Robert L Barrack

Barnes Jewish Hospital, San Luis, Missouri, United States

Are you Robert L Barrack?

Claim your profile

Publications (302)731.25 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Prior studies have associated coronal alignment after total knee arthroplasty (TKA) with implant survivorship. Results have been based on either the femorotibial angle (FTA) on a short knee film or the hip-knee-ankle angle (HKA) on a full-length radiograph. The purpose of this study was to determine if the FTA on short knee radiographs can accurately predict the true, HKA alignment following TKA. Two orthopaedic surgeons measured the FTA, HKA, medial proximal tibial angle, and lateral distal femoral angle in 262 patients who had both short and full-length standing radiographs before and/or after primary TKA. Overall coronal alignment was considered neutral if the FTA was between [2.4°-7.2°] on short knee x-rays or if the HKA was between [-3° to 3°] on full-length films. Preoperatively, 13.9% (26/187) of knees had a neutral FTA on short films, but 50% (13/26) of those were in varus or valgus on full-length films. Postoperatively, 51.4% (106/206) of knees had a neutral FTA on short films, but 27.4% (29/106) of those knees were in varus or valguson full-length films. When comparing alignment classifications (neutral, varus, or valgus) based on the short versus full-length images, 13.9% (26/187) of patients had discordant classifications on preoperative imaging and 33.0% (68/206) had discordant classifications on postoperative imaging. A significant proportion of patients were misclassified as varus, valgus, or neutral based on the FTA when compared to the HKA. Short knee x-rays serve as an inaccurate proxy for full-length films when assessing coronal alignment after TKA.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Previous data on the survivorship of the Birmingham Hip Resurfacing (BHR) implant have come from design surgeons and large national databases outside of the United States, and there is a lack of reported outcomes of surface replacement arthroplasty from US centers. A retrospective study was undertaken of 1271 hips treated with a BHR system (Smith & Nephew, Memphis, Tennessee) between June 2006 and September 2008 at 6 high-volume total joint centers in the United States. Demographic features, Harris Hip Score (HHS), and radiographic findings were recorded. Patients who did not have a 2-year follow-up visit were contacted by telephone. All patients were asked about complications, reoperations, or failure of the implants. Of the treated hips, 1144 (90%) had a minimum of 2 years of clinical follow-up (mean, 2.9 years; range, 1.8-4.2 years). Mean age was 52.3 years, and 75% of patients were men. Mean HHS improved from 55.8 preoperatively to 97.4 at the most recent follow-up (P<.001). There were 16 (1.4%) revisions to total hip arthroplasty (THA) for fracture (7), early dislocation (3), acetabular component malpositioning with pain (3; 1 with metallosis), infection (1), femoral loosening (1), and pseudotumor (1). There were 9 additional complications (0.8%) that did not require revision, including 3 dislocations treated with closed reduction, 2 fractures, 3 nerve injuries, and 1 pseudotumor. At 2 to 4 years of follow-up, the revision rate and the major complication rate with the BHR system were similar to those in previous reports of primary THA. Excellent clinical results were observed, but further follow-up is necessary to assess mid- and long-term results with the BHR system in US patients. [Orthopedics. 2015; 38(8):e715-e721.]. Copyright 2015, SLACK Incorporated.
    Orthopedics 08/2015; 38(8):e715-21. DOI:10.3928/01477447-20150804-60 · 0.98 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study's purpose was to present the use of a risk stratification protocol in which "routine" risk patients receive a mobile compression device with aspirin and "high" risk patients receive warfarin for thromboprophylaxis after hip arthroplasty. 1859 hip arthroplasty patients were prospectively enrolled (1402 routine risk - 75.4%, 457 high risk - 24.6%). The cumulative rate of venous thromboembolism events was 0.5% in the routine versus 0.5% in the high-risk cohort within 6weeks postoperatively (P=1.00). Patients in the routine risk cohort had a lower rate of major bleeding (0.5% versus 2.0%, P=0.006) and wound complications (0.2% versus 1.2%, P=0.01). Use of our risk stratification protocol allowed the avoidance of more aggressive anticoagulation in 75% of patients while achieving a low overall incidence of symptomatic VTE. Copyright © 2015. Published by Elsevier Inc.
    The Journal of arthroplasty 07/2015; DOI:10.1016/j.arth.2015.06.045 · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to compare whole blood metal ion levels in young, active patients undergoing primary total hip arthroplasty with the use of a cobalt-alloy (ten patients), ceramic (15 patients), or oxinium (11 patients) femoral head and highly crosslinked polyethylene acetabular liner. At 2years postoperatively, mean cobalt concentrations were 3.0 times higher in the cobalt-alloy cohort versus the ceramic cohort, and 2.3 times higher versus the oxinium cohort (P=0.3-0.5). Titanium levels were consistently elevated at all postoperative time points versus preoperatively in all cohorts. Young, active patients following THA demonstrate elevated cobalt and titanium concentrations. Use of a ceramic or oxinium femoral head decreased the degree of cobalt elevation versus a cobalt-alloy femoral head, but did not reach statistical significance. Copyright © 2015. Published by Elsevier Inc.
    The Journal of arthroplasty 06/2015; DOI:10.1016/j.arth.2015.06.025 · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We assessed whether sequential incorporation of initiatives to decrease postoperative surgical complications were similarly effective in reducing 30-day readmission rates following total knee arthroplasty (TKA) and total hip arthroplasty (THA). Readmission rates following TKA decreased substantially (5.6% vs. 3.0%, P<0.001), but readmissions following THA (4.0% vs. 3.4%, P=0.41) were not significantly reduced. The greatest impact of the multimodal treatment approach was a reduction of surgically related TKA complications. Advanced medical disease, facility discharge status, and Medicare or Medicaid coverage contributed to the highest risk for 30-day readmission after THA. Risk models defining expected readmission rates should account for these factors to avoid penalizing hospitals that provide higher proportional care to Centers for Medicaid and Medicare Services (CMS) beneficiaries. Copyright © 2015. Published by Elsevier Inc.
    The Journal of arthroplasty 06/2015; DOI:10.1016/j.arth.2015.06.007 · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We assessed the impact of minority and socioeconomic status on 30-day readmission rates after 3825 primary total hip arthroplasty (THA) and 3118 primary total knee arthroplasty (TKA) procedures. Minority patients had higher THA (7.4% vs 3.2%, P=0.001) and TKA (5.4% vs 3.7%, P<0.001) readmission rates. Low socioeconomic status was associated with higher THA (6.0% vs 3.1%, P<0.001) and TKA (6.3% vs 3.8%, P=0.02) readmission rates. Risk reduction initiatives were effective after TKA, but minority status and low socioeconomic status were still associated with higher 30-day readmission rates (4.6% vs 1.8%, P<0.01). Focused postoperative engagement for Centers for Medicare and Medicaid Services (CMS) beneficiaries less than 65years of age may help reduce complications and 30-day readmissions. Copyright © 2015. Published by Elsevier Inc.
    The Journal of arthroplasty 06/2015; DOI:10.1016/j.arth.2015.06.031 · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Persistent pain following hip arthroplasty remains a concern, especially in young, active patients. Four hundred twenty patients less than 60years of age with a pre-symptomatic UCLA score≥6 (196 total hip arthroplasty [THA]; 224 surface replacement arthroplasty [SRA]) completed a pain-drawing questionnaire investigating the location, severity, and frequency of pain around the hip. At a mean of 2.9years of follow-up, 40% reported pain in at least one location around the hip. There was no difference in the incidence of groin pain between SRA and THA patients (32% vs. 29%, P=0.6), but THA patients had a greater incidence of anterior (25% vs. 8%, P<0.001) and lateral (20% vs. 10%, P=0.01) thigh pain. A high percentage of young, active patients experience persistent pain following hip arthroplasty. Copyright © 2015. Published by Elsevier Inc.
    The Journal of Arthroplasty 05/2015; DOI:10.1016/j.arth.2015.05.030 · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This article highlights some hot topics and controversies in total hip arthroplasty. It discusses the use of pharmacologic agents, mechanical compression devices, and aspirin for thromboembolic prophylaxis. It also reviews the use of long versus short stems, as well as ceramic-on-ceramic and ceramic-on-highly cross-linked polyethylene bearing surfaces.
    05/2015; 15(7):21-22. DOI:10.1177/1559897715585507
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Custom cutting guides (CCGs; sometimes called patient-specific instrumentation [PSI]) in total knee arthroplasty (TKA) use preoperative three-dimensional imaging to fabricate cutting blocks specific to a patient's native anatomy. The purposes of this study were to determine if CCGs (1) improve clinical outcomes as measured by UCLA activity, SF-12, and Oxford knee scores; and (2) coronal mechanical alignment versus standard alignment guides. This was a retrospective cohort study of patients undergoing primary TKA using the same cruciate-retaining, cemented TKA system between January 2009 and April 2012. Patients were included if they were candidates for a unilateral, cruciate-retaining TKA and met other prespecified criteria; patients were allowed to self-select either an MRI-based CCG procedure or standard TKA. Ninety-seven of 120 (80.8%) patients in the standard and 104 of 124 (83.9%, p = 0.5) in the CCG cohort with a minimum of 1-year followup were available for analysis. The first 95 patients in the standard (mean followup, 3 years; range, 1-4 years) and CCG (mean followup, 2 years; range, 1-4 years) cohorts were compared. The alignment goal for all TKAs was a hip-knee-ankle (HKA) angle of 0°. UCLA, SF-12, and Oxford knee scores were collected preoperatively and at each patient's most recent followup visit. Postoperative, rotationally controlled coronal scout CT scans were used to measure HKA alignment. Independent-sample t-tests and chi-square tests were used for comparisons with a p value ≤ 0.05 considered significant. At the most recent followup, no differences were present between the two cohorts for range of motion (114° ± 14° in CCG versus 115° ± 15° in standard, p = 0.7), UCLA (6 ± 2 in CCG versus 6 ± 2 in standard, p = 0.7), SF-12 physical (44 ± 12 in CCG versus 41 ± 12 in standard, p = 0.07), or Oxford knee scores (39 ± 9 in CCG versus 37 ± 10 in standard, p = 0.1). No differences were present for the incremental improvement in the UCLA (1 ± 4 in CCG versus 1 ± 3 in standard, p = 0.5), SF-12 physical (12 ± 20 in CCG versus 11 ± 21, p = 0.8), or Oxford knee scores (16 ± 9 in CCG versus 19 ± 10 in standard, p = 0.1) from preoperatively to postoperatively. There was no difference in the percentage of outliers for alignment (23% in standard versus 31% in CCG with HKA outside of 0° ± 3°; p = 0.2) between the two cohorts. At a mean followup of greater than 2 years, CCGs fail to demonstrate any advantages in validated knee outcome measure scores or coronal alignment as measured by CT scan versus the use of standard instrumentation in TKA. The clinical benefit of CCGs must be proven before continued implementation of this technology. Level III, retrospective controlled study.
    Clinical Orthopaedics and Related Research 02/2015; DOI:10.1007/s11999-015-4216-y · 2.88 Impact Factor
  • Denis Nam · Ryan M Nunley · Staci R Johnson · John C Clohisy · Robert L Barrack
    [Show abstract] [Hide abstract]
    ABSTRACT: We hypothesized that the time period studied would have a greater impact on perioperative outcomes than the hip arthroplasty procedure performed, demonstrating concerns with studies comparing new techniques to "historical" controls. One hundred total hip arthroplasty (THA) and 100 surface replacement arthroplasty (SRA) patients performed between 2004 and 2010 ("historical" period) were matched and compared to 50 THA and 50 SRA patients performed between 2010 and 2012 ("recent" period). Time to discharge was significantly improved for both the THA and SRA groups in the recent versus historical period by 16hours (P<0.001). At both periods, THA patients were discharged earlier by 9hours versus SRAs (P<0.0001). Study time frame had a greater impact than the operative procedure on perioperative metrics. Copyright © 2015 Elsevier Inc. All rights reserved.
    The Journal of Arthroplasty 02/2015; 30(7). DOI:10.1016/j.arth.2015.02.002 · 2.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aims of this retrospective study were to compare the mid-term outcomes following revision total knee replacement (TKR) in 76 patients (81 knees) < 55 years of age with those of a matched group of primary TKRs based on age, BMI, gender and comorbid conditions. We report the activity levels, functional scores, rates of revision and complications. Compared with patients undergoing primary TKR, those undergoing revision TKR had less improvement in the mean Knee Society function scores (8.14 (-55 to +60) vs 23.3 points (-40 to +80), p < 0.001), a similar improvement in UCLA activity level (p = 0.52), and similar minor complication rates (16% vs 13%, p = 0.83) at a mean follow-up of 4.6 years (2 to 13.4). Further revision surgery was more common among revised TKRs (17% vs 5%, p = 0.02), with deep infection and instability being the most common reasons for failure. As many as one-third of patients aged < 55 years in the revision group had a complication or failure requiring further surgery. Young patients undergoing revision TKR should be counselled that they can expect somewhat less improvement and a higher risk of complications than occur after primary TKR.
    The Bone & Joint Journal 12/2014; 96-B(12):1657-1662. DOI:10.1302/0301-620X.96B12.34486 · 2.80 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Potential sources of alignment variability not yet investigated with the use of custom cutting guides (CCG) in total knee arthroplasty (TKA) are weight-bearing and lower extremity rotation. This study compared the preoperative planned bone resections created using an MRI-based CCG system to those from 3-dimensional, weight-bearing, full-length lower extremity images in 53 patients undergoing TKA. The angular difference between the proposed resections of the two systems was greater than 2° in 30.2% of patients for the distal femur, and 52.8% for the proximal tibia. An increased preoperative varus alignment had a slight association with an increased angular difference for the tibial resection (r=0.4). This study demonstrates weight-bearing and lower extremity rotation to be potential sources of alignment variability when using MRI-based CCGs. Copyright © 2014 Elsevier Inc. All rights reserved.
    The Journal of Arthroplasty 11/2014; 30(4). DOI:10.1016/j.arth.2014.11.009 · 2.37 Impact Factor
  • D Nam · R M Nunley · R L Barrack
    [Show abstract] [Hide abstract]
    ABSTRACT: A national, multi-centre study was designed in which a questionnaire quantifying the degree of patient satisfaction and residual symptoms in patients following total knee replacement (TKR) was administered by an independent, blinded third party survey centre. A total of 90% of patients reported satisfaction with the overall functioning of their knee, but 66% felt their knee to be 'normal', with the reported incidence of residual symptoms and functional problems ranging from 33% to 54%. Female patients and patients from low-income households had increased odds of reporting dissatisfaction. Neither the use of contemporary implant designs (gender-specific, high-flex, rotating platform) or custom cutting guides (CCG) with a neutral mechanical axis target improved patient-perceived outcomes. However, use of a CCG to perform a so-called kinematically aligned TKR showed a trend towards more patients reporting their knee to feel 'normal' when compared with a so called mechanically aligned TKR This data shows a degree of dissatisfaction and residual symptoms following TKR, and that several recent modifications in implant design and surgical technique have not improved the current situation. Cite this article: Bone Joint J 2014;96-B(11 Suppl A):96-100.
    Bone and Joint Journal 11/2014; 96-B(11 Supple A):96-100. DOI:10.1302/0301-620X.96B11.34152
  • Denis Nam · Ryan M Nunley · Staci R Johnson · James A Keeney · Robert L Barrack
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, Levy et al questioned the effectiveness of mobile compression devices (MCDs) as the sole method of thromboprophylaxis following simultaneous bilateral total knee arthroplasty (TKA). This study's purpose was to assess if the addition of aspirin to MCDs improves venous thromboembolism (VTE) prevention following simultaneous bilateral TKA. Ninety-six patients (192 TKAs) were retrospectively reviewed: 47 patients received MCDs for 10days and aspirin for 6weeks postoperatively based on a risk stratification protocol, while 49 patients received warfarin for 4weeks postoperatively. One symptomatic VTE was noted in the warfarin cohort, while one patient in the MCD/aspirin cohort and three patients in the warfarin cohort were readmitted within 3months of surgery. In appropriately selected patients, MCDs with aspirin shows promise in VTE prevention following simultaneous bilateral TKA. Copyright © 2014 Elsevier Inc. All rights reserved.
    The Journal of Arthroplasty 10/2014; 30(3). DOI:10.1016/j.arth.2014.10.018 · 2.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Return to sexual activity is important to patients, but there is limited information regarding sexual function following total hip arthroplasty (THA) and total knee arthroplasty (TKA). A multicenter study of 806 THA, 542 TKA, and 181 control patients less than 60 years of age was conducted using an independent survey center to question subjects about their sexual function. Only 1.3% of THA and 1.6% of TKA patients stated they were not sexually active due to their operation. No statistically significant differences were noted in any sexual function outcome categories based on the bearing surface, femoral head size, or use of surface replacement arthroplasty in the hip cohort. Multivariate analysis revealed no difference in the percentage of patients sexually active following a THA or TKA (OR 1.19, p = 0.38). Most young active patients return to their baseline or higher level of sexual activity after hip and knee arthroplasty.
    The Journal of Arthroplasty 10/2014; 30(2). DOI:10.1016/j.arth.2014.09.029 · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to determine the percentage of time that patients are subtherapeutic, therapeutic, and supratherapeutic based on the recommended INR for therapeutic efficacy when prescribed warfarin for chemical thromboprophylaxis following a hip or knee arthroplasty procedure. One hundred eighty-four patients receiving warfarin for 4 weeks postoperatively, dosed using a web-application accounting for patient demographics, INR levels, and concomitant medication use, were included for analysis. On average, patients with a target INR range between 1.7-2.7 were therapeutic for only 54.4% of the time (32.5% subtherapeutic, 13.0 supratherapeutic) while patients with a target INR range between 2.0 and 3.0 were therapeutic for only 45.9% of the time (39.2% subtherapeutic, 14.8% supratherapeutic) of their warfarin regimen. This study confirms that patients receiving warfarin for chemical thromboprophylaxis are within their targeted INR range for only a limited period of time during their postoperative course.
    The Journal of Arthroplasty 09/2014; 30(2). DOI:10.1016/j.arth.2014.08.032 · 2.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Preoperative planning for patient-specific guides (PSGs) in total knee arthroplasty (TKA) requires identification of anatomic landmarks on three-dimensional imaging studies. The aim of this study was to assess the accuracy and precision with which landmarks commonly used to determine rotational alignment in TKA can be identified on magnetic resonance imaging (MRI). Two orthopaedic surgeons and two musculoskeletal radiologists independently reviewed a sequential series of 114 MRIs of arthritic knees. The magnitude of interobserver variability was high, suggesting an inherent risk of inconsistency when these landmarks are used in PSG fabrication. Additionally, there was a high degree of physiologic variation among patients, indicating that assuming standard relationships among anatomic landmarks when placing TKA components may lead to rotational malalignment relative to each patient’s native anatomy.
    The Journal of Arthroplasty 09/2014; 30(2). DOI:10.1016/j.arth.2014.08.015 · 2.37 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objectives Although vitamin D is recognized as an important factor in bone health, its role in osteoarticular infections is unclear. We hypothesized that low vitamin D (25-hydroxycholecalciferol) levels are associated with a lower likelihood of treatment success in osteoarticular infections. Methods This was a retrospective cohort study of patients with orthopedic infections who had a 25-hydroxycholecalciferol level drawn when their infection was diagnosed. Outcomes were determined at early (3–6 months) and late (≥6 months) follow-up after completing intravenous antibiotics. Results We included 223 patients seen during an 11-month period with osteoarticular infections and baseline 25-hydroxycholecalciferol levels. During the initial inpatient management of the infection, hypovitaminosis D was identified and treated. The mean 25-hydroxycholecalciferol level was 23 ± 14 ng/ml; 167 (75%) patients had levels <30 ng/ml. Overall, infection treatment success was 91% (159/174) at early follow-up and 88% (145/164) at late follow-up. 25-Hydroxycholecalciferol baseline levels were similar in those with and without successful clinical outcomes, both at early (25 ± 15 vs. 21 ± 9 ng/ml; p = 0.3) and late follow-up (25 ± 15 vs. 23 ± 16 ng/ml; p = 0.6). Conclusions To our knowledge this is the first report on hypovitaminosis D and its impact on outcomes of osteoarticular infections. Hypovitaminosis D was frequent in this cohort. With vitamin D repletion, there was no difference in treatment success whether patients had baseline hypovitaminosis or not.
    International Journal of Infectious Diseases 09/2014; 26. DOI:10.1016/j.ijid.2014.05.004 · 2.33 Impact Factor
  • Adam Sassoon · Denis Nam · Ryan Nunley · Robert Barrack
    [Show abstract] [Hide abstract]
    ABSTRACT: Patient-specific cutting blocks have been touted as a more efficient and reliable means of achieving neutral mechanical alignment during TKA with the proposed downstream effect of improved clinical outcomes. However, it is not clear to what degree published studies support these assumptions.
    Clinical Orthopaedics and Related Research 07/2014; 473(1). DOI:10.1007/s11999-014-3804-6 · 2.88 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background A recent proposed modification in surgical technique in total knee arthroplasty (TKA) has been the introduction of the “kinematically aligned” TKA, in which the angle and level of the posterior joint line of the femoral component and joint line of the tibial component are aligned to those of the “normal,” pre-arthritic knee. The purpose of this study was to establish the relationship of the posterior femoral axis of the “kinematically aligned” total knee arthroplasty (TKA) to the traditional axes used to set femoral component rotation. Methods 114 consecutive, unselected patients with preoperative MRI images undergoing TKA were retrospectively reviewed. The transepicondylar axis (TEA), posterior condylar axis (PCA), antero-posterior axis (APA) of the trochlear groove, and posterior femoral axis of the kinematically aligned TKA (KAA) were templated on axial MRI images by two, independent observers. The relationships between the KAA, TEA, APA, and PCA were determined, with a negative value indicating relative internal rotation of the axis. Results On average, the KAA was 0.5° externally rotated relative to the PCA (minimum of − 3.6°, maximum of 5.8°), − 4.0° internally rotated relative to the TEA (minimum of − 10.5°, maximum of 2.3°), and − 96.4° internally rotated relative to the APA (minimum of − 104.5°, maximum of − 88.5°). Each of these relationships exhibited a wide range of potential values. Conclusions Using a kinematically aligned surgical technique internally rotates the posterior femoral axis relative to the transepicondylar axis, which significantly differs from current alignment instrument targets.
    The Knee 07/2014; 21(6). DOI:10.1016/j.knee.2014.07.025 · 1.70 Impact Factor

Publication Stats

7k Citations
731.25 Total Impact Points

Top co-authors View all

Institutions

  • 2006–2015
    • Barnes Jewish Hospital
      San Luis, Missouri, United States
  • 2004–2015
    • Washington University in St. Louis
      • Department of Orthopaedic Surgery
      San Luis, Missouri, United States
    • Louisiana State University Health Sciences Center New Orleans
      • Department of Orthopaedic Surgery
      Shreveport, LA, United States
  • 2009–2011
    • Johns Hopkins University
      • Department of Orthopaedic Surgery
      Baltimore, MD, United States
    • Rush University Medical Center
      • Department of Orthopaedic Surgery
      Chicago, IL, United States
  • 2008–2009
    • Thomas Jefferson University
      Filadelfia, Pennsylvania, United States
    • Thomas Jefferson University Hospitals
      Philadelphia, Pennsylvania, United States
  • 2007
    • Albert Einstein College of Medicine
      New York, New York, United States
  • 1983–2003
    • Tulane University
      • • Department of Medicine
      • • Department of Orthopaedics
      New Orleans, Louisiana, United States
  • 2001
    • University of Miami
      كورال غيبلز، فلوريدا, Florida, United States
  • 2000
    • The University of Western Ontario
      • Division of Orthopaedic Surgery
      London, Ontario, Canada
    • Anderson Orthopaedic Clinic
      Alexandria, Virginia, United States
  • 1995
    • Naval Medical Research Center
      Silver Spring, Maryland, United States
  • 1994
    • Harvard Medical School
      • Department of Orthopaedic Surgery
      Boston, Massachusetts, United States
  • 1992
    • Massachusetts General Hospital
      • Department of Orthopaedic Surgery
      Boston, Massachusetts, United States
  • 1991
    • Naval Hospital Bremerton
      Бремертон, Washington, United States