Specific joints

Shoulder

This is one of the commonest joints affected by dislocation ofwhich the vast majority are anterior dislocations (Fig. 22.18). Posterior dislocations are associated with electrocution and epileptic seizures. Anterior dislocation is particularly associated with violent contact sports injuries (e.g. rugby). It is not uncommon to sustain injuries to the axillary nerve or brachial plexus, although the former may spontaneously recover. In the older age group, glenohumeral joint dislocations are associated with rotator cuff tears and fractures of the greater tuberosity. The pathological lesion in younger age groups is the Bankart lesion and predisposes the shoulder to recurrent dislocation. It is an avulsion or tear of the anterior labrum off the glenoid articular margin with capsular striping off the anterior neck of the glenoid. It may be associated with a small fracture off the anterior rim of the glenoid ('bony Bankart lesion'). Dislocation is associated with early degenerative changes in the joint.

Figure 22.17. Anterior fracture-dislocation of the glenohumeral joint pre (top) and post (bottom) reduction.

Anteroposterior and axillary lateral (especially in the case of possible posterior dislocation) plain radiographs are required as well as specialized views (e.g. Wallace view) if it is impossible to obtain an axillary lateral view due to pain. Associated bony lesions should be looked for and assessed, for example impression fracture of posterior humeral head

Figure 22.18. Anterior dislocation of the glenohumeral joint.

(Hill Sachs lesion) and fracture of anterior glenoid (bony Bankart lesion). Recurrent dislocation should be investigated with MRI and arthroscopic evaluation of the joint.

The patient should be given analgesia, sedation and muscle relaxant (but beware of hypoventilation) and closed reduction attempted with the Hippocrates or Kocher techniques or traction/countertraction. Prompt reduction reduces the risk of neurovascular damage. If unsuccessful, the dislocation should be manipulated under general anaesthesia; open reduction is rarely required unless it is associated with fracture of the surgical neck of humerus. Treatment of recurrent dislocation is by arthroscopic or open anterior soft-tissue stabilization (i.e. repair of Bankart lesion).

Following reduction, the shoulder should be immobilized with a sling and swathe. The duration of immobilization is controversial for anterior (ranging from 0 to 6 weeks), with some arguing that immobilization makes no difference to the recurrence rate.

Dislocation can be anterior (Fig. 22.19), posterior or central, where it is associated with fracture of the acetabular floor. Major trauma is usually involved and care should be taken to note associated injuries to pelvis, vasculature, sciatic nerve and ipsilateral knee. Urgent reduction is required, generally under general anaesthesia (Fig. 22.20). As hip dislocation is often associated with fractures of acetabular wall, prolonged skeletal traction may be required post-reduction or simultaneous open internal fixation to stabilize the joint. This

Figure 22.19. Anterior dislocation of the hip.

allows early mobilization. There is a significant risk of long-term degenerative changes within the joint.

Elbow

This is a relatively uncommon dislocation and is usually posterior. It can be associated with minor trauma. There is the possibility of neural injury: median, ulna and radial. Elbow dislocation requires prompt reduction, which can be performed under sedation. Post-reduction radiographs should be checked for associated fractures of the radial head, capitellum and trochlea with resultant intra-articular base bodies. These may predispose to locking of the joint. Early mobilization of the joint is essential to avoid post-traumatic stiffness and a hinged cast brace to prevent full flexion or extension should be used. Loss of extension is very common following elbow injuries and myositis ossificans (see above) is a not uncommon sequelae.

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