needed to validate our major findings.Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

  View details for DOI 10.1007/s11999-013-3197-y

  View details for PubMedID 23897505

• A quantitative assessment of the insertional footprints of the hip joint capsular ligaments and their spanning fibers for reconstruction CLINICAL ANATOMY Telleria, J. J., Lindsey, D. P., Giori, N. J., Safran, M. R. 2014; 27 (3): 489-497

  Abstract

  Quantitative descriptions of the hip joint capsular ligament insertional footprints have been reported. Using a three-dimensional digitizing system, and computer modeling, the area, and dimensions of the three main hip capsular ligaments and their insertional footprints were quantified in eight cadaveric hips. The iliofemoral ligament (ILFL) attaches proximally to the anterolateral supra-acetabular region (mean area = 4.2 cm(2)). The mean areas of the ILFL lateral and medial arm insertional footprints are 4.8 and 3.1 cm(2), respectively. The pubofemoral ligament (proximal footprint mean area = 1.4 cm(2)) blends with the medial ILFL anteriorly and the proximal ischiofemoral ligament (ISFL) distally without a distal bony insertion. The proximal and distal ISFL footprint mean areas are 6.4 and 1.2 cm(2), respectively. The hip joint capsular ligaments have consistent anatomic and insertional patterns. Quantification of the ligaments and their attachment sites may aid in improving anatomic repairs and reconstructions of the hip joint capsule using open and/or arthroscopic techniques.

  View details for DOI 10.1002/ca.22272

  View details for Web of Science ID 000332794400033

  View details for PubMedID 24293171

• Many Diabetic Total Joint Arthroplasty Candidates Are Unable to Achieve a Preoperative Hemoglobin A1c Goal of 7% or Less JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Giori, N. J., Ellerbe, L. S., Bowe, T., Gupta, S., Harris, A. H. 2014; 96A (6): 500-504

  Abstract

  Patients with poorly controlled diabetes have an elevated risk of complications and death following total joint arthroplasty. Some centers set a threshold hemoglobin A1c (HbA1c) value above which surgery is delayed pending better glycemic control. The purpose of this study was to examine how many diabetic patients scheduled for primary total joint arthroplasty underwent a delay because of an HbA1c value of >7.0%, how many subsequently achieved this goal, and how much time was necessary to achieve this goal.The study involved a retrospective chart review at one Veterans Affairs medical center. Patients with an HbA1c of >7.0% were referred to their primary care provider for better diabetic control. Unless reduction of the HbA1c to ≤7.0% was deemed medically inadvisable, surgery proceeded only after the patient returned with an HbA1c of ≤7.0%.A total of 404 diabetic patients were scheduled for total joint arthroplasty. In fifty-nine cases, the surgery was delayed because of an HbA1c of >7.0%. Thirty-five of these patients were able to reduce the HbA1c level to ≤7.0% after a median of 141 days (range, seven to 1043 days), and twenty-four failed to achieve this goal. If an HbA1c goal of ≤8.0% had been used, the surgery would have been delayed in thirty cases, and twenty-one of these patients would have subsequently achieved the goal.When establishing a goal designed to reduce perioperative risks, there should be an expectation that the goal is achievable. Overall, an HbA1c of ≤7.0% was achieved by 380 of the 404 diabetic patients (94%; 95% confidence interval [CI], 91% to 96%), but it was achieved by only thirty-five (59%; 95% CI, 46% to 72%) of the fifty-nine patients presenting with an HbA1c of >7.0%. An HbA1c of 8.0% was achieved by 395 (98%; 95% CI, 96% to 99%) of the diabetic patients and by twenty-one (70%; 95% CI, 50% to 85%) of the thirty patients presenting with an HbA1c of >8.0%. Achieving an HbA1c value of ≤7.0% may not be possible for certain diabetic patients, and such a requirement may risk access to total joint arthroplasty treatment.

  View details for DOI 10.2106/JBJS.L.01631

  View details for Web of Science ID 000333072700010

• Many diabetic total joint arthroplasty candidates are unable to achieve a preoperative hemoglobin A1c goal of 7% or less. journal of bone and joint surgery. American volume Giori, N. J., Ellerbe, L. S., Bowe, T., Gupta, S., Harris, A. H. 2014; 96 (6): 500-504

  Abstract

  Patients with poorly controlled diabetes have an elevated risk of complications and death following total joint arthroplasty. Some centers set a threshold hemoglobin A1c (HbA1c) value above which surgery is delayed pending better glycemic control. The purpose of this study was to examine how many diabetic patients scheduled for primary total joint arthroplasty underwent a delay because of an HbA1c value of >7.0%, how many subsequently achieved this goal, and how much time was necessary to achieve this goal.The study involved a retrospective chart review at one Veterans Affairs medical center. Patients with an HbA1c of >7.0% were referred to their primary care provider for better diabetic control. Unless reduction of the HbA1c to ≤7.0% was deemed medically inadvisable, surgery proceeded only after the patient returned with an HbA1c of ≤7.0%.A total of 404 diabetic patients were scheduled for total joint arthroplasty. In fifty-nine cases, the surgery was delayed because of an HbA1c of >7.0%. Thirty-five of these patients were able to reduce the HbA1c level to ≤7.0% after a median of 141 days (range, seven to 1043 days), and twenty-four failed to achieve this goal. If an HbA1c goal of ≤8.0% had been used, the surgery would have been delayed in thirty cases, and twenty-one of these patients would have subsequently achieved the goal.When establishing a goal designed to reduce perioperative risks, there should be an expectation that the goal is achievable. Overall, an HbA1c of ≤7.0% was achieved by 380 of the 404 diabetic patients (94%; 95% confidence interval [CI], 91% to 96%), but it was achieved by only thirty-five (59%; 95% CI, 46% to 72%) of the fifty-nine patients presenting with an HbA1c of >7.0%. An HbA1c of 8.0% was achieved by 395 (98%; 95% CI, 96% to 99%) of the diabetic patients and by twenty-one (70%; 95% CI, 50% to 85%) of the thirty patients presenting with an HbA1c of >8.0%. Achieving an HbA1c value of ≤7.0% may not be possible for certain diabetic patients, and such a requirement may risk access to total joint arthroplasty treatment.

  View details for DOI 10.2106/JBJS.L.01631

  View details for PubMedID 24647507

• Component Alignment During Total Knee Arthroplasty with Use of Standard or Custom Instrumentation A Randomized Clinical Trial Using Computed Tomography for Postoperative Alignment Measurement JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Woolson, S. T., Harris, A. H., Wagner, D. W., Giori, N. J. 2014; 96A (5): 366-372

  Abstract

  Patient-specific femoral and tibial cutting blocks produced with use of data from preoperative computed tomography (CT) or magnetic resonance imaging (MRI) scans have been employed recently to optimize component alignment in total knee arthroplasty. We report the results of a randomized controlled trial in which CT scans were used to compare postoperative component alignment between patients treated with custom instruments and those managed with traditional instruments.The in-hospital data and early clinical outcomes, including Knee Society scores, were determined in a randomized clinical trial of forty-seven patients who had undergone a total of forty-eight primary total knee arthroplasties with patient-specific instruments (twenty-two knees) or standard instruments (twenty-six knees). Orientation of the implants was compared by using three-dimensional CT data.No significant differences were found between the study and control groups with respect to any clinical outcome after a minimum of six months of follow-up. The patient-specific tibial cutting block was abandoned in favor of a standard external alignment jig in seven of the twenty-two study knees because of possible malalignment. A detailed analysis of intent-to-treat and per-protocol groups of study and control knees did not show any significant improvement in component alignment, including femoral component rotation in the axial plane, in the patients treated with the custom instruments. The percentage of outliers-defined as less than -3° or more than 3° from the correct orientation of the tibial slope-was significantly higher in the group treated with use of patient-specific blocks than it was in the control group, in both the intent-to-treat (32% versus 8%, p = 0.032) and the per-protocol (47% versus 6%, p = 0.0008) analysis.There were no significant improvements in clinical outcomes or knee component alignment in patients treated with patient-specific cutting blocks as compared with those treated with standard instruments. The group treated with patient-specific cutting blocks had a significantly higher prevalence of malalignment in terms of tibial component slope than the knees treated with standard instruments.Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

  View details for DOI 10.2106/JBJS.L.01722

  View details for Web of Science ID 000332440100003

• Component alignment during total knee arthroplasty with use of standard or custom instrumentation: a randomized clinical trial using computed tomography for postoperative alignment measurement. journal of bone and joint surgery. American volume Woolson, S. T., Harris, A. H., Wagner, D. W., Giori, N. J. 2014; 96 (5): 366-372

  Abstract

  Patient-specific femoral and tibial cutting blocks produced with use of data from preoperative computed tomography (CT) or magnetic resonance imaging (MRI) scans have been employed recently to optimize component alignment in total knee arthroplasty. We report the results of a randomized controlled trial in which CT scans were used to compare postoperative component alignment between patients treated with custom instruments and those managed with traditional instruments.The in-hospital data and early clinical outcomes, including Knee Society scores, were determined in a randomized clinical trial of forty-seven patients who had undergone a total of forty-eight primary total knee arthroplasties with patient-specific instruments (twenty-two knees) or standard instruments (twenty-six knees). Orientation of the implants was compared by using three-dimensional CT data.No significant differences were found between the study and control groups with respect to any clinical outcome after a minimum of six months of follow-up. The patient-specific tibial cutting block was abandoned in favor of a standard external alignment jig in seven of the twenty-two study knees because of possible malalignment. A detailed analysis of intent-to-treat and per-protocol groups of study and control knees did not show any significant improvement in component alignment, including femoral component rotation in the axial plane, in the patients treated with the custom instruments. The percentage of outliers-defined as less than -3° or more than 3° from the correct orientation of the tibial slope-was significantly higher in the group treated with use of patient-specific blocks than it was in the control group, in both the intent-to-treat (32% versus 8%, p = 0.032) and the per-protocol (47% versus 6%, p = 0.0008) analysis.There were no significant improvements in clinical outcomes or knee component alignment in patients treated with patient-specific cutting blocks as compared with those treated with standard instruments. The group treated with patient-specific cutting blocks had a significantly higher prevalence of malalignment in terms of tibial component slope than the knees treated with standard instruments.Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

  View details for DOI 10.2106/JBJS.L.01722

  View details for PubMedID 24599197

• Successful Limb Salvage of a "Too-Short Segment" of the Proximal Part of the Femur with Use of a Compression Osseointegration Implant: A Case Report. JBJS case connector Avedian, R. S., Giori, N. J., Mohler, D. n. 2014; 4 (3): e63–e6

  View details for PubMedID 29252502

• MENISCECTOMIZED KNEES REGAIN NORMAL WALKING FLEXION RANGE OF MOTION WITH TIME PAST SURGERY Edd, S. N., Netravali, N. A., Favre, J., Giori, N. J., Andriacchi, T. P., ASME AMER SOC MECHANICAL ENGINEERS. 2014

  View details for Web of Science ID 000359389300052

• Hemoglobin A1C as a Marker for Surgical Risk in Diabetic Patients Undergoing Total Joint Arthroplasty. journal of arthroplasty Harris, A. H., Bowe, T. R., Gupta, S., Ellerbe, L. S., Giori, N. J. 2013; 28 (8): 25-29

  Abstract

  Diabetes is a risk factor for complications following total joint arthroplasty (TJA). This retrospective cohort study of 6088 diabetic patients from the Veterans Health Administration (VHA) undergoing TJA sought to determine if hemoglobin A1c, an accessible and objective lab value, has utility as a predictor of risk of complications in TJA after controlling for demographic, surgical, and medical center effects, and to evaluate the benefits and risks of alternative thresholds. Analysis of the functional relationship between hemoglobin A1c and complications revealed that the risk linearly increases through, rather than surging at, the threshold of 7%. Before delaying surgery to achieve better diabetic control, surgeons and patients should weigh the estimated risks of TJA against the potential benefits.

  View details for DOI 10.1016/j.arth.2013.03.033

  View details for PubMedID 23910511

• Hemoglobin A1C as a Marker for Surgical Risk in Diabetic Patients Undergoing Total Joint Arthroplasty JOURNAL OF ARTHROPLASTY Harris, A. H., Bowe, T. R., Gupta, S., Ellerbe, L. S., Giori, N. J. 2013; 28 (8): 25-29

  Abstract

  Diabetes is a risk factor for complications following total joint arthroplasty (TJA). This retrospective cohort study of 6088 diabetic patients from the Veterans Health Administration (VHA) undergoing TJA sought to determine if hemoglobin A1c, an accessible and objective lab value, has utility as a predictor of risk of complications in TJA after controlling for demographic, surgical, and medical center effects, and to evaluate the benefits and risks of alternative thresholds. Analysis of the functional relationship between hemoglobin A1c and complications revealed that the risk linearly increases through, rather than surging at, the threshold of 7%. Before delaying surgery to achieve better diabetic control, surgeons and patients should weigh the estimated risks of TJA against the potential benefits.

  View details for DOI 10.1016/j.arth.2013.03.033

  View details for Web of Science ID 000209487600007

• Physeal cartilage exhibits rapid consolidation and recovery in intact knees that are physiologically loaded JOURNAL OF BIOMECHANICS Song, Y., Lee, D., Shin, C. S., Carter, D. R., Giori, N. J. 2013; 46 (9): 1516-1523

  Abstract

  The growth plate (physis) is responsible for long bone growth through endochondral ossification, a process which can be mechanically modulated. However, our understanding of the detailed mechanical behavior of physeal cartilage occurring in vivo is limited. In this study, we aimed to quantify the time-dependent deformational behavior of physeal cartilage in intact knees under physiologically realistic dynamic loading, and compare physeal cartilage deformation with articular cartilage deformation. A 4.7 T MRI scanner continuously scanned a knee joint in the sagittal plane through the central load-bearing region of the medial compartment every 2.5 min while a realistic cyclic loading was applied. A custom auto-segmentation program was developed to delineate complex physeal cartilage boundaries. Physeal volume changes at each time step were calculated. The new auto-segmentation was found to be reproducible with COV of the volume measurements being less than 0.5%. Time-constants of physeal cartilage consolidation (1.31±0.74 min) and recovery (1.63±0.70 min) were significantly smaller than the values (5.53±1.78/17.71±13.88 min for consolidation/recovery) in articular cartilage (P<0.05). The rapid consolidation and recovery of physeal cartilage may due to a relatively free metaphyseal fluid boundary which would allow rapid fluid exchange with the adjacent cancellous bone. This may impair the generation of hydrostatic pressure in the cartilage matrix when the physis is under chronic compressive loading, and may be related to the premature ossification of the growth plate under such conditions. Research on the growth plate fluid exchange may provide a more comprehensive understanding of mechanisms and disorders of long bone growth.

  View details for DOI 10.1016/j.jbiomech2013.03.026

  View details for Web of Science ID 000320827700006

  View details for PubMedID 23608339

• A Randomized Comparison of Long- and Short-Axis Imaging for In-Plane Ultrasound-Guided Femoral Perineural Catheter Insertion JOURNAL OF ULTRASOUND IN MEDICINE Mariano, E. R., Kim, T. E., Funck, N., Walters, T., Wagner, M. J., Harrison, T. K., Giori, N., Woolson, S., Ganaway, T., Howard, S. K. 2013; 32 (1): 149-156

  Abstract

  Continuous femoral nerve blocks provide effective analgesia after knee arthroplasty, and infusion effects depend on reliable catheter location. Ultrasound-guided perineural catheter insertion using a short-axis in-plane technique has been validated, but the optimal catheter location relative to target nerve and placement orientation remain unknown. We hypothesized that a long-axis in-plane technique for femoral perineural catheter insertion results in faster onset of sensory anesthesia compared to a short-axis in-plane technique.Preoperatively, patients receiving an ultrasound-guided nonstimulating femoral perineural catheter for knee surgery were randomly assigned to either the long-axis in-plane or short-axis in-plane technique. A local anesthetic was administered via the catheter after successful insertion. The primary outcome was the time to achieve complete sensory anesthesia. Secondary outcomes included the procedural time, the onset time of the motor block, pain and muscle weakness reported on postoperative day 1, and procedure-related complications.The short-axis group (n = 23) took a median (10th-90th percentiles) of 9.0 (6.0-20.4) minutes compared to 6.0 (3.0-14.4) minutes for the long-axis group (n = 23; P = .044) to achieve complete sensory anesthesia. Short-axis procedures took 5.0 (4.0-7.8) minutes to perform compared to 9.0 (7.0-14.8) minutes for long-axis procedures (P < .001). In the short-axis group, 19 of 23 (83%) achieved a complete motor block within the testing period compared to 18 of 23 (78%) in the long-axis group (P = .813); short-axis procedures took 12.0 (6.0-15.0) minutes versus 15.0 (5.1-27.9) minutes for long-axis procedures (P = .048). There were no statistically significant differences in other secondary outcomes.Long-axis in-plane femoral perineural catheters result in a slightly faster onset of sensory anesthesia, but placement takes longer to perform without other clinical advantages.

  View details for Web of Science ID 000313607400017

  View details for PubMedID 23269720

• Prevalence of Hepatitis C Virus Infection in the Veteran Population Undergoing Total Joint Arthroplasty JOURNAL OF ARTHROPLASTY Calore, B. L., Cheung, R. C., Giori, N. J. 2012; 27 (10): 1772-1776

  Abstract

  Many orthopedic surgeons train or are employed at the Department of Veterans Affairs (VA) hospitals. We sought to determine the prevalence of hepatitis C antibody-positive and hepatitis C-viremic patients in the VA population undergoing total joint arthroplasty. In this prospective cohort study, 381 of 408 patients undergoing primary total joint arthroplasty for 22 consecutive months were tested for hepatitis C virus (HCV) infection preoperatively. Thirty-two (8.4%) of 381 patients were positive for hepatitis C virus antibody. Seventeen were actually viremic at the time of total joint arthroplasty (4.5%). The prevalence of detectable hepatitis C antibody in VA patients undergoing total joint arthroplasty is about 6 times the general population (1.3%). Surgeons practicing on populations with a high prevalence of hepatitis C such as this should do all they can to minimize the risk of sharps injury.

  View details for DOI 10.1016/j.arth.2012.05.016

  View details for Web of Science ID 000311583500006

  View details for PubMedID 22770853

• A relationship between mechanically-induced changes in serum cartilage oligomeric matrix protein (COMP) and changes in cartilage thickness after 5 years OSTEOARTHRITIS AND CARTILAGE Erhart-Hledik, J. C., Favre, J., Asay, J. L., Smith, R. L., Giori, N. J., Muendermann, A., Andriacchi, T. P. 2012; 20 (11): 1309-1315

  Abstract

  To evaluate the hypothesis that a mechanical stimulus (30-min walk) will produce a change in serum concentrations of cartilage oligomeric matrix protein (COMP) that is associated with cartilage thickness changes on magnetic resonance imaging (MRI).Serum COMP concentrations were measured by enzyme-linked immunosorbent assay in 17 patients (11 females, age: 59.0±9.2 years) with medial compartment knee osteoarthritis (OA) at study entry immediately before, immediately after, 3.5 h, and 5.5 h after a 30-min walking activity. Cartilage thickness changes in the medial femur and medial tibia were determined from MR images taken at study entry and at 5-year follow-up. Relationships between changes in cartilage thickness and COMP levels, with post-activity concentrations expressed as a percentage of pre-activity levels, were assessed by the calculation of Pearson correlation coefficients and by multiple linear regression analysis, with adjustments for age, sex, and body mass index (BMI).Changes in COMP levels 3.5 h and 5.5 h post-activity were correlated with changes in cartilage thickness in the medial femur and tibia at the 5-year follow-up. The results were strengthened after analyses were adjusted for age, sex, and BMI. Neither baseline pre-activity COMP levels nor changes in COMP levels immediately post-activity were correlated with cartilage thickness changes.The results of this study support the hypothesis that a change in COMP concentration induced by a mechanical stimulus is associated with cartilage thinning at 5 years. Mechanically-induced changes in mechano-sensitive biomarkers should be further explored in the context of stimulus-response models to improve the ability to assess OA progression.

  View details for DOI 10.1016/j.joca.2012.07.018

  View details for Web of Science ID 000309853400013

• Sensitivity of gait parameters to the effects of anti-inflammatory and opioid treatments in knee osteoarthritis patients JOURNAL OF ORTHOPAEDIC RESEARCH Boyer, K. A., Angst, M. S., Asay, J., Giori, N. J., Andriacchi, T. P. 2012; 30 (7): 1118-1124

  Abstract

  The study aim was to address the need for objective markers of pain-modifying interventions by testing the hypothesis that selective gait measures of knee joint loading can distinguish differences between non-steroidal anti-inflammatory (NSAID), analgesic treatment (opioid-receptor agonist), and placebo in patients medial knee osteoarthritis (OA). A randomized, single-blind washout, double-blind treatment, double-dummy cross-over trial using three treatment arms placebo, opioid (Oxycodone), and NSAID (Celecoxib) in medial compartment knee OA patients. Six patients with Kellgren-Lawrence radiographic severity grades of 2 or 3 completed six testing sessions (gait and pain assessment) at 2-week intervals. A significant increase was found in the knee total reaction moment and vertical ground reaction force (GRF) for Celecoxib compared to placebo (p=0.005, p=0.003), but not for Oxycodone compared to placebo (p=0.20, p=0.27) treatments. Walking speed was significantly higher for the Celecoxib and Oxycodone compared to placebo treatment (p=0.041 and p=0.031, respectively). Self-reported function (WOMAC scores) was not different among treatments (p>0.05). The changes in total reaction moments and GRFs for only the NSAID suggest that greater increases in joint loading occurs when joint inflammation is treated in addition to pain. The total knee reaction moment, representing the magnitude of the extrinsic moment, appears to be a sensitive marker, more so than self-reported metrics, for evaluating knee OA treatment effects.

  View details for DOI 10.1002/jor.22037

  View details for Web of Science ID 000303810000016

  View details for PubMedID 22179861

• The low permeability of healthy meniscus and labrum limit articular cartilage consolidation and maintain fluid load support in the knee and hip JOURNAL OF BIOMECHANICS Haemer, J. M., Carter, D. R., Giori, N. J. 2012; 45 (8): 1450-1456

  Abstract

  The knee meniscus and hip labrum appear to be important for joint health, but the mechanisms by which these structures perform their functions are not fully understood. The fluid phase of articular cartilage provides compressive stiffness and aids in maintaining a low friction articulation. Healthy fibrocartilage, the tissue of meniscus and labrum, has a lower fluid permeability than articular cartilage. In this study we hypothesized that an important function of the knee meniscus and the hip labrum is to augment fluid retention in the articular cartilage of a mechanically loaded joint. Axisymmetric hyperporoelastic finite element models were analyzed for an idealized knee and an idealized hip. The results indicate that the meniscus maintained fluid pressure and inhibited fluid exudation in knee articular cartilage. Similar, but smaller, effects were seen with the labrum in the hip. Increasing the fibrocartilage permeability relative to that of articular cartilage gave a consolidation rate and loss of fluid load support comparable to that predicted by meniscectomy or labrectomy. The reduced articular cartilage fluid pressure that was calculated for the joint periphery is consistent with patterns of endochondral ossification and osteophyte formation in knee and hip osteoarthritis. High articular central strains and loss of fluid load support after meniscectomy could lead to fibrillation. An intact low-permeability fibrocartilage is important for limiting fluid exudation from articular cartilage in the hip and knee. This may be an important aspect of the role of fibrocartilage in protecting these joints from osteoarthritis.

  View details for DOI 10.1016/j.jbiomech.2012.02.015

  View details for Web of Science ID 000304216100017

  View details for PubMedID 22391467

• Effect of variable-stiffness walking shoes on knee adduction moment, pain, and function in subjects with medial compartment knee osteoarthritis after 1 year JOURNAL OF ORTHOPAEDIC RESEARCH Erhart-Hledik, J. C., Elspas, B., Giori, N. J., Andriacchi, T. P. 2012; 30 (4): 514-521

  Abstract

  This study investigated the load-modifying and clinical efficacy of variable-stiffness shoes after 12 months in subjects with medial compartment knee osteoarthritis. Subjects who completed a prior 6-month study were asked to wear their assigned constant-stiffness control or variable-stiffness intervention shoes during the remainder of the study. Changes in peak knee adduction moment, total Western Ontario and McMaster Universities (WOMAC), and WOMAC pain scores were assessed. Seventy-nine subjects were enrolled, and 55 completed the trial. Using an intention-to-treat analysis, the variable-stiffness shoes reduced the within-day peak knee adduction moment (-5.5%, p < 0.001) in the intervention subjects, while the constant-stiffness shoes increased the peak knee adduction moment in the control subjects (+3.1%, p = 0.015) at the 12-month visit. WOMAC pain and total scores for the intervention group were significantly reduced from baseline to 12 months (-32%, p = 0.002 and -35%, p = 0.007, respectively). The control group had a reduction of 27% in WOMAC pain score (p = 0.04) and no significant reduction in total WOMAC score. Reductions in WOMAC pain and total scores were similar between groups (p = 0.8 and p = 0.47, respectively). In the intervention group, reductions in adduction moment were related to improvements in pain and function (R(2)  = 0.11, p = 0.04). Analysis by disease severity revealed greater efficacy in adduction moment reduction in the less severe intervention group. While the long-term effects of the intervention shoes on pain and function did not differ from control, the data suggest wearing the intervention shoe reduces the within-day adduction moment after long-term wear, and thus should reduce loading on the affected medial compartment of the knee.

  View details for DOI 10.1002/jor.21563

  View details for Web of Science ID 000299935900002

  View details for PubMedID 21953877

• "Not statistically different" does not necessarily mean "the same": the important but underappreciated distinction between difference and equivalence studies. journal of bone and joint surgery. American volume Harris, A. H., Fernandes-Taylor, S., Giori, N. 2012; 94 (5)

  View details for DOI 10.2106/JBJS.K.00568

  View details for PubMedID 22398743

• Articular cartilage friction increases in hip joints after the removal of acetabular labrum JOURNAL OF BIOMECHANICS Song, Y., Ito, H., Kourtis, L., Safran, M. R., Carter, D. R., Giori, N. J. 2012; 45 (3): 524-530

  Abstract

  The acetabular labrum is believed to have a sealing function. However, a torn labrum may not effectively prevent joint fluid from escaping a compressed joint, resulting in impaired lubrication. We aimed to understand the role of the acetabular labrum in maintaining a low friction environment in the hip joint. We did this by measuring the resistance to rotation (RTR) of the hip, which reflects the friction of the articular cartilage surface, following focal and complete labrectomy. Five cadaveric hips without evidence of osteoarthritis and impingement were tested. We measured resistance to rotation of the hip joint during 0.5, 1, 2, and 3 times body weight (BW) cyclic loading in the intact hip, and after focal and complete labrectomy. Resistance to rotation, which reflects articular cartilage friction in an intact hip was significantly increased following focal labrectomy at 1-3 BW loading, and following complete labrectomy at all load levels. The acetabular labrum appears to maintain a low friction environment, possibly by sealing the joint from fluid exudation. Even focal labrectomy may result in increased joint friction, a condition that may be detrimental to articular cartilage and lead to osteoarthritis.

  View details for DOI 10.1016/j.jbiomech.2011.11.044

  View details for Web of Science ID 000300863600017

  View details for PubMedID 22176711

• EFFECT OF PARTIAL MEDIAL MENISCECTOMY ON THE INTERACTION BETWEEN PRIMARY AND SECONDARY KNEE MOTION DURING GAIT ASME Summer Bioengineering Conference (SBC) Edd, S. N., Netravali, N. A., Giori, N. J., Andriacchi, T. P. AMER SOC MECHANICAL ENGINEERS. 2012: 1061–1062

  View details for Web of Science ID 000325036600530

• Nine-Year Incidence of Kidney Disease in Patients Who Have Had Total Hip Arthroplasty JOURNAL OF ARTHROPLASTY Chandran, S. E., Giori, N. J. 2011; 26 (6): 24-27

  Abstract

  Metal-metal total hip arthroplasty (THA) is contraindicated in patients with impaired renal function due to increased metal ion output relative to other bearings and renal excretion of metal ions. Although one can avoid a metal-metal THA in a patient with renal disease, a patient may be destined to develop renal disease later in life. In this study, we sought to determine the incidence of newly diagnosed renal disease in the 9 years after THA. Using the Department of Veterans Affairs national database, we identified 1709 patients who had a primary THA in 2000 without preexisting renal disease. We found the 9-year risk of developing chronic renal disease after primary THA to be 14% and severe or end-stage renal disease to be 6%.

  View details for DOI 10.1016/j.arth.2011.03.016

  View details for Web of Science ID 000294393000006

  View details for PubMedID 21507606

• Changes in articular cartilage mechanics with meniscectomy: A novel image-based modeling approach and comparison to patterns of OA JOURNAL OF BIOMECHANICS Haemer, J. M., Song, Y., Carter, D. R., Giori, N. J. 2011; 44 (12): 2307-2312

  Abstract

  Meniscectomy is a significant risk factor for osteoarthritis, involving altered cell synthesis, central fibrillation, and peripheral osteophyte formation. Though changes in articular cartilage contact pressure are known, changes in tissue-level mechanical parameters within articular cartilage are not well understood. Recent imaging research has revealed the effects of meniscectomy on the time-dependent deformation of physiologically loaded articular cartilage. To determine tissue-level cartilage mechanics that underlie observed deformation, a novel finite element modeling approach using imaging data and a contacting indenter boundary condition was developed. The indenter method reproduces observed articular surface deformation and avoids assumptions about tangential stretching. Comparison of results from an indenter model with a traditional femur-tibia model verified the method, giving errors in displacement, solid and fluid stress, and strain below 1% (RMS) and 7% (max.) of the absolute maximum of the parameters of interest. Indenter finite element models using real joint image data showed increased fluid pressure, fluid exudation, loss of fluid load support, and increased tensile strains centrally on the tibial condyle after meniscectomy-patterns corresponding to clinical observations of cartilage matrix damage and fibrillation. Peripherally there was decreased consolidation, which corresponds to reduced contact and fluid pressure in this analysis. Clinically, these areas have exhibited advance of the subchondral growth front, biological destruction of the cartilage matrix, cartilage thinning, and eventual replacement of the cartilage via endochondral ossification. Characterizing the changes in cartilage mechanics with meniscectomy and correspondence with observed tissue-level effects may help elucidate the etiology of joint-level degradation seen in osteoarthritis.

  View details for DOI 10.1016/j.jbiomech.2011.04.014

  View details for Web of Science ID 000294033200019

  View details for PubMedID 21741046

• Strains Across the Acetabular Labrum During Hip Motion A Cadaveric Model AMERICAN JOURNAL OF SPORTS MEDICINE Safran, M. R., Giordano, G., Lindsey, D. P., Gold, G. E., Rosenberg, J., Zaffagnini, S., Giori, N. J. 2011; 39: 92S-102S

  Abstract

  Labral tears commonly cause disabling intra-articular hip pain and are commonly treated with hip arthroscopy. However, the function and role of the labrum are still unclear.(1) Flexion, adduction, and internal rotation (a position clinically defined as the position for physical examination known as the impingement test) places greatest circumferential strain on the anterolateral labrum and posterior labrum; (2) extension with external rotation (a position clinically utilized during physical examination to assess for posterior impingement and for anterior instability) places significant circumferential strains on the anterior labrum; (3) abduction with external rotation during neutral flexion-extension (the position the extremity rests in when a patient lies supine) places the greatest load on the lateral labrum.Descriptive laboratory study. Methods: Twelve cadaveric hips (age, 79 years) without labral tears or arthritis were studied. Hips were dissected free of soft tissues, except the capsuloligamentous structures. Differential variable reluctance transducers were placed in the labrum anteriorly, anterolaterally, laterally, and posteriorly to record circumferential strains in all 4 regions as the hip was placed in 36 different positions.The posterior labrum had the greatest circumferential strains identified; the peak was in the flexed position, in adduction or neutral abduction-adduction. The greatest strains anteriorly were in flexion with adduction. The greatest strains anterolaterally were in full extension. External rotation had greater strains than neutral rotation and internal rotation. The greatest strains laterally were at 90° of flexion with abduction, and external or neutral rotation. In the impingement position, the anterolateral strain increased the most, while the posterior labrum showed decreased strain (greatest magnitude of strain change). When the hip is externally rotated and in neutral flexion-extension or fully extended, the posterior labrum has significantly increased strain, while the anterolateral labrum strain is decreased.These are the first comprehensive strain data (of circumferential strain) analyzing the whole hip labrum. For the intact labrum, the greatest strain change was at the posterior acetabulum, whereas clinically, acetabular labral tears occur most frequently anterolaterally or anteriorly. The results are consistent with the impingement test as an assessment of anterolateral acetabular labral stress. The hyperextension-rotation test, often used clinically to assess anterior hip instability and posterior impingement, did not show a change in strain anteriorly, but did reveal an increase in strain posteriorly.Although this study does not include muscular forces across the hip joint, it does provide a clue as to the stresses about the labrum through the complete range of motions of the hip, which may help in providing a better understanding of the cause of labral tears and in the protection of labral repairs.

  View details for DOI 10.1177/0363546511414017

  View details for Web of Science ID 000292167400014

  View details for PubMedID 21709038

• An Anatomic Arthroscopic Description of the Hip Capsular Ligaments for the Hip Arthroscopist ARTHROSCOPY-THE JOURNAL OF ARTHROSCOPIC AND RELATED SURGERY Telleria, J. J., Lindsey, D. P., Giori, N. J., Safran, M. R. 2011; 27 (5): 628-636

  Abstract

  To examine and describe the normal anatomic intra-articular locations of the hip capsular ligaments in the central and peripheral compartments of the hip joint.Eight paired fresh-frozen human cadaveric hips (mean age, 73.3 years) were carefully dissected free of soft tissue to expose the hip capsule. Needles were placed through the capsule along the macroscopic borders of the hip capsular ligaments. Arthroscopy was performed on each hip, and the relations of the needles, and thus the ligaments, to the arthroscopic portals and other soft-tissue and osseous landmarks in the hip were recorded by use of a clock-face reference system.The iliofemoral ligament (ILFL) ran from 12:45 to 3 o'clock. The ILFL was pierced by the anterolateral and anterior portals just within its lateral and medial borders, respectively. The pubofemoral ligament was located from the 3:30 to the 5:30 clock position; the lateral border was at the psoas-U perimeter, and the medial border was at the junction of the anteroinferior acetabulum and the cotyloid fossa. The ischiofemoral ligament (ISFL) ran from the 7:45 to the 10:30 clock position. The posterolateral portal pierced the ISFL just inside its superior/lateral border, and the inferior/lateral border was located at the posteroinferior acetabulum. In the peripheral compartment the lateral ILFL and superior/lateral ISFL borders were in proximity to the lateral synovial fold. The medial ILFL and lateral pubofemoral ligament borders were closely approximated to the medial synovial fold.The hip capsular ligaments have distinct and consistent arthroscopic locations within the hip joint and are associated with clearly identifiable landmarks in the central and peripheral compartments. The standard hip arthroscopy portals are closely related to the borders of the hip capsular ligaments.These findings will help orthopaedic surgeons know which structures are being addressed during arthroscopic surgery and may help in the development of future hip procedures.

  View details for DOI 10.1016/j.arthro.2011.01.007

  View details for Web of Science ID 000289557700006

  View details for PubMedID 21663720

• Local infiltration analgesia in TKA patients reduces length of stay and postoperative pain scores. Orthopedics Tripuraneni, K. R., Woolson, S. T., Giori, N. J. 2011; 34 (3): 173-?

  Abstract

  Numerous postoperative pain protocols exist for patients undergoing total knee arthroplasty (TKA). We compared the length of stay, early range of motion (ROM), and pain scores of a control group with a femoral nerve block to those of a group with femoral nerve block and local infiltration analgesia following TKA. In a consecutive series of patients undergoing primary TKA at a Veteran's Administration hospital, 40 patients (40 TKAs) who had local infiltration analgesia were compared to a historical group of 43 patients (43 TKAs) who had a long-acting femoral nerve block without local infiltration analgesia. Local infiltration analgesia consisted of intraoperative injection of 150 mL of 300 mg ropivacaine, 30 mg ketorolac, and 500 μg epinephrine using 50 mL into each of 3 areas: (1) posterior capsule, (2) medial and lateral capsule, and (3) anterior capsule and subcutaneous tissues. A 17-gauge intra-articular catheter was used to inject an additional 100 mg of ropivacaine on postoperative day 1. The control group had a single-shot femoral nerve block using 150 mg of ropivacaine with epinephrine. Mean length of stay for the local infiltration analgesia group compared to controls was 3.2±1.4 days vs 3.8±1.6 days, respectively (P=.03). No significant differences existed in average ROM (6 weeks), discharge hematocrit, transfusions, and temperature. Mean pain scores were lower in the local infiltration analgesia group on postoperative day 1 (P=.04), but not on postoperative day 2 or 3. Maximum visual analog scale scores (P<.01) were reduced in the local infiltration analgesia group. Our early experience with local infiltration analgesia demonstrated a significantly reduced length of stay due to decreased postoperative pain.

  View details for DOI 10.3928/01477447-20110124-11

  View details for PubMedID 21410125

• Local Infiltration Analgesia in TKA Patients Reduces Length of Stay and Postoperative Pain Scores ORTHOPEDICS Tripuraneni, K. R., Woolson, S. T., Giori, N. J. 2011; 34 (3)

  Abstract

  Numerous postoperative pain protocols exist for patients undergoing total knee arthroplasty (TKA). We compared the length of stay, early range of motion (ROM), and pain scores of a control group with a femoral nerve block to those of a group with femoral nerve block and local infiltration analgesia following TKA. In a consecutive series of patients undergoing primary TKA at a Veteran's Administration hospital, 40 patients (40 TKAs) who had local infiltration analgesia were compared to a historical group of 43 patients (43 TKAs) who had a long-acting femoral nerve block without local infiltration analgesia. Local infiltration analgesia consisted of intraoperative injection of 150 mL of 300 mg ropivacaine, 30 mg ketorolac, and 500 μg epinephrine using 50 mL into each of 3 areas: (1) posterior capsule, (2) medial and lateral capsule, and (3) anterior capsule and subcutaneous tissues. A 17-gauge intra-articular catheter was used to inject an additional 100 mg of ropivacaine on postoperative day 1. The control group had a single-shot femoral nerve block using 150 mg of ropivacaine with epinephrine. Mean length of stay for the local infiltration analgesia group compared to controls was 3.2±1.4 days vs 3.8±1.6 days, respectively (P=.03). No significant differences existed in average ROM (6 weeks), discharge hematocrit, transfusions, and temperature. Mean pain scores were lower in the local infiltration analgesia group on postoperative day 1 (P=.04), but not on postoperative day 2 or 3. Maximum visual analog scale scores (P<.01) were reduced in the local infiltration analgesia group. Our early experience with local infiltration analgesia demonstrated a significantly reduced length of stay due to decreased postoperative pain.

  View details for DOI 10.3928/01477447-20110124-11

  View details for Web of Science ID 000209016700005

• Preoperative alcohol screening scores: association with complications in men undergoing total joint arthroplasty. journal of bone and joint surgery. American volume Harris, A. H., Reeder, R., Ellerbe, L., Bradley, K. A., Rubinsky, A. D., Giori, N. J. 2011; 93 (4): 321-327

  Abstract

  The risks associated with preoperative alcohol misuse by patients before undergoing total joint arthroplasty are not well known, yet alcohol misuse by surgical patients is common and has been linked to an increased risk of complications after other procedures. The purpose of this study was to evaluate the association between a patient's preoperative standardized alcohol-misuse screening score and his or her risk of complications after total joint arthroplasty.The Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) is an alcohol-misuse screening instrument administered annually to all patients receiving care through the Veterans Health Administration (VHA). The scores range from 0 to 12, with higher scores signifying greater and more frequent consumption. In a study of 185 male patients who had alcohol screening scores recorded in the year preceding surgery at a Palo Alto VHA facility, and who reported at least some alcohol use, we estimated the association between preoperative screening scores and the number of surgical complications in an age and comorbidity-adjusted regression analyses.Of the 185 patients reporting at least some drinking in the year before their total joint replacement, 17% (thirty-two) had an alcohol screening score suggestive of alcohol misuse; six of those thirty-two patients had one complication, four had two complications, and two had three complications. The screening scores were significantly related to the number of complications in a negative binomial regression analysis (exp[β] = 1.29, p = 0.035), which demonstrated a 29% increase in the expected number of complications with every additional point of the screening score above 1, although with wide confidence intervals for the higher scores.Complications following total joint arthroplasty were significantly related to alcohol misuse in this group of male patients treated at a VHA facility. The AUDIT-C has three simple questions that can be incorporated into a preoperative evaluation and can alert the treatment team to patients with increased postoperative risk. Preoperative screening for alcohol misuse, and perhaps preoperative counseling or referral to treatment for heavy drinkers, may be indicated for patients who are to undergo total joint arthroplasty.

  View details for DOI 10.2106/JBJS.I.01560

  View details for PubMedID 21325583

• Preoperative Alcohol Screening Scores: Association with Complications in Men Undergoing Total Joint Arthroplasty JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Harris, A. H., Reeder, R., Ellerbe, L., Bradley, K. A., Rubinsky, A. D., Giori, N. J. 2011; 93A (4): 321-327

  Abstract

  The risks associated with preoperative alcohol misuse by patients before undergoing total joint arthroplasty are not well known, yet alcohol misuse by surgical patients is common and has been linked to an increased risk of complications after other procedures. The purpose of this study was to evaluate the association between a patient's preoperative standardized alcohol-misuse screening score and his or her risk of complications after total joint arthroplasty.The Alcohol Use Disorders Identification Test-Consumption (AUDIT-C) is an alcohol-misuse screening instrument administered annually to all patients receiving care through the Veterans Health Administration (VHA). The scores range from 0 to 12, with higher scores signifying greater and more frequent consumption. In a study of 185 male patients who had alcohol screening scores recorded in the year preceding surgery at a Palo Alto VHA facility, and who reported at least some alcohol use, we estimated the association between preoperative screening scores and the number of surgical complications in an age and comorbidity-adjusted regression analyses.Of the 185 patients reporting at least some drinking in the year before their total joint replacement, 17% (thirty-two) had an alcohol screening score suggestive of alcohol misuse; six of those thirty-two patients had one complication, four had two complications, and two had three complications. The screening scores were significantly related to the number of complications in a negative binomial regression analysis (exp[β] = 1.29, p = 0.035), which demonstrated a 29% increase in the expected number of complications with every additional point of the screening score above 1, although with wide confidence intervals for the higher scores.Complications following total joint arthroplasty were significantly related to alcohol misuse in this group of male patients treated at a VHA facility. The AUDIT-C has three simple questions that can be incorporated into a preoperative evaluation and can alert the treatment team to patients with increased postoperative risk. Preoperative screening for alcohol misuse, and perhaps preoperative counseling or referral to treatment for heavy drinkers, may be indicated for patients who are to undergo total joint arthroplasty.

  View details for DOI 10.2106/JBJSJ.01560

  View details for Web of Science ID 000287570300001

• Acetabular Component Positioning Using the Transverse Acetabular Ligament Can You Find It and Does It Help? 77th Annual Meeting of the American-Academy-of-Orthopaedic-Surgeons (AAOS) Epstein, N. J., Woolson, S. T., Giori, N. J. SPRINGER. 2011: 412–16

  Abstract

  Several studies have reported that the transverse acetabular ligament (TAL) can be used to orient the acetabular component during total hip arthroplasty and that it can be identified in nearly all patients.We attempted to determine how often the TAL could be identified during primary THA and its accuracy as a guide for acetabular component positioning.In a prospective series of 63 patients (64 hips) undergoing primary THA, two surgeons attempted to identify the TAL and, if it was found, to use it for acetabular component orientation. Patients in whom the TAL was identified served as the study group and the ligament was used for cup orientation in those patients; the remaining patients in whom the ligament could not be identified served as a control group and had free-hand cup positioning. Anteversion was determined by radiographic measurement from true lateral views.The TAL was identified in only 30 hips (47%) and was more likely to be found in patients who did not have inferior acetabular osteophytes. Acetabular position was not improved using this ligament for reference.The TAL could not be routinely identified at surgery and when used for cup orientation it was no more accurate for cup positioning than free-hand technique.

  View details for DOI 10.1007/s11999-010-1523-1

  View details for Web of Science ID 000286939300013

  View details for PubMedID 20737303

  View details for PubMedCentralID PMC3018210

• Femoral Fracture After Harvesting of Autologous Bone Graft Using a Reamer/Irrigator/Aspirator JOURNAL OF ORTHOPAEDIC TRAUMA Giori, N. J., Beaupre, G. S. 2011; 25 (2): E12-E14

  Abstract

  A case of postoperative fracture in the donor femur after obtaining autologous bone graft with a reamer/irrigator/aspirator is presented. This procedure was successful in healing a difficult femoral nonunion, but the patient sustained a fracture of the contralateral (bone graft donor) femur 20 days after surgery. A mechanical analysis is conducted of this case and recommendations are made. Unrestricted weightbearing on a limb that has undergone reamer/irrigator/aspirator bone graft harvesting, particularly in a noncompliant patient, is probably inadvisable. If possible, one should obtain bone graft from the same limb as the fracture being treated because this will leave the patient with one unaltered limb for mobilization.

  View details for DOI 10.1097/BOT.0b013e3181e39bf4

  View details for Web of Science ID 000286375000001

  View details for PubMedID 21245702

• The Effect of Kinematic and Kinetic Changes on Meniscal Strains During Gait JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME Netravali, N. A., Koo, S., Giori, N. J., Andriacchi, T. P. 2011; 133 (1)

  Abstract

  The menisci play an important role in load distribution, load bearing, joint stability, lubrication, and proprioception. Partial meniscectomy has been shown to result in changes in the kinematics and kinetics at the knee during gait that can lead to progressive meniscal degeneration. This study examined changes in the strains within the menisci associated with kinematic and kinetic changes during the gait cycle. The gait changes considered were a 5 deg shift toward external rotation of the tibia with respect to the femur and an increased medial-lateral load ratio representing an increased adduction moment. A finite element model of the knee was developed and tested using a cadaveric specimen. The cadaver was placed in positions representing heel-strike and midstance of the normal gait, and magnetic resonance images were taken. Comparisons of the model predictions to boundaries digitized from images acquired in the loaded states were within the errors produced by a 1 pixel shift of either meniscus. The finite element model predicted that an increased adduction moment caused increased strains of both the anterior and posterior horns of the medial meniscus. The lateral meniscus exhibited much lower strains and had minimal changes under the various loading conditions. The external tibial rotational change resulted in a 20% decrease in the strains in the posterior medial horn and increased strains in the anterior medial horn. The results of this study suggest that the shift toward external tibial rotation seen clinically after partial medial meniscectomy is not likely to cause subsequent degenerative medial meniscal damage, but the consequence of this kinematic shift on the pathogenesis of osteoarthritis following meniscectomy requires further consideration.

  View details for DOI 10.1115/1.4003008

  View details for Web of Science ID 000285767600006

  View details for PubMedID 21186896

• Lateral and High-Angle Oblique Radiographs of the Pelvis Aid in Diagnosing Pelvic Discontinuity After Total Hip Arthroplasty JOURNAL OF ARTHROPLASTY Giori, N. J., Sidky, A. O. 2011; 26 (1): 110-112

  Abstract

  Diagnosis of a pelvic discontinuity before revision total hip arthroplasty is critical for adequate preoperative planning. The lateral view of the pelvis or high-angle oblique views can aid in visualizing the posterior column when hip hardware obscures the view on standard anteroposterior and Judet views of the pelvis. These views are easy to obtain and can provide valuable information when planning revision total hip arthroplasty.

  View details for DOI 10.1016/j.arth.2009.12.006

  View details for Web of Science ID 000286286200018

  View details for PubMedID 20206468

• Bioabsorbable Tricalcium Phosphate Bone Cement Strengthens Fixation of Suture Anchors CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Oshtory, R., Lindsey, D. P., Giori, N. J., Mirza, F. M. 2010; 468 (12): 3406-3412

  Abstract

  Failure of suture anchor fixation in rotator cuff repair can occur at different interfaces. Prior studies show fixation at the bone-anchor interface can be augmented using polymethylmethacrylate (PMMA) cement, and screw fixation into bone can be strengthened using bioabsorbable tricalcium phosphate cement.We wished to determine whether augmentation of suture anchor fixation using bioabsorbable tricalcium phosphate cement would increase pullout strength of suture anchors from bone and the number of cycles to failure, to determine the mode of failure after cement augmentation, and to compare strength and mode of failure with those after augmentation with PMMA.We used 10 matched pairs of cadaveric proximal humeri and implanted a metal screw-type suture anchor in one side and on the other side injected tricalcium phosphate cement into the anchor holes before anchor placement. We tested all specimens to failure using a ramped cyclic loading protocol.Tricalcium phosphate cement augmentation increased the final load to failure by 29% and the number of cycles to failure by 20%. Visual inspection confirmed that failure occurred at the cement-bone interface.Tricalcium phosphate cement appears to augment suture anchor fixation into bone, reducing the risk of anchor pullout and failure.When relying on suture anchor fixation in bone of questionable quality, we suggest considering augmentation of suture anchor fixation with bioabsorbable cement. This method also provides potential for bioabsorbability and may be more amenable to arthroscopic application.

  View details for DOI 10.1007/s11999-010-1412-7

  View details for Web of Science ID 000288440700037

  View details for PubMedID 20521128

  View details for PubMedCentralID PMC2974857

• Partial medial meniscectomy and rotational differences at the knee during walking JOURNAL OF BIOMECHANICS Netravali, N. A., Giori, N. J., Andriacchi, T. P. 2010; 43 (15): 2948-2953

  Abstract

  Loss of meniscal function due to injury or partial meniscectomy is common and represents a significant risk factor for premature osteoarthritis. The menisci can influence the transverse plane movements (anterior-posterior (AP) translation and internal-external (IE) rotation) of the knee during walking. While walking is the most frequent activity of daily living, the kinematic differences at the knee during walking associated with the meniscal injury are not well understood. This study examined the influence of partial medial meniscectomy (PMM) on the kinematics and kinetics of the knee during the stance phase of gait by testing the differences in anterior-posterior translation, internal-external rotation, knee flexion range of movement, peak flexion/extension moments, and adduction moments between the PMM and healthy contralateral limbs. Ten patients (45±9 years old, height 1.75±0.06m, weight 76.7±13.5kg) who had undergone partial medial meniscectomy (33±100 months post-op) in one limb with a healthy contralateral limb were tested during normal walking. The contralateral limb was compared to a matched control group and no differences were found. The primary kinematic difference was a significantly greater external rotation (3.2°) of the tibia that existed through stance phase, with 8 of 10 subjects demonstrating the same pattern. The PMM subjects also exhibited significantly lower peak flexion and extension moments in their PMM limbs. The altered rotational position found likely results in changes of tibio-femoral contact during walking and could cause the type of degenerative changes found in the articular cartilage following meniscal injury.

  View details for DOI 10.1016/j.jbiomech.2010.07.013

  View details for Web of Science ID 000285122900013

  View details for PubMedID 20719317

• Incidence of radiographic unicompartmental arthritis in patients undergoing knee arthroplasty. Orthopedics Woolson, S. T., Shu, B., Giori, N. J. 2010; 33 (11): 798-?

  Abstract

  Unicompartmental knee arthroplasty is increasing in popularity with the advent of less invasive procedures for knee arthritis. The percentage of patients undergoing knee arthroplasty who could be candidates for unicompartmental knee arthroplasty depends on the surgeon's evaluation of the radiographs, and this evaluation may depend on the surgeon's bias regarding partial knee arthroplasty. A retrospective radiographic and chart review was performed on a consecutive series of patients who had undergone tricompartmental knee arthroplasty to determine the percentage of those patients who could have been candidates for unicompartmental knee arthroplasty. Two hundred eighty-eight patients who underwent 308 tricompartmental knee arthroplasties over a 3-year period at a Veteran's Administration Hospital comprised the study group. Assessment of preoperative radiographs was done by 2 surgeons, 1 who favored unicompartmental knee arthroplasty and the other who preferred tricompartmental knee arthroplasty, to determine the percentage of these patients, from each surgeon's viewpoint, who had unicompartmental arthritis. Patients who had radiographic unicompartmental arthritis were then eliminated as candidates for unicompartmental knee arthroplasty, if, on chart review, they had a flexion contracture >10°, an arc of motion <100°, or inflammatory arthritis. The surgeon who was a proponent of unicompartmental knee arthroplasty found that 26% of these patients had acceptable radiologic and clinical indications for unicompartmental knee arthroplasty, whereas the surgeon who had a bias against the procedure felt that only 12% of these patients were unicompartmental knee arthroplasty candidates. A considerable percentage of Veteran's Administration patients undergoing arthroplasty for knee arthritis may be potential candidates for unicompartmental knee arthroplasty, despite the surgeon's bias for or against the procedure.

  View details for DOI 10.3928/01477447-20100924-07

  View details for PubMedID 21053889

• Rotational References for Total Knee Arthroplasty Tibial Components Change with Level of Resection CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Graw, B. P., Harris, A. H., Tripuraneni, K. R., Giori, N. J. 2010; 468 (10): 2734-2738

  Abstract

  Various landmarks can guide tibial component rotational alignment in routine TKA, but with the deeper tibial resection levels common in complex primary and revision TKAs, it is unknown whether these landmarks remain reliable.We asked whether three techniques for determining tibial component rotation based on local anatomic landmarks are reliable deeper tibial resection levels.The femoral transepicondylar axis was identified by three independent reviewers on MR images of knees from 24 men and 24 women and transposed at a traditional tibial resection level and at the level of the proximal, middle, and distal parts of the proximal tibiofibular joint. Three axes were drawn on axial slices at these levels: the geometric center of the tibial plateau to the medial 1/3 of the tubercle, the posterior condylar line of the tibia, and the largest mediolateral dimension of the tibia. These lines were compared with the transposed femoral epicondylar axis line.The posterior condylar line of the tibia is the least variable local landmark for tibial component positioning at deep resection levels.Assuming the normal posterior condylar line of the tibia is visible at revision, setting the tibial component at 10° external rotation with respect to the posterior condylar axis of the tibia gets the tibial component within 10° of proper rotation in 86% to 98% of patients, even to the distal part of the proximal tibiofibular joint. The experienced surgeon then can adjust this position based on cues from an assortment of other axes.

  View details for DOI 10.1007/s11999-010-1330-8

  View details for Web of Science ID 000281843200024

  View details for PubMedID 20352384

  View details for PubMedCentralID PMC3049615

• Changes in knee adduction moment, pain, and functionality with a variable-stiffness walking shoe after 6 months. Journal of orthopaedic research Erhart, J. C., Mündermann, A., Elspas, B., Giori, N. J., Andriacchi, T. P. 2010; 28 (7): 873-879

  Abstract

  This study tested the effects of variable-stiffness shoes on knee adduction moment, pain, and function in subjects with symptoms of medial compartment knee osteoarthritis over 6 months. Patients were randomly and blindly assigned to a variable-stiffness intervention or constant-stiffness control shoe. The Western Ontario and McMaster Universities (WOMAC) score served as the primary outcome measure. Joint loading, the secondary outcome measure, was assessed using the external knee adduction moment. Peak external knee adduction moment, total WOMAC, and WOMAC pain scores were assessed at baseline and after 6 months. The total WOMAC and WOMAC pain scores for the intervention group were reduced from baseline to 6 months (p = 0.017 and p = 0.002, respectively), with no significant reductions for the control group. There was no difference between groups in magnitude of the reduction in total WOMAC (p = 0.50) or WOMAC pain scores (p = 0.31). The proportion of patients achieving a clinically important improvement in pain was greater in the intervention group than in the control group (p = 0.012). The variable-stiffness shoes reduced the peak knee adduction moment (-6.6% vs. control, p < 0.001) in the 34 intervention subjects at 6 months. The adduction moment reduction significantly improved (p = 0.03) from the baseline reduction. The constant-stiffness control shoe increased the peak knee adduction moment (+6.3% vs. personal, p = 0.004) in the 26 control subjects at 6 months. The results of this study showed that wearing the variable-stiffness shoe lowered the adduction moment, reduced pain, and improved functionality after 6 months of wear. The lower adduction moment associated with wearing this shoe may slow the rate of progression of osteoarthritis after long-term use.

  View details for DOI 10.1002/jor.21077

  View details for PubMedID 20058261

• Changes in Knee Adduction Moment, Pain, and Functionality with a Variable-Stiffness Walking Shoe after 6 Months JOURNAL OF ORTHOPAEDIC RESEARCH Erhart, J. C., Muendermann, A., Elspas, B., Giori, N. J., Andriacchi, T. P. 2010; 28 (7): 873-879

  Abstract

  This study tested the effects of variable-stiffness shoes on knee adduction moment, pain, and function in subjects with symptoms of medial compartment knee osteoarthritis over 6 months. Patients were randomly and blindly assigned to a variable-stiffness intervention or constant-stiffness control shoe. The Western Ontario and McMaster Universities (WOMAC) score served as the primary outcome measure. Joint loading, the secondary outcome measure, was assessed using the external knee adduction moment. Peak external knee adduction moment, total WOMAC, and WOMAC pain scores were assessed at baseline and after 6 months. The total WOMAC and WOMAC pain scores for the intervention group were reduced from baseline to 6 months (p = 0.017 and p = 0.002, respectively), with no significant reductions for the control group. There was no difference between groups in magnitude of the reduction in total WOMAC (p = 0.50) or WOMAC pain scores (p = 0.31). The proportion of patients achieving a clinically important improvement in pain was greater in the intervention group than in the control group (p = 0.012). The variable-stiffness shoes reduced the peak knee adduction moment (-6.6% vs. control, p < 0.001) in the 34 intervention subjects at 6 months. The adduction moment reduction significantly improved (p = 0.03) from the baseline reduction. The constant-stiffness control shoe increased the peak knee adduction moment (+6.3% vs. personal, p = 0.004) in the 26 control subjects at 6 months. The results of this study showed that wearing the variable-stiffness shoe lowered the adduction moment, reduced pain, and improved functionality after 6 months of wear. The lower adduction moment associated with wearing this shoe may slow the rate of progression of osteoarthritis after long-term use.

  View details for DOI 10.1002/jor.21077

  View details for Web of Science ID 000278654500006

• Unexpected finding of a fractured metal prosthetic femoral head in a nonmodular implant during revision total hip arthroplasty. journal of arthroplasty Giori, N. J. 2010; 25 (4): 659 e13-5

  Abstract

  Though there are many reports of fractured femoral components after total hip arthroplasty; there are no reports of a fractured metal femoral head. This is a report of a fractured metal femoral head in a nonmodular total hip replacement discovered unexpectedly during revision total hip arthroplasty for acetabular failure. This surprise finding, which was not appreciated on preoperative x-rays, required unplanned extraction of a well-ingrown, fully porous coated cylindrical femoral stem. Though rare, fracture of the metal femoral head in a DePuy (Warsaw, Ind.) monoblock Anatomic Medullary Locking (AML) component is possible, and one cannot expect the fracture to be apparent on preoperative radiographs as the 2 pieces may not necessarily dissociate. As usual, the surgeon performing revision arthroplasty should be prepared to revise all components.

  View details for DOI 10.1016/j.arth.2009.02.022

  View details for PubMedID 20022458

• Single column locking plate fixation is inadequate in two column acetabular fractures. A biomechanical analysis. Journal of orthopaedic surgery and research Khajavi, K., Lee, A. T., Lindsey, D. P., Leucht, P., Bellino, M. J., Giori, N. J. 2010; 5: 30-?

  Abstract

  The objective of this study was to determine whether one can achieve stable fixation of a two column (transverse) acetabular fracture by only fixing a single column with a locking plate and unicortical locking screws. We hypothesized that a locking plate applied to the anterior column of a transverse acetabular fracture would create a construct that is more rigid than a non-locking plate, and that this construct would be biomechanically comparable to two column fixation.Using urethane foam models of the pelvis, we simulated transverse acetabular fractures and stabilized them with 1) an anterior column plate with bicortical screws, 2) an anterior locking plate with unicortical screws, 3) an anterior plate and posterior column lag screw, and 4) a posterior plate with an anterior column lag screw. These constructs were mechanically loaded on a servohydraulic material testing machine. Construct stiffness and fracture displacement were measured.We found that two column fixation is 54% stiffer than a single column fixation with a conventional plate with bicortical screws. There was no significant difference between fixation with an anterior column locking plate with unicortical screws and an anterior plate with posterior column lag screw. We detected a non-significant trend towards more stiffness for the anterior locking plate compared to the anterior non-locking plate.In conclusion, a locking plate construct of the anterior column provides less stability than a traditional both column construct with posterior plate and anterior column lag screw. However, the locking construct offers greater strength than a non-locking, bicortical construct, which in addition often requires extensive contouring and its application is oftentimes accompanied by the risk of neurovascular damage.

  View details for DOI 10.1186/1749-799X-5-30

  View details for PubMedID 20459688

• Single column locking plate fixation is inadequate in two column acetabular fractures. A biomechanical analysis JOURNAL OF ORTHOPAEDIC SURGERY AND RESEARCH Khajavi, K., Lee, A. T., Lindsey, D. P., Leucht, P., Bellino, M. J., Giori, N. J. 2010; 5

  Abstract

  The objective of this study was to determine whether one can achieve stable fixation of a two column (transverse) acetabular fracture by only fixing a single column with a locking plate and unicortical locking screws. We hypothesized that a locking plate applied to the anterior column of a transverse acetabular fracture would create a construct that is more rigid than a non-locking plate, and that this construct would be biomechanically comparable to two column fixation.Using urethane foam models of the pelvis, we simulated transverse acetabular fractures and stabilized them with 1) an anterior column plate with bicortical screws, 2) an anterior locking plate with unicortical screws, 3) an anterior plate and posterior column lag screw, and 4) a posterior plate with an anterior column lag screw. These constructs were mechanically loaded on a servohydraulic material testing machine. Construct stiffness and fracture displacement were measured.We found that two column fixation is 54% stiffer than a single column fixation with a conventional plate with bicortical screws. There was no significant difference between fixation with an anterior column locking plate with unicortical screws and an anterior plate with posterior column lag screw. We detected a non-significant trend towards more stiffness for the anterior locking plate compared to the anterior non-locking plate.In conclusion, a locking plate construct of the anterior column provides less stability than a traditional both column construct with posterior plate and anterior column lag screw. However, the locking construct offers greater strength than a non-locking, bicortical construct, which in addition often requires extensive contouring and its application is oftentimes accompanied by the risk of neurovascular damage.

  View details for DOI 10.1186/1749-799X-5-30

  View details for Web of Science ID 000208386400030

  View details for PubMedCentralID PMC2876138

• Accuracy of 3D Cartilage Models Generated From MR Images Is Dependent on Cartilage Thickness: Laser Scanner Based Validation of In Vivo Cartilage JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME Koo, S., Giori, N. J., Gold, G. E., Dyrby, C. O., Andriacchi, T. P. 2009; 131 (12)

  Abstract

  Cartilage morphology change is an important biomarker for the progression of osteoarthritis. The purpose of this study was to assess the accuracy of in vivo cartilage thickness measurements from MR image-based 3D cartilage models using a laser scanning method and to test if the accuracy changes with cartilage thickness. Three-dimensional tibial cartilage models were created from MR images (in-plane resolution of 0.55 mm and thickness of 1.5 mm) of osteoarthritic knees of ten patients prior to total knee replacement surgery using a semi-automated B-spline segmentation algorithm. Following surgery, the resected tibial plateaus were laser scanned and made into 3D models. The MR image and laser-scan based models were registered to each other using a shape matching technique. The thicknesses were compared point wise for the overall surface. The linear mixed-effects model was used for statistical test. On average, taking account of individual variations, the thickness measurements in MRI were overestimated in thinner (<2.5 mm) regions. The cartilage thicker than 2.5 mm was accurately predicted in MRI, though the thick cartilage in the central regions was underestimated. The accuracy of thickness measurements in the MRI-derived cartilage models systemically varied according to native cartilage thickness.

  View details for DOI 10.1115/1.4000087

  View details for Web of Science ID 000273614400004

  View details for PubMedID 20524727

  View details for PubMedCentralID PMC3072833

• Relationship Between Dental Caries and Total Joint Arthroplasty at a Veterans Administration Hospital ORTHOPAEDIC NURSING Green-Riviere, E., Giori, N. 2009; 28 (6): 302-304

  Abstract

  It has previously been suspected that patients who undergo extensive dental procedures after having had a total joint arthroplasty (TJA) within the preceding 2 years may be at risk for seeding their TJA with infection if prophylaxis antibiotic coverage is not implemented one hour prior to the dental procedure. A review of the literature was performed to determine whether there may be other infections which may be accountable for TJA infections within the first 2 years following a TJA. Patients with systemic diseases, those who undergo extensive dental procedures, those with bladder or skin infection were found to be at risk for development of a TJA if prophylactic antibiotic therapy was not implemented in a timely manner.

  View details for Web of Science ID 000272627400005

  View details for PubMedID 20016347

• The Proximal Hip Joint Capsule and the Zona Orbicularis Contribute to Hip Joint Stability in Distraction JOURNAL OF ORTHOPAEDIC RESEARCH Ito, H., Song, Y., Lindsey, D. P., Safran, M. R., Giori, N. J. 2009; 27 (8): 989-995

  Abstract

  The structure and function of the proximal hip joint capsule and the zona orbicularis are poorly understood. We hypothesized that the zona orbicularis is an important contributor to hip stability in distraction. In seven cadaveric hip specimens from seven male donors we distracted the femur from the acetabulum in a direction parallel to the femoral shaft with the hip in the neutral position. Eight sequential conditions were assessed: (1) intact specimen (muscle and skin removed), (2) capsule vented, (3) incised iliofemoral ligament, (4) circumferentially incised capsule, (5) partially resected capsule (distal to the zona orbicularis), (6) completely resected capsule, (7) radially incised labrum, and (8) completely resected labrum. The reduction of the distraction load was greatest between the partially resected capsule phase and completely resected capsule phase at 1, 3, and 5 mm joint distraction (p = 0.018). The proximal to middle part of the capsule, which includes the zona orbicularis, appears grossly and biomechanically to act as a locking ring wrapping around the neck of the femur and is a key structure for hip stability in distraction.

  View details for DOI 10.1002/jor.20852

  View details for Web of Science ID 000267848200002

  View details for PubMedID 19148941

• Timing of Tourniquet Release in Total Knee Arthroplasty When Using a Postoperative Blood Salvage Drain JOURNAL OF ARTHROPLASTY Steffin, B., Green-Riviere, E., Giori, N. J. 2009; 24 (4): 539-542

  Abstract

  The purpose of this study is to examine the effect of a postoperative blood salvage drain and timing of tourniquet release on the maximal hematocrit drop after total knee arthroplasty. Thirty-seven total knees were prospectively randomized into either an early or late tourniquet release group. Hematocrit drop and drainage amounts were recorded. We found no significant difference in maximal hematocrit drop, drainage amounts, or total surgical time between the groups. We conclude that the use of a blood salvage drain should not influence the surgeon's preference on timing of tourniquet release in total knee arthroplasty.

  View details for DOI 10.1016/j.arth.2008.01.302

  View details for Web of Science ID 000266846500008

  View details for PubMedID 18534405

• MENISCAL MOVEMENT DURING THE GAIT CYCLE IS SENSITIVE TO THE ATTACHMENT PROPERTIES OF THE MENISCAL HORNS ASME Summer Bioengineering Conference Netravali, N. A., Giori, N. J., Andriacchi, T. P. AMER SOC MECHANICAL ENGINEERS. 2009: 981–982

  View details for Web of Science ID 000280089000491

• REGIONAL CARTILAGE THINNING OCCURS FIRST IN THE WALKING WEIGHT BEARING REGIONS OF THE FEMUR IN MEDIAL COMPARTMENT KNEE OSTEOARTHRITIS ASME Summer Bioengineering Conference Erhart, J. C., Muendermann, A., Koo, S., Merrick, B., Deagon, A., Giori, N. J., Andriacchi, T. P. AMER SOC MECHANICAL ENGINEERS. 2009: 835–836

  View details for Web of Science ID 000263364700418

• Meniscectomy alters the dynamic deformational behavior and cumulative strain of tibial articular cartilage in knee joints subjected to cyclic loads OSTEOARTHRITIS AND CARTILAGE Song, Y., Greve, J. M., Carter, D. R., Giori, N. J. 2008; 16 (12): 1545-1554

  Abstract

  Meniscectomy-induced osteoarthritis may be mechanically based. We asked how meniscectomy alters time-dependent deformation of physiologically loaded articular cartilage. We hypothesized that meniscectomy alters nominal strain in tibial articular cartilage, and that meniscectomy affects cartilage thickness recovery following cessation of loading.A cyclic load simulating normal gait was applied to four sheep knees. A custom device was used to obtain MR images of cartilage at 4.7T during cyclic loading. Articular cartilage thickness and nominal strain were measured every 2.5 min during 1h of cyclic loading, and during 2.5h after cessation of loading.Following meniscectomy the loaded joints rapidly developed high strain centrally and minimal strain peripherally. Maximum nominal strains after 1h of loading were about 55% in the intact knees and 72% in the meniscectomized knees. Nominal strains in the peripheral tibial cartilage were significantly reduced in the meniscectomized knees. Strain recovery was markedly prolonged in the meniscectomized knees.With meniscectomy, tibial articular cartilage in the central load bearing region remains chronically deformed and dehydrated, even after cessation of loading. Post-meniscectomy osteoarthritis may be initiated in this region by direct damage to the cartilage matrix, or by altering the hydration of the tissue. In peripheral regions, reduced loading and strain may facilitate subchondral vascular invasion, and endochondral ossification. This is consistent with the central fibrillation and peripheral osteophyte formation seen in post-meniscectomy osteoarthritis.

  View details for DOI 10.1016/j.joca.2008.04.011

  View details for Web of Science ID 000261339700015

  View details for PubMedID 18514552

• Posterior Cruciate Ligament Removal Contributes to Abnormal Knee Motion during Posterior Stabilized Total Knee Arthroplasty JOURNAL OF ORTHOPAEDIC RESEARCH Cromie, M. J., Siston, R. A., Giori, N. J., Delp, S. L. 2008; 26 (11): 1494-1499

  Abstract

  Abnormal anterior translation of the femur on the tibia has been observed in mid flexion (20-60 degrees ) following posterior stabilized total knee arthroplasty. The underlying biomechanical causes of this abnormal motion remain unknown. The purpose of this study was to isolate the effects of posterior cruciate ligament removal on knee motion after total knee arthroplasty. We posed two questions: Does removing the posterior cruciate ligament introduce abnormal anterior femoral translation? Does implanting a posterior stabilized prosthesis change the kinematics from the cruciate deficient case? Using a navigation system, we measured passive knee kinematics of ten male osteoarthritic patients during surgery after initial exposure, after removing the anterior cruciate ligament, after removing the posterior cruciate ligament, and after implanting the prosthesis. Passively flexing and extending the knee, we calculated anterior femoral translation and the flexion angle at which femoral rollback began. Removing the posterior cruciate ligament doubled anterior translation (from 5.1 +/- 4.3 mm to 10.4 +/- 5.1 mm) and increased the flexion angle at which femoral rollback began (from 31.2 +/- 9.6 degrees to 49.3 +/- 7.3 degrees). Implanting the prosthesis increased the amount of anterior translation (to 16.1 +/- 4.4 mm), and did not change the flexion angle at which femoral rollback began. Abnormal anterior translation was observed in low and mid flexion (0-60 degrees) after removing the posterior cruciate ligament, and normal motion was not restored by the posterior stabilized prosthesis.

  View details for DOI 10.1002/jor.20664

  View details for Web of Science ID 000260195800012

  View details for PubMedID 18464260

• Averaging different alignment axes improves femoral rotational alignment in computer-navigated total knee arthroplasty. journal of bone and joint surgery. American volume Siston, R. A., Cromie, M. J., Gold, G. E., Goodman, S. B., Delp, S. L., Maloney, W. J., Giori, N. J. 2008; 90 (10): 2098-2104

  Abstract

  Computer navigation systems generally establish the rotational alignment axis of the femoral component on the basis of user-defined anatomic landmarks. However, navigation systems can also record knee kinematics and average alignment axes established with multiple techniques. We hypothesized that establishing femoral rotational alignment with the use of kinematic techniques is more accurate and precise (repeatable) than the use of anatomic techniques and that establishing femoral rotational alignment by averaging the results of different alignment techniques is more accurate and precise than the use of a single technique.Twelve orthopaedic surgeons used three anatomic and two kinematic alignment techniques to establish femoral rotational alignment axes in a series of nine cadaver knees. The axes derived with the individual anatomic and kinematic techniques as well as the axes derived with six combination techniques--i.e., those involving averaging of the alignments established with two of the individual techniques--were compared against a reference axis established with computed tomography images of each femur.The kinematic methods were not more accurate (did not have smaller mean errors) or more precise (repeatable) than the anatomic techniques. The combination techniques were accurate (five of the six had a mean error of <5 degrees ) and significantly more precise than all but one of the single methods. The percentage of measurements with <5 degrees of error as compared with the reference epicondylar axis was 37% for the individual anatomic techniques, 30% for the individual kinematic techniques, and 58% for the combination techniques.Averaging the results of kinematic and anatomic techniques, which is possible with computer navigation systems, appears to improve the accuracy of rotational alignment of the femoral component. The number of rotational alignment outliers was reduced when combination techniques were used; however, they are still a problem and continued improvement in methods to accurately establish rotation of the femoral component in total knee arthroplasty is needed.

  View details for DOI 10.2106/JBJS.G.00996

  View details for PubMedID 18829906

• Averaging Different Alignment Axes Improves Femoral Rotational Alignment in Computer-Navigated Total Knee Arthroplasty JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Siston, R. A., Cromie, M. J., Gold, G. E., Goodman, S. B., Delp, S. L., Maloney, W. J., Giori, N. J. 2008; 90A (10): 2098-2104

  Abstract

  Computer navigation systems generally establish the rotational alignment axis of the femoral component on the basis of user-defined anatomic landmarks. However, navigation systems can also record knee kinematics and average alignment axes established with multiple techniques. We hypothesized that establishing femoral rotational alignment with the use of kinematic techniques is more accurate and precise (repeatable) than the use of anatomic techniques and that establishing femoral rotational alignment by averaging the results of different alignment techniques is more accurate and precise than the use of a single technique.Twelve orthopaedic surgeons used three anatomic and two kinematic alignment techniques to establish femoral rotational alignment axes in a series of nine cadaver knees. The axes derived with the individual anatomic and kinematic techniques as well as the axes derived with six combination techniques--i.e., those involving averaging of the alignments established with two of the individual techniques--were compared against a reference axis established with computed tomography images of each femur.The kinematic methods were not more accurate (did not have smaller mean errors) or more precise (repeatable) than the anatomic techniques. The combination techniques were accurate (five of the six had a mean error of <5 degrees ) and significantly more precise than all but one of the single methods. The percentage of measurements with <5 degrees of error as compared with the reference epicondylar axis was 37% for the individual anatomic techniques, 30% for the individual kinematic techniques, and 58% for the combination techniques.Averaging the results of kinematic and anatomic techniques, which is possible with computer navigation systems, appears to improve the accuracy of rotational alignment of the femoral component. The number of rotational alignment outliers was reduced when combination techniques were used; however, they are still a problem and continued improvement in methods to accurately establish rotation of the femoral component in total knee arthroplasty is needed.

  View details for DOI 10.2106/JBJS.G.00996

  View details for Web of Science ID 000259873300006

• A variable-stiffness shoe lowers the knee adduction moment in subjects with symptoms of medial compartment knee osteoarthritis. Journal of biomechanics Erhart, J. C., Mündermann, A., Elspas, B., Giori, N. J., Andriacchi, T. P. 2008; 41 (12): 2720-2725

  Abstract

  The purpose of this study was to evaluate the effectiveness of variable-stiffness shoes in lowering the peak external knee adduction moment during walking in subjects with symptomatic medial compartment knee osteoarthritis. The influence on other lower extremity joints was also investigated. The following hypotheses were tested: (1) variable-stiffness shoes will lower the knee adduction moment in the symptomatic knee compared to control shoes; (2) reductions in knee adduction moment will be greater at faster speeds; (3) subjects with higher initial knee adduction moments in control shoes will have greater reductions in knee adduction moment with the intervention shoes; and (4) variable-stiffness shoes will cause secondary changes in the hip and ankle frontal plane moments. Seventy-nine individuals were tested at self-selected slow, normal, and fast speeds with a constant-stiffness control shoe and a variable-stiffness intervention shoe. Peak moments for each condition were assessed using a motion capture system and force plate. The intervention shoes reduced the peak knee adduction moment compared to control at all walking speeds, and reductions increased with increasing walking speed. The magnitude of the knee adduction moment prior to intervention explained only 11.9% of the variance in the absolute change in maximum knee adduction moment. Secondary changes in frontal plane moments showed primarily reductions in other lower extremity joints. This study showed that the variable-stiffness shoe reduced the knee adduction moment in subjects with medial compartment knee osteoarthritis without the discomfort of a fixed wedge or overloading other joints, and thus can potentially slow the progression of knee osteoarthritis.

  View details for DOI 10.1016/j.jbiomech.2008.06.016

  View details for PubMedID 18675981

• Variable-stiffness shoe lowers the knee adduction moment in subjects with symptoms of medial compartment knee osteoarthritis JOURNAL OF BIOMECHANICS Erhart, J. C., Muendermann, A., Elspas, B., Giori, N. J., Andriacchi, T. P. 2008; 41 (12): 2720-2725

  Abstract

  The purpose of this study was to evaluate the effectiveness of variable-stiffness shoes in lowering the peak external knee adduction moment during walking in subjects with symptomatic medial compartment knee osteoarthritis. The influence on other lower extremity joints was also investigated. The following hypotheses were tested: (1) variable-stiffness shoes will lower the knee adduction moment in the symptomatic knee compared to control shoes; (2) reductions in knee adduction moment will be greater at faster speeds; (3) subjects with higher initial knee adduction moments in control shoes will have greater reductions in knee adduction moment with the intervention shoes; and (4) variable-stiffness shoes will cause secondary changes in the hip and ankle frontal plane moments. Seventy-nine individuals were tested at self-selected slow, normal, and fast speeds with a constant-stiffness control shoe and a variable-stiffness intervention shoe. Peak moments for each condition were assessed using a motion capture system and force plate. The intervention shoes reduced the peak knee adduction moment compared to control at all walking speeds, and reductions increased with increasing walking speed. The magnitude of the knee adduction moment prior to intervention explained only 11.9% of the variance in the absolute change in maximum knee adduction moment. Secondary changes in frontal plane moments showed primarily reductions in other lower extremity joints. This study showed that the variable-stiffness shoe reduced the knee adduction moment in subjects with medial compartment knee osteoarthritis without the discomfort of a fixed wedge or overloading other joints, and thus can potentially slow the progression of knee osteoarthritis.

  View details for DOI 10.1016/j.jbiomech.2008.06.016

  View details for Web of Science ID 000259552700018

• Coronal plane stability before and after total knee arthroplasty CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Siston, R. A., Goodman, S. B., Delp, S. L., Giori, N. J. 2007: 43-49

  Abstract

  The success of total knee arthroplasty depends in part on proper soft tissue management to achieve a stable joint. It is unknown to what degree total knee arthroplasty changes joint stability. We used a surgical navigation system to intraoperatively measure joint stability in 24 patients under going primary total knee arthroplasty to address two questions: (1) Is the total arc of varus-valgus motion after total knee arthroplasty different from the arc of varus-valgus motion in an osteoarthritic knee? (2) Does total knee arthroplasty produce equal amounts of varus/valgus motion (ie, is the knee "balanced")? We observed no difference between the total arc of varus-valgus motion before and after total knee arthroplasty; the total amount of motion was unchanged. On average, osteoarthritic knees were "unbalanced" but were "balanced" after prosthesis implantation. We found a negative correlation between the relative amount of varus/valgus motion in extension before and after prosthesis implantation in extension and a positive correlation between how well the knees were balanced after prosthesis implantation in extension and in flexion. Our data suggest immediately after implantation knees retain a greater than normal amount of varus-valgus motion, but this motion is more evenly distributed.

  View details for DOI 10.1097/BLO.0b013e318137a182

  View details for PubMedID 17621236

• Benefit of single-leaf resection for horizontal meniscus tear CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Haemer, J. M., Wang, M. J., Carter, D. R., Giori, N. J. 2007: 194-202

  Abstract

  When treating a horizontal meniscus tear, the surgeon must decide whether to resect one or both leaves of the tear. We asked whether there is a biomechanical advantage to sparing one leaf when performing a partial meniscectomy for horizontal meniscus tear. We used pressure-sensitive film to measure the contact area, mean pressure, and peak pressure on the lateral tibial plateau of cadaveric sheep knees loaded to 2x body weight. For tears restricted to the posterior third, single-leaf resection decreased contact area by 40% compared with the intact case. Sparing one leaf was beneficial because resection of the second leaf reduced contact area an additional 15%. Similarly, mean pressure was increased 24% for single-leaf resection and an additional 27% for double-leaf resection. Peak pressure showed no differences with single- and double-leaf resections. For tears that span the entire meniscus, single-leaf resection reduced contact area by 59%, increased mean pressure by 55%, and increased peak pressure by 19%. Double-leaf resection in this situation did not change these values substantially, suggesting sparing one leaf offers no benefit over resecting both leaves with extensive horizontal meniscus tears.

  View details for DOI 10.1097/BLO.0b0I13e3180303b5c

  View details for Web of Science ID 000245575600030

  View details for PubMedID 17179782

• Two ulnar collateral ligament reconstruction methods: The docking technique versus bioabsorbable interference screw fixation - A biomechanical evaluation with cyclic loading JOURNAL OF SHOULDER AND ELBOW SURGERY McAdams, T. R., Lee, A. T., Centeno, J., Giori, N. J., Lindsey, D. P. 2007; 16 (2): 224-228

  Abstract

  We compared the effects of cyclic valgus loading on 2 techniques for reconstruction of the elbow ulnar collateral ligament (UCL): the docking procedure and the bioabsorbable interference screw procedure. A cyclic valgus load was applied to the 16 unembalmed elbows, and the valgus angle was measured at 1, 10, 100, and 1000 cycles. Testing was repeated after UCL palmaris tendon reconstruction via either the docking technique or bioabsorbable interference screw fixation. At cycle 1, the valgus angle was not different between treated and intact cases. At cycles 10 and 100, the valgus angle for the docking technique was significantly greater than that for both the intact cases and the interference screw technique. By the 1000th cycle, no difference was measured between the 2 techniques. In this study, bioabsorbable interference screw fixation resulted in less valgus angle widening in response to early cyclic valgus load as compared with the docking technique.

  View details for DOI 10.1016/j.jse.2005.12.012

  View details for PubMedID 17254812

• Surgical navigation for total knee arthroplasty: A perspective JOURNAL OF BIOMECHANICS Siston, R. A., Giori, N. J., Goodman, S. B., Delp, S. L. 2007; 40 (4): 728-735

  Abstract

  A new generation of surgical tools, known as surgical navigation systems, has been developed to help surgeons install implants more accurately and reproducibly. Navigation systems also record quantitative information such as joint range of motion, laxity, and kinematics intra-operatively. This article reviews the history of surgical navigation for total knee arthroplasty, the biomechanical principles associated with this technology, and the related clinical research studies. We describe how navigation has the potential to address three main challenges for total knee arthroplasty: ensuring excellent and consistent outcomes, treating younger and more physically active patients, and enabling less invasive surgery.

  View details for DOI 10.1016/j.jbiomech.2007.01.006

  View details for PubMedID 17317419

• The high variability of tibial rotational alignment in total knee arthroplasty Open Scientific Meeting of the Knee-Society Siston, R. A., Goodman, S. B., Patel, J. J., Delp, S. L., Giori, N. J. SPRINGER. 2006: 65–69

  Abstract

  Although various techniques are advocated to establish tibial rotational alignment during total knee arthroplasty, it is unknown which is most repeatable. We evaluated the precision and accuracy of five tibial rotational alignment techniques to determine whether computer-assisted navigation systems can reduce variability of tibial component rotational alignment when compared to traditional instrumentation. Eleven orthopaedic surgeons used four computer-assisted techniques that required identification of anatomical landmarks and one that used traditional extramedullary instrumentation to establish tibial rotational alignment axes on 10 cadaver legs. Two computer-assisted techniques (axes between the most medial and lateral border of the tibial plateau, and between the posterior cruciate ligament [PCL] and the anterior tibial crest) and the traditional technique were least variable, with standard deviations of 9.9 degrees, 10.8 degrees, and 12.1 degrees, respectively. Computer-assisted techniques referencing the tibial tubercle (axes between the PCL and the medial border or medial 1/3 of the tubercle) were most variable, with standard deviations of 27.4 degrees and 28.1 degrees. The axis between the medial border of the tibial tubercle and the PCL was internally rotated compared to the other techniques. None of the techniques consistently established tibial rotational alignment, and navigation systems that establish rotational alignment by identifying anatomic landmarks were not more reliable than traditional instrumentation.

  View details for DOI 10.1097/01.blo.0000229335.36900.a0

  View details for PubMedID 16906095

• Bone cement improves suture anchor fixation CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Giori, N. J., Sohn, D. H., Mirza, F. M., Lindsey, D. P., Lee, A. T. 2006: 236-241

  Abstract

  Suture anchor fixation failure can occur if the anchor pulls out of bone. We hypothesized that suture anchor fixation can be augmented with polymethylmethacrylate cement, and that polymethylmethacrylate can be used to improve fixation in a stripped anchor hole. Six matched cadaveric proximal humeri were used. On one side, suture anchors were placed and loaded to failure using a ramped cyclic loading protocol. The stripped anchor holes then were injected with approximately 1 cc polymethylmethacrylate, and anchors were replaced and tested again. In the contralateral humerus, polymethylmethacrylate was injected into anchor holes before anchor placement and testing. In unstripped anchors, polymethylmethacrylate increased the number of cycles to failure by 34% and failure load by 71% compared with anchors not augmented with polymethylmethacrylate. Polymethylmethacrylate haugmentation of stripped anchors increased the cycles to failure by 31% and failure load by 111% compared with unstripped uncemented anchors. No difference was found in cycles to failure or failure load between cemented stripped anchors and cemented unstripped anchors. Polymethylmethacrylate can be used to augment fixation, reducing the risk of anchor pull-out failure, regardless whether the suture anchor hole is stripped or unstripped.

  View details for DOI 10.1097/01.blo.0000223984.67325.af

  View details for Web of Science ID 000243021200043

  View details for PubMedID 16702922

• Gene regulation ex vivo within a wrap-around tendon TISSUE ENGINEERING Li, K. W., Lindsey, D. P., Wagner, D. R., Giori, N. J., Schurman, D. J., Goodman, S. B., Smith, R. L., Carter, D. R., Beaupre, G. S. 2006; 12 (9): 2611-2618

  Abstract

  This study tested the hypothesis that physiologic tendon loading modulates the fibrous connective tissue phenotype in undifferentiated skeletal cells. Type I collagen sponges containing human bone marrow stromal cells (MSCs) were implanted into the midsubstance of excised sheep patellar tendons. An ex vivo loading system was designed to cyclically stretch each tendon from 0 to 5% at 1.0 Hz. The MSC-sponge constructs were implanted into 2 tendon sites: the first site subjected to tension only and a second site located at an artificially created wrap-around region in which an additional compressive stress was generated transverse to the longitudinal axis of the tendon. The induced contact pressure at the wraparound site was 0.55 +/- 0.12 MPa, as quantified by pressure-sensitive film. An MSC-sponge construct was maintained free swelling in the same bath as an unloaded control. After 2 h of tendon stretching, the MSC-sponge constructs were harvested and real-time PCR was used to quantify Fos, Sox9, Cbfa1 (Runx2), and scleraxis mRNA expression as markers of skeletal differentiation. Two hours of mechanical loading distinctly altered MSC differentiation in the wrap-around region and the tensile-only region, as evidenced by differences in Fos and Sox9 mRNA expression. Expression of Fos mRNA was 13 and 52 times higher in the tensile-only and wrap-around regions, respectively, compared to the free-swelling controls. Expression of Sox9 mRNA was significantly higher (2.5-3 times) in MSCs from the wraparound region compared to those from the tensile-only region or in free-swelling controls. In contrast, expression levels for Cbfa1 did not differ among constructs. Scleraxis mRNA was not detected in any construct. This study demonstrates that the physiologic mechanical environment in the wrap-around regions of tendons provides stimuli for upregulating early response genes and transcription factors associated with chondrogenic differentiation. These differentiation responses begin within as little as 2 h after the onset of mechanical stimulation and may be the basis for the formation of fibrocartilage that is typically found in the wrap-around region of mature tendons in vivo.

  View details for Web of Science ID 000240780900021

  View details for PubMedID 16995794

• Articular cartilage MR imaging and thickness mapping of a loaded knee joint before and after meniscectomy OSTEOARTHRITIS AND CARTILAGE Song, Y., Greve, J. M., Carter, D. R., Koo, S., Giori, N. J. 2006; 14 (8): 728-737

  Abstract

  We describe a technique to axially compress a sheep knee joint in an MRI scanner and measure articular cartilage deformation. As an initial application, tibial articular cartilage deformation patterns after 2 h of static loading before and after medial meniscectomy are compared.Precision was established for repeated scans and repeated segmentations. Accuracy was established by comparing to micro-CT measurements. Four sheep knees were then imaged unloaded, and while statically loaded for 2 h at 1.5 times body weight before and after medial meniscectomy. Images were obtained using a 3D gradient echo sequence in a 4.7 T MRI. Corresponding 3D cartilage thickness models were created. Nominal strain patterns for the intact and meniscectomized conditions were compared.Coefficients of variation were all 2% or less. Root mean squared errors of MR cartilage thickness measurements averaged less than 0.09 mm. Meniscectomy resulted in a 60% decrease in the contact area (P=0.001) and a 13% increase in maximum cartilage deformation (P=0.01). Following meniscectomy, there were greater areas of articular cartilage experiencing abnormally high and low nominal strains. Areas of moderate nominal strain were reduced.Medial meniscectomy resulted in increased medial tibial cartilage nominal strains centrally and decreased strains peripherally. Areas of abnormally high nominal strain following meniscectomy correlated with areas that are known to develop fibrillation and softening 16 weeks after medial meniscectomy. Areas of abnormally low nominal strain correlated with areas of osteophyte formation. Studies of articular cartilage deformation may prove useful in elucidating the mechanical etiology of osteoarthritis.

  View details for DOI 10.1016/j.joca.2006.01.011

  View details for Web of Science ID 000239386900002

  View details for PubMedID 16533610

• Intraoperative passive kinematics of osteoarthritic knees before and after total knee arthroplasty JOURNAL OF ORTHOPAEDIC RESEARCH Siston, R. A., Giori, N. J., Goodman, S. B., Delp, S. L. 2006; 24 (8): 1607-1614

  Abstract

  Total knee arthroplasty is a successful procedure to treat pain and functional disability due to osteoarthritis. However, precisely how a total knee arthroplasty changes the kinematics of an osteoarthritic knee is unknown. We used a surgical navigation system to measure normal passive kinematics from 7 embalmed cadaver lower extremities and in vivo intraoperative passive kinematics on 17 patients undergoing primary total knee arthroplasty to address two questions: How do the kinematics of knees with advanced osteoarthritis differ from normal knees?; and, Does posterior substituting total knee arthroplasty restore kinematics towards normal? Osteoarthritic knees displayed a decreased screw-home motion and abnormal varus/valgus rotations between 10 degrees and 90 degrees of knee flexion when compared to normal knees. The anterior-posterior motion of the femur in osteoarthritic knees was not different than in normal knees. Following total knee arthroplasty, we found abnormal varus/valgus rotations in early flexion, a reduced screw-home motion when compared to the osteoarthritic knees, and an abnormal anterior translation of the femur during the first 60 degrees of flexion. Posterior substituting total knee arthroplasty does not appear to restore normal passive varus/valgus rotations or the screw motion and introduces an abnormal anterior translation of the femur during intraoperative evaluation.

  View details for DOI 10.1002/jor.20163

  View details for PubMedID 16770795

• Prepolarized magnetic resonance imaging around metal orthopedic implants MAGNETIC RESONANCE IN MEDICINE Venook, R. D., Matter, N. I., Ramachandran, M., Ungersma, S. E., Gold, G. E., Giori, N. J., Macovski, A., Scott, G. C., Conolly, S. M. 2006; 56 (1): 177-186

  Abstract

  A prepolarized MRI (PMRI) scanner was used to image near metal implants in agar gel phantoms and in in vivo human wrists. Comparison images were made on 1.5- and 0.5-T conventional whole-body systems. The PMRI experiments were performed in a smaller bore system tailored to extremity imaging with a prepolarization magnetic field of 0.4 T and a readout magnetic field of 27-54 mT (1.1-2.2 MHz). Scan parameters were chosen with equal readout gradient strength over a given field of view and matrix size to allow unbiased evaluation of the benefits of lower readout frequency. Results exhibit substantial reduction in metal susceptibility artifacts under PMRI versus conventional scanners. A new artifact quantification technique is also presented, and phantom results confirm that susceptibility artifacts improve as expected with decreasing readout magnetic field using PMRI. This proof-of-concept study demonstrates that prepolarized techniques have the potential to provide diagnostic cross-sectional images for postoperative evaluation of patients with metal implants.

  View details for DOI 10.1002/mrm.20927

  View details for Web of Science ID 000238823600019

  View details for PubMedID 16724303

• Evaluation of methods that locate the center of the ankle for computer-assisted total knee arthroplasty CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Siston, R. A., Daub, A. C., Giori, N. J., Goodman, S. B., Delp, S. L. 2005: 129-135

  Abstract

  Accurate alignment of the mechanical axis of the limb is important to the success of a total knee arthroplasty. Although computer-assisted navigation systems can align implants more accurately than traditional mechanical guides, the ideal technique to determine the distal end point of the mechanical axis, the center of the ankle, is unknown. In this study, we evaluated the accuracy, precision, objectivity, and speed of five anatomic methods and two kinematic methods for estimating the ankle center in 11 healthy subjects. Magnetic resonance images were used to characterize the shape of the ankle and establish the true ankle center. The most accurate and precise anatomic method was establishing the midpoint of the most medial and most lateral aspects of the malleoli (4.5 +/- 4.1 mm lateral error; 2.7 +/- 4.5 mm posterior error). A biaxial model of the ankle (2.0 +/- 6.4 mm medial error; 0.3 +/- 7.6 mm anterior error) was the most accurate kinematic method. Establishing the midpoint of the most medial and most lateral aspects of the malleoli was an accurate, precise, objective, and fast method for establishing the center of the ankle.

  View details for DOI 10.1097/01.blo.0000170873.88306.56

  View details for PubMedID 16205151

• The variability of femoral rotational alignment in total knee arthroplasty JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Siston, R. A., Patel, J. J., Goodman, S. B., Delp, S. L., Giori, N. J. 2005; 87A (10): 2276-2280

  Abstract

  Several reference axes are used to establish femoral rotational alignment during total knee arthroplasty, but debate continues with regard to which axis is most accurately and easily identified during surgery. Computer-assisted navigation systems have been developed in an attempt to more accurately and consistently align implants during total knee arthroplasty, but it is unknown if navigation systems can improve the accuracy of femoral rotational alignment as compared with that achieved with more traditional techniques involving mechanical guides. The purposes of the present study were to characterize the variability associated with femoral rotational alignment techniques and to determine whether the use of a computer-assisted surgical navigation system reduced this variability.Eleven orthopaedic surgeons used five alignment techniques (including one computer-assisted technique and four traditional techniques) to establish femoral rotational alignment axes on ten cadaveric specimens, and the orientation of these axes was recorded with use of a navigation system. These derived axes were compared against a reference transepicondylar axis on each femur that was established after complete dissection of all soft tissues.There was no difference between the mean errors of all five techniques (p > 0.11). Only 17% of the knees were rotated <5 degrees from the reference transepicondylar axis, with alignment errors ranging from 13 degrees of internal rotation to 16 degrees of external rotation. There were significant differences among the surgeons with regard to their ability to accurately establish femoral rotational alignment axes (p < 0.001).All techniques resulted in highly variable rotational alignment, with no technique being superior. This variability was primarily due to the particular surgeon who was performing the alignment procedure. A navigation system that relies on directly digitizing the femoral epicondyles to establish an alignment axis did not provide a more reliable means of establishing femoral rotational alignment than traditional techniques did.

  View details for DOI 10.2106/JBJS.D.02945

  View details for Web of Science ID 000232421500018

• The variability of femoral rotational alignment in total knee arthroplasty. journal of bone and joint surgery. American volume Siston, R. A., Patel, J. J., Goodman, S. B., Delp, S. L., Giori, N. J. 2005; 87 (10): 2276-2280

  Abstract

  Several reference axes are used to establish femoral rotational alignment during total knee arthroplasty, but debate continues with regard to which axis is most accurately and easily identified during surgery. Computer-assisted navigation systems have been developed in an attempt to more accurately and consistently align implants during total knee arthroplasty, but it is unknown if navigation systems can improve the accuracy of femoral rotational alignment as compared with that achieved with more traditional techniques involving mechanical guides. The purposes of the present study were to characterize the variability associated with femoral rotational alignment techniques and to determine whether the use of a computer-assisted surgical navigation system reduced this variability.Eleven orthopaedic surgeons used five alignment techniques (including one computer-assisted technique and four traditional techniques) to establish femoral rotational alignment axes on ten cadaveric specimens, and the orientation of these axes was recorded with use of a navigation system. These derived axes were compared against a reference transepicondylar axis on each femur that was established after complete dissection of all soft tissues.There was no difference between the mean errors of all five techniques (p > 0.11). Only 17% of the knees were rotated <5 degrees from the reference transepicondylar axis, with alignment errors ranging from 13 degrees of internal rotation to 16 degrees of external rotation. There were significant differences among the surgeons with regard to their ability to accurately establish femoral rotational alignment axes (p < 0.001).All techniques resulted in highly variable rotational alignment, with no technique being superior. This variability was primarily due to the particular surgeon who was performing the alignment procedure. A navigation system that relies on directly digitizing the femoral epicondyles to establish an alignment axis did not provide a more reliable means of establishing femoral rotational alignment than traditional techniques did.

  View details for PubMedID 16203894

• Load-shifting brace treatment for osteoarthritis of the knee: A minimum 2 1/2-year follow-up study JOURNAL OF REHABILITATION RESEARCH AND DEVELOPMENT Giori, N. J. 2004; 41 (2): 187-193

  Abstract

  Objectives in treating primarily unicompartmental knee arthritis with a load-shifting brace are pain relief, compliance, brace durability, and complication-free treatment over multiple years. This was a single institution retrospective chart review, radiograph review, and telephone survey of patients treated from 1997 to 1999 with a load-shifting knee brace. Forty-six patients (49 knees) with a minimum 2 1/2-year follow-up (average 3.3 years) were reviewed. Kaplan-Meier survivorship analysis revealed that load-shifting brace use had a survival of 76% at 1 year, 69% at 2 years, and 61% at 3 years. Younger patients had a higher likelihood of longer brace use than older patients. One patient had ipsilateral leg swelling and a pulmonary embolus after initiating bracing. Eliminating the high numbers of early failures would be desirable. One should be aware of the potential complication of venous thrombosis and thromboembolism.

  View details for Web of Science ID 000221807600011

  View details for PubMedID 15558372

• Acetabular retroversion is associated with osteoarthritis of the hip CLINICAL ORTHOPAEDICS AND RELATED RESEARCH Giori, N. J., Trousdale, R. T. 2003: 263-269

  Abstract

  Primary osteoarthritis of the hip may have a structural basis. It was hypothesized that the radiographic appearance of acetabular retroversion could be created by altering the morphologic features of the acetabular walls, and that acetabular retroversion, as defined on an anteroposterior radiograph of the pelvis, is associated with osteoarthritis of the hip. A model pelvis was used to simulate normal, augmented, deficient, and rotated walls of the acetabulum, and radiographs were taken to compare the projections of the modified acetabular walls with the known plain radiographic appearance of a retroverted acetabulum. One hundred thirty-one good quality anteroposterior radiographs of the pelvis taken before total hip arthroplasty for idiopathic hip osteoarthritis were compared with 99 good quality radiographs taken for nonorthopaedic reasons. The prevalence of radiographic acetabular retroversion is 20% among patients with idiopathic hip osteoarthritis and 5% among the general population. The appearance of acetabular retroversion on an anteoroposterior radiograph of the pelvis is created by deficiency of the posterior wall of the acetabulum. There is a statistically significant association between radiographic acetabular retroversion and hip osteoarthritis. These findings have applicability to understanding the mechanical etiology of hip osteoarthritis, and to surgical technique during periacetabular osteotomy and total hip arthroplasty.

  View details for DOI 10.1097/01.blo.0000093014.90435.64

  View details for Web of Science ID 000188760900030

  View details for PubMedID 14646725

• Offset acetabular components introduce torsion on the implant and may increase the risk of fixation failure JOURNAL OF ARTHROPLASTY Giori, N. J. 2003; 18 (1): 89-91

  Abstract

  Loading of an offset acetabular component causes torsion on the implant around the center of the reamed acetabular bed. A mechanical analysis was performed to determine this torsional moment. A 70 kg person walking normally on a well-positioned, 4-mm offset acetabular component will produce torsion on the prosthesis of approximately 3.86 Nm. A 10-mm offset increases the applied torsion to 9.65 Nm. Vertical placement of the cup further increases this torsion. These torsional moments are comparable to moments shown to cause failure of the initial interference fit of cementless acetabular components in vitro. If using an offset cementless acetabular component, one should initially limit weight bearing and consider using pegs or screws to augment fixation and minimize the risk of interference fit failure.

  View details for DOI 10.1054/arth.2003.50018

  View details for Web of Science ID 000180808600016

  View details for PubMedID 12555189

• Total knee arthroplasty in limbs affected by poliomyelitis. journal of bone and joint surgery. American volume Giori, N. J., Lewallen, D. G. 2002; 84-A (7): 1157-1161

  Abstract

  Little information is available regarding the results and complications of total knee arthroplasty in limbs affected by poliomyelitis with severe knee degeneration.We performed a retrospective chart and radiograph review of patients with a history of poliomyelitis involving a limb that subsequently underwent primary total knee arthroplasty between 1970 and 2000. Sixteen total knee arthroplasties were performed in limbs affected by poliomyelitis in fifteen patients. Eleven patients were followed for a minimum of two years, one (two knees) died before the minimum two-year follow-up could be completed, and three were followed for less than two years. No patient was lost to follow-up.There were two periprosthetic fractures, one peroneal nerve palsy, one avulsion of the patellar tendon, and four cases of recurrent instability. These complications were related to the poor bone quality, valgus deformity, patella baja, poor musculature, and attenuated soft tissues commonly found in knees affected by poliomyelitis. Knee Society pain and knee scores were improved postoperatively for all nine knees with a two-year follow-up that had had at least antigravity quadriceps strength prior to surgery. However, Knee Society function scores remained at 0 or worsened for six of the eleven knees followed for at least two years, including those with less than antigravity strength, and four of the nine knees with at least antigravity strength. None of the prostheses loosened.Pain and knee scores improved following total knee arthroplasty in patients with a history of poliomyelitis and antigravity quadriceps strength, but there was less pain relief in patients with less than antigravity quadriceps strength. Recurrence of instability and progressive functional deterioration is possible in all knees affected by poliomyelitis that have undergone total knee replacement, but they appear to occur more commonly in more severely affected knees.

  View details for PubMedID 12107315

• Total knee arthroplasty in limbs affected by poliomyelitis JOURNAL OF BONE AND JOINT SURGERY-AMERICAN VOLUME Giori, N. J., Lewallen, D. G. 2002; 84A (7): 1157-1161

  Abstract

  Little information is available regarding the results and complications of total knee arthroplasty in limbs affected by poliomyelitis with severe knee degeneration.We performed a retrospective chart and radiograph review of patients with a history of poliomyelitis involving a limb that subsequently underwent primary total knee arthroplasty between 1970 and 2000. Sixteen total knee arthroplasties were performed in limbs affected by poliomyelitis in fifteen patients. Eleven patients were followed for a minimum of two years, one (two knees) died before the minimum two-year follow-up could be completed, and three were followed for less than two years. No patient was lost to follow-up.There were two periprosthetic fractures, one peroneal nerve palsy, one avulsion of the patellar tendon, and four cases of recurrent instability. These complications were related to the poor bone quality, valgus deformity, patella baja, poor musculature, and attenuated soft tissues commonly found in knees affected by poliomyelitis. Knee Society pain and knee scores were improved postoperatively for all nine knees with a two-year follow-up that had had at least antigravity quadriceps strength prior to surgery. However, Knee Society function scores remained at 0 or worsened for six of the eleven knees followed for at least two years, including those with less than antigravity strength, and four of the nine knees with at least antigravity strength. None of the prostheses loosened.Pain and knee scores improved following total knee arthroplasty in patients with a history of poliomyelitis and antigravity quadriceps strength, but there was less pain relief in patients with less than antigravity quadriceps strength. Recurrence of instability and progressive functional deterioration is possible in all knees affected by poliomyelitis that have undergone total knee replacement, but they appear to occur more commonly in more severely affected knees.

  View details for Web of Science ID 000176772700010

• Measurement of perioperative flexion-extension mechanics of the knee joint JOURNAL OF ARTHROPLASTY Giori, N. J., Giori, K. L., Woolson, S. T., Goodman, S. B., Lannin, J. V., Schurman, D. J. 2001; 16 (7): 877-881

  Abstract

  Perioperative knee mechanics currently are evaluated Perioperative knee mechanics currently are evaluated by measuring range of motion. This is an incomplete measurement, however, because the torque applied to achieve the motion is not measured. We hypothesized that a custom goniometer and force transducer could measure the torque required to passively flex a knee through its full range of motion. This measurement was done in the operating room immediately before and after surgery in 20 knees having total knee arthroplasty and 9 having surgery on another limb. Surgery changed the mechanics of 8 knees, whereas unoperated knees remained unchanged. This measurement technique is safe, easy, and repeatable. It improves on the current standard of perioperative knee measurement and can be applied to investigate the effects of surgery and rehabilitation on ultimate knee motion.

  View details for PubMedID 11607904

• Continuous passive motion (CPM): Theory and principles of clinical application JOURNAL OF REHABILITATION RESEARCH AND DEVELOPMENT O'Driscoll, S. W., Giori, N. J. 2000; 37 (2): 179-188

  Abstract

  Stiffness following surgery or injury to a joint develops as a progression of four stages: bleeding, edema, granulation tissue, and fibrosis. Continuous passive motion (CPM) properly applied during the first two stages of stiffness acts to pump blood and edema fluid away from the joint and periarticular tissues. This allows maintenance of normal periarticular soft tissue compliance. CPM is thus effective in preventing the development of stiffness if full motion is applied immediately following surgery and continued until swelling that limits the full motion of the joint no longer develops. This concept has been applied successfully to elbow rehabilitation, and explains the controversy surrounding CPM following knee arthroplasty. The application of this concept to clinical practice requires a paradigm shift, resulting in our attention being focused on preventing the initial or delayed accumulation of periarticular interstitial fluids.

  View details for Web of Science ID 000165733400011

  View details for PubMedID 10850824

• Coincident development of sesamoid bones and clues to their evolution ANATOMICAL RECORD Sarin, V. K., Erickson, G. M., Giori, N. J., Bergman, A. G., Carter, D. R. 1999; 257 (5): 174-180

  Abstract

  Sesamoid bones form within tendons in regions that wrap around bony prominences. They are common in humans but variable in number. Sesamoid development is mediated epigenetically by local mechanical forces associated with skeletal geometry, posture, and muscular activity. In this article we review the literature on sesamoids and explore the question of genetic control of sesamoid development. Examination of radiographs of 112 people demonstrated that the relatively infrequent appearances of the fabella (in the lateral gastrocnemius tendon of the knee) and os peroneum (in the peroneus longus tendon of the foot) are related within individuals (P < 0.01). This finding suggests that the tendency to form sesamoids may be linked to intrinsic genetic factors. Evolutionary character analyses suggest that the formation of these sesamoids in humans may be a consequence of phylogeny. These observations indicate that variations of intrinsic factors may interact with extrinsic mechanobiological factors to influence sesamoid development and evolution.

  View details for Web of Science ID 000083555500005

  View details for PubMedID 10597342

• Mechanobiology of skeletal regeneration Workshop on Fracture Healing Enhancement Carter, D. R., Beaupre, G. S., Giori, N. J., Helms, J. A. SPRINGER. 1998: S41–S55

  Abstract

  Skeletal regeneration is accomplished by a cascade of biologic processes that may include differentiation of pluripotential tissue, endochondral ossification, and bone remodeling. It has been shown that all these processes are influenced strongly by the local tissue mechanical loading history. This article reviews some of the mechanobiologic principles that are thought to guide the differentiation of mesenchymal tissue into bone, cartilage, or fibrous tissue during the initial phase of regeneration. Cyclic motion and the associated shear stresses cause cell proliferation and the production of a large callus in the early phases of fracture healing. For intermittently imposed loading in the regenerating tissue: (1) direct intramembranous bone formation is permitted in areas of low stress and strain; (2) low to moderate magnitudes of tensile strain and hydrostatic tensile stress may stimulate intramembranous ossification; (3) poor vascularity can promote chondrogenesis in an otherwise osteogenic environment; (4) hydrostatic compressive stress is a stimulus for chondrogenesis; (5) high tensile strain is a stimulus for the net production of fibrous tissue; and (6) tensile strain with a superimposed hydrostatic compressive stress will stimulate the development of fibrocartilage. Finite element models are used to show that the patterns of tissue differentiation observed in fracture healing and distraction osteogenesis can be predicted from these fundamental mechanobiologic concepts. In areas of cartilage formation, subsequent endochondral ossification normally will proceed, but it can be inhibited by intermittent hydrostatic compressive stress and accelerated by octahedral shear stress (or strain). Later, bone remodeling at these sites can be expected to follow the same mechanobiologic adaptation rules as normal bone.

  View details for Web of Science ID 000077173200007

  View details for PubMedID 9917625

• Stress governs tissue phenotype at the femoral insertion of the rabbit MCL. Journal of biomechanics Giori, N. J., Beaupré, G. S., Carter, D. R. 1996; 29 (4): 573-574

  View details for PubMedID 8964789

• MECHANICAL INFLUENCES ON TISSUE DIFFERENTIATION AT BONE-CEMENT INTERFACES JOURNAL OF ARTHROPLASTY Giori, N. J., Ryd, L., Carter, D. R. 1995; 10 (4): 514-522

  Abstract

  Retrieval studies have shown that tissue at the bone-cement or bone-implant interface can develop into fibrous tissue, fibrocartilage, and bone, and that tissue differentiation appears to be mechanically influenced. A prior histologic analysis of retrieved interface tissues supporting cemented Marmor unicondylar knee components found that beneath the central portion of these implants, a thick, mature layer of fibrocartilage consistently developed, whereas fibrous tissue formed beneath the prosthesis periphery and adjacent to the bone beneath the tibial spine. Finite-element analysis was used to model the interface tissue supporting a cemented Marmor tibial component and interpreted patterns of stress and strain generated in the interface according to a mechanically based tissue differentiation theory. Distortional strain and hydrostatic stress, mechanical stimuli that are hypothesized to be associated with fibrous matrix and cartilaginous matrix production, respectively, were found to correlate well with the previous histologic findings. Given the biologic environments in which the retrieved interface tissues developed, frequently applied hydrostatic stress of approximately 0.7 MPa may be sufficient to stimulate cartilaginous extracellular matrix production in the interface tissue, and frequently applied distortional strain of 10% may be sufficient to stimulate fibrous extracellular matrix production.

  View details for Web of Science ID A1995RT19900017

  View details for PubMedID 8523012

• CELLULAR-SHAPE AND PRESSURE MAY MEDIATE MECHANICAL CONTROL OF TISSUE COMPOSITION IN TENDONS JOURNAL OF ORTHOPAEDIC RESEARCH Giori, N. J., Beaupre, G. S., Carter, D. R. 1993; 11 (4): 581-591

  Abstract

  In vivo studies have suggested that mechanical factors are involved in the regulation of the morphology and biochemical composition of tendons that wrap around bones. In these tendons, fibrocartilage is found in the segment wrapped around the bone, and tendon far from the bone displays normal tendon histomorphology. Recent in vitro studies have shown that intermittently loaded connective tissue cells are sensitive to changes in cellular shape and hydrostatic pressure: stretching and distortion of the cells enhances production of fibrous matrix and hydrostatic pressure enhances production of cartilaginous matrix. We used finite-element analysis to determine whether the regions of increased development of cartilaginous matrix in tendons that wrap around bones correspond to regions in which tendon cells are subjected to higher pressures, and whether the maintenance and rearrangement of fibrous extracellular matrix in these tendons is associated with regions of stretching and distortion of cells. We found that regions of cartilaginous matrix and fibrous matrix formation and turnover correlate well with patterns of hydrostatic compressive stress and distortional strain in the tendon. Although further experiments clearly are needed to establish the predictive value of our approach, hydrostatic stress and distortional strain history--parameters intimately related to changes in cellular pressure and shape, respectively--appear to be important tissue-level mechanical stimuli that regulate cartilaginous and fibrous matrix composition of connective tissues.

  View details for Web of Science ID A1993LQ68800012

  View details for PubMedID 8340830

• A comparison of unicortical and bicortical end screw attachment of fracture fixation plates. Journal of orthopaedic trauma Beaupré, G. S., Giori, N. J., CALER, W. E., CSONGRADI, J. 1992; 6 (3): 294-300

  Abstract

  Plate fixation is considered by many clinicians to be the treatment of choice for displaced diaphyseal fractures of the forearm. One possible complication associated with plate fixation is refracture with the plate in situ or after plate removal. With the plate in situ, refracture typically occurs through the last screw hole near the end of the plate. Some clinicians have advocated the use of unicortical end screws to minimize the risk of such refractures. In this study, we performed a series of in vitro tests to compare the breaking strength of plated bone analogues that used either unicortical or bicortical end screws. The plated constructs that used unicortical end screws were significantly weaker in the two most important physiologic loading modes. Based on these results, we conclude that the use of unicortical end screws may result in a greater risk of refracture with the plate in situ.

  View details for PubMedID 1403247

• THE INFLUENCE OF FIXATION PEG DESIGN ON THE SHEAR STABILITY OF PROSTHETIC IMPLANTS JOURNAL OF ORTHOPAEDIC RESEARCH Giori, N. J., Beaupre, G. S., Carter, D. R. 1990; 8 (6): 892-898

  Abstract

  The variety of fixation peg designs existing on prosthetic implants indicates uncertainty regarding the optimum design of fixation pegs for the reduction of stress and relative motion at the bone-implant interface. Fixation pegs have a number of important functions on a prosthesis, one of which is to reduce shear stress and shear displacement at the bone-implant interface. This is a parametric study intended to identify trends in the shear stability of prostheses incorporating a range of fixation peg designs. The parameters varied included the number of fixation pegs on a surface, the size of the pegs, and the aspect ratio (length/diameter) of the pegs. Mechanical tests were performed on urethane foam blocks with mechanical properties comparable to trabecular bone. The results indicated the following: (a) Fixation pegs act independently in resisting shearing force if they are spaced sufficiently far apart. (b) For any given shear displacement, smaller pegs generate a greater resistive shear force per unit of peg projected area in the direction of the applied load than larger pegs having the same aspect ratio. (c) Smaller diameter pegs cause the supporting material to yield at lower displacements. (d) Pegs with a high aspect ratio provide high shear stability with a minimum amount of bone removed, but may bend if the aspect ratio becomes excessive. (e) Smaller, slender pegs generate a greater resistive shear force at a given displacement per unit of peg volume than larger, lower aspect ratio pegs.(ABSTRACT TRUNCATED AT 250 WORDS)

  View details for Web of Science ID A1990EF13000014

  View details for PubMedID 2213346