Effect of displacement of fractures of the greater tuberosity on the mechanics of the shoulder

Using a dynamic biomechanical model of malunion of the shoulder, we have determined the change in deltoid force required for abduction with various combinations of superior and posterior displacement of fractures of the greater tuberosity of the humerus. We tested eight fresh human cadaver shoulders in a dynamic shoulder-testing apparatus during cycles of glenohumeral abduction from 0 degrees to 90 degrees. The greater tuberosities were...