Shoulder dislocation

What it is

Dislocation of the shoulder comes in three types: anterior, which is the commonest, posterior, and inferior.

Causes and risk

Anterior dislocation follows forceful abduction and external rotation of the arm. Posterior dislocation follows forceful adduction and internal rotation, and a history of an epileptic shock points to it.

How it presents

Both types give severe pain, and the arm itself separates them:

• Anterior: the arm is externally rotated and abducted, with flattening of the contour over the deltoid
• Posterior: the arm is internally rotated and adducted

In an anterior dislocation the movements most likely to be restricted are external rotation and abduction. The nerve to be examined in either type is the axillary nerve; axillary nerve injury shows as loss of sensation at the lower area of the deltoid muscle, loss of abduction 25-90 and loss of external rotation.