Shoulder subluxation, a subset of shoulder instability, occurs when the shoulder joint partially dislocates. In this condition the humeral head slips out of the glenoid cavity as a result of weakness of rotator cuff or looseness of the glenohumeral ligaments.
Traumatic cause: more frequent in active young individuals. Prevalent in for example: boxers, non-contact sport with repetitive shoulder movements, a hand in the outstretched position.
Non-traumatic cause: multifactorial. For example: patients may have suboptimal shoulder muscle control or tendon/ligament injury in the rotator cuff interval.
Neuromuscular causes: stroke, cerebral palsy, and brachial plexus injury.