Luxation means dislocation of a joint. At the shoulder, the humerus head jumps out of the socket (glenoid = shoulder socket).
Most dislocations happen in accidents. However, they can also occur in people who have very flexible joint ligaments (joint hypermobility) even if not much force is applied. The younger the patient is, the greater the risk that a shoulder dislocation occurs a second or third time. This is then referred to as recurrent dislocation or shoulder instability.