ANTERIOR DISLOCATION OF GLENOHUMERAL JOINT: PATHOLOGIC LESIONS
Commonly seen in traumatic anterior dislocation of the shoulder is a Bankart lesion, which is an avulsion of the anterior inferior glenohumeral ligaments along with the anterior inferior labrum. In most cases of recurrent anterior instability associated with an avulsion of the anterior inferior labrum and glenohumeral ligaments, a Bankart-type procedure is performed in which these tissues are sewn back to the original attachment site along the anterior and inferior rim of the glenoid.
If there is an acute fracture of the glenoid rim associated with a first-time or recurrent dislocation, then open reduction and internal fixation of the fragment can restore both the glenoid fossa surface area and the attached ligaments. If there is bone deficiency that is not associated with a bone fragment that can be reduced and fixed to achieve these surgical goals, then a bone graft procedure is preferred. Several types of bone substitution procedures are available for these types of surgery. The most popular of these bone transfer procedures uses the coracoid process and the associated tendons (short head of the biceps and the coracobrachialis) placed along the anterior inferior glenoid defect and held in place with screw fixation. This procedure (Bristow or Laterjet) provides both restoration of the bone loss of the glenoid and a dynamic stabilization by the sling effect of the transferred tendon and muscle tissue.
All of these types of shoulder stabilization procedures can be done by either open or arthroscopic methods. In addition, there is, in many cases, a variably sized impaction-type fracture in the posterosuperior aspect of the humeral head that is termed a Hill-Sachs lesion. This lesion occurs in anterior dislocation when the softer bone of the humeral head is impacted against the harder bone of the anterior glenoid rim. These lesions may be large and are occasionally treated with placement of a humeral head allograft or small partial head prosthetic replacement into this defect. Hill-Sachs lesions can also be treated by suturing the posterior rotator cuff and capsule tissue into the defect.