[Possibilities of sonography in the diagnosis of instabilities of the shoulder joint].

We present ultrasound investigation as a diagnostic tool for shoulder instability. The following structures are visible in the posterior transversal plane: subcutis, deltoid muscle, infraspinatus muscle, infraspinatus tendon, humeral head, scapula, dorsal glenoid rim, dorsal labrum, and the joint capsule. The relation of the humeral head to the glenoid can be judged statically and dynamically. Anterior and posterior instabilities and secondary signs of dislocation such as Hill-Sachs lesion and effusion can be seen. This technique is easy to learn. By comparing the injured with the normal shoulder the examiner can control his diagnosis. There is no need for positioning the patient in a special way. Sonographic evaluation is non-invasive and inexpensive.