The Fragility Index of Statistically Significant Findings From Randomized Controlled Trials Comparing the Management Strategies of Anterior Shoulder Instability

Abstract

Background: Debate centering on the management of anterior shoulder instability (ASI) in recent years has led to many randomized controlled trials (RCTs) being published on the topic. The fragility index (FI) has subsequently emerged as a novel method of assessing significant findings reported in RCTs, particularly those with small sample sizes. Purpose: To evaluate the FI of statistically significant findings in RCTs that reported the outcomes of management strategies of patients with ASI. Study Design: Systematic review; Level of evidence, 1. Methods: Using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, 2 independent reviewers performed a systematic review of RCTs focusing on the outcomes of management strategies of patients with ASI. There were 3 main categories of RCTs included: (1) nonoperative management in internal rotation (IR) versus external rotation (ER), (2) nonoperative management versus a surgical intervention, and (3) surgical management with arthroscopic Bankart repair versus open Bankart repair. The Fisher exact test was utilized to calculate the FI for the reversal of statistical significance in all statistically significant dichotomous outcomes. Results: A total of 21 RCTs were included, including 1589 shoulders (mean age, 29.4 years) with a mean follow–up of 26.8 months. There were 10 RCTs (831 shoulders) that reported outcomes after the nonoperative management of ASI in IR versus ER, with a mean FI of 6.8. There were 5 RCTs (324 shoulders) that reported outcomes comparing the nonoperative and operative management of ASI, with a mean FI of 3.5. There were 6 RCTs (434 shoulders) that reported outcomes after the operative management of ASI with either arthroscopic Bankart repair or open Bankart repair, with a mean FI of 9.6. Conclusion: The overall FI of RCTs reporting the outcomes of management strategies for patients with ASI was high, suggesting a moderate fragility of statistically significant outcomes including recurrence, revision stabilization, and return to play.