James M. Mok, MD

All Publications

• Can We Anticipate Epidural Hematoma After Unilateral Biportal Endoscopic Surgery? Insights From Drain Output and Early Magnetic Resonance Imaging JOURNAL OF MINIMALLY INVASIVE SPINE SURGERY AND TECHNIQUE Umarani, A., Park, C., Oh, J., Shin, J. H., Park, D., Mok, J., Park, S., Kumar, P. 2026; 11: S273-S282

  View details for DOI 10.21182/jmisst.2026.03181

  View details for Web of Science ID 001848986800004

• Dental Composite Offers Comparable or Greater Pullout and Shear Strength to Lateral Mass Screw Fixation in a Human Cadaveric Model. International journal of spine surgery Wadhwa, H., Castro, J., Okoli, O., Chan, C., Ahmad, S. H., Karnowska, A., Hu, S. S., Koltsov, J. C., Bruckman, K. C., Mok, J. M. 2026

  Abstract

  Lateral mass screw fixation is the common method of fixation for an instrumented posterior fusion of the subaxial cervical spine. While screws have established efficacy, adhesive material that can be applied to the bony surface may be a promising alternative strategy owing to ease of application, size, and avoidance of screw loosening, malposition, or fracture.Eighteen fresh frozen human cadaveric subaxial cervical vertebrae were prepared for biomechanical testing. In each vertebra, 1 side underwent lateral mass screw fixation, and the contralateral side underwent composite fixation. On the screw side, a 12 × 3.5-mm lateral mass screw was inserted using a standard free-hand technique by a spine surgeon. For the dental composite side, the lamina was treated with etching acid solution and a dental bonding agent over a 10-mm diameter area before an orthodontic metal bracket was attached using dental composite. Nine specimens in each group were subjected to an axial load to failure (pullout) test, where the load was perpendicular to the vertebral surface. The remaining specimens were subjected to cyclical testing, where the load was applied cranially (shear) relative to each vertebra and gradually increased with each cycle until failure occurred. Differences were assessed with paired t tests with a 2-sided level of significance of α = 0.05.Under axial load (pullout), the dental composite (203.4 ± 43.4 N) showed higher ultimate load than the screws (127.7 ± 21.2 N; P < 0.001). The predominant failure mode under axial load was the composite pulling off the cortical bone surface, whereas the screw pulled through the cancellous and cortical bone. In cyclical testing, the ultimate shear load of dental composite (163.7 ± 48.4 N) did not differ from lateral mass screws (173.6 ± 65.5 N; P = 0.7). The composite failure mechanism under shear loading for half of the specimens was composite separation from bone, whereas the rest failed due to fractures distant from the composite site, indicating robust fixation integrity of composite to bone.Dental composite displayed similar shear strength and greater pullout strength compared with lateral mass screws.An adhesion-based fixation strategy may serve as a viable alternative to traditional screws in specific clinical scenarios that are worthy of further investigation.

  View details for DOI 10.14444/8871

  View details for PubMedID 41932832

• Dental Cement Augmentation Increases Pullout Strength with Comparable Removal Torque for Lateral Mass Screws. Spine Castro, J., Wadhwa, H., Okoli, O., Chan, C., Ahmad, S. H., Karnowska, A., Hu, S., Koltsov, J., Bruckman, K., Mok, J. 2025

  Abstract

  Biomechanical/basic science.To evaluate efficacy of dental cement augmentation of lateral mass screws in the cervical spine.Premature loosening and fixation failure is a known problem of screw fixation of the spine, especially in cases of poor bone quality. Cement augmentation of screws with PMMA has limited utility in the cervical spine due to the small size of the bone and high risk of extravasation. Augmentation with dental cement may present a viable solution for posterior cervical spinal screw fixation.15 cadaveric cervical vertebra were prepared. Lateral mass screw fixation (3.5×12 mm) was performed bilaterally with standard freehand technique by an attending spine surgeon. For augmented screws, dental composite was applied into the screw hole before placement of the screw. 9 vertebrae were used for pull-out testing. Screws were attached to a material testing machine and axially loaded until failure. In the remaining 6 vertebrae, peak torque required to remove the screws from bone was measured via a digital torque driver. A t-test was used to analyze the results between the augmented and non-augmented groups with significance set to P<0.05.Augmented lateral mass screws exhibited significantly higher pullout strength (263.8±79.4N) compared to non-augmented screws (127.7±21.2N). (P=0.0005) There was no significant difference in the mean torque required for screw removal between the augmented (4.20±2.83 lb-in) and non-augmented groups (4.49±2.09 lb-in) (P=0.9). The dental composite was radio-opaque and observable on xray.Augmentation with dental composite enhanced pullout strength without altering removal torque of cervical lateral mass screws in human bone. Dental cement augmentation of lateral mass screws during subaxial cervical spine fusion may be a safe and effective method of improving fixation strength without affecting ease of revision.

  View details for DOI 10.1097/BRS.0000000000005461

  View details for PubMedID 40705348

• Biomechanical Comparison of Unilateral and Bilateral Pedicle Screw Fixation after Multilevel Lumbar Lateral Interbody Fusion. Global spine journal Mok, J. M., Forsthoefel, C., Diaz, R. L., Lin, Y., Amirouche, F. 2024; 14 (5): 1524-1531

  Abstract

  Human Cadaveric Biomechanical Study.Lumbar Lateral Interbody Fusion (LLIF) utilizing a wide cage has been reported as having favorable biomechanical characteristics. We examine the biomechanical stability of unilateral pedicle screw and rod fixation after multilevel LLIF utilizing 26 mm wide cages compared to bilateral fixation.Eight human cadaveric specimens of L1-L5 were included. Specimens were attached to a universal testing machine (MTS 30/G). Three-dimensional specimen range of motion (ROM) was recorded using an optical motion-tracking device. Specimens were tested in 3 conditions: 1) intact, 2) L1-L5 LLIF (4 levels) with unilateral rod, 3) L1-L5 LLIF with bilateral rods.From the intact condition, LLIF with unilateral rod decreased flexion-extension by 77%, lateral bending by 53%, and axial rotation by 26%. In LLIF with bilateral rods, flexion-extension decreased by 83%, lateral bending by 64%, and axial rotation by 34%. Comparing unilateral and bilateral fixation, LLIF with bilateral rods reduced ROM by a further 23% in flexion-extension, 25% in lateral bending, and 11% in axial rotation. The difference was statistically significant in flexion-extension and lateral bending (P < .005).Considerable decreases in ROM were observed after multilevel (4-level) LLIF utilizing 26 mm cages supplemented with both unilateral and bilateral pedicle screws and rods. The addition of bilateral fixation provides a 10-25% additional decrease in ROM. These results can inform surgeons of the incremental biomechanical benefit when considering unilateral or bilateral posterior fixation after multilevel LLIF.

  View details for DOI 10.1177/21925682221149392

  View details for PubMedID 36583232

  View details for PubMedCentralID PMC11394497

• Characterization of ion release from a novel biomaterial, Molybdenum-47.5Rhenium, in physiologic environments. The spine journal : official journal of the North American Spine Society Mok, J. M., Poelstra, K., Ammar, K., McGirt, M., Cormier, J., Hart, R., Bauman, J., Cowart, P., Sheth, I., Singh, P., Yadav, J. 2023; 23 (6): 900-911

  Abstract

  Metals from spinal implants are released into surrounding tissues by various mechanisms. Metal ion release has been associated with clinical implant failure, osteolysis, and remote site accumulation with adverse events. Significant corrosion and associated metal ion release has been described with currently used spinal implant alloys. A novel metal alloy, Molybdenum-47.5Rhenium alloy (MoRe®), was approved for use in medical implants in 2019 by the FDA.To evaluate the metal ion release profile of MoRe alloy after immersion in both a stable physiologic, as well as in an inflammatory environment.In vitro study.The ion release profile of the MoRe alloy was comprehensively evaluated in-vitro after prolonged immersion in physiologic and inflammatory environments. Ion concentration analyses were then conducted using inductively coupled plasma-mass spectrometry (ICP-MS) methods. Comparative testing of titanium (Ti-6Al-4V) and cobalt chromium (Co-28Cr-6Mo) was also performed.Under baseline physiologic conditions, the MoRe alloy demonstrates very low molybdenum and rhenium ion release rates throughout the 30-day test period. During the first time interval (day 0-1), low levels of molybdenum and rhenium ions are detected (<0.3 μg/cm2 day) followed by a rapid reduction in the ion release rates to <0.05 μg/cm2 day during the second time interval (days 1-3) followed by a further reduction to very low steady-state rates <0.01 μg/cm2 day during the third time interval (days 3-7), which were maintained through 30 days. In the inflammatory condition (H2O2 solution), there was a transient increase in the release of molybdenum and rhenium ions, followed by a return to baseline ion release rates (days 2-4), with a further reduction to low steady-state rates of ∼0.01 μg/cm2 day (days 4-8). The measured molybdenum and rhenium ion release rates in both steady state (<0.01 μg/cm2 day), and inflammatory environments (0.01 μg/cm2 day) were far below the established FDA-permitted daily exposure (PDE) of 1,900 μg/cm2 day for molybdenum and 4,400 μg/cm2 day for rhenium. In contrast, titanium and cobalt chromium approached or exceeded their established PDE values in an inflammatory environment.The novel biomaterial MoRe demonstrated a lower metal ion release profile in both a physiologic and inflammatory environment and was well below the established PDE.  Comparative testing of the cobalt-chromium and titanium alloys found higher levels of ion release in the inflammatory environment that exceeded the PDE for cobalt and vanadium.

  View details for DOI 10.1016/j.spinee.2023.01.007

  View details for PubMedID 36706920

• Biomechanical Comparison of Multilevel Stand-Alone Lumbar Lateral Interbody Fusion With Posterior Pedicle Screws: An In Vitro Study. Neurospine Mok, J. M., Lin, Y., Tafur, J. C., Diaz, R. L., Amirouche, F. 2023; 20 (2): 478-486

  Abstract

  Lumbar lateral interbody fusion (LLIF) allows placement of large interbody cages while preserving ligamentous structures important for stability. Multiple clinical and biomechanical studies have demonstrated the feasibility of stand-alone LLIF in single-level fusion. We sought to compare the stability of 4-level stand-alone LLIF utilizing wide (26 mm) cages with bilateral pedicle screw and rod fixation.Eight human cadaveric specimens of L1-5 were included. Specimens were attached to a universal testing machine (MTS 30/G). Flexion, extension, and lateral bending were attained by applying a 200 N load at a rate of 2 mm/sec. Axial rotation of ± 8° of the specimen was performed at 2°/sec. Three-dimensional specimen motion was recorded using an optical motion-tracking device. Specimens were tested in 4 conditions: (1) intact, (2) bilateral pedicle screws and rods, (3) 26-mm stand-alone LLIF, (4) 26-mm LLIF with bilateral pedicle screws and rods.Compared to the stand-alone LLIF, bilateral pedicle screws and rods had 47% less range of motion in flexion-extension (p < 0.001), 21% less in lateral bending (p < 0.05), and 20% less in axial rotation (p = 0.1). The addition of bilateral posterior instrumentation to the stand-alone LLIF resulted in decreases of all 3 planes of motion: 61% in flexion-extension ( p < 0.001), 57% in lateral bending (p < 0.001), 22% in axial rotation (p = 0.002).Despite the biomechanical advantages associated with the lateral approach and 26 mm wide cages, stand-alone LLIF for 4-level fusion is not equivalent to pedicle screws and rods.

  View details for DOI 10.14245/ns.2244734.367

  View details for PubMedID 37401066

  View details for PubMedCentralID PMC10323329

• Anterior Transpsoas Approach for Removal of Cement Leakage after Sacroplasty. Spine surgery and related research M Mok, J., A Strelzow, J., L Vallina, V., P Zebala, L. 2022; 6 (5): 563-568

  Abstract

  Sacroplasty is a minimally invasive treatment option for severe pain due to sacral insufficiency fracture. Cement leakage is a known risk of sacroplasty. Despite the elevated risk to the L5 nerve root and lumbosacral trunk from cement leakage anterior to the sacral ala, there are no reports regarding surgical management of this complication.We describe an anterior retroperitoneal transpsoas approach to the sacral ala to remove cement leakage causing acute L5 radiculopathy in a 57-year-old gentleman who had undergone sacroplasty for sacral insufficiency fracture (Denis zone 1). The approach provides rapid and excellent visualization of the sacral ala without manipulation of the iliac vessels.We recommend that surgery be considered in a timely fashion, to utilize neuromonitoring, and that surgeons be aware of the considerable variability of the neurologic structures that will be encountered, which is described in this technical note.

  View details for DOI 10.22603/ssrr.2021-0097

  View details for PubMedID 36348685

  View details for PubMedCentralID PMC9605746

• The impact of mental health on patient-reported outcomes in cervical radiculopathy or myelopathy surgery. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia Diebo, B. G., Tishelman, J. C., Horn, S., Poorman, G. W., Jalai, C., Segreto, F. A., Bortz, C. A., Gerling, M. C., Lafage, V., White, A. P., Mok, J. M., Cha, T. D., Eastlack, R. K., Radcliff, K. E., Paulino, C. B., Passias, P. G. 2018; 54: 102-108

  Abstract

  Optimizing functional outcomes and disability status are essential for effective surgical treatment of cervical spine disorders. Mental impairment is common among patients with cervical spine complaints; yet little is known about the impact of baseline mental status with respect to overall patient-reported outcomes. This was a retrospective analysis of patients with cervical spondylosis with myelopathy(CM) or radiculopathy(CR: cervical disc herniation, stenosis, or spondylosis without myelopathy) at 2-year follow-ups. Patients were assessed for several health-related quality of life HRQOL) measures at baseline and 24-months post-operatively: Neck Disability Index (NDI), Visual Analog Scale(VAS), Short Form-36(SF) Physical(PCS) and Mental(MCS) Components. Patients were dichotomized by MCS score: LOW-MCS(SF-MCS < 40th percentile) vs. HIGH-MCS(SF-MCS > 60th percentile). Independent and paired t-tests compared improvement in each group for HIGH-MCS and LOW-MCS cohorts. 375 patients were analyzed(65.4yrs, 67.6%F). LOW-MCS radiculopathy patients showed significant improvement in NDI, VAS Neck and Arm Pain(p < 0.05). HIGH-MCS radiculopathy patients showed greater improvement in NDI score, VAS Neck and Arm Pain, and improvement in PCS(all p < 0.05). Comparing baseline and 2-year follow-up, LOW-MCS CM patients showed significant improvement in PCS, NDI, VAS Neck and Arm Pain(p < 0.05). HIGH-MCS myelopathy patients group showed marked improvement in NDI scores, VAS Neck and Arm Pain(p < 0.05). LOW-MCS CR patients were more likely to be less satisfied 2-years post-op(p < 0.001). Postoperative CR patients with lower baseline mental status saw less improvement and significantly worse outcomes than patients with higher baseline mental status. Improving baseline mental health may improve post-operative recovery. Implementing additional screening and care can optimize functional outcomes and disability status for patients with CR.

  View details for DOI 10.1016/j.jocn.2018.06.014

  View details for PubMedID 29907392

• Transforaminal Lumbar Interbody Fusion: Traditional Open Versus Minimally Invasive Techniques. The Journal of the American Academy of Orthopaedic Surgeons Lee, M. J., Mok, J., Patel, P. 2018; 26 (4): 124-131

  Abstract

  Recently, minimally invasive spine arthrodesis has gained popularity among spine surgeons. Minimally invasive techniques have advantages and disadvantages compared with traditional open techniques. Comparisons between short-term outcomes of minimally invasive transforaminal interbody fusion and open transforaminal interbody fusion in terms of estimated blood loss, postoperative pain, and hospital length of stay have been well documented and generally favor the minimally invasive technique. However, the advantages of minimally invasive transforaminal interbody fusion must be evaluated in the context of long-term results, such as patient-reported outcomes and the success of arthrodesis. Because the literature is equivocal in identifying the superior technique for successful long-term outcomes, more study is needed. Patient safety, the risk of complications, and the cost of these techniques also must be considered.

  View details for DOI 10.5435/JAAOS-D-15-00756

  View details for PubMedID 29337717

• Direct Measurement of Tissue Oxygenation as a Method of Diagnosis of Acute Compartment Syndrome. Journal of orthopaedic trauma Weick, J. W., Kang, H., Lee, L., Kuether, J., Liu, X., Hansen, E. N., Kandemir, U., Rollins, M. D., Mok, J. M. 2016; 30 (11): 585-591

  Abstract

  The aim of this study was to investigate the utility of direct measurement of tissue oxygenation during compartment syndrome (CS) and tourniquet-induced ischemia in a large animal model. We hypothesize that as compartment pressure (CP) rises, circulation within the compartment will decrease resulting in a decreased level of oxygen in the muscle.This study used a dog model of both CS- and tourniquet-based ischemia. In 15 animals, CS was induced in 1 hind limb with varying degrees of severity using an infusion model. Tourniquet ischemia was induced in the contralateral hind limb for varying durations. The partial pressure of oxygen (PmO2) was continuously monitored using a polarographic oxygen probe in the muscle of both hind limbs. CP was monitored in the CS limb. PmO2 and CP were analyzed after fasciotomy, performed after approximately 7 hours of warm ischemia, or release of tourniquet.With the application of tourniquet ischemia, PmO2 fell from 38.40 to 1.30 mm Hg (P < 0.001) and subsequently rose after release of the tourniquet to 39.81 mm Hg (P < 0.001). Elevated CP induced by infusion was relieved by fasciotomy (52.04-11.37 mm Hg postfasciotomy, P < 0.001). PmO2 readings in the infusion model were significantly higher in pre-CS than during CS (31.77 mm Hg vs. 3.88 mm Hg, P < 0.001) and rebounded after fasciotomy (50.24 mm Hg, P < 0.001), consistent with hyperemic response.Increased CP caused an observable decrease in PmO2 that was reversed by fasciotomy. PmO2 can be directly measured in real time with a polarographic tissue pO2 probe. This study is the first step of evaluating an alternative method for diagnosing acute CS.

  View details for DOI 10.1097/BOT.0000000000000651

  View details for PubMedID 27392158

• How Effective is Physical Therapy for Common Low Back Pain Diagnoses?: A Multivariate Analysis of 4597 Patients. Spine Eleswarapu, A. S., Divi, S. N., Dirschl, D. R., Mok, J. M., Stout, C., Lee, M. J. 2016; 41 (16): 1325-1329

  Abstract

  A retrospective review.The aim of this study is to evaluate whether the treatment of low back pain with physical therapy results in clinically significant improvements in patient-reported pain and functional outcomes.Low back pain is a major cause of morbidity and disability in health care. Previous studies have found poor efficacy for surgery in the absence of specific indications. A variety of nonoperative treatments are available; however, there is scant evidence to guide the practitioner as to the efficacy of these treatments.Four thousand five hundred ninety-seven patients who underwent physical therapy for the nonoperative treatment of low back pain were included. The primary outcome measures were pre-and post-treatment scores on the Oswestry Disability Index (ODI), Numeric Pain Rating Scale (NPRS) during activity, and NPRS during rest. Previously published thresholds for minimal clinically important difference (MCID) were used to determine the proportion of patients meeting MCID for each of our outcomes. Patients with starting values below the MCID for each variable were excluded from analysis. Logistic regression analysis was used to determine patient risk factors predictive of treatment failure.About 28.5% of patients met the MCID for improvement in ODI. Presence of night symptoms, obesity, and smoking were predictors of treatment failure for ODI. Fifty-nine percent of patients met the MCID for improvement in resting NPRS, with a history of venous thromboembolism, night symptoms, psychiatric disease, workers' compensation status, smoking, and obesity predictive of treatment failure. Sixty percent of patients met the MCID for improvement in activity NPRS, with night symptoms, workers' compensation status, and smoking predictive of treatment failure.We observed that a substantial percentage of the population did not meet MCID for pain and function following treatment of low back pain with physical therapy. Common risk factors for treatment failure included smoking and presence of night symptoms.4.

  View details for DOI 10.1097/BRS.0000000000001506

  View details for PubMedID 26890953

• Impact of a Bundled Payment System on Resource Utilization During Spine Surgery. International journal of spine surgery Mok, J. M., Martinez, M., Smith, H. E., Sciubba, D. M., Passias, P. G., Schoenfeld, A., Isaacs, R. E., Vaccaro, A. R., Radcliff, K. E. 2016; 10: 19

  Abstract

  In a bundled payment system, a single payment covers all costs associated with a single episode of care. Spine surgery may be well suited for bundled payments because of clearly defined episodes of care, but the impact on current practice has not been studied. We sought to examine how a theoretical bundled payment strategy with financial disincentives to resource utilization would impact practice patterns.A multiple-choice survey was administered to spine surgeons describing eight clinical scenarios. Respondents were asked about their current practice, and then their practice in a hypothetical bundled payment system. Respondents could choose from multiple types of implants, bone grafts, and other resources utilized at the surgeon's discretion.Forty-three respondents completed the survey. Within each scenario, 24%-49% of respondents changed at least one aspect of management. The proportion of cases performed without implants was unchanged for four scenarios and increased in four by an average of 8%. Use of autologous iliac crest bone graft increased across all scenarios by an average of 18%. Use of neuromonitoring decreased in all scenarios by an average of 21%. Differences in costs were not statistically significant.Financial disincentives to resource utilization may result in some changes to surgeons' practices but these appear limited to items with less clear benefits to patients. Choices of implants, which account for the majority of intra-operative costs, did not change meaningfully. A bundling strategy targeting peri-operative costs solely related to surgical practice may not yield substantive savings while rationing potentially beneficial treatments to patient care.5.

  View details for DOI 10.14444/3019

  View details for PubMedID 27441177

  View details for PubMedCentralID PMC4943167

• Characterization of scaffold carriers for BMP9-transduced osteoblastic progenitor cells in bone regeneration. Journal of biomedical materials research. Part A Shui, W., Zhang, W., Yin, L., Nan, G., Liao, Z., Zhang, H., Wang, N., Wu, N., Chen, X., Wen, S., He, Y., Deng, F., Zhang, J., Luu, H. H., Shi, L. L., Hu, Z., Haydon, R. C., Mok, J. M., He, T. C. 2014; 102 (10): 3429-38

  Abstract

  Successful bone tissue engineering at least requires sufficient osteoblast progenitors, efficient osteoinductive factors, and biocompatible scaffolding materials. We have demonstrated that BMP9 is one of the most potent factors in inducing osteogenic differentiation of mesenchymal progenitors. To facilitate the potential use of cell-based BMP9 gene therapy for bone regeneration, we characterize the in vivo osteoconductive activities and bone regeneration potential of three clinically used scaffold materials, type I collagen sponge, hydroxyapatite-tricalcium phosphate (HA-TCP), and demineralized bone matrix (DBM), using BMP9-expressing C2C12 osteoblastic progenitor cells. We find that recombinant adenovirus-mediated BMP9 expression effectively induces osteogenic differentiation in C2C12 cells. Although direct subcutaneous injection of BMP9-transduced C2C12 cells forms ectopic bony masses, subcutaneous implantation of BMP9-expressing C2C12 cells with collagen sponge or HA-TCP scaffold yields the most robust and mature cancellous bone formation, whereas the DBM carrier group forms no or minimal bone masses. Our results suggest that collagen sponge and HA-TCP scaffold carriers may provide more cell-friendly environment to support the survival, propagation, and ultimately differentiation of BMP9-expressing progenitor cells. This line of investigation should provide important experimental evidence for further preclinical studies in BMP9-mediated cell-based approach to bone tissue engineering.

  View details for DOI 10.1002/jbma.35006

  View details for PubMedID 24133046

  View details for PubMedCentralID PMC4476251

• Evaluation of immediate postoperative complications and outcomes among military personnel treated for spinal trauma in Afghanistan: a cohort-control study of 50 cases. Journal of spinal disorders & techniques Schoenfeld, A. J., Mok, J. M., Cameron, B., Jackson, K. L., Serrano, J. A., Freedman, B. A. 2014; 27 (7): 376-81

  Abstract

  Retrospective case-control study.The objective of the study was to compare neurological outcomes and complication rates between a series of combat-injured patients treated in Afghanistan (AFG) and those treated at Landstuhl Regional Medical Center (LRMC).At present, no studies have addressed the ideal timing and setting for surgical stabilization in combat-injured soldiers who sustain spinal trauma.Soldiers who sustained spine injuries while deployed to Afghanistan and who underwent surgery in theater or at LRMC between 2010 and 2011 were identified. Demographic information, injury-specific data, neurological status, type of surgical intervention, postoperative complications, and need for additional surgery were abstracted for all patients. Neurological improvement was the primary dependent variable. Secondary variables included the risk of developing complications and the need for additional surgery. Statistical analysis was performed using t tests, and the Fisher exact test was used for categorical variables.Between 2010 and 2011, 30 individuals were treated in AFG, and 20 received surgery at LRMC. Neurological improvement occurred in 10% of AFG patients and 5% of those treated at LRMC. Complications occurred in 40% of AFG patients and in 20% of the LRMC group. Twenty-three percent of AFG patients required additional spine surgery after leaving Afghanistan. There was no statistical difference in neurological improvement between the AFG and LRMC groups (P=0.64). Soldiers who received surgery in AFG were at significantly increased risk of requiring additional procedures (P=0.03).Soldiers treated in theater did not have statistically higher rates of neurological improvement as compared with those treated at LRMC. Patients treated in-theater were at elevated risk for the need for additional surgery. This study is among the first to evaluate clinical outcomes after surgical intervention for war-related spinal trauma.Level III (case-control).

  View details for DOI 10.1097/BSD.0b013e3182a355c6

  View details for PubMedID 24999556

• Morbidity of early spine surgery in the multiply injured patient. Archives of orthopaedic and trauma surgery Galvin, J. W., Freedman, B. A., Schoenfeld, A. J., Cap, A. P., Mok, J. M. 2014; 134 (9): 1211-7

  Abstract

  The optimal timing of surgery for multiply injured patients with operative spinal injuries remains unknown. The purported benefits of early intervention must be weighed against the morbidity of surgery in the early post-injury period. The performance of spine surgery in the Afghanistan theater permits analysis of the morbidity of early surgery on military casualties. The objective is to compare surgical morbidity of early spinal surgery in multiply injured patients versus stable patients.Patients were retrospectively categorized as stable or borderline unstable depending on the presence of at least one of the following: ISS >40, ISS >20 and chest injury, exploratory laparotomy or thoracotomy, lactate >2.5 mEq/L, platelet <110,000/mm(3), or >10 U PRBCs transfused pre-operatively. Surgical morbidity, complications, and neurologic improvement between the two groups were compared retrospectively.30 casualties underwent 31 spine surgeries during a 12-month period. 16 of 30 patients met criteria indicating a borderline unstable patient. Although there were no significant differences in the procedures performed for stable and borderline unstable patients as measured by the Surgical Invasiveness Index (7.5 vs. 6.9, p = 0.8), borderline unstable patients had significantly higher operative time (4.3 vs. 3.0 h, p = 0.01), blood loss (1,372 vs. 366 mL, p = 0.001), PRBCs transfused intra-op (3.88 vs. 0.14 U, p < 0.001), and total PRBCs transfused in theater (10.18 vs. 0.31 U, p < 0.001).The results indicate that published criteria defining a borderline unstable patient may have a role in predicting increased morbidity of early spine surgery. The perceived benefits of early intervention should be weighed against the greater risks of performing extensive spinal surgeries on multiply injured patients in the early post-injury period, especially in the setting of combat trauma.

  View details for DOI 10.1007/s00402-014-2068-7

  View details for PubMedID 25077784

• Bone Morphogenetic Protein (BMP) signaling in development and human diseases. Genes & diseases Wang, R. N., Green, J., Wang, Z., Deng, Y., Qiao, M., Peabody, M., Zhang, Q., Ye, J., Yan, Z., Denduluri, S., Idowu, O., Li, M., Shen, C., Hu, A., Haydon, R. C., Kang, R., Mok, J., Lee, M. J., Luu, H. L., Shi, L. L. 2014; 1 (1): 87-105

  Abstract

  Bone Morphogenetic Proteins (BMPs) are a group of signaling molecules that belongs to the Transforming Growth Factor-β (TGF-β) superfamily of proteins. Initially discovered for their ability to induce bone formation, BMPs are now known to play crucial roles in all organ systems. BMPs are important in embryogenesis and development, and also in maintenance of adult tissue homeostasis. Mouse knockout models of various components of the BMP signaling pathway result in embryonic lethality or marked defects, highlighting the essential functions of BMPs. In this review, we first outline the basic aspects of BMP signaling and then focus on genetically manipulated mouse knockout models that have helped elucidate the role of BMPs in development. A significant portion of this review is devoted to the prominent human pathologies associated with dysregulated BMP signaling.

  View details for DOI 10.1016/j.gendis.2014.07.005

  View details for PubMedID 25401122

  View details for PubMedCentralID PMC4232216

• Effect of vacuum spine board immobilization on incidence of pressure ulcers during evacuation of military casualties from theater. The spine journal : official journal of the North American Spine Society Mok, J. M., Jackson, K. L., Fang, R., Freedman, B. A. 2013; 13 (12): 1801-8

  Abstract

  In the summer of 2009, the vacuum spine board (VSB) was designated by the US Air Force as the preferred method of external spinal immobilization during aeromedical transport of patients with suspected unstable thoracolumbar spine fractures. One purported advantage of the VSB is that, by distributing weight over a larger surface area, it decreases the risk of skin pressure ulceration.To examine whether the rate of pressure ulcers has changed since the introduction of the VSB.Retrospective cohorts.Injured US service members undergoing spinal immobilization during evacuation from the Iraq and Afghanistan theaters to Landstuhl, Germany.Presence and stage of pressure ulceration, and deterioration in neurologic status.Records of the initial 60 patients medically evacuated on the VSB to Landstuhl Regional Medical Center were retrospectively analyzed for patient demographics, injury characteristics, and incidence of pressure injury. The incidence of pressure ulcers after the use of VSB was compared with that in a historical control consisting of 30 patients with unstable spinal injuries evacuated before the introduction of the VSB. No sources of external funding were used for this investigation.The combined cohort had a mean age of 28.8 years and mean Injury Severity Score (ISS) of 20.63 and comprised 96% men. Most injury mechanisms were blunt (58%). The rate of neurological injury was 19%. There were no cases of progressive neurological deficit or deformity in either cohort. In the VSB group, using a broad definition of pressure ulcer, incidence was 13 of 60 patients (22%). Using a strict definition, incidence was eight of 60 (13%): five Stage I and three Stage II. In the non-VSB group, incidence of pressure ulcers was three of 30 (10%), using either definition, all Stage II. Difference in incidence between the groups was not statistically significant. Intubated patients had a significantly higher incidence of pressure ulcers.Both the VSB and historic means (non-VSB) of spinal immobilization appear to be safe and produce only transient morbidity despite an average of 9 to 10 hours of transport. Intubated status was identified as the most important risk factor for the development of a pressure ulcer.

  View details for DOI 10.1016/j.spinee.2013.05.028

  View details for PubMedID 23816354

• Psychological distress in the active duty military spine patient. Military medicine Brooks, D. E., Agochukwu, U. F., Arrington, E. D., Mok, J. M. 2013; 178 (10): 1059-64

  Abstract

  Disorders of the spine are a substantial burden to the military health care system that degrades readiness in the overall force. Because treatment outcomes are affected by psychosocial factors, assessment of psychological distress is important for patients with spine complaints. The incidence of psychological distress in the unique military population is not well described. The purpose of this retrospective case-control study was to determine the rate of psychological distress and identify associated patient characteristics among many variables collected in the military health system. A consecutive cohort of active duty service members presenting to a spine specialty clinic was assessed as Normal, At Risk, or Distressed using the Distress and Risk Assessment Method. Of 74 active duty patients (63 male, 11 female), 43 (58%) had some level of psychological distress: 29 (39%) At Risk, 12 (16%) Distressed-Depressive, and 2 (3%) Distressed-Somatic. Multivariate regression analysis identified female gender (odds ratio [OR] 7.90), higher disability as measured by Oswestry Disability Index/Neck Disability Index (OR 8.0 per 13.8 point increase), and assignment to a Warrior Transition Unit or Medical Evaluation Board (OR 7.35) as statistically significant variables. The results indicate that active duty patients are subject to similarly high levels of psychological distress as their civilian counterparts.

  View details for DOI 10.7205/MILMED-D-13-00162

  View details for PubMedID 24083918

• Lumbar plexus anatomy within the psoas muscle: implications for the transpsoas lateral approach to the L4-L5 disc. The Journal of bone and joint surgery. American volume Davis, T. T., Bae, H. W., Mok, J. M., Rasouli, A., Delamarter, R. B. 2011; 93 (16): 1482-7

  Abstract

  The transpsoas lateral surgical approach has been advocated as an alternative to direct anterior approaches for less invasive or minimally invasive access to the spine. Postoperative thigh pain, paresthesia, and/or weakness have been described after the use of this surgical approach. The purpose of this cadaveric anatomic study is to provide a description of the lumbar plexus as it relates to the transpsoas lateral surgical approach.Dissection of the lumbar plexus was performed in eighteen cadaveric specimens. Needle markers were placed in the L2-L3, L3-L4, and L4-L5 discs in the midcoronal plane. The anatomic structures were surveyed, and the proximity of the needle to the neural structures was observed.In thirteen of the eighteen specimens, the femoral nerve received its contributions from the L2 to L4 nerve roots and was formed at the L4-L5 disc space. In all specimens, the femoral nerve passed dorsal to or directly at the midpoint of the disc. In three specimens, the needle displaced or was immediately adjacent to the femoral nerve. The femoral nerve was found between the needle and the posterior aspect of the L4-L5 disc space in thirteen of the eighteen specimens.Because of the proximity of the neural elements, in particular the femoral nerve, to the center of the disc space, the transpsoas lateral surgical approach to the L4-L5 disc space will likely cause intraoperative displacement of neural structures from their anatomic course during retractor dilation. Careful attention should be paid to retractor placement and dilation time during transpsoas lateral access surgery, particularly at the L4-L5 disc.

  View details for DOI 10.2106/JBJS.J.00962

  View details for PubMedID 22204003

• Adjacent Segment Motion After Anterior Cervical Discectomy and Fusion Versus ProDisc-C Cervical Total Disk Arthroplasty SPINE Kelly, M. P., Mok, J. M., Frisch, R. F., Tay, B. K. 2011; 36 (15): 1171-1179

  Abstract

  Post hoc analysis of data acquired in a prospective, randomized, controlled trial.To compare adjacent segment motion after anterior cervical discectomy and fusion (ACDF) versus cervical total disc arthroplasty (TDA).TDA has been designed to be a motion-preserving device, thus theoretically normalizing adjacent segment kinematics. Clinical studies with short-term follow-up have yet to demonstrate a consistent significant difference in the incidence of adjacent segment disease.Two hundred nine patients at 13 sites were treated in a prospective, randomized, controlled trial of ACDF versus TDA for single-level symptomatic cervical degenerative disc disease (SCDD). Flexion and extension radiographs were obtained at all follow-up visits. Changes in ROM were compared using the Wilcoxon signed-rank test and the Mann-Whitney U test. Predictors of postoperative ROM were determined by multivariate analysis using mixed effects linear regression.Data for 199 patients were available with 24-month follow-up. The groups were similar with respect to baseline demographics. A significant increase in motion at the cranial and caudal adjacent segments after surgery was observed in the ACDF group only (cranial: ACDF: +1.4° (0.4, 2.4), P = 0.01; TDA: +0.8°, (-0.1, +1.7), P = 0.166; caudal: ACDF: +2.6° (1.3, 3.9), P < 0.0001; TDA: +1.3, (-0.2, +2.8), P = 0.359). No significant difference in adjacent segment ROM was observed between ACDF and TDA. Only time was a significant predictor of postoperative ROM at both the cranial and caudal adjacent segments.Adjacent segment kinematics may be altered after ACDF and TDA. Multivariate analysis showed time to be a significant predictor of changes in adjacent segment ROM. No association between the treatment chosen (ACDF vs. TDA) and ROM was observed. Furthermore clinical follow-up is needed to determine whether possible differences in adjacent segment motion affect the prevalence of adjacent segment disease in the two groups.

  View details for DOI 10.1097/BRS.0b013e3181ec5c7d

  View details for Web of Science ID 000291852500012

  View details for PubMedID 21217449

• Dynamic Constructs for Spinal Fusion: An Evidence-Based Review ORTHOPEDIC CLINICS OF NORTH AMERICA Kelly, M. P., Mok, J. M., Berven, S. 2010; 41 (2): 203-+

  Abstract

  Dynamic stabilization of the spine has applications in cervical and lumbar degenerative disease and in thoracolumbar trauma. There is little evidence to support the use of dynamic cervical plates rather than rigid anterior cervical fixation. Evidence to support the use of dynamic constructs for fusion in the lumbar spine is also limited. Fusion rates, implant loosening, and failure are significant concerns that limit the adoption of current devices. This article provides a synopsis of the literature on human subjects. There is a need for high-quality evidence for interventions for spinal pathology. An evidence-based approach to the management of spinal disorders will require ongoing assessment of clinical outcomes and comparison of effectiveness between alternatives.

  View details for DOI 10.1016/j.ocl.2009.12.004

  View details for Web of Science ID 000277461800009

  View details for PubMedID 20399359

• Admitting service and morbidity and mortality in elderly patients after hip fracture: finding a threshold for medical versus orthopedic admission. American journal of orthopedics (Belle Mead, N.J.) Mok, J. M., Durrani, S. K., Yamamoto, A., Kim, H. T. 2010; 39 (2): 80-7

  Abstract

  Outcomes by admitting service of 355 consecutive patients admitted for hip fracture at an academic medical center were retrospectively studied. An adverse event occurred in 53 patients (14.9%): 10 in-hospital deaths, 37 intensive care unit transfers, and 25 deaths within 30 days. No significant difference was found between percentages of patients with adverse events admitted to a medical service versus an orthopedic service (52.8% vs 47.2%; P = .8). Criteria that determine admitting service based on medical acuity do not adequately allocate patients at risk for serious morbidity and early mortality to a medical service. Addition of American Society of Anesthesiologists grade 4 and men 85 or older to existing criteria would increase the percentage of patients with adverse events admitted to a medical service (72% vs 28%; P<.005).

  View details for PubMedID 20396681

• Delayed presentation of tetraparesis following posterior thoracolumbar spinal fusion and instrumentation for adolescent idiopathic scoliosis. Spine Dapunt, U. A., Mok, J. M., Sharkey, M. S., Davis, A. A., Foster-Barber, A., Diab, M. 2009; 34 (25): E936-41

  Abstract

  Case report.We present a case of delayed tetraparesis in a patient after posterior spinal fusion for adolescent idiopathic scoliosis.The reported rate of neural complications after scoliosis surgery is low. Intraoperative neuromonitoring is used to detect and prevent spinal cord injury.Review of medical record.Delayed tetraparesis developed on the second postoperative day after unremarkable T3-L4 posterior fusion. MRI revealed evidence of cord ischemia at C4-C7. Angiogram revealed a hypervascular T4 body resulting in arteriovenous shunting into the epidural venous plexus.Venous congestive myelopathy due to arteriovenous shunting or unrecognized syrinx are presented as possible etiologies of this patient's spinal cord injury. A preoperative MRI may have helped discern the cause of this patient's spinal cord injury.

  View details for DOI 10.1097/BRS.0b013e3181b2e04f

  View details for PubMedID 19940725

• Reoperation after primary fusion for adult spinal deformity: rate, reason, and timing. Spine Mok, J. M., Cloyd, J. M., Bradford, D. S., Hu, S. S., Deviren, V., Smith, J. A., Tay, B., Berven, S. H. 2009; 34 (8): 832-9

  Abstract

  Retrospective cohort study of consecutive patients undergoing primary fusion with segmental fixation for adult spinal deformity.We sought to determine the survivorship of primary fusion for adult spinal deformity and identify patient-specific predictors of complications requiring reoperation.Compared with the adolescent population, surgery for adult deformity is often more complex and technically difficult, contributing to a high reported rate of complications that can result in the need for reoperation. Reported complication rates vary widely.From 1999-2004 all patients who underwent primary instrumented fusion for nonparalytic adult spinal deformity at a single center were included. Inclusion criteria included minimum age at surgery of 20 years and minimum fusion length of 4 motion segments. Surgical, demographic, and comorbidity data were recorded. Reoperation was defined as any additional surgery involving levels of the spine operated on during the index procedure and/or adjacent levels. Comparisons were performed between patients who required reoperation and those who did not.Eighty-nine patients met inclusion criteria. Endpoint (minimum 2 years follow-up or reoperation) was reached for 91%. Mean follow-up was 3.8 years. Cumulative reoperation rate was 25.8%. Survival was 86.4% at 1 year, 77.2% at 2 years, and 75.2% at 3 years. Reasons for reoperation included infection (n = 8), pseudarthrosis (n = 3), adjacent segment problems (n = 5), implant failure (n = 4), and removal of painful implants (n = 3). Multivariate analysis showed smoking was significantly higher in the reoperation group.Using a strict definition of reoperation for a well-defined cohort, in the presence of relevant risk factors, many patients undergoing primary fusion for adult spinal deformity required reoperation. The results indicate that complex medical and surgical factors contribute to the treatment challenges posed by patients with adult spinal deformity. This represents the largest cohort reported to date of patients undergoing primary fusion using third-generation instrumentation techniques.

  View details for DOI 10.1097/BRS.0b013e31819f2080

  View details for PubMedID 19365253

• Clinical outcome of deep wound infection after instrumented posterior spinal fusion: a matched cohort analysis. Spine Mok, J. M., Guillaume, T. J., Talu, U., Berven, S. H., Deviren, V., Kroeber, M., Bradford, D. S., Hu, S. S. 2009; 34 (6): 578-83

  Abstract

  Retrospective case control study.Determine the impact of infection on clinical outcome in patients undergoing posterior spinal fusion surgery.The outcome of patients treated for infection after spinal surgery is not well established because of variability in cohort identification, definition of infection, outcomes instrument, use of a control group, and/or sample size.Thirty-two patients were included. Sixteen patients ("infection group") met inclusion criteria of deep wound infection after spinal fusion with posterior segmental instrumentation (including combined approach). A 1:1 matched cohort ("control group") was created based on primary or revision status, length of fusion, diagnosis, and age. Postoperative patient outcomes were evaluated using the physical components of SF-36 v2.0 with minimum 2-year follow-up.No significant difference in the Physical Function, Role Physical, Bodily Pain, and General Health domains was detected between the infection group and control group. Mean follow-up was 62 months. Mean Physical Component Summary was 41.4 in the infection group and 44.3 in the control group (P = 0.6). Infection occurred early in 12 patients and late in 4 patients. Most common organisms isolated were Staphylococcus epidermidis, Enterococcus sp., and Staphylococcus aureus. Multiple debridements were significantly associated with polymicrobial infections and later pseudarthrosis requiring reoperation.An aggressive approach to deep wound infection emphasizing early irrigation and debridement allowed preservation of instrumentation and successful fusion in most cases. At the conclusion of treatment, patients can expect a medium-term clinical outcome similar to patients in whom this complication did not occur.

  View details for DOI 10.1097/BRS.0b013e31819a827c

  View details for PubMedID 19240667

• Extravasation of rhBMP-2 with use of postoperative drains after posterolateral spinal fusion. Spine Mok, J. M., Durrani, S. K., Piper, S. L., Hu, S. S., Deviren, V., Berven, S. H., Burch, S. 2008; 33 (15): 1668-74

  Abstract

  Prospective measurement of rhBMP-2 from drains in a cohort of patients undergoing posterolateral spinal fusion.To quantify the amount of rhBMP-2 that extravasates into drains after posterolateral fusion using its current commercially available form, rhBMP-2 within an absorbable collagen sponge.Retention of rhBMP-2 at the fusion site is essential for clinical efficacy and avoidance of unintentional bony growth in other areas of the spine. In vitro studies have shown a large degree of rhBMP-2 release from the sponge within the first 48 hours. It is unknown what effect drainage may have on changing the local concentration of BMP at the posterolateral site.The entire contents of drains were collected for 48 hours after surgery from 9 patients who underwent instrumented posterolateral fusion with rhBMP-2. The total amount collected was calculated from the concentration of BMP-2 as measured by enzyme-linked immunosorbent assay.A median 68 microg of BMP-2 (range, 13-498) was recovered from drains, representing a median 0.58% (range, 0.21%-4.2%) of the amount implanted; adjusted for yield rate, a median 1.08% was recovered. No significant relationships were found between percentage of BMP-2 extravasation and amount implanted, number of levels, blood loss, and drainage output. A mean 54% of the total amount recovered was in the drain within the first 6 hours.The greater bleeding and muscular compression associated with posterolateral fusion did not result in a substantial amount of rhBMP-2 extravasation into postoperative drains. Based on the small rates of recovery, suction drains may be placed after even complex surgeries involving large blood loss without the loss of significant amounts of the implanted rhBMP-2 into the drain.

  View details for DOI 10.1097/BRS.0b013e31817b6229

  View details for PubMedID 18594460

• Monitoring of nerve root injury using transcranial motor-evoked potentials in a pig model. Spine Mok, J. M., Lyon, R., Lieberman, J. A., Cloyd, J. M., Burch, S. 2008; 33 (14): E465-73

  Abstract

  Animal experiment using transcranial motor-evoked potentials (tcMEPs) in a pig model.To validate measurement of tcMEPs from multiple myotomes in a pig model and determine the capacity to detect injury to a single nerve root.The ability of intraoperative neuromonitoring methods to give information about a single nerve root remains poorly understood. Reports suggest that tcMEPs may be a reliable and accurate method to detect nerve root injury. An animal model to study the sensitivity and specificity of this technique has yet to be validated.Transcranial stimulation was delivered through customized electrodes placed in burr holes over the motor cortex in 7 pigs. Spontaneous and evoked muscle potential activity was recorded in 5 myotomes (rectus femoris, vastus lateralis, vastus medialis, tibialis anterior, and gastrocnemius) bilaterally. After unilateral exposure of the L3-S1 nerve roots, sequential ligations were performed. The tcMEP responses from all myotomes were measured after ligation of each nerve root.Robust MEP responses (range, 37-1165 mV) were achieved in all monitored myotomes. Significant decreases in tcMEP amplitudes occurred in specific myotomes after ligation of the corresponding nerve root. Consistent and substantial decreases were observed after L3 and L5 ligations in rectus femoris (48%) and tibialis anterior (67%), respectively.Our results validate monitoring of tcMEPs in multiple myotomes to detect nerve root injury in pigs. This model may be used for further study of the use of tcMEPs to detect predictors and risk factors of nerve root injury during spinal surgery.

  View details for DOI 10.1097/BRS.0b013e318178e67f

  View details for PubMedID 18552661

• Use of C-reactive protein after spinal surgery: comparison with erythrocyte sedimentation rate as predictor of early postoperative infectious complications. Spine Mok, J. M., Pekmezci, M., Piper, S. L., Boyd, E., Berven, S. H., Burch, S., Deviren, V., Tay, B., Hu, S. S. 2008; 33 (4): 415-21

  Abstract

  This is a prospective observational study of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) in a cohort of patients undergoing spinal surgery.We sought to characterize the normal kinetics of ESR and CRP after spinal surgery and compare their usefulness as predictors of infectious complications in the early postoperative period.ESR and CRP are nonspecific markers of inflammation used to evaluate postoperative infection. CRP is a quantitative test that exhibits predictable kinetics consisting of a postoperative rise and a peak followed by a decrease toward the normal value. Deviation from normal kinetics may be an indicator of infection.ESR and CRP were collected before surgery and daily after surgery in consecutive patients. All infectious complications were recorded.One hundred forty-nine patients met inclusion criteria. Infectious complications occurred in 20 patients. A postoperative peak, which is necessary to apply the test, was observed in 78% of patients for CRP and 48% for ESR. Multiple linear regression analysis revealed preoperative CRP, number of levels, and lumbar region as significant predictors of greater CRP peak value (r = 0.435, P = 0.001). After the peak, CRP showed an exponential decrease with a half-life of 2.6 days (r = 0.701, P < 0.001). No trend could be determined for ESR. A second rise or failure to decrease as expected had a sensitivity, specificity, positive predictive value, and negative predictive value of 82%, 48%, 41%, and 86% for infectious complications, respectively. Of 8 cases of deep wound infection, 7 exhibited substantial deviations from expected CRP values.CRP is more applicable, predictable, and responsive in the early postoperative period compared with ESR. The postoperative kinetics of CRP derived in this study seems to be conserved regardless of operation, magnitude, or region. Knowledge of the kinetics allows assessment of the degree of difference between actual and expected values. Using a second rise or failure to decrease as expected for CRP is sensitive for infection. A negative test is reassuring that infection is unlikely.

  View details for DOI 10.1097/BRS.0b013e318163f9ee

  View details for PubMedID 18277874

• Surgical strategies and choosing levels for spinal deformity: how high, how low, front and back. Neurosurgery clinics of North America Mok, J. M., Hu, S. S. 2007; 18 (2): 329-37

  Abstract

  The purpose of this article is to describe general strategies in the surgical treatment of adolescent and adult scoliosis, including radiographic evaluation, curve selection, principles guiding the selection of the upper and lower instrumented vertebrae, and indications for anterior surgery. Sagittal plane deformity, including Scheuermann's kyphosis, is discussed. Avoidance and treatment of postoperative flatback deformity is also briefly mentioned. There are multiple and sometimes conflicting considerations that must be reviewed when planning surgical stabilization of spinal deformity. Although there may be significant variation in surgeon decision making, careful adherence to primary principles, such as achieving coronal and sagittal balance in all patients and minimizing fusion levels, particularly in young patients, should be of paramount importance.

  View details for DOI 10.1016/j.nec.2007.01.008

  View details for PubMedID 17556135

• Chemical, structural properties, and osteoconductive effectiveness of bone block derived from porcine cancellous bone. Journal of biomedical materials research. Part B, Applied biomaterials Kim, S. H., Shin, J. W., Park, S. A., Kim, Y. K., Park, M. S., Mok, J. M., Yang, W. I., Lee, J. W. 2004; 68 (1): 69-74

  Abstract

  The purpose of this study is to determine the efficacy of bioactive calcium phosphate obtained from porcine cancellous bone for the treatment of bone defects and nonunion. Porcine cancellous bone blocks were heat treated at 1300 degrees C for 2 h. The chemical composition, calcium-to-phosphate ratio, and microstructure of the porcine bone blocks were examined. For in vivo implantation, bone defects were created on the anteromedial aspect of the proximal tibia in seven beagle dogs and the xenograft bone blocks were placed into these defects. Plain radiographs were taken at 2-week intervals for roentgenographic evaluation. At 12 weeks, the specimens were stained with hematoxylin and eosin (H&E). The composition and morphology of heat-treated porcine cancellous bone were found to be similar to heat-treated human cancellous bone. Radiographs showed union between the host bone/bone-block interfaces. At 12 weeks, uniform and substantial new bone formation was observed. It is concluded that heat-treated porcine cancellous bone demonstrated effective osteoconductivity. This high-temperature heat-treatment technique has several advantages, including decreased risk of disease transmission and immunoreactivity, while also offering excellent biocompatibility.

  View details for DOI 10.1002/jbm.b.10084

  View details for PubMedID 14689498

• Intracellular pH regulation in neurons from chemosensitive and nonchemosensitive regions of Helix aspersa. American journal of physiology. Regulatory, integrative and comparative physiology Goldstein, J. I., Mok, J. M., Simon, C. M., Leiter, J. C. 2000; 279 (2): R414-23

  Abstract

  We used 2',7'-bis(carboxyethyl)-5(6)-carboxyflourescein (BCECF), a pH-sensitive fluorescent dye, to study intracellular pH (pH(i)) regulation in neurons in CO(2) chemoreceptor and nonchemoreceptor regions in the pulmonate, terrestrial snail, Helix aspersa. We studied pH(i) during hypercapnic acidosis, after ammonia prepulse, and during isohydric hypercapnia. In all treatment conditions, pH(i) fell to similar levels in chemoreceptor and nonchemoreceptor regions. However, pH(i) recovery was consistently slower in chemoreceptor regions compared with nonchemoreceptor regions, and pH(i) recovery was slower in all regions when extracellular pH (pH(e)) was also reduced. We also studied the effect of amiloride and DIDS on pH(i) regulation during isohydric hypercapnia. An amiloride-sensitive mechanism was the dominant pH(i) regulatory process during acidosis. We conclude that pH(e) modulates and slows pH(i) regulation in chemoreceptor regions to a greater extent than in nonchemoreceptor regions by inhibiting an amiloride-sensitive Na(+)/H(+) exchanger. Although the phylogenetic distance between vertebrates and invertebrates is large, similar results have been reported in CO(2)-sensitive regions within the rat brain stem.

  View details for DOI 10.1152/ajpregu.2000.279.2.R414

  View details for PubMedID 10938227