Humeral Retroversion and Capsule Thickening in the Overhead Throwing Athlete: A Systematic Review.

PURPOSE: To investigate the humeral and soft-tissue adaptations, including humeral retroversion, range of motion, and posterior capsule changes, in overhead throwing athletes. METHODS: We performed a systematic review in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. PubMed, MEDLINE, CENTRAL (Cochrane Central Register of Controlled Trials), and Embase were searched from January 1, 2011, through April 23, 2017, by 2 reviewers independently and in duplicate. The methodologic quality of all included articles was assessed using the Methodological Index for Non-randomized Studies criteria. Interobserver agreement for assessments of eligibility was calculated with the Cohen κ statistic. Descriptive statistics and raw counts were used to summarize data. RESULTS: We identified 14 studies (6 Level IV and 8 Level III) including 1,152 overhead throwing athletes. The mean age of the included athletes was 18.37 years (standard deviation, 1.52 years), with 59% of the athletes being pitchers and 41% being position players. Significantly greater humeral retroversion was found across all studies evaluating bony morphology in the dominant arm of overhead throwing athletes (range of mean differences, 9.6°-25.8°). Each of these studies also found decreased internal rotation in the dominant arm (range of mean internal rotation differences, -28° to -7.8°). Five studies found a significant negative correlation between the difference in humeral retroversion between the 2 arms and the difference in internal rotation (range of Pearson correlation coefficients, -0.56 to -0.35). Soft-tissue adaptations were assessed in 5 studies, with 4 identifying significantly thicker posterior capsules and 2 identifying significantly stiffer posterior capsules (P < .05). CONCLUSIONS: Overhead throwing athletes consistently show several distinct changes in their dominant shoulder. These include increased humeral retroversion and the presence of a thickened and stiff posterior capsule. Concomitantly, there is often reduced internal rotation and increased external rotation of the dominant arm. LEVEL OF EVIDENCE: Level IV, systematic review of Level III and IV studies.

Platform shoulder arthroplasty: a systematic review.

BACKGROUND: Platform shoulder arthroplasty systems may allow conversion to a reverse total shoulder arthroplasty (RTSA) without removing a well-fixed, well-positioned humeral stem. We sought to evaluate the complications associated with humeral stem exchange versus retention in patients undergoing conversion shoulder arthroplasty with a platform shoulder arthroplasty system. METHODS: PubMed, MEDLINE, CINAHL (Cumulative Index to Nursing and Allied Health Literature), and Embase were searched from database inception through October 9, 2016, for all articles comparing humeral stem retention versus exchange during conversion RTSA or that pertained to conversion RTSA with stem retention alone. All studies were screened in duplicate for eligibility. A methodologic quality assessment was completed for included studies. Pooled outcomes assessing complications, operative time, blood loss, and reoperations were determined. RESULTS: We included 7 studies (236 shoulders), including 1 level III and 6 level IV studies. Pooled analysis demonstrated significantly higher overall complications (odds ratio, 6.89; 95% confidence interval [CI], 2.48-19.13; P = .0002), fractures (odds ratio, 4.62; 95% CI, 1.14-18.67; P = .03), operative time (mean difference, 62.09 minutes; 95% CI, 51.17-73.01 minutes; P < .00001), and blood loss (mean difference, 260.06 mL; 95% CI, 165.30-354.83 mL; P < .00001) with humeral stem exchange. Stem exchange was also associated with increased risk of reoperation (P = .0437). CONCLUSION: Conversion arthroplasty with retention of the humeral stem is associated with lower overall complications, blood loss, operative time, and reoperations in comparison with stem exchange.

The Fragility of Statistically Significant Findings From Randomized Trials in Sports Surgery: A Systematic Survey.

BACKGROUND: High-quality, evidence-based orthopaedic care relies on the generation and translation of robust research evidence. The Fragility Index is a novel method for evaluating the robustness of statistically significant findings from randomized controlled trials (RCTs). It is defined as the minimum number of patients in 1 arm of a trial that would have to change status from a nonevent to an event to alter the results of the trial from statistically significant to nonsignificant. PURPOSE: To calculate the Fragility Index of statistically significant results from clinical trials in sports medicine and arthroscopic surgery to characterize the robustness of the RCTs in these fields. METHODS: A search was conducted in Medline, EMBASE, and PubMed for RCTs related to sports medicine and arthroscopic surgery from January 1, 2005, to October 30, 2015. Two reviewers independently assessed titles and abstracts for study eligibility, performed data extraction, and assessed risk of bias. The Fragility Index was calculated using the Fisher exact test for all statistically significant dichotomous outcomes from parallel-group RCTs. Bivariate correlation was performed to evaluate associations between the Fragility Index and trial characteristics. RESULTS: A total of 48 RCTs were included. The median sample size was 64 (interquartile range [IQR], 48.5-89.5), and the median total number of outcome events was 19 (IQR, 10-27). The median Fragility Index was 2 (IQR, 1-2.8), meaning that changing 2 patients from a nonevent to an event in the treatment arm changed the result to a statistically nonsignificant result, or P ≥ .05. CONCLUSION: Most statistically significant RCTs in sports medicine and arthroscopic surgery are not robust because their statistical significance can be reversed by changing the outcome status on only a few patients in 1 treatment group. Future work is required to determine whether routine reporting of the Fragility Index enhances clinicians' ability to detect trial results that should be viewed cautiously.