Glenohumeral dislocations may be either anterior or posterior. Anterior dislocations (90%) result from a direct posterior blow or abduction and external rotation of the shoulder. Posterior dislocations (10%) result from seizures, direct anterior force, or adduction and axial loading of the arm.

A concavity at the glenoid fossa is noted. The patient is unable to elevate the arm to the head area. A neurovascular examination is done to determine any deficits. Shoulder dislocation may affect the brachial plexus or axillary nerve. Anterior dislocation patients hold the arm in external rotation. With posterior dislocations, the arm is held in internal rotation and adduction.

A true anteroposterior (AP) view and scapula views should be taken. The true AP view should display overlap of the anterior and posterior articular surface of the glenoid. The view should show the humerus head centered on the glenoid.

Conscious sedation is often necessary to reduce a dislocated shoulder. The sooner the shoulder is reduced, the easier it is. Straight traction in line with the humerus with gentle internal and external rotation reduces the dislocation. This reduction method is safe even if a fracture is present. It is necessary to apply countertraction via a sheet wrapped around the chest wall. The shoulder is abducted 30 degrees for the reduction. After a neurovascular examination, immobilization is carried out in a shoulder immobilizer or sling and swathe.

It is standard care to reduce a shoulder dislocation as an emergency even if the patient has just eaten. The longer the shoulder is dislocated, the higher the incidence of avascular necrosis.

Uncomplicated dislocations are immobilized for 3 weeks, beginning isometrics immediately. Patients younger than 18 years of age should be referred to an orthopedist on the first dislocation. This is due to potential growth plate injury and high rate of recurrence.

A vascular compromise is an emergency and should be surgically addressed immediately. Dislocations associated with fractures of the head or diaphysis, or both, should be seen by an orthopedist. Also, dislocations more than a day or two old or a recurrent dislocation should be managed by an orthopedist.

Complications may include stiffness and rotator cuff tears, which may be surgically treated. The axillary nerve may be injured. Signs include loss of light touch over the lateral shoulder, where the skin in a silver dollar-sized area is supplied by sensory branches only from the axillary nerve. Another sign of axillary neuropraxia is inferior subluxation of the shoulder on the AP x-ray after reduction. This is due to the deltoid upward pull on the humerus being absent until the nerve recovers. It almost always recovers.

Fractures of the proximal humerus often result from an impact to the shoulder from a low-energy fall in the elderly or from high-energy trauma in the young. A dislocation may occur concurrently.