The purpose of this study is to investigate postoperative changes of MRI findings after rotator cuff repair within 1 year and over 1 year. 43 shoulders, which received open repair by a trans-osseous method and acromioplasty, were evaluated with MRI postoperatively within 1 year and over 1 year. 21 males and 22 females were involved; the average age at the operation was 65.1 years. The average follow-up period was 38.6 months. The clinical outcome was evaluated by JOA score. MRI was performed on a 0.5-T system and T2-weighted images were obtained. Intensity of the tendon or the bone-tendon interface is defined as ’high’ when it is as high as joint fluid, as ’low’ when it was the same as the normal tendon, and as ’medium’ when it was between ’high’ and ’low’. At final follow-up, 6 shoulders which showed low within 1 year, showed low continuously. In 21 shoulders which showed medium within 1 year, 19 changed to low at average 20.5 months (90.5%) after repair, 1 remained medium (4.75%), and 1 changed to high (4.75%). In 16 shoulders which showed high first, 4 changed to low at average 36.3 months (25%) after repair, 1 remained medium (6.25%), 11 remained high (68.75%) finally. An average of postoperative JOA score was 93.7 in low, and it was significantly higher than 84.7 in high at final follow-up. 90.5% cases of medium changed to low, compared with 25% cases of high at final follow-up. Therefore, it is suggested that medium of the tendon within 1 year after repair results in a good clinical outcome.
