Re-tear Rate of Sugaya III Tendons Between 1 and 2 Years Postoperatively After Arthroscopic Rotator Cuff Repair Is Over 30% and Associated With Higher Tear Size and Fatty Degeneration

PURPOSE: To evaluate the integrity of the repaired rotator cuff between 1 and 2 years postoperatively after arthroscopic rotator cuff repair (ARCR) using magnetic resonance imaging (MRI), investigate the factors affecting its change, and assess the association between the change and postoperative clinical outcomes. METHODS: Rotator cuff tear patients who underwent ARCR and were evaluated by MRI before surgery, and 1 and 2 years after ARCR with a minimum of 2-year follow-up were included in this study. Repair integrity was evaluated using Sugaya's classification, and according to the classification types IV and V were defined as retears. In addition, fatty degeneration of the rotator cuff muscles was evaluated using Goutallier's classification. Furthermore, the clinical scores were also assessed. RESULTS: In total, 346 patients were evaluated. Retears were detected in 51 cases 1 year postoperatively, and the number of retear cases increased to 65 at 2 years' postoperation. The retear rate 1 to 2 years postoperatively was 33.3% of patients classified as Sugaya type III 1 year postoperatively, the highest among all types. The incidence of retears was significantly associated with preoperative tear size (P < .01) and fatty degeneration (P < .01) among these patients. The 2-year postoperative clinical scores of the retear group were significantly lower than those of the repaired group, although there was no significant difference 1 year postoperatively. Fatty degeneration after repair did not improve regardless of whether the repair was successful or not. CONCLUSIONS: Retears between 1 and 2 years postoperatively are not uncommon. A follow-up of at least 2 years is necessary to determine short-term outcome after surgery, especially in patients with severe fatty degeneration preoperatively and those with diminished muscle thickness without discontinuity seen on MRI 1-year postoperatively. LEVEL OF EVIDENCE: Level IV, therapeutic case series.