The Statistical Fragility of Anterior Shoulder Instability using Arthroscopic vs. Open Bankart Repair: A Systematic Review of Randomized Controlled Trials

Author(s): Michael N. Megafu, Justin M. Hajicek, Travis H. Rushton, Chase B. Barnwell, Keaton A. Taber, Bailey C. Hasken, Anthony Vicini, Robert L. Parisien

Background: Randomized controlled trials (RCTs) play a significant role in guiding treatment decisions and addressing concerns surrounding ASI management. The importance of data derived from RCTs is often evaluated by the use of a P value. The purpose of this study was to analyze the statistical stability of RCTs evaluating the surgical management of anterior shoulder instability using arthroscopic Bankart repair (ABR) vs. open Bankart repair (OBR) and calculate the fragility index (FI) and fragility quotient (FQ).

Methods: Using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, PubMed, Embase, and MEDLINE were queried for RCTs examining ASI literature reporting dichotomous outcomes from 2000 to 2023. The FI is defined as the number of outcome reversals required to alter statistical significance for any outcome. The FQ was determined by dividing the FI by the sample size of each study. The interquartile range (IQR) was calculated for each outcome.

Results: Out of 103 total studies, an overall FI, incorporating all 99 outcomes across 18 RCTs was 4 (IQR 2-7) and the overall FQ was 0.073 (IQR 0.060-0.100). Of the 18 RCTs, 12 RCTs (66.7%) reported an LTF greater than or equal to the overall FI of 4.

Conclusions: The statistical findings in ASI management are fragile and should be interpreted with caution. We recommend standardized reporting of P values with FI and FQ metrics to allow effective interpretation of ASI literature.