Defining clinical significance following primary stabilization of posterior shoulder instability

Background: Posterior glenohumeral instability is a common cause of shoulder pain and significant disability. Current literature about clinical significance thresholds for patient-reported outcome measures (PROMs) following posterior stabilization have been poorly defined. The purpose of this study was to define the minimal clinically important difference (MCID), patient acceptable symptomatic state (PASS), and substantial clinical benefit (SCB) for the American Shoulder and Elbow Surgeons (ASES) score, Brophy shoulder score, Patient-Reported Outcomes Measurement Information System (PROMIS-10) physical health (PH) and mental health (MH) scores, Subjective Shoulder Value (SSV), and visual analog pain scale (VAS) for patients undergoing arthroscopic stabilization for posterior instability. Methods: This was a retrospective review of shoulder PROMs in patients who underwent arthroscopic posterior stabilization between 2013 and 2023. The MCID, PASS, and SCB were calculated for the ASES, Brophy, PROMIS-10, SSV, and VAS utilizing either anchor- or distribution-based methods. For MCID, a distribution-based method used both the Standard Error of Measurement and the 95% Minimum Detectable Change. For PASS and SCB, anchor-based methods were used based on receiver operating characteristic (ROC) curve analysis to identify optimal cutoffs using the Youden J statistic. Results: Ninety-eight patients were included. The most common etiologies of posterior shoulder instability were chronic posterior instability (60.2%), followed by sport related injury (37.4%), and trauma (13.3%). The MCID values for Standard Error of Measurement and Minimum Detectable Change methods were 7.31 and 20.26 for ASES, 0.90 and 2.50 for Brophy, 9.54 and 26.45 for SSV, 0.43 and 1.19 for VAS, 1.06 and 2.93 for PROMIS-10 MH, and 0.67 and 1.85 for PROMIS-10 PH, respectively. The PASS values for ROC methods were 91.75 for ASES, 10.5 for Brophy, 67.5 for SSV, 1.5 for VAS, 18.5 for PROMIS-10 MH, and 14.5 for PROMIS-10 PH, respectively. Finally, the SCB values for ROC methods were 85.76 for ASES, 9.5 for Brophy, 92.25 for SSV, 2.5 for VAS, 14.5 for PROMIS-10 MH, and 14.5 for PROMIS-10 PH, respectively. Conclusion: MCID, PASS, and SCB provide clinical context to PROMs, allowing a more accurate assessment of patient outcomes. The thresholds defined in this study can provide a guideline for interpreting patient outcomes following arthroscopic stabilization for posterior shoulder instability, allowing for earlier detection of recurrent posterior instability.