Minimal Clinically Important Differences and Correlating Factors for the Rowe Score and the American Shoulder and Elbow Surgeons Score After Arthroscopic Stabilization Surgery for Anterior Shoulder Instability

Purpose: To determine the minimal clinically important differences (MCIDs) for the Rowe score and the American Shoulder and Elbow Surgeons (ASES) score after arthroscopic stabilization surgery for anterior shoulder instability and to evaluate the effect of various patient- and treatment-related factors on MCIDs. Methods: The study enrolled 216 patients who underwent arthroscopic stabilization surgery for anterior shoulder instability. The patients were categorized into "no-change" and "minimal-change" groups by a 15-item questionnaire at the 1-year postoperative visit. The Rowe and ASES scores were assessed preoperatively and at the 1-year postoperative follow-up visit. MCIDs were calculated using an anchor-based method. Correlations between MCIDs and several factors were evaluated using Spearman correlation analysis and univariate regression analysis. Results: On the basis of the questionnaires administered at the 1-year postoperative follow-up visit, 10 patients were assigned to the no-change group and 33 patients were placed in the minimal-change group. MCIDs for the Rowe and ASES scores were 9.7 and 8.5, respectively. Body mass index was negatively correlated with the MCID for the Rowe score (P = .01). Number of dislocations, symptom duration, and presence of Hill-Sachs lesions were positively correlated with the MCID for the ASES score (P = .02, P = .04, and P = .02, respectively). Other variables such as age, sex, and arm dominance were not related to the MCIDs for either the Rowe or ASES score. Conclusions: In patients who underwent arthroscopic stabilization surgery, differences of at least 9.7 in the Rowe score and 8.5 in the ASES score were clinically relevant. Patients with a greater body mass index required a smaller change in the Rowe score and patients with a greater number of dislocations, a longer symptom duration, or a Hill-Sachs lesion required a larger change in the ASES score to feel clinically relevant changes.