Association of Recurrent Tear After Arthroscopic Rotator Cuff Repair and Superoxide-Induced Oxidative Stress

BACKGROUND: Recurrent tears after arthroscopic rotator cuff repair (ARCR) remain a significant clinical problem. Oxidative stress contributes to the degeneration of the rotator cuff, and a degenerative rotator cuff can lead to recurrent tear after ARCR. However, the correlation between oxidative stress and retear after ARCR is unclear. PURPOSE: To investigate the correlation between superoxide-induced oxidative stress and recurrent tear after ARCR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 68 patients who underwent ARCR using a suture-bridge technique participated in this study. Specimens were collected from the edge of the torn tendon during surgery. The modified Bonar score was used to evaluate degeneration of the rotator cuff on histological specimens, and fluorescence intensity on dihydroethidium (DHE) staining was used to detect oxidative stress. Superoxide dismutase (SOD) enzyme activity was also measured. The following were used for clinical evaluation: age, tear size on magnetic resonance imaging (MRI) before surgery, Goutallier classification on MRI before surgery, and Japanese Orthopaedic Association score before and 6 months after surgery. After the repaired rotator cuffs were evaluated on MRI 6 months after surgery, the patients were divided into groups: those with a healed rotator cuff (healed group; n = 46) and those with a recurrent tear (retear group; n = 22). The significant differences between the groups were determined with regard to clinical evaluation, modified Bonar score, DHE intensity, and SOD activity. In addition, multivariate logistic regression analysis was performed to investigate risk factors for recurrent tear. RESULTS: Age, tear size, Goutallier classification, modified Bonar score, DHE intensity, and SOD activity were significantly greater in the retear group than in the healed group, although the Japanese Orthopaedic Association score was not significantly different. Multiple logistic regression analysis demonstrated that age, tear size, and SOD activity were significantly correlated with recurrent tear. CONCLUSION: In addition to tear size and age, superoxide-induced oxidative stress may be an exacerbating factor for retear after ARCR.