抄録
We wish to report on the analysis of arm rotation during abduction of the shoulder.7 normal male's right shoulders were chosen for this study. Their arms were put in braces from their shoulder to their wrist joint in order to keep their elbow in an extended position. An equilateral triangular shaped lead with sides 40mm in length was fixed to the proximal end of these braces with the triangular base parallel to the longitudinal axis of the braces and perpendicular to the horizontal axis of the braces. All the examinations were performed in a sitting position. The subjects were asked to elevate both their arms in the scapular plane and the resting position was considered as the starting point. Right scapulo-humeral rhythms were recorded continuously with an image intensifier, video recorder and computer. The upward rotation angles of the arm at every 10-15 abducted position were calculated with the three edges of the triangle described above. There were individual variations of arm rotations, as well as of the change of rotation in the starting phase. However, after 40 degrees of elevation, the rotation was smooth and increased to 1.0 degrees for each 10 degrees of abduction in 4 subjects and decreased to 1.2 degrees for each 10 degrees of abduction in 3 subjects. From this study, we can easily suggest that an analysis of the arm rotation is useful for patients with a disturbance of the scapulohumeral rhythm.
