Luxatio erecta, aka inferior shoulder dislocation, is an uncommon form of shoulder dislocation (0.5-2%)
2 Mechanisms: 1) Forceful, direct axial loading of an ABducted arm.
2) Hyperabduction of the arm leads to impingement of the humeral head against the acromion, If forceful enough, this leverage can rupture the capsule and drive the humeral head downward, resulting in an inferior dislocation. This mechanism is more common.
Classic presentation: Arm locked in marked ABduction with the flexed forearm lying above the head.
One may palpate the humeral head against the lateral chest wall
Bony injuries include fractures to surrounding structures such as the coracoid process, acromion, glenoid rim, clavicle, greater tuberosity and humeral head.
Nerve injuries include damage to the brachial plexus/axillary nerve (usually reversed with reduction)
