Abstract

A 54-year-old man who had palmoplantar pustulosis showed bilateral, complete osseous fusion of the sternoclavicular and acromioclavicular joints. No significant abnormality was seen in the glenohumeral joint. The left clavicle had a nonunion develop, whereas the right did not. The elevation of the right shoulder was limited to 100 degrees in active and passive measurements. The total external rotation and internal rotation at the side was 135 degrees. This decreased to 90 degrees at 60 degrees elevation and to 10 degrees at maximum (100 degrees) elevation. Based on the kinematic data on normal shoulders, it was thought that the ankylosis of both ends of the clavicle held the scapula unrotated during the arm movement so that, at the arm to trunk angle of 100 degrees, the position of the humerus relative to the scapula was equivalent to that of a normal shoulder in complete elevation. The current case provided an extremely rare clinical setting where shoulder mobility depended only on glenohumeral motion as a result of the complete loss of scapulothoracic motion.