Treatment of osseous defects associated with anterior shoulder instability

Bone loss of the glenoid and/or humerus is a common consequence of traumatic anterior shoulder instability and can be a cause of recurrent instability after a Bankart repair. Accurate characterization of the size and location of osseous defects associated with traumatic instability is important when planning treatment. Open or arthroscopic soft tissue repairs are usually sufficient when less than 25% of the width of the glenoid bone has been lost. Bone replacement techniques may be necessary when glenoid bone loss is greater than 25% of the glenoid width. Glenoid bone restoration techniques include the use of a tricortical iliac crest graft or the transfer of the coracoid process to the area of glenoid deficiency. Bone grafting becomes a strong consideration when soft tissue repairs have failed to restore stability. Treatment of these severe defects may be followed by osteoarthritis. The destabilizing effects of anterior glenoid bone defects are compounded by concurrent defects of the posterior-lateral humeral head, commonly known as Hill-Sachs lesions, which can engage the glenoid defect. Large humeral head defects can be treated by transhumeral bone grafting techniques or osteoarticular allograft reconstruction. Prosthetic replacement of the proximal humerus is considered for humeral head defects involving more than 40% of the articular surface. Understanding the importance of humeral and glenoid bone deficiencies may help guide the treatment of recurrent anterior glenohumeral instability.