Shoulder Dislocation
The glenohumeral joint sacrifices bony stability for range of movement, so it dislocates more often than any other joint, typically anteriorly after a fall onto an abducted, externally rotated arm, putting the axillary nerve at risk.
First principles
Why the shoulder is the most commonly dislocated joint
The glenohumeral joint trades bony congruity for mobility: the glenoid fossa is shallow and covers only a small fraction of the humeral head, with stability relying heavily on the labrum, capsule, ligaments and rotator cuff rather than bony constraint, unlike a deep, inherently stable joint such as the hip. This inherent instability, combined with the huge range of movement the shoulder is asked to perform, is why it dislocates far more often than any other major joint.
Educational content pending clinical review. Not medical advice.