Careful with that motion: A prospective cohort study evaluating the relationship of passive shoulder motion on repair integrity in 136 consecutive arthroscopic rotator cuff repairs

Background Retear is the most common complication following arthroscopic rotator cuff repair. Reduced early shoulder motion is associated with lower retear rates, but previous studies dichotomised shoulders at chosen cut-points. Whether retear risk changes at a discrete threshold or rises continuously is unknown. Methods In this prospective cohort study, 136 patients underwent primary arthroscopic supraspinatus repair by a single surgeon. Passive range of motion and patient-reported stiffness was recorded preoperatively, at 6, 12 and 24 weeks. Repair integrity was assessed by ultrasound at 6 months. Firth penalised logistic regression, restricted cubic splines and changepoint regression were used for statistical analysis. Results Eighteen patients (13%) sustained a retear. Greater forward flexion, abduction and global range of motion at 6 and 12 weeks were associated with retear (p = 0.002–0.026), independent of tear size. No changepoint or non-linearity was detected. Predicted retear risk rose from 4% to 6% at 60° to 21% to 26% at 150°. Patients reporting no stiffness at 6 weeks had a retear rate of 26%, compared with 4% among those reporting any stiffness. Discussion Greater passive shoulder motion early after rotator cuff repair was associated with a higher risk of retear, and the risk rose progressively across the full range of motion.