2000 Volume 24 Issue 3 Pages 371-375
A rotator interval lesion is caused by the excessive tension between rotator cuff tendons in a throwing motion. The tension of the sutures used to repair the rotator intervals was intraoperatively measured while the upper arms were moved. The pathomechanism was studied from the results and analysis of a throwing motion.
Subjests and methods: The tension of the sutures was measured in five patients with rotator interval lesion. A digital force gauge DPX-T (IMADA co. ) was used for the measurement.. A 1-0 monofilament nylon suture was connected to the device and the tension was measured. The change of the tension was measured and recorded while performing a throwing-like motion. The motion analyser (Peak co. ) and two analog videos were used for the motion analysis of six professional pitchers in Osaka. The angle and velocity were calculated by manual tracking of the frames (60 frames/sec).
Results: The rotational center of the trunk was the shoulder of a nonthrowing side. The arm was abducted and remained in this position during the arm cocking, acceleration, and deceleration phases. The major feature of the throwing motion was the quick and wide internal and external rotation of the arm. The tension of the sutures increased from an internal rotated position to a external rotated pos ition. We suggest that the rotator interval lesion was accelerated by arm cocking motion.
