A shoulder dislocation is where the bones of the main shoulder joint (where the upper arm bone connects to the shoulder blade) are forced out of their normal positions.
Partial dislocation is when the head of the upper arm bone partially in and partially out of the shoulder socket.
The main shoulder joint is a ball and socket joint. The socket that the ball of the upper arm (humerus) sits on is small and very shallow. This allows a large range of motion – the largest range of motion of any joint in the body. Because of its structure, the shoulder is dislocated more often than any other joint.
The shoulder may dislocate after a fall or forceful blow to the shoulder. The ligaments and/or tendons that hold the joint together may be stretched or torn when the shoulder dislocates.
A shoulder dislocation may cause sudden, intense pain. There is visible deformity of the joint. In the vast majority of shoulder dislocations, the head of the humerus ends up in front of the shoulder blade. There may be numbness or tingling radiating down the arm, an inability to move the arm, bruising or swelling.
Immediate medical attention is required. Apply ice immediately to reduce swelling and pain. Place the shoulder in a sling. The shoulder joint should be kept still (moving it will probably be impossible anyways) to avoid further damage to the surrounding tissue, nerves, and blood vessels.
X-rays will show the dislocation and any fractured bones. A physician first will try manipulating the shoulder bones to put them back in place (called a reduction). If this is too painful, a local or general anesthetic may be administered first.
Other diagnostic testing may be ordered to determine the extent of soft tissue damage or nerve damage. If ligaments are severely torn, surgery may be required.
For the first couple of days, applying ice for 20 minutes at a time every couple of hours will help limit pain and swelling.
In some cases, a sling may have to be worn for several weeks. The amount of time the arm is in a sling is usually gradually reduced. As muscles will atrophy from disuse, an exercise program will be necessary to regain strength and mobility in the shoulder once the sling is no longer worn. Total rest of the shoulder can result in frozen shoulder. Gentle stretching exercises help prevent frozen shoulder from occurring. Stretching exercises are started earlier than strengthening exercise. A physician or physical therapist can determine when the shoulder is ready for exercises.
If the ligaments heal too loosely, the shoulder joint may be unstable and more likely to dislocate again. An exercise program can help strengthen and stabilize the shoulder to help prevent another dislocation. In some cases, surgery may be needed to tighten loose ligaments.
It usually takes several weeks to regain normal function of the shoulder after a shoulder dislocation.