Examining the Statistical Fragility of Randomized Trials on Operative Versus Nonoperative Treatment of Acromioclavicular Joint Separation Using the Reverse Continuous Fragility Index.

Abstract

Background: The aim of this study was to analyze nonsignificant, continuous outcomes and establish the reverse continuous fragility index (rCFI) of randomized controlled trials (RCTs) comparing operative and nonoperative treatment of acromioclavicular (AC) joint separations.

Materials and methods: Databases were searched from inception to February 2025 using "('Acromioclavicular' OR 'AC joint') AND ('Randomized controlled trial' OR 'RCT')". Included studies were RCTs published after 2004 comparing operative versus nonoperative treatment. rCFI was calculated for primary nonsignificant outcomes, and an rCFI quotient was derived by dividing each study's rCFI by its sample size.

Results: Seven studies involving 362 patients (92.3% male; mean age, 39.2 ± 7.7 years) with an average 5.29-year follow-up were analyzed. All studies included Rockwood type III injuries; 2 included type IV and 4 included type V. Mean rCFI was 14.9 ± 6.5. Four studies favored operative treatment. A total of 80 patients were lost to follow-up (mean, 13.3 per study), exceeding the rCFI in 3 of 7 studies. The mean rCFI quotient was 0.21 ± 0.06.

Conclusion: The rCFI of included RCTs highlights the fragility of the conclusion that nonoperative management of type III-V AC joint injuries provides noninferior clinical outcomes to operative management of these injuries.