Injury/Instability

Sometimes the bones in one of the shoulder joints move (or, in an injury, are forced) out of their normal position. This condition, instability, can result in dislocation of one of the joints in the shoulder. Recurring dislocations, which may be partial or complete, cause pain and unsteadiness when you raise your arm or move it away from your body. When you lift your arm over your head, the shoulder may feel as if it is slipping out of place or an uncomfortable, unusual feeling that some people refer to as having a "dead" arm.