We reported the method of the accurate 3D kinematics of the normal shoulder which includes the sternoclavicular (SC) joint. We also thought this method can be applied clinically. The subjects of this study were 3 patients of clavicular non-union. Computer tomographies of the shoulder (including sternum, clavicle, scapula and humeral) were obtained in the neutral position and head touching position. 3D models of each bone were created from CTs and the movement of each bone was calculated by Volume Merge (custom computer program). The movements of the bone were seen by the Euler angle, which used 3 rotational parameters and 3 quantities of movement. We measured the rotation and quantity of movement of each bone from the neutral to head touching positions. We calculated the SC joint movement as the difference of movement of the clavicle from the sternum, AC joint movement as the difference of the scapula from the clavicle. In X axis rotation, cases 2 and 3 were similar to normal pattern and the rotation in clavicular non-union was little. But in case 1, the rotation in clavicular non-union was large and the SC and AC joint rotation were less than normal. The X axis rotation was similar to the clavicle posterior rotation. In case 1, clavicular non-union rotated instead of the SC and AC joint. This method can be useful to clinically.
