Shoulder disclocation

Anterior (forward)

Anterior dislocations are usually caused by a direct blow to or fall on an outstretched arm. The patient typically appears holding their arm externally rotated and slightly abducted.

Posterior (backward)

Posterior dislocations are occasionally due to electric shock or seizure and may be caused by strength imbalance of the rotator cuff muscles. Patients typically present holding their arm internally rotated and adducted, and exhibiting flattening of the anterior shoulder and a prominent coracoid process.

Inferior (downward)

Inferior dislocation is the least likely form, occurring in less than 1% of all shoulder dislocation cases. This condition is also called luxatio erecta because the arm appears to be permanently held upward or behind the head. It is caused by a hyper abduction of the arm that forces the humeral head against the acromion.