We prospectively analyzed the time course changes in the signal intensity of repaired rotator cuff with serial MRI to investigate the healing process and retear rate after arthroscopic rotator cuff repair. 48 patients with full-thickness rotator cuff tear underwent arthroscopic rotator cuff repair. There were 7 small, 30 medium, and 11 large tears. MRI was performed at 6 and 12 months postoperatively for all the patients. Cuff integrity on MRI was classified into 5 categories according to Sugaya's classification. Type IV and type V were considered as postoperative retear.
Postoperative MRIs showed 9 type I, 24 type II, 3 type III, 8 type IV, 4 type V at 6 months, and 13 type I, 22 type II, 3 type III,4 type IV, and 6 type V at 12 months. From 6 months to 12 months, 4 type II changed to type 1, 2 type VI changed to type II, and other 2 type IV changed to type V. All type V at 6 months did not change at 12 months. Postoperative retear rate at 12 months was 20.8 %. Although type IV at 6 month does not always mean postoperative retear, most of the type V is already found at 6 months postoperatively. Type V retear might have occurred by 6 months, so that we have to modify the postoperative protocol for the patients with a high risk.
