The shoulder joint is like a ball and a cup. With a shoulder dislocation, the ball comes out of the socket. For this to occur, the ligaments and capsule stabilizing the shoulder must tear or stretch. The labrum is a thin rim of tissue surrounding the edge of the shoulder socket. When the labrum tears, this is called a 'Bankart lesion'.
Most shoulder dislocations are due to a traumatic injury, such as a fall.
A loose, or unstable shoulder that is not dislocated may cause feelings of not being able to 'trust' the shoulder. This is especially true when the arm is overhead and out to the side. There may be a sense of 'catching' in the shoulder, followed by vague aching. A positive 'apprehension' test, or being able to recreate the feeling that the shoulder is about to 'come out of the socket'. Workup The diagnosis is primarily based on history and physical examination.