Abstract
Background: Postoperative retear of the repaired rotator cuff tendon may decrease postoperative shoulder muscle strength, worsen patient outcome, and decrease patient satisfaction. Although superior capsule reconstruction for reinforcement of rotator cuff repair (SCR-R) is reported to prevent postoperative retear, the biomechanical benefit of SCR-R is yet to be explored. Hypothesis: SCR-R would restore superior glenohumeral stability and decrease subacromial contact pressure in a simulated degenerated supraspinatus tendon tear. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric shoulders were tested using a custom shoulder-testing system. Subacromial peak contact pressure, glenohumeral superior translation, and glenohumeral range of motion (ROM) were compared for 6 conditions: (1) intact shoulder, (2) traumatic reparable supraspinatus tendon tear model, (3) rotator cuff repair of condition 2, (4) degenerated reparable supraspinatus tendon tear model, (5) rotator cuff repair of condition 4, and (6) SCR-R of condition 4. Results: Creation of the degenerated reparable supraspinatus tear significantly increased superior glenohumeral translation at 0° (P <.0001) and 30° (P =.003) of glenohumeral abduction. Rotator cuff repair of degenerated reparable supraspinatus tendon tear did not significantly improve superior glenohumeral translation in any abduction position. Compared with that after creation of degenerated reparable supraspinatus tear (condition 4), SCR-R significantly decreased superior glenohumeral translation at 0° (P =.0001), 30° (P =.0002), and 60° (P =.004) of glenohumeral abduction, and significantly decreased subacromial peak contact pressure at 0° (P =.03) and 60° (P =.04) of glenohumeral abduction. Neither rotator cuff repair alone (condition 5) nor SCR-R significantly decreased glenohumeral ROM compared with creating the degenerated reparable supraspinatus tear (condition 4) in any abduction position. Conclusion: SCR-R completely restored superior glenohumeral translation and subacromial peak contact pressure when the torn tendon had no superior shoulder capsule, as seen in degenerated supraspinatus tendon tear, whereas rotator cuff repair alone did not provide a significant improvement. Clinical Relevance: SCR-R is recommended for degenerated reparable supraspinatus tendon tear to improve glenohumeral superior stability after surgery. © The Author(s) 2025.