Shoulder arthroplasty device clearance: an ancestral network analysis.

BACKGROUND: The US Food and Drug Administration (FDA) oversees medical device regulation and oversight in the United States, and the majority of shoulder arthroplasty devices are cleared via the 510(k) pathway, in which a device demonstrates "substantial equivalence" to a previously cleared predicate. The purpose of this study was to determine an interconnected ancestral network of shoulder arthroplasty devices and determine equivalency ties to devices subsequently recalled by the FDA for design-related issues. METHODS: The FDA 510(k) database was used to identify all legally marketed shoulder arthroplasty devices from May 28, 1976, to July 1, 2021. Direct predicate information obtained via clearance summary documents associated with each device was used to generate an ancestral genealogy network for all shoulder arthroplasty devices cleared between July 1, 2020, and July 1, 2021. FDA design recalls were analyzed, and the number of descendant devices was calculated for each recalled device. RESULTS: An evaluation of all 476 510(k) premarket notification pathway-cleared shoulder devices since 1976 identified 0-313 descendant devices for each. Eighty of these devices (16.8%) have since been recalled, of which 10 recalls were directly related to implant design issues. Furthermore, among 29 of the most recently cleared devices (July 1, 2020-July 1, 2021), 16 (55.2%) claim predicates devices that have subsequently been withdrawn from the market because of design-related failures. CONCLUSIONS: Shoulder arthroplasty devices are linked together via an interconnected FDA 510(k) equivalency approval network dating back to 1976 despite substantive changes in material specifications and device design, many of which have since been recalled. Many of the cleared modern devices claim predicates based on subsequently recalled prostheses.

Biomechanical analysis of anterior stability after 15% glenoid bone loss: comparison of Bankart repair, dynamic anterior stabilization, dynamic anterior stabilization with Bankart repair, and Latarjet.

BACKGROUND: Dynamic anterior shoulder stabilization (DAS) with Bankart repair is a recently described stabilization technique thought to be more robust than an isolated Bankart repair while avoiding many coracoid transfer-related complications and technical demands. DAS involves transfer of the long head biceps through a subscapularis split to the anterior glenoid to create a sling effect. We hypothesize that DAS with Bankart repair will restore anterior stability in a human-cadaveric model with subcritical (15%) glenoid bone loss. METHODS: Eight cadaveric shoulders were tested using an established shoulder simulator to record glenohumeral translations with an accuracy of ±0.2 mm. Shoulders were tested in 5 states-intact soft tissues, Bankart defect with 15% bone loss, isolated Bankart repair, DAS with Bankart repair, isolated DAS, and Latarjet. A 45 N anterior force was applied through the pectoralis major tendon, and translation of the humeral head was recorded and compared with repeated measures analysis of variance. RESULTS: The anterior translation in the intact (native) glenoid was 4.7 mm at neutral position and 4.6 mm at 45° external rotation. Anterior translation significantly increased after introducing a Bankart defect with 15% glenoid bone loss to 9.1 mm (neutral, P = .002) and 9.5 mm (45° external rotation, P < .001). All repair conditions showed a significant decrease in anterior translation relative to Bankart defect. DAS with Bankart repair decreased anterior translation compared with the Bankart defect: 2.7 mm (neutral, P < .001) and 2.1 mm (45° external rotation, P < .001). DAS with Bankart repair significantly decreased anterior translation compared with the isolated Bankart repair (2.7 mm vs. 4.7 mm, P = .023) and the isolated DAS (2.7 mm vs. 4.3 mm, P = .041) in neutral position. The Latarjet procedure resulted in the greatest reduction in anterior translation compared with the Bankart defect: 1.2 mm (neutral, P < .001) and 1.9 mm (45° external rotation, P < .001). CONCLUSIONS: DAS with Bankart repair is a viable alternative to restore anterior glenohumeral stability with a 15% glenoid defect at a greater degree than either DAS or Bankart repair alone. The Latarjet procedure was the most effective in reducing anterior translation but restrained the anterior translation significantly more than the native glenoid.

Histologic Improvements in Irradiated Bone Through Pharmaceutical Intervention in Mandibular Distraction Osteogenesis.

PURPOSE: Despite the relative surgical ease and reduced donor-site morbidity of distraction osteogenesis (DO) in comparison with free tissue transfer, DO is currently precluded as a reconstructive option for head and neck cancer (HNC) patients because of the destructive effects of radiotherapy (XRT). This study investigates the ability of a novel combined therapy (CT) of radioprotective amifostine (AMF) and angiogenic deferoxamine (DFO) to mitigate XRT-induced bone injury in a murine model of DO. MATERIALS AND METHODS: Thirty male Sprague-Dawley rats were divided into 5 groups: DO (primary control), XRT (secondary control), AMF, DFO, and CT. With the exclusion of the DO group, all rats were administered a fractionated, human-equivalent XRT dose of 35 Gy, comparable with 70 Gy administered to HNC patients clinically. All groups underwent mandibular osteotomy and distraction to 5.1 mm. After euthanasia administration on postoperative day 40, the mandibles were sectioned and stained with Gomori trichrome. Osteocyte number, bone volume, and osteoid volume were compared between all groups by analysis of variance (P < .05). RESULTS: All rats survived and were included in the final analysis. The XRT group exhibited substantial bone injury, evidenced by a decreased osteocyte number and bone volume, as well as an increase in immature osteoid volume, compared with DO controls. The AMF, DFO, and CT groups showed significant increases in osteocyte proliferation compared with the XRT group and were not statistically different from the DO group. Notably, the CT group showed remediation of XRT-induced impairment of bone maturation and exhibited significantly greater bone volume and reduced osteoid volume in comparison with all groups. CONCLUSIONS: Combined AMF and DFO treatment showed the capacity to remediate the deleterious effects of XRT, restore cellularity to nonirradiated levels, and surpass all groups in mature bone formation. Although further investigations of AMF and DFO are warranted, this study provides preliminary support for the potential use of DO in HNC patients through pharmaceutical facilitation of irradiated bone healing.

Evaluation of Feedback Systems for the Third-Year Surgical Clerkship.

OBJECTIVE: To compare faculty-to-student feedback rates from 2 different data sets: direct observation cards (direct evidence) and end-of-clerkship questionnaires (ECQs, secondary student reporting). We as authors hypothesized that direct evidence from observation cards would yield higher rates of feedback, compared with student-reported ECQs. DESIGN: Data were gathered from 2 consecutive medical classes of the third-year surgical clerkship. Data were analyzed retrospectively. Subjects and authors were blinded during data collection and analysis. SETTING: University of Michigan Medical School (UMMS) and University of Michigan Health System (UMHS). UMHS is an academic tertiary care center, located in Ann Arbor, Michigan. PARTICIPANTS: Data were gathered from all third-year medical students completing the surgical clerkship from 2012 to 2014. Data were available for 309 students, compared to 313 students who graduated from UMMS during that time. RESULTS: Directly measured rates of feedback showed higher rates of midclerkship feedback (95.43% vs 83.57%, p < 0.05), feedback on an observed history-taking (97.62% vs 84.87%, p < 0.05), and feedback on an observed physical examination (99.67% vs 79.71%, p < 0.05), when compared with the ECQ. CONCLUSION: These data suggest that solely using ECQs to assess feedback rates may be inadequate. The use of multiple methods to assess feedback may therefore be a prudent choice for surgical clerkships.

Significant Differences in the Bone of an Isogenic Inbred Versus Nonisogenic Outbred Murine Mandible: A Study in Rigor and Reproducibility.

Inattention to differences between animal strains is a potential cause of irreproducibility of basic science investigations. Accordingly, the authors' laboratory sought to ensure that cross-comparisons of results generated from studies of mandibular physiology utilizing the Sprague Dawley and Lewis rat strains are valid. The authors specifically investigated baseline histomorphometrics, bone mineral density, and biomechanical strength of the unaltered endogenous mandibles of the inbred, isogenic Lewis rat, and the outbred, nonisogenic Sprague Dawley rat to determine if they are indeed equal. The authors hypothesized that little difference would be found within these metrics.The authors' study utilized 20 male Lewis and Sprague Dawley rats, which underwent no manipulation other than final dissection and analysis. Ten rats from each strain underwent bone mineral density and biomechanical strength analysis. The remaining rats underwent histological analysis. Descriptive and bivariate statistics were computed and the P value was set at 0.05.Lewis rats had a significantly greater number of empty lacunae. Sprague Dawley rats exhibited a significantly greater ratio of bone volume-to-total volume, bone mineral density, tissue mineral density, bone volume fraction, and total mineral content. No differences were found during biomechanical testing.This study demonstrates that differences exist between the Lewis and Sprague Dawley rat within unaltered baseline mandibular tissue. However, these differences appear to have limited functional impact, as demonstrated by similar biomechanical strength metrics. Other specific differences not addressed in this manuscript may exist. However, the authors believe that researchers may confidently cross-compare results between the 2 strains, while taking into account the differences found within this study.

A Comparison of Vascularity, Bone Mineral Density Distribution, and Histomorphometrics in an Isogenic Versus an Outbred Murine Model of Mandibular Distraction Osteogenesis.

PURPOSE: The vascularity, bone mineral density distribution, and histomorphometric data between the inbred, isogenic Lewis rat and the outbred, nonisogenic Sprague Dawley rat within mandibular distraction osteogenesis (MDO) were evaluated to allow future researchers to compare the results generated from these 2 animals. We hypothesized that little difference would be found between the 2 strains within these metrics. MATERIALS AND METHODS: We implemented a comparative study between the Lewis and Sprague Dawley rat strains within MDO. The sample was composed of 17 male Lewis and 17 male Sprague Dawley rats that underwent surgical external fixation and distraction. The rats' hemimandibles were distracted to a total distance of 5.1 mm. After 28 days of consolidation, 9 rats from each group underwent bone mineral density distribution analysis. The remaining rats from each group were analyzed for the vascular and histologic metrics. Descriptive and bivariate statistics were computed, and the P value was set at .05. RESULTS: We demonstrated successful MDO in all the rats, with no significant difference found in the histologic or bone mineral density distribution metrics. No significant differences were found in any of the vascular metrics, with the exception of vascular separation, which was not normalized to the mandibular volume (P = .048). CONCLUSIONS: The results of the present study have demonstrated that little dissimilarity exists between the isogenic Lewis and outbred Sprague Dawley models of MDO. Thus, researchers can confidently compare the gross results between the 2 strains, with consideration of the very small differences between the 2 models. For studies that require an isogenic strain, the Lewis rat is an apt surrogate for the Sprague Dawley strain.