[CT diagnosis in instability of the shoulder joint]

CT is able to demonstrate the predisposing factors for recurrent and posttraumatic subluxation of the shoulder. In addition to demonstrating bony changes in the glenoid (Bankart lesion) and in the humeral head (Hill-Sachs lesion), CT can measure the degree of retroversion of the glenoid and torsion of the humerus. Measurements on 17 shoulders with habitual and 24 shoulders with recurrent posttraumatic subluxation showed low values for glenoid retroversion as compared with a control group. Particularly patients with habitual anterior subluxation frequently showed anteversion of the glenoid. Measurements of humeral torsion showed wide scatter amongst all groups, indicating wide biological variability. The results were compared with those published in the literature and the indications and limitations of CT for the investigation of shoulder instability are discussed.