Your shoulder is one of the most mobile joints in your body. It lets you reach over your head, out to the side, and behind you. The shoulder joint is where the upper arm (proximal humerus or humeral head) connects to the shoulder blade (scapula). The part of the scapula that touches the humeral head is called the glenoid. Muscles that surround the shoulder include the rotator cuff muscles, deltoid muscle, pectorals muscle, and several strong muscles from your back. The arteries and nerves that supply the arm come out from under the collar bone (clavicle) and then go down the arm in front of the shoulder and on the inside of the arm.
Mechanism and Epidemiology
Because the shoulder is so mobile, it is one of the easiest joints to dislocate, or "pop out of the socket." Most shoulder dislocations are the result of a twisting movement, forceful pulling of the arm, or from a fall or direct blow to the shoulder.
The shoulder joint has many ligaments (which connect bone to bone) and tendons (which connect muscles to bone). When the joint is dislocated, these ligaments and tendons can be torn. In some cases, parts of the humeral head or glenoid can be broken. The most common fractures seen with a shoulder dislocation are fractures of the humeral head, the greater tuberosity, or fractures of the edge of the glenoid.
When your shoulder is dislocated, it is usually painful and very hard to move the arm. Your arm might feel weak or numb. Shoulder dislocations should be put back in the socket (reduced). Usually, this is done in an emergency room after you have been given pain medication and light sedation. After your joint is back in place, an x-ray will be taken to see if there are any broken bones.
After your shoulder is back in place, you can usually return home and don’t have to stay overnight in the hospital. You will most likely be given a sling and asked to not use your arm or lift anything until you have an appointment with an orthopaedic surgeon.
The red arrows show areas of interest – in each picture the right arrow illustrates the humeral head. This needs to be within the cup of the glenoid (Right image) in order to be reduced. Usually more than one radiograph is needed to make sure it is reduced. The left arrows both show t e fracture of the greater tuberosity. Reduction of the shoulder has also reduced the tuberosity into the correct spot (right image).
Shoulder dislocations can often be managed without surgery using a sling. In general, you will need to work with a physical therapist to slowly get your shoulder moving again and to strengthen the muscles around your shoulder. Your surgeon will tell you when you can come out of the sling and you are able to use your shoulder and arm again. You may be instructed to move your elbow and wrist several times a day so they do not become stiff.
If a part of your shoulder fractured when it dislocated, you may need surgery. The type of surgery needed depends on the type of injury. The operation can sometimes be done arthroscopically (with small cuts), or may require a larger cut with plates, screws, and sutures.
If surgery is needed, you will likely need to keep your arm in a sling for a time. You will also need to avoid lifting heavy objects. Similar to non-operative treatment, a physical therapist will work with you to slowly increase your motion and strength over time. As your bone and tissues heal, it will become easier to move your shoulder and use your arm. It is important to listen to the specific instructions of your surgeon, as therapy may vary depending on what type of surgery you received.
Long-term effects after a shoulder dislocation can include stiffness, weakness, and (less commonly) lingering discomfort or pain. Sometimes people have numbness over the outside of their shoulder. This may be permanent. You may not be able to move your shoulder as freely as you could before the injury. If you have surgery, rare complications can include infection or lack of healing, which may require further surgery.
If your shoulder dislocated and you did not have any other shoulder injuries, it may take 4 to 6 weeks before your motion and strength improve. If you have other injuries, such as damage to the tendons, ligaments, or fractures of bones, recovery may take much longer—even up to 6 months.
Occasionally, a shoulder may dislocate again. If that happens to you, your surgeon will discuss your options.
- American Academy of Orthopaedic Surgeons - Shoulder Trauma (Fractures and Dislocations)
- American Academy of Orthopaedic Surgeons - Dislocated Shoulder
Sara Putnam, MD
Edited by the OTA Patient Education Committee
X-rays and images from the personal collection of Dr Putnam and Dr Chris Domes