Clinical Focus

  • Osteomyelitis
  • Nonunions and Malunions
  • Limb Lengthening and Reconstruction
  • Limb Salvage
  • Limb Transplantation via Immunotolerance
  • Orthopaedic Trauma
  • Orthopaedic Surgery

Academic Appointments

Administrative Appointments

  • Unit Based Medical Director, Stanford Hospital and Clinics (2016 - 2019)

Honors & Awards

  • Landstuhl Distinguished Visiting Scholar, United States Department of Defense (May, 2010)

Boards, Advisory Committees, Professional Organizations

  • President, Osteosynthesis and Trauma Care Foundation (OTC) International (2018 - 2019)
  • President, Limb Lengthening and Reconstruction Society of North America (2006 - 2007)
  • President, Foundation for Orthopaedic Trauma (2013 - 2016)

Professional Education

  • Medical Education: UCLA David Geffen School Of Medicine Registrar (1985) CA
  • Residency: University of California at San Francisco School of Medicine (1990) CA
  • Internship: University of California at San Francisco School of Medicine (1986) CA
  • Board Certification: American Board of Orthopaedic Surgery, Orthopaedic Surgery (1992)

Current Research and Scholarly Interests

Dr. Lowenberg is a Past President of the Limb Lengthening and Reconstruction Society of North America. His clinical and research interests are in the treatment of nonunions and malunions with or without accompanying osteomyelitis and infection. He is well-published in the field of limb salvage and treatment of devastating limb injuries. He has ongoing research in limb transplantation via immunotolerance as well as biomechanics.

2023-24 Courses

All Publications

  • Are Postoperative Complications of Joint Replacement Correlated With the Phase of the Moon? An Analysis of Data From the Medicare Registry DEUTSCHES ARZTEBLATT INTERNATIONAL Walter, N., Hinterberger, T., Loew, T., Lowenberg, D. W., Alt, V., Lau, E. C., Rupp, M. 2023; 120 (51-52): 888-889

    View details for DOI 10.3238/arztebl.m2023.0249

    View details for Web of Science ID 001158482200006

    View details for PubMedID 38315655

    View details for PubMedCentralID PMC10859748

  • Complications and associated risk factors after surgical management of proximal femoral fractures. Bone & joint open Walter, N., Szymski, D., Kurtz, S. M., Lowenberg, D. W., Alt, V., Lau, E. C., Rupp, M. 2023; 4 (10): 801-807


    This work aimed at answering the following research questions: 1) What is the rate of mechanical complications, nonunion and infection for head/neck femoral fractures, intertrochanteric fractures, and subtrochanteric fractures in the elderly USA population? and 2) Which factors influence adverse outcomes?Proximal femoral fractures occurred between 1 January 2009 and 31 December 2019 were identified from the Medicare Physician Service Records Data Base. The Kaplan-Meier method with Fine and Gray sub-distribution adaptation was used to determine rates for nonunion, infection, and mechanical complications. Semiparametric Cox regression model was applied incorporating 23 measures as covariates to identify risk factors.Union failure occured in 0.89% (95% confidence interval (CI) 0.83 to 0.95) after head/neck fracturs, in 0.92% (95% CI 0.84 to 1.01) after intertrochanteric fracture and in 1.99% (95% CI 1.69 to 2.33) after subtrochanteric fractures within 24 months. A fracture-related infection was more likely to occur after subtrochanteric fractures than after head/neck fractures (1.64% vs 1.59%, hazard ratio (HR) 1.01 (95% CI 0.87 to 1.17); p < 0.001) as well as after intertrochanteric fractures (1.64% vs 1.13%, HR 1.31 (95% CI 1.12 to 1.52); p < 0.001). Anticoagulant use, cerebrovascular disease, a concomitant fracture, diabetes mellitus, hypertension, obesity, open fracture, and rheumatoid disease was identified as risk factors. Mechanical complications after 24 months were most common after head/neck fractures with 3.52% (95% CI 3.41 to 3.64; currently at risk: 48,282).The determination of complication rates for each fracture type can be useful for informed patient-clinician communication. Risk factors for complications could be identified for distinct proximal femur fractures in elderly patients, which are accessible for therapeutical treatment in the management.

    View details for DOI 10.1302/2633-1462.410.BJO-2023-0088.R1

    View details for PubMedID 37866820

    View details for PubMedCentralID PMC10590671

  • What Are the Mortality, Infection, and Nonunion Rates After Periprosthetic Femoral Fractures in the United States? Clinical orthopaedics and related research Walter, N., Szymski, D., Kurtz, S. M., Alt, V., Lowenberg, D. W., Lau, E. C., Rupp, M. 2023


    BACKGROUND: Periprosthetic femoral fractures are a serious complication that put a high burden on patients. However, comprehensive analyses of their incidence, mortality, and complication rates based on large-registry data are scarce.QUESTIONS/PURPOSES: In this large-database study, we asked: (1) What is the incidence of periprosthetic femoral fractures in patients 65 years and older in the United States? (2) What are the rates of mortality, infection, and nonunion, and what factors are associated with these outcomes?METHODS: In this retrospective, comparative, large-database study, periprosthetic femoral fractures occurring between January 1, 2010, and December 31, 2019, were identified from Medicare physician service records encompassing services rendered in medical offices, clinics, hospitals, emergency departments, skilled nursing facilities, and other healthcare institutions from approximately 2.5 million enrollees. These were grouped into proximal, distal, and shaft fractures after TKA and THA. We calculated the incidence of periprosthetic femur fractures by year. Incidence rate ratios (IRR) were calculated by dividing the incidence in 2019 by the incidence in 2010. The Kaplan-Meier method with Fine and Gray subdistribution adaptation was used to calculate the cumulative incidence rates of mortality, infection, and nonunion. Semiparametric Cox regression was applied with 23 measures as covariates to determine factors associated with these outcomes.RESULTS: From 2010 to 2019, the incidence of periprosthetic femoral fractures increased steeply (TKA for distal fractures: IRR 3.3 [95% CI 1 to 9]; p = 0.02; THA for proximal fractures: IRR 2.3 [95% CI 1 to 4]; p = 0.01). One-year mortality rates were 23% (95% CI 18% to 28%) for distal fractures treated with THA, 21% (95% CI 19% to 24%) for proximal fractures treated with THA, 22% (95% CI 19% to 26%) for shaft fractures treated with THA, 21% (95% CI 18% to 25%) for distal fractures treated with TKA , 22% (95% CI 17% to 28%) for proximal fractures treated with TKA, and 24% (95% CI 19% to 29%) for shaft fractures treated with TKA. The 5-year mortality rate was 63% (95% CI 54% to 70%) for distal fractures treated with THA, 57% (95% CI 54% to 62%) for proximal fractures treated with THA, 58% (95% CI 52% to 63%) for shaft fractures treated with THA, 57% (95% CI 52% to 62%) for distal fractures treated with TKA , 57% (95% CI 49% to 65%) for proximal fractures treated with TKA, and 57% (95% CI 49% to 64%) for shaft fractures treated with TKA. Age older than 75 years, male sex, chronic obstructive pulmonary disease (HR 1.48 [95% CI 1.32 to 1.67] after THA and HR 1.45 [95% CI 1.20 to 1.74] after TKA), cerebrovascular disease after THA, chronic kidney disease (HR 1.28 [95% CI 1.12 to 1.46] after THA and HR 1.50 [95% CI 1.24 to 1.82] after TKA), diabetes mellitus, morbid obesity, osteoporosis, and rheumatoid arthritis were clinical risk factors for an increased risk of mortality. Within the first 2 years, fracture-related infections occurred in 5% (95% CI 4% to 7%) of patients who had distal fractures treated with THA, 5% [95% CI 5% to 6%]) of patients who had proximal fractures treated with THA, 6% (95% CI 5% to 7%) of patients who had shaft fractures treated with THA, 6% (95% CI 5% to 7%) of patients who had distal fractures treated with TKA , 7% (95% CI 5% to 9%) of patients who had proximal fractures treated with TKA, and 6% (95% CI 4% to 8%) of patients who had shaft fractures treated with TKA. Nonunion or malunion occurred in 3% (95% CI 2% to 4%) of patients with distal fractures treated with THA, 1% (95% CI 1% to 2%) of patients who had proximal fractures treated with THA, 2% (95% CI 1% to 3%) of patients who had shaft fractures treated with THA, 4% (95% CI 3% to 5%) of those who had distal fractures treated with TKA, , 2% (95% CI 1% to 4%) of those who had proximal fractures treated with TKA, and 3% (95% CI 2% to 4%) of those who had shaft fractures treated with TKA.CONCLUSION: An increasing number of periprosthetic fractures were observed during the investigated period. At 1 and 5 years after periprosthetic femur fracture, there was a substantial death rate in patients with Medicare. Conditions including cerebrovascular illness, chronic kidney disease, diabetes mellitus, morbid obesity, osteoporosis, and rheumatoid arthritis are among the risk factors for increased mortality. After the surgical care of periprosthetic femur fractures, the rates of fracture-related infection and nonunion were high, resulting in a serious risk to affected patients. Patient well-being can be enhanced by an interdisciplinary team in geriatric traumatology and should be improved to lower the risk of postoperative death. Additionally, it is important to ensure that surgical measures to prevent fracture-related infections are followed diligently. Furthermore, there is a need to continue improving implants and surgical techniques to avoid often-fatal complications such as fracture-associated infections and nonunion, which should be addressed in further studies.LEVEL OF EVIDENCE: Level III, therapeutic study.

    View details for DOI 10.1097/CORR.0000000000002825

    View details for PubMedID 37678213

  • Epidemiology and treatment of proximal femoral fractures in the elderly U.S. population. Scientific reports Walter, N., Szymski, D., Kurtz, S. M., Lowenberg, D. W., Alt, V., Lau, E. C., Rupp, M. 2023; 13 (1): 12734


    Proximal femoral fractures are a serious complication, especially for elderly patients. Detailed epidemiological analyzes provide a valuable resource for stakeholders in the health care system in order to foresee future development possibly influenceable by adaption of therapeutic procedures and prevention strategies. This work aimed at answering the following research questions: (1) What are the incidence rates of proximal femoral fractures in the elderly U.S. population? (2) What is the preferred treatment procedure for these fractures? Proximal femoral fractures occurred between January 1, 2009 and December 31, 2019 in patients ≥ 65 years were identified from the Medicare Physician Service Records Data Base. The 5% sample of Medicare beneficiaries, equivalent to the records from approximately 2.5 million enrollees formed the basis of this study. Fractures were grouped into head/neck, intertrochanteric, and subtrochanteric fractures. The overall incidence rate, age and sex specific incidence rates as well as incidence rate ratios were calculated. Common Procedural Terminology (CPT) codes were used to identify procedures and operations. In 2019, a total number of 7982 femoral head/neck fractures was recorded. In comparison to 9588 cases in 2009, the incidence substantially decreased by 26.6% from 666.7/100,000 inhabitants to 489.3/100,000 inhabitants (z =  - 5.197, p < 0.001). Also, in intertrochanteric fractures, a significant decline in the incidence by 17.3% was evident over the years from 367.7/100,000 inhabitants in 2009 to 304.0 cases per 100,000 inhabitants in 2019 (z =  - 2.454, p = 0.014). A similar picture was observable for subtrochanteric fractures, which decreased by 29.6% (51.0 cases per 100,000 to 35.9 cases per 100,000) over the time period (z =  - 1.612, p = 0.107). Head/neck fractures were mainly treated with an arthroplasty (n = 36,301, 40.0%). The majority of intertrochanteric fractures and subtrochanteric fractures received treatment with an intramedullary device (n = 34,630, 65.5% and n = 5870, 77.1%, respectively). The analysis indicated that the incidence of all types of proximal femoral neck fractures decreased for the population of elderly patients in the U.S. within the last decade. Treatment of head and neck fractures was mainly conducted through arthroplasty, while intertrochanteric and subtrochanteric fractures predominantly received an intramedullary nailing.

    View details for DOI 10.1038/s41598-023-40087-8

    View details for PubMedID 37543668

    View details for PubMedCentralID 5790076

  • Factors associated with mortality after proximal femoral fracture. Journal of orthopaedics and traumatology : official journal of the Italian Society of Orthopaedics and Traumatology Walter, N., Szymski, D., Kurtz, S., Alt, V., Lowenberg, D. W., Lau, E., Rupp, M. 2023; 24 (1): 31


    Proximal femoral fractures are a serious complication, especially for elderly patients. Therefore, we have aimed to answer the following research question: What is the postfracture mortality rate in the elderly population and what are associated risk factors? For this, proximal femoral fractures that occurred between 1 January 2009 and 31 December 2019 were identified from the Medicare Physician Service Records database. The Kaplan-Meier (KM) method with the Fine and Gray subdistribution adaptation was used to determine rates of mortality. A semiparametric Cox regression model was applied, incorporating 23 measures as covariates to identify risk factors. The estimated 1year mortality rate was 26.8% after head/neck fracture, 28.2% after intertrochanteric fracture, and 24.2% after subtrochanteric fracture. Male sex, age over 70years, chronic obstructive pulmonary disease (COPD), cerebrovascular disease, chronic kidney disease, a concomitant fracture, congestive heart failure, diabetes mellitus, hypertension, insulin use, ischemic heart disease, morbid obesity, osteoporosis, tobacco dependence, and median household income were determined as risk factors for increased mortality. An early assessment of individual risk factors accessible for therapeutic treatment is crucial in the management of proximal femur fractures to aid in attempts at reducing the high mortality apparent in the elderly US population.

    View details for DOI 10.1186/s10195-023-00715-5

    View details for PubMedID 37365418

  • Proximal Humerus Fractures in the Elderly U.S. Population: A Cross-Sectional Study of Treatment Trends and Comparison of Complication Rates after Joint Replacement, Open Reduction and Internal Fixation, and Non-Surgical Management. Journal of clinical medicine Walter, N., Szymski, D., Riedl, M., Kurtz, S. M., Alt, V., Lowenberg, D. W., Lau, E. C., Rupp, M. 2023; 12 (10)


    Proximal humerus fracture (PHF) treatment remains challenging. Multiple therapy options exist, and the optimal choice of management has been increasingly discussed in the literature. The aim of this study was to (1) analyze trends in the propensity of proximal humerus fracture treatments and (2) compare complication rates after joint replacement, surgical repair, and non-surgical treatment in terms of mechanical complications, union failure, and infection rates. In this cross-sectional study, patients aged 65 years or older with proximal humerus fractures occurring between 1 January 2009 and 31 December 2019 were identified from Medicare physician service claims records. The Kaplan-Meier method with the Fine and Gray adjustment was used to calculate the cumulative incidence rates for malunion/nonunion, infection, and mechanical complications for the following treatment categories: shoulder arthroplasty, open reduction and internal fixation (ORIF), and non-surgical treatment, respectively. Semiparametric Cox regression was performed incorporating 23 demographic, clinical, and socioeconomic covariates to determine risk factors. Between 2009 through 2019, conservative procedures decreased by 0.9%. ORIF procedures decreased from 9.51% (95% CI: 8.7-10.4) to 6.95% (95% CI: 6.2-7.7), whereas shoulder arthroplasties rose from 1.99% (95% CI: 1.6-2.4), to 5.45% (95% CI: 4.8-6.2). PHFs managed through ORIF were associated with higher union failure rates compared to conservatively treated fractures (HR = 1.31, 95% CI: 1.15-1.5, p < 0.001). The risk of developing an infection was increased after joint replacement compared to ORIF (2.66% vs. 1.09%, HR = 2.09, 95% CI: 1.46-2.98, p < 0.001). Mechanical complications were more common after joint replacement (6.37% vs. 4.85%, HR = 1.66, 95% CI: 1.32-2.09, p < 0.001). Complication rates differed significantly across treatment modalities. This should be considered when choosing a management procedure. Vulnerable elderly patient cohorts could be identified, and the optimization of modifiable risk factors might lead to a decrease of complication rates in both surgically and non-surgically treated patients.

    View details for DOI 10.3390/jcm12103506

    View details for PubMedID 37240612

  • Femoral shaft fractures in eldery patients - An epidemiological risk analysis of incidence, mortality and complications. Injury Walter, N., Szymski, D., Kurtz, S. M., Alt, V., Lowenberg, D. W., Lau, E. C., Rupp, M. 2023


    OBJECTIVES: This work aimed at answering the following research questions: (1) What is the incidence of femoral shaft fractures in the geriatric population in the U.S.? (2) What is the rate of mortality, mechanical complications, nonunion and infection, and what are the associated risk factors?STUDY DESIGN AND SETTING: In this cross-sectional study, femoral shaft fractures occurred between January 1, 2009, and December 31, 2019, were identified from Medicare records. Rates of mortality, nonunion, infection, and mechanical complications were calculated with the Kaplan-Meier method with Fine and Gray sub-distribution adaptation. Semiparametric Cox regression was applied with twenty-three covariates to determine risk factors.RESULTS: Between 2009 through 2019 the incidence of femoral shaft fractures decreased by 12.07% to 40.8/100,000 inhabitants (p=0.549). The 5-year mortality risk was 58.5%. Male sex, age over 75 years, chronic obstructive pulmonary disease, cerebrovascular disease, chronic kidney disease, congestive heart failure, diabetes mellitus, osteoporosis, tobacco dependence, and lower median household income were significant risk factors. The infection rate was 2.22% [95%CI: 1.90-2.58] and the union failure rate 2.52% [95%CI: 2.17-2.92] after 24 months.CONCLUSION: An early assessment of individual patient risk factors may be beneficial in the care and treatment of patients with these fractures.

    View details for DOI 10.1016/j.injury.2023.05.053

    View details for PubMedID 37208254

  • Selecting a High-dose Antibiotic-laden Cement Knee Spacer. Journal of orthopaedic research : official publication of the Orthopaedic Research Society Hollyer, I., Ivanov, D., Kappagoda, S., Lowenberg, D. W., Goodman, S. B., Amanatullah, D. F. 2023


    Periprosthetic infection (PJI) after total knee arthroplasty (TKA) remains a common and challenging problem for joint replacement surgeons and patients. Once the diagnosis of PJI has been made, patient goals and characteristics and the infection timeline dictate treatment. Most commonly, this involves a two-stage procedure with removal of all implants, debridement, and placement of a static or dynamic antibiotic spacer. Static spacers are commonly indicated for older, less healthy patients that would benefit from soft tissue rest after initial debridement. Mobile spacers are typically used in younger, healthier patients to improve quality of life and reduce soft tissue contractures during antibiotic spacer treatment. Spacers are highly customizable with regard to antibiotic choice, cement variety, and spacer design, each with reported advantages, drawbacks, and indications that will be covered in this article. While no spacer has yet to be demonstrated as superior to any other, the modern arthroplasty surgeon must be familiar with the available modalities to optimize treatment for each patient. Here we propose a treatment algorithm to assist surgeons in deciding on treatment for PJI after TKA. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/jor.25570

    View details for PubMedID 37127938

  • Proximal humerus fractures - epidemiology, comparison of mortality rates after surgical versus non-surgical treatment, and analysis of risk factors based on Medicare registry data. Bone & joint research Walter, N., Szymski, D., Kurtz, S. M., Lowenberg, D. W., Alt, V., Lau, E., Rupp, M. 2023; 12 (2): 103-112


    AIMS: The optimal choice of management for proximal humerus fractures (PHFs) has been increasingly discussed in the literature, and this work aimed to answer the following questions: 1) what are the incidence rates of PHF in the geriatric population in the USA; 2) what is the mortality rate after PHF in the elderly population, specifically for distinct treatment procedures; and 3) what factors influence the mortality rate?METHODS: PHFs occurring between 1 January 2009 and 31 December 2019 were identified from the Medicare physician service records. Incidence rates were determined, mortality rates were calculated, and semiparametric Cox regression was applied, incorporating 23 demographic, clinical, and socioeconomic covariates, to compare the mortality risk between treatments.RESULTS: From 2009 to 2019, the incidence decreased by 11.85% from 300.4 cases/100,000 enrollees to 266.3 cases/100,000 enrollees, although this was not statistically significant (z = -1.47, p = 0.142). In comparison to matched Medicare patients without a PHF, but of the same five-year age group and sex, a mean survival difference of -17.3% was observed. The one-year mortality rate was higher after nonoperative treatment with 16.4% compared to surgical treatment with 9.3% (hazard ratio (HR) = 1.29, 95% confidence interval (CI) 1.23 to 1.36; p < 0.001) and to shoulder arthroplasty with 7.4% (HR = 1.45, 95% CI 1.33 to 1.58; p < 0.001). Statistically significant mortality risk factors after operative treatment included age older than 75 years, male sex, chronic obstructive pulmonary disease (COPD), cerebrovascular disease, chronic kidney disease, a concomitant fracture, congestive heart failure, and osteoporotic fracture.CONCLUSION: Mortality risk factors for distinct treatment modes after PHF in elderly patients could be identified, which may guide clinical decision-making.Cite this article: Bone Joint Res2023;12(2):103-112.

    View details for DOI 10.1302/2046-3758.122.BJR-2022-0275.R1

    View details for PubMedID 36718643

  • Revision Rates and Associated Risk Factors after Shoulder Arthroplasty. Journal of clinical medicine Walter, N., Lowenberg, D. W., Kurtz, S. M., Alt, V., Lau, E. C., Rupp, M. 2022; 11 (24)


    This study aims at answering the following questions (1) How high is the revision rate after osteoarthritis-, and rotator cuff-related compared to proximal humerus fracture (PHF)-related shoulder arthroplasty? (2) What are the associated risk factors for a revision after shoulder arthroplasty? Shoulder arthroplasty procedures occurring between 1 January 2009 and 31 December 2019 were identified from the Medicare database. First, revision rates for PHF patients and age- and sex-matched non-fracture patients, grouped into osteoarthritis-related and rotator cuff-related arthroplasty, were compared. Second, revision rates between total shoulder arthroplasty and hemiarthroplasty after PHF were compared. Semiparametric Cox regression was applied, incorporating 23 demographic, clinical, and socioeconomic covariates, to investigate risk factors for revision surgery. Between the considered time period from 2009 through 2019, a total number of 47,979 PHFs was identified. A shoulder arthroplasty procedure was performed in n = 2639 (5.5%, 95%CI: 4.8-6.1) of the cases. The five-year survivorship of the implant was 96.3 (95%CI: 93.8-97.9) after hemiarthroplasty and 96.1% (05%CI: 94.2-97.3) after total shoulder arthroplasty. To compare the revision rates, n = 14,775 patients with osteoarthritis and n = 4268 patients with rotator cuff arthropathy, who received a shoulder arthroplasty, served as a non-fracture control group. Patients receiving a rotator cuff-related arthroplasty were more likely to require a revision compared to patients treated for osteoarthritis (HR: 1.27, 95%CI: 1.04-1.44, p = 0.018). Identified significant risk factors for revision surgery after shoulder arthroplasty included age ≤ 75 years, male sex, and osteoporosis. High implant survival was found for hemiarthroplasty and total shoulder arthroplasty for the treatment of PHF in elderly patients. The risk of revision surgery was elevated in patients receiving a rotator cuff-related arthroplasty as well as in patients with osteoporosis, male patients and patients older than 75 years.

    View details for DOI 10.3390/jcm11247256

    View details for PubMedID 36555873

  • Approach to Complex Lower Extremity Reconstruction. Seminars in plastic surgery Cholok, D., Saberski, E., Lowenberg, D. W. 2022; 36 (4): 233-242


    Composite injuries to the lower extremity from etiologies including trauma and infection present a complex dilemma for the reconstructive surgeon, and require multidisciplinary collaboration amongst plastic, vascular, and orthopaedic surgical specialties. Here we present our algorithm for lower-extremity reconstructive management, refined over the last decades to provide an optimized outcome for our patients. Reconstruction is predicated on the establishment of a clean and living wound, where quality of the wound-bed is prioritized over timing to soft-tissue coverage. Once established, soft-tissues and fractures are provisionally stabilized; our preference for definitive coverage is for microvascular free-tissue, due to the paucity of healthy soft-tissue available at the injury, and ability to avoid the zone of injury for microvascular anastomosis. Finally, definitive bony reconstruction is dictated by the length and location of long-bone defect, with a preference to utilize bone transport for defects longer than 5 cm.

    View details for DOI 10.1055/s-0042-1758205

    View details for PubMedID 36561427

    View details for PubMedCentralID PMC9762997

  • Terminology of bone and joint infection BONE & JOINT RESEARCH Rupp, M., Walter, N., Baertl, S., Lang, S., Lowenberg, D. W., Alt, V. 2021; 10 (11): 742-743
  • Terminology of bone and joint infection. Bone & joint research Rupp, M., Walter, N., Baertl, S., Lang, S., Lowenberg, D. W., Alt, V. 2021; 10 (11): 742-743
  • Tolerant Small-colony Variants Form Prior to Resistance Within a Staphylococcus aureus Biofilm Based on Antibiotic Selective Pressure. Clinical orthopaedics and related research Manasherob, R. n., Mooney, J. A., Lowenberg, D. W., Bollyky, P. L., Amanatullah, D. F. 2021


    The treatment of periprosthetic joint infection (PJI) is focused on the surgical or chemical removal of biofilm. Antibiotics in isolation are typically ineffective against PJI. Bacteria survive after antibiotic administration because of antibiotic tolerance, resistance, and persistence that arise in the resident bacteria of a biofilm. Small-colony variants are typically slow-growing bacterial subpopulations that arise after antibiotic exposure and are associated with persistent and chronic infections such as PJI. The role of biofilm-mediated antibiotic tolerance in the emergence of antibiotic resistance remains poorly defined experimentally.We asked: (1) Does prior antibiotic exposure affect how Staphylococcus aureus survives within a developing biofilm when exposed to an antibiotic that penetrates biofilm, like rifampicin? (2) Does exposure to an antibiotic with poor biofilm penetration, such as vancomycin, affect how S. aureus survives within a developing biofilm? (3) Do small-colony variants emerge from antibiotic-tolerant or-resistant bacteria in a S. aureus biofilm?We used a porous membrane as an in vitro implant model to grow luminescent S. aureus biofilms and simultaneously track microcolony expansion. We evaluated the impact of tolerance on the development of resistance by comparing rifampicin (an antibiotic that penetrates S. aureus biofilm) with vancomycin (an antibiotic that penetrates biofilm poorly). We performed viability counting after membrane dissociation to discriminate among tolerant, resistant, and persistent bacteria. Biofilm quantification and small-colony morphologies were confirmed using scanning electron microscopy. Because of experimental variability induced by the starting bacterial inoculum, relative changes were compared since absolute values may not have been statistically comparable.Antibiotic-naïve S. aureus placed under the selective pressure of rifampicin initially survived within an emerging biofilm by using tolerance given that biofilm resident cell viability revealed 1.0 x 108 CFU , of which 7.5 x 106 CFU were attributed to the emergence of resistance and 9.3 x 107 CFU of which were attributed to the development of tolerance. Previous exposure of S. aureus to rifampicin obviated tolerance-mediate survival when rifampicin resistance was present, since the number of viable biofilm resident cells (9.5 x 109 CFU) nearly equaled the number of rifampicin-resistant bacteria (1.1 x 1010 CFU). Bacteria exposed to an antibiotic with poor biofilm penetration, like vancomycin, survive within an emerging biofilm by using tolerance as well because the biofilm resident cell viability for vancomycin-naïve (1.6 x 1010 CFU) and vancomycin-resistant (1.0 x 1010 CFU) S. aureus could not be accounted for by emergence of resistance. Adding rifampicin to vancomycin resulted in a nearly 500-fold reduction in vancomycin-tolerant bacteria from 1.5 x 1010 CFU to 3.3 x 107 CFU. Small-colony variant S. aureus emerged within the tolerant bacterial population within 24 hours of biofilm-penetrating antibiotic administration. Scanning electron microscopy before membrane dissociation confirmed the presence of small, uniform cells with biofilm-related microstructures when unexposed to rifampicin as well as large, misshapen, lysed cells with a small-colony variant morphology [29, 41, 42, 63] and a lack of biofilm-related microstructures when exposed to rifampicin. This visually confirmed the rapid emergence of small-colony variants within the sessile niche of a developing biofilm when exposed to an antibiotic that exerted selective pressure.Tolerance explains why surgical and nonsurgical modalities that rely on antibiotics to "treat" residual microscopic biofilm may fail over time. The differential emergence of resistance based on biofilm penetration may explain why some suppressive antibiotic therapies that do not penetrate biofilm well may rely on bacterial control while limiting the emergence of resistance. However, this strategy fails to address the tolerant bacterial niche that harbors persistent bacteria with a small-colony variant morphology.Our work establishes biofilm-mediated antibiotic tolerance as a neglected feature of bacterial communities that prevents the effective treatment of PJI.

    View details for DOI 10.1097/CORR.0000000000001740

    View details for PubMedID 33835090

  • Interlocking screw configuration influences distal tibial fracture stability in torsional loading after intramedullary nailing. European journal of orthopaedic surgery & traumatology : orthopedie traumatologie Lowenberg, D. W., DeBaun, M. R., Behn, A., Sox-Harris, A. 2020


    PURPOSE: This study evaluated the influence of fracture obliquity and locking screw configuration on interfragmentary motion during torsional loading of distal metaphyseal tibial fractures fixed by intramedullary (IM) nailing.METHODS: The stability of six IM nail locking screw configurations used to fix distal metaphyseal tibial fractures of various obliquities was evaluated. A coronal osteotomy from proximal lateral to distal medial was made in sawbone tibiae at different obliquities from 0° to 60°. After fixation, motion at the fracture was assessed during internal and external rotation tests to 7 Nm under two compressive loading conditions: 20N and 500N.RESULTS: With results organized by interlocking configuration, significant differences in interfragmentary rotation between fracture obliquities are observed when the number of interlocking screws is decreased to one distal static and one proximal dynamic during internal rotation. During external rotation testing, significant rotational differences between fracture obliquities are encountered with two distal static screws and one proximal dynamic. No significant differences were seen between different distal interlocking screw orientations (two parallel versus perpendicular distal screws) for all fracture obliquity patterns tested.CONCLUSION: Fracture obliquity influences rotational stability which can be mitigated by interlocking screw configurations when nailing distal tibia fractures. At least two distal and one proximal interlocking screwin a static mode is recommended to resist torsional loading of distal tibia fractures undergoing intramedullary nailing. The addition of more interlocking screws than this did not significantly alter control of torsional displacement with load.

    View details for DOI 10.1007/s00590-020-02686-3

    View details for PubMedID 32367222

  • Pain management in the orthopaedic trauma patient: Non-opioid solutions INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED Gessner, D. M., Horn, J., Lowenberg, D. W. 2020; 51: S28–S36
  • Synthetic bone tissue engineering graft substitutes: What is the future? Injury Valtanen, R. S., Yang, Y. P., Gurtner, G. C., Maloney, W. J., Lowenberg, D. W. 2020


    The management of large segmental bone defects caused by trauma or disease remains clinically challenging within orthopaedics. The major impediment to bone healing with current treatment options is insufficient vascularization and incorporation of graft material. Lack of rapid adequate vascularization leads to cellular necrosis within the inner regions of the implanted material and a failure of bone regeneration. Current treatment options for critical size bone defects include the continued "gold standard" autograft, allograft, synthetic bone graft substitutes, vascularized fibular graft, induced membrane technique, and distraction osteogenesis. Bone tissue engineering (BTE) remains an exciting prospect for the treatment of large segmental bone defects; however, current clinical integration of engineered scaffolds remains low. We believe that the barrier to clinical application of bone tissue engineering constructs lies in the lack of concomitant vascularization of these scaffolds. This mini-review outlines the progress made and the significant limitations remaining in successful clinical incorporation or engineered synthetic bone substitutes for segmental defects.

    View details for DOI 10.1016/j.injury.2020.07.040

    View details for PubMedID 32732118

  • Distal Tibial Fractures With or Without Articular Extension: Fixation With Circular External Fixation or Open Plating? A Personal Point of View. Journal of orthopaedic trauma Lowenberg, D. W., Smith, R. M. 2019; 33 Suppl 8: S7–S13


    The treatment of very distal tibial (pilon) fractures remains one of the great challenges for the orthopaedic traumatologist. It is essential that the treating surgeon have a proper understanding of the fracture, the soft tissue injury, and the skills to deal with these often-complicated injuries to minimize the risk of complications that can occur after these often higher energy injuries. Bone stability can be achieved with both circular ring fixation and plating, and both can yield good results in experienced hands. This debate considers the advantages and disadvantages of each technique.

    View details for DOI 10.1097/BOT.0000000000001640

    View details for PubMedID 31688521

  • Influence of fracture obliquity and interlocking nail screw configuration on interfragmentary motion in distal metaphyseal tibia fractures. European journal of orthopaedic surgery & traumatology : orthopedie traumatologie Lowenberg, D. W., DeBaun, M. R., Sox-Harris, A., Behn, A. 2019


    The indications for the use of intramedullary (IM) nails have been extended to include extra-articular distal metaphyseal tibia fractures. We hypothesize that interfragmentary motion during physiologic compressive loading of distal tibia fractures is influenced by fracture obliquity and can be modulated by interlocking screw configuration. Sawbone specimens were osteotomized with frontal plane obliquities ranging from 0° to 60° and then fixed by IM nailing with six interlocking screw configurations. Interfragmentary motion was evaluated during loading in axial compression to 1000N. Comparisons of interfragmentary motions were made (1) between configurations for the various fracture obliquities and (2) between fracture obliquities for the various screw configurations using a mixed-effects regression model. As the degree of fracture obliquity increased, significantly more interfragmentary displacement was shown in configurations with two distal interlocking screws and one proximal screw set in dynamic mode. Fracture obliquity beyond 30° causes demonstrated instability in configurations with less than two distal locking screws and one proximal locking screw. Optimizing the available screw configurations can minimize fracture site motion and shear in distal tibial fractures with larger fracture obliquities.

    View details for DOI 10.1007/s00590-019-02553-w

    View details for PubMedID 31571003

  • Newer perspectives in the treatment of chronic osteomyelitis: A preliminary outcome report INJURY-INTERNATIONAL JOURNAL OF THE CARE OF THE INJURED Lowenberg, D. W., DeBaun, M., Suh, G. A. 2019; 50: S56–S61
  • Congenital internal rotation deformity of the distal femur presenting as patellofemoral instability and pain JOURNAL OF ISAKOS JOINT DISORDERS & ORTHOPAEDIC SPORTS MEDICINE Zhang, X., Attenello, J., Safran, M. R., Lowenberg, D. W. 2019; 4 (2): 93-97
  • Pain management in the orthopaedic trauma patient: Non-opioid solutions. Injury Gessner, D. M., Horn, J. L., Lowenberg, D. W. 2019


    When treating pain in the orthopaedic trauma patient opioids have classically represented the mainstay of treatment. They are relatively inexpensive and modestly effective for basic pain management. However, they are fraught with considerable side effects as well as the very high risk of addiction. Their use in pain management has been implicated in the opioid epidemic. For this reason, as well as their only moderate efficacy, alternative modes of treatment have been sought for both the patient with isolated limb trauma and the patient with poly trauma. We review alternative treatment methods in pain management for those with isolated limb trauma and poly trauma. These methods include topical agents, as well as non steroidal anti-inflammatory medications, acetaminophen, gabapetoids, intravenous agents, varying degrees of local anesthetic infiltration and peripheral nerve blocks, and the newer modality of fascial plane blocks. Often, it is a combination of these analgesic modalities that gives the most optimum treatment for the trauma patient. This also, more frequently than not, must be individually tailored to the patient, as no two patients act the same in this regard. It is therefore of importance that the physician managing such patients's pain be experienced and well-versed in all these treatment modalities. We also provide a basic stepwise algorithm we have found useful in treating those with single extremity or single site trauma versus those patients with poly trauma and resultant multiple sources as pain generators. It is hoped that this breakdown of the different modalities along with a better understanding of each modality's potential benefits and indications will aid the surgeon in providing better care to patients following orthopedic trauma.

    View details for PubMedID 31079833

  • Newer Perspectives In the Treatment of Chronic Osteomyelitis: A Preliminary Outcome Report. Injury Lowenberg, D. W., DeBaun, M., Suh, G. A. 2019: S56-S61
  • Newer perspectives in the treatment of chronic osteomyelitis: A preliminary outcome report. Injury Lowenberg, D. W., DeBaun, M. n., Suh, G. A. 2019


    The prevalence of chronic osteomyelitis due to trauma and surgical complications does not seem to be diminishing in our society. In many African Nations, with the urbanization and shift to the larger cities that has been occurring, Trauma has been classified as the number one disease problem plaguing such societies. This brings along with it the ensuing infections. With our better understanding of how microbes gain attachment to sites in our body and morph from a planktonic state to the slow growing sessile phase of growth, combined with their formation of a highly structured biofilm colony, we have come to realize that we must resort to other forms of treatment. This means changing our philosophical approach to treatment utilized over the past nearly 70 years involving complete reliance on chemotherapeutic agents with their resultant questionable efficacy in the treatment of chronic osteomyelitis. We report on preliminary early outcome results in the treatment of 127 patients with chronic osteomyelitis treated by a single surgeon in which all patients except those with underlying immunological impairment were treated with in-hospital intravenous antibiotics only. Only 5.5% of the patient population then received intravenous antibiotics following hospital discharge, and with this treatment approach there remained a 98.4% cure rate in the treatment of this chronic infection.

    View details for PubMedID 31079834

  • Effect of Electron Beam Sterilization on Three-Dimensional-Printed Polycaprolactone/Beta-Tricalcium Phosphate Scaffolds for Bone Tissue Engineering TISSUE ENGINEERING PART A Bruyas, A., Moeinzadeh, S., Kim, S., Lowenberg, D. W., Yang, Y. 2019; 25 (3-4): 248–56
  • Fracture Healing Adjuncts-The World's Perspective on What Works JOURNAL OF ORTHOPAEDIC TRAUMA Giannoudis, P., Krettek, C., Lowenberg, D. W., Tosounidis, T., Borrelli, J. 2018; 32: S43–S47


    Treatment of bone defects remains a challenging clinical problem. Despite our better understanding of bone repair mechanisms and advances made in microsurgical techniques and regenerative medicine, the reintervention rates and morbidity remain high. Surgical techniques such as allograft implantation, free vascularized fibular graft, distraction osteogenesis, loaded titanium cages, and the induced membrane technique continue to evolve, but the outcome can be affected by a number of parameters including the age of the patient, comorbidities, systemic disorders, the location of the defect, and the surgeon's preference and experience. In the herein article, a brief summary of the most currently used techniques for the management of bone defects is presented.

    View details for PubMedID 29461403

  • Cement Arthrodesis of the Knee with a Custom Long Recon Nail After Failed Total Knee Arthroplasty: Surgical Technique and Results. The Open Orthopaedics Journal Lowenberg, D. W., DeBaun, M. R., Goodman, S. B. 2018; December (1): 554-566
  • Proper Use of Antibiotic Agents in the Management of Musculoskeletal Infection. Instructional course lectures Lowenberg, D. W., Goel, R. n., Parvizi, J. n. 2018; 67: 543–54


    Musculoskeletal infections have plagued all creatures for millions of years. The ability to manage infection via antibiotic agents has emerged only in the past 100 years. The use of antibiotic agents has not always been appropriate and judicious, which has led to widespread microbial resistance to certain antibiotic agents. Although antibiotic resistance is a considerable consequence of inappropriate antibiotic use, the systemic adverse effects of chronic antibiotic use on patients have largely been ignored. These systemic adverse effects may have been prevented if surgeons had a better understanding of the microbiology of the pathogens involved in musculoskeletal infections. Most importantly, the formation of biofilm as an infection becomes chronic makes bacteria relatively impervious to systemic antibiotic agents. Therefore, surgeons must understand the difference between and how to appropriately manage acute and chronic musculoskeletal infections. This dichotomous approach in the management of infection also must be applied in patients with periprosthetic joint infection. The appropriate use of antibiotic agents in the management of musculoskeletal infections may help mitigate the spread of antibiotic resistance and the adverse effects of inappropriate antibiotic use.

    View details for PubMedID 31411438

  • Proper Understanding and Usage of Antibiotics in Musculoskeletal Infections Instr Course Lect. American Academy of Orthopaedic Surgeons Lowenberg, D. W., Parvizi, J. 2018; 67: 543-554
  • Unstable Proximal Femur Fractures Treated With Proximal Femoral Locking Plates: A Retrospective, Multicenter Study of 111 Cases. Journal of orthopaedic trauma Collinge, C. A., Hymes, R., Archdeacon, M., Streubel, P., Obremskey, W., Weber, T., Watson, J. T., Lowenberg, D. 2016; 30 (9): 489-495


    A few small case series have found that proximal femur fractures treated with a proximal femur locking plate (PFLP) have experienced more failures than expected. The purpose of this study was to review the clinical results of patients with acute, unstable proximal femur fractures treated with proximal femoral locking plates in a large, multicenter patient cohort.This is a retrospective clinical study.The study included patients from 12 regional trauma centers and tertiary referral hospitals.One hundred eleven consecutive patients with unstable proximal femur fractures stabilized with a PFLP and having required clinical and radiographic follow-up at a minimum of 12 months after injury.Surgical repair of an unstable proximal femur fracture with a PFLP.Treatment failures (failure of fixation, nonunion, and malunion) and need for revision surgery.Forty-six patients (41.4%) experienced a major treatment failure, including failed fixation with or without nonunion (39), surgical malalignment or malunion (18), deep infection (8), or a combination of these. Thirty-eight (34%) patients underwent secondary surgeries, including 30 for failed fixation, nonunion, or both. Treatment failure was found to occur at a significantly higher rate in patients with major comorbidities, in femurs repaired in varus malalignment, and using specific plate designs.Proximal femoral locking plates are associated with a high complication rate, frequently requiring revision or secondary surgeries in the treatment of unstable proximal femur fractures. Given the high complication rate with PFLPs, careful attention to reduction, use of a PFLP implant, and consideration should be given to alternative implants or fixation techniques when appropriate.Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

    View details for DOI 10.1097/BOT.0000000000000602

    View details for PubMedID 27144821

  • A Technotheoretical Approach to the Management of Osteomyelitis TECHNIQUES IN ORTHOPAEDICS Lowenberg, D. W. 2015; 30 (4): 209–14
  • In Memorium: George Cierny, MD - Modern Father of Osteomyelitis Surgery TECHNIQUES IN ORTHOPAEDICS Lowenberg, D. W. 2015; 30 (4): 207–8
  • Complex Limb Reconstruction With Simultaneous Muscle Transfer and Circular External Fixation TECHNIQUES IN ORTHOPAEDICS Lowenberg, D. W., Githens, M. 2015; 30 (3): 156–60
  • A Clinical Perspective on Musculoskeletal Infection Treatment Strategies and Challenges JOURNAL OF THE AMERICAN ACADEMY OF ORTHOPAEDIC SURGEONS Shirwaiker, R. A., Springer, B. D., Spangehl, M. J., Garrigues, G. E., Lowenberg, D. W., Garras, D. N., Yoo, J. U., Pottinger, P. S. 2015; 23: S44-S54


    Orthopaedic implants improve the quality of life of patients, but the risk of postoperative surgical site infection poses formidable challenges for clinicians. Future directions need to focus on prevention and treatment of infections associated with common arthroplasty procedures, such as the hip, knee, and shoulder, and nonarthroplasty procedures, including trauma, foot and ankle, and spine. Novel prevention methods, such as nanotechnology and the introduction of antibiotic-coated implants, may aid in the prevention and early treatment of periprosthetic joint infections with goals of improved eradication rates and maintaining patient mobility and satisfaction.

    View details for DOI 10.5435/JAAOS-D-14-00379

    View details for Web of Science ID 000354129700008

    View details for PubMedID 25808969

  • Advances in the understanding and treatment of musculoskeletal infections. Instructional course lectures Lowenberg, D. W., Watson, J. T., Levin, L. S. 2015; 64: 37-49


    Musculoskeletal infections are a challenging treatment problem for orthopaedic surgeons. Despite advances in aseptic techniques and improved chemotherapeutic options, there has not been a substantial decrease in the incidence of musculoskeletal infections for the past quarter century. Understanding how microbes gain a foothold in tissue and bone and establish a chronic infectious state is imperative to the successful treatment of bone and soft-tissue infections. The methodic establishment of microbes in a sessile state in a mature biofilm represents the basis for instituting a chronic microbial defense system and sustainability in a host. To properly eradicate such infections requires a stepwise treatment algorithm of meticulous and thorough débridement, dead-space management, and soft-tissue and bone reconstruction. A comprehensive understanding of the reconstruction ladder combined with a detailed treatment plan from the initial staging of an infection through final reconstruction can cure an infection and achieve good functional results for patients.

    View details for PubMedID 25745893

  • Malignant Transformation in Chronic Osteomyelitis: Recognition and Principles of Management JOURNAL OF THE AMERICAN ACADEMY OF ORTHOPAEDIC SURGEONS Panteli, M., Puttaswamaiah, R., Lowenberg, D. W., Giannoudis, P. V. 2014; 22 (9): 586-594


    Malignant transformation as a result of chronic osteomyelitis represents a relatively rare and late complication with a declining incidence in the modern world. For most patients, the interval between the occurrence of the original bacterial infection and the transformation to malignant degeneration is several years. The diagnosis of malignant transformation in a chronic discharging sinus requires a high index of clinical suspicion. Wound biopsies should be obtained early, especially with the onset of new clinical signs such as increased pain, a foul smell, and changes in wound drainage. Squamous cell carcinoma is the most common presenting malignancy. Definitive treatment is amputation proximal to the tumor or wide local excision, combined with adjuvant chemotherapy and radiation therapy in selected patients. Early diagnosis may sometimes allow for treatment consisting of en bloc excision and limb salvage techniques. However, the most effective treatment is prevention with definitive treatment of the osteomyelitis, including adequate débridement, wide excision of the affected area, and early reconstruction.

    View details for DOI 10.5435/JAAOS-22-09-586

    View details for Web of Science ID 000341068800006

  • Temporal trends in the incidence, treatment and outcomes of hip fracture after first kidney transplantation in the United States. American journal of transplantation Sukumaran Nair, S., Lenihan, C. R., Montez-Rath, M. E., Lowenberg, D. W., Chertow, G. M., Winkelmayer, W. C. 2014; 14 (4): 943-951


    It is currently unknown whether any secular trends exist in the incidence and outcomes of hip fracture in kidney transplant recipients (KTR). We identified first-time KTR (1997-2010) who had >1 year of Medicare coverage and no recorded history of hip fracture. New hip fractures were identified from corresponding diagnosis and surgical procedure codes. Outcomes studied included time to hip fracture, type of surgery received and 30-day mortality. Of 69 740 KTR transplanted in 1997-2010, 597 experienced a hip fracture event during 155 341 person-years of follow-up for an incidence rate of 3.8 per 1000 person-years. While unadjusted hip fracture incidence did not change, strong confounding by case mix was present. Using year of transplantation as a continuous variable, the hazard ratio (HR) for hip fracture in 2010 compared with 1997, adjusted for demographic, dialysis, comorbid and most transplant-related factors, was 0.56 (95% confidence interval [CI]: 0.41-0.77). Adjusting for baseline immunosuppression modestly attenuated the HR (0.68; 95% CI: 0.47-0.99). The 30-day mortality was 2.2 (95% CI: 1.3-3.7) per 100 events. In summary, hip fractures remain an important complication after kidney transplantation. Since 1997, case-mix adjusted posttransplant hip fracture rates have declined substantially. Changes in immunosuppressive therapy appear to be partly responsible for these favorable findings.

    View details for DOI 10.1111/ajt.12652

    View details for PubMedID 24712332

  • Principles of Tibial Fracture Management with Circular External Fixation ORTHOPEDIC CLINICS OF NORTH AMERICA Lowenberg, D. W., Githens, M., Boone, C. 2014; 45 (2): 191-?


    There is a growing mass of literature to suggest that circular external fixation for high-energy tibial fractures has advantages over traditional internal fixation, with potential improved rates of union, decreased incidence of posttraumatic osteomyelitis, and decreased soft tissue problems. To further advance our understanding of the role of circular external fixation in the management of these tibial fractures, randomized controlled trials should be implemented. In addition to complication rates and radiographic outcomes, validated functional outcome tools and cost analysis of this method should be compared with open reduction with internal fixation.

    View details for DOI 10.1016/j.ocl.2013.11.003

    View details for PubMedID 24684913

  • Long-term results and costs of muscle flap coverage with Ilizarov bone transport in lower limb salvage. Journal of orthopaedic trauma Lowenberg, D. W., Buntic, R. F., Buncke, G. M., Parrett, B. M. 2013; 27 (10): 576-581


    OBJECTIVES:: To determine long-term outcomes and costs of Ilizarov bone transport and flap coverage for lower limb salvage. DESIGN:: Case series with retrospective review of outcomes with at least six year follow-up. SETTING:: Academic, tertiary care medical center. PATIENTS:: Thirty-four consecutive patients with traumatic lower extremity wounds and tibial defects who were recommended amputation but instead underwent complex limb salvage from 1993 to 2005. INTERVENTION:: Flap reconstruction and Ilizarov bone transport. MAIN OUTCOME MEASUREMENTS:: Outcomes assessed were flap complications, infection, union, malunion, need for chronic narcotics, ambulation status, employment status, and need for re-operations. A cost analysis was performed comparing this treatment modality to amputation. RESULTS:: Thirty-four patients (mean age, 40 years) were included with 14 acute Gustilo IIIB/C defects and 20 chronic tibial defects (nonunion with osteomyelitis). Thirty five muscle flaps were performed with one flap loss (2.9%). The mean tibial bone defect was 8.7 cm, mean duration of bone transport was 10.8 months, and mean follow-up was 11 years. Primary nonunion rate at the docking site was 8.8% and malunion rate was 5.9%. All patients achieved final union with no cases of recurrent osteomyelitis. No patients underwent future amputations, 29% required re-operations, 97% were ambulating without assistance, 85% were working full time, and only 5.9% required chronic narcotics. Mean lifetime cost per patient per year after limb salvage was significantly less than the published cost for amputation. CONCLUSIONS:: The long-term results and costs of bone transport and flap coverage strongly support complex limb salvage in this patient population. LEVEL OF EVIDENCE:: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

    View details for DOI 10.1097/BOT.0b013e31828afde4

    View details for PubMedID 23412507

  • Temporal Trends in the Incidence, Treatment, and Outcomes of Hip Fracture in Older Patients Initiating Dialysis in the United States CLINICAL JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY Nair, S. S., Mitani, A. A., Goldstein, B. A., Chertow, G. M., Lowenberg, D. W., Winkelmayer, W. C. 2013; 8 (8): 1336-1342


    BACKGROUND AND OBJECTIVES: Patients with ESRD experience a fivefold higher incidence of hip fracture than the age- and sex-matched general population. Despite multiple changes in the treatment of CKD mineral bone disorder, little is known about long-term trends in hip fracture incidence, treatment patterns, and outcomes in patients on dialysis. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Fourteen annual cohorts (1996-2009) of older patients (≥67 years) initiating dialysis in the United States were studied. Eligible patients had Medicare fee-for-service coverage for ≥2 years before dialysis initiation and were followed for ≤3 years for a first hip fracture. Type of treatment (internal fixation or partial or total hip replacement) was ascertained along with 30-day mortality. Cox and modified Poisson regressions were used to describe trends in study outcomes. RESULTS: This study followed 409,040 patients over 607,059 person-years, during which time 17,887 hip fracture events were recorded (29.3 events/1000 person-years). Compared with patients incident for ESRD in 1996, adjusted hip fracture rates increased until the 2004 cohort (+41%) and declined thereafter. Surgical treatment included internal fixation in 56%, partial hip replacement in 29%, and total hip replacement in 2%, which remained essentially unchanged over time; 30-day mortality after hip fracture declined from 20% (1996) to 16% (2009). CONCLUSIONS: Hip fracture incidence rates remain higher today than in patients reaching ESRD in 1996, despite multiple purported improvements in the management of CKD mineral bone disorder. Although recent declines in incidence and steady declines in associated short-term mortality are encouraging, hip fractures remain among the most common and consequential noncardiovascular complications of ESRD.

    View details for DOI 10.2215/CJN.10901012

    View details for PubMedID 23660182

  • Assessment of Compromised Fracture Healing JOURNAL OF THE AMERICAN ACADEMY OF ORTHOPAEDIC SURGEONS Bishop, J. A., Palanca, A. A., Bellino, M. J., Lowenberg, D. W. 2012; 20 (5): 273-282


    No standard criteria exist for diagnosing fracture nonunion, and studies suggest that assessment of fracture healing varies among orthopaedic surgeons. This variability can be problematic in both clinical and orthopaedic trauma research settings. An understanding of risk factors for nonunion and of diagnostic tests used to assess fracture healing can facilitate a systematic approach to evaluation and management. Risk factors for nonunion include medical comorbidities, age, and the characteristics of the injury. The method of fracture management also influences healing. Comprehensive evaluation includes an assessment of the patient's symptoms, signs, and immune and endocrine status as well as the biologic capacity of the fracture, presence of infection, and quality of reduction and fixation. Diagnostic tests include plain radiography, CT, ultrasonography, fluoroscopy, bone scan, MRI, and several laboratory tests, including assays for bone turnover markers in the peripheral circulation. A systematic approach to evaluating fracture union can help surgeons determine the timing and nature of interventions.

    View details for DOI 10.5435/JAAOS-20-05-273

    View details for PubMedID 22553099