Scapular endurance, dyskinesis, and functional outcomes after rotator cuff repair: A cross-sectional mediation analysis

This cross-sectional study investigates the relationship between scapular muscle endurance and shoulder function in patients who had undergone arthroscopic rotator cuff repair (RCR) 6–18 months before study enrollment. A total of 110 patients were assessed using the Scapular Retraction Endurance Test (SRET), the Scapular Dyskinesis Test, and the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST). Patient-reported outcomes were measured using the American Shoulder and Elbow Surgeons (ASES) score, the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, and a Numerical Rating Scale (NRS) for pain. Findings revealed that higher scapular endurance and better CKCUEST performance were significantly associated with improved shoulder function (higher ASES scores) and reduced disability (lower DASH scores). Scapular dyskinesis was associated with poorer clinical and functional outcomes and mediated the relationship between scapular endurance and functional status. Mediation analyses confirmed that both scapular dyskinesis and CKCUEST performance partially explained the impact of endurance on functional recovery. The results suggest that scapular muscle endurance is a key predictor of postoperative shoulder function and is influenced by scapular motion quality and upper extremity stability. These findings support the incorporation of endurance training and scapular control assessments into rehabilitation protocols for patients following RCR.