Shoulder impingement syndrome influence of shoulder position on rotator cuff impingement - An anatomic study

OBJECTIVE. The purpose of the study was to investigate the relationship of the distal supraspinatus tendon to the coracoacromial arch on radiographs and MR imaging at various shoulder positions. MATERIALS AND METHODS. Radiopaque and gadolinium-impregnated markers were sutured to the distal aspect of the supraspinatus tendon and along the coracoacromial ligament in three cadavers. While varying positions of the shoulder, we obtained gross anatomic visualization, radiographs, and MR images. RESULTS. Impingement of the distal aspect of the supraspinatus tendon between the acromion and the greater tuberosity of the humerus was well visualized during forward flexion and abduction of more than 30 degrees. Shoulder impingement was best seen at 60 degrees forward flexion, 60 degrees abduction, and internal rotation. CONCLUSION. MR imaging of different shoulder positions may help reveal the pathogenesis of shoulder impingement syndrome.