Assessing Tendon-to-Bone Healing in Arthroscopic Subscapularis Augmentation for Anterior Shoulder Instability: A second look arthroscopy study

Background: Recurrent anterior shoulder instability with subcritical bone loss is a significant clinical challenge, particularly in active individuals. Arthroscopic Subscapularis Augmentation (ASA) has emerged as an adjunct to the classic Bankart repair to enhance stability. Purpose: This study aimed to evaluate the tendon-to-bone healing rate of the subscapularis tendon following ASA using second-look arthroscopy. Methods: This prospective cohort study included 21 patients undergoing ASA to augment Bankart repair with or without a bone block procedure. All procedures were performed arthroscopically. Six months postoperatively, second-look arthroscopy was performed to assess the healing and integration of the subscapularis tendon onto the glenoid. The integrity of the repair was evaluated both visually and using a probe to assess fixation. Interim analyses were planned after the 10th and 20th patients to ensure robust outcomes and enable early study termination if indicated. Statistical analyses were performed to establish confidence in the observed outcome, which was the healing rate of the subscapularis tendon to the glenoid. Results: Second-look arthroscopy demonstrated evidence of subscapularis tendon healing to the glenoid in all patients. Probe testing confirmed secure fixation in all cases. Interim analyses confirmed a 100% healing rate after the 20th patient, leading to early study termination. No evidence of inflammation or arthritic changes was observed during follow-up. Post hoc analysis reinforced the reliability of the findings, with a 95% confidence interval of 0.916 to 1.000. Conclusion: Arthroscopic subscapularis augmentation demonstrates secure fixation of the subscapularis tendon to the glenoid as assessed by second-look arthroscopy and probe testing. While these results support the technique’s potential, longer follow-up studies and additional imaging modalities such as MRI are needed to further evaluate healing and long-term clinical outcomes.