Analysis of Three Dimensional Motion of the Scapula for Rotator Cuff Tears

Three dimensional motion of the scapula during arm elevation in the scapular plane was measured and analyzed in patients with rotator cuff tears using a fluoroscope. Patients were asked to elevate both arms to a maximum abduction position in the scapular plane slowly from a resting position over a time span of ten seconds. During this movement several recordings were taken and then analyzed in a micro-computer. There was a great deal of variation in the elevation angle of the arm with rotator cuff tears. However, there were no significant differences in the upward rotation angles, both in the resting position and in the maximum elevated position between the affected side and contralateral side. Downward tilting angle in the maximum elevated position of the affected side was significantly greater than that of the normal side.The present study suggests that rotation of the scapula is not only maintained by the rotator cuff muscles but other shoulder girdle muscles are also responsible.