The purpose of this study was to evaluate the functional results after surgical repair of rotator cuff tears using the rate of improvement for muscle force of shoulder abduction. Thirty-eight shoulders in 38 patients with a rotator cuff tear underwent cuff repair. Abduction power of the shoulder was evaluated with spring scale preoperatively and 6 months after operation. There were 29 males and 9 females. Their averaged age was 61.2 years old. Duration of symptoms averaged 28 months. Twenty-nine patients had obvious trauma. Eighteen patients had a subacromial spur. Based on the intraoperative tear size, patients were classified into 2 groups (S group: partial thickness tear and full thickness tear<3cm, L group: full thickness tear≥3cm). Using the rate of improvement before and after surgery, we compared the results with sex, age, duration after tear, with or without subacromial spur and trauma and tear size. There was a significant difference in abduction power of the shoulder between the trauma group and the non-trauma group. The surgical outcome after a rotator cuff repair in the trauma group was better than that in the non-trauma group.
