Glenohumeral instability

Glenohumeral instability can be defined as pain associated with loss of shoulder function due to excessive translation of the humeral head on the glenoid fossa. It can be classified according to many factors, such as direction, degree, mechanism, and frequency. A thorough understanding of the anatomy and biomechanics of the shoulder joint as they relate to instability is helpful in understanding the pathophysiology of this condition. All components of the instability must be correctly diagnosed so that appropriate treatment can be selected. Clinical examination is most important in making the correct diagnosis, but plain radiographs, arthrography, computed tomography, magnetic resonance imaging, examination under anesthesia, and arthroscopy can be helpful in difficult and challenging cases. Conservative treatment with a rehabilitation program can be successful in a large percentage of cases and should be the initial approach for most patients. Operative treatment is based on the direction and type of instability and is recommended only after an adequate trial of conservative therapy has failed to improve recurrent instability.