Analysis of the scapulo-humeral rhythm for periarthritis scapulohumeralis

To clarify the scapulo-humeral rhythm in twenty-five patients with periarthritis scapulo-humeralis, the movements of the scapula and the humerus during arm elevation were measured and analysed using a fluoroscope and a computer, and the rhythm of five patient with rotator cuff tear was compared with that of seven normal subjects. The ratio of scapular movement to humeral one in the patients with severe shoulder contracture due to periarthritis scapulohumeralis was greater than that of patients with mild contracture and that of normal subjects. In the patients with rotator cuff tear, wider range of scapular rotation was observed in the early phase of the motion. During the early phase of arm elevation, the humeral head moved to the upper direction by means of gliding in the patients with severely contracted shoulder and rotator cuff tear, and in the patients with mildly contracted shoulder the humeral head moved to the upper direction by means of ball rolling. In the normal subjects no such upward movement of the humeral head was observed. We believe that the restriction of the glenohumeral joint motion and dysfunction of the rotator cuff, which were caused by periarthritis scapulohumeralis, may break down the scapulohumeral rhythm.