A dislocated shoulder is an injury in which the upper arm bone pops out of the cup-shaped socket that's part of the shoulder blade. The shoulder is the body's most flexible joint, which makes it more likely to dislocate.

If you suspect a dislocated shoulder, seek prompt medical attention. Most people regain full use of their shoulder within a few weeks. However, once a shoulder dislocates, the joint might be prone to repeat dislocations.

The shoulder joint is the most frequently dislocated joint of the body. Because it moves in several directions, the shoulder can dislocate forward, backward or downward. It might dislocate completely or partially.

Most dislocations occur through the front of the shoulder. The ligaments — tissue that joins the bones — of the shoulder can be stretched or torn, often making the dislocation worse.

It takes a strong force, such as a sudden blow to the shoulder, to pull the bones out of place. Extreme twisting of the shoulder joint can pop the ball of the upper arm bone out of the shoulder socket. In a partial dislocation, the upper arm bone is partially in and partially out of the shoulder socket.

Causes of a dislocated shoulder include:

• Sports injuries. Shoulder dislocation is a common injury in contact sports, such as football and hockey. It's also common in sports that might involve falls, such as downhill skiing, gymnastics and volleyball.
• Trauma not related to sports. A hard blow to the shoulder during a motor vehicle accident can cause dislocation.
• Falls. Landing awkwardly after a fall, such as from a ladder or from tripping on a loose rug, can dislocate a shoulder.

Anyone can dislocate a shoulder. However, dislocated shoulders occur most often in people in their teens and 20s, particularly athletes involved in contact sports.

Complications of a dislocated shoulder might include:

• Tearing of the muscles, ligaments and tendons that reinforce the shoulder joint
• Nerve or blood vessel damage in or around the shoulder joint
• Becoming more prone to repeat dislocations, especially if the injury is severe

Stretched or torn ligaments or tendons in the shoulder or damaged nerves or blood vessels around the shoulder might require surgery for repair.

To help prevent a dislocated shoulder:

• Take care to avoid falls and other shoulder injuries
• Wear protective gear when playing contact sports
• Exercise regularly to maintain strength and flexibility in joints and muscles

Having a dislocated shoulder joint can increase the risk of future shoulder dislocations. To help avoid a recurrence, keep doing the strength and stability exercises prescribed for the injury.

A health care provider inspects the affected area for tenderness, swelling or deformity and checks for signs of nerve or blood vessel injury. An X-ray of the shoulder joint can show the dislocation and possibly reveal broken bones or other damage to the shoulder joint.

Dislocated shoulder treatment might involve:

• Closed reduction. In this procedure, some gentle maneuvers might help move the shoulder bones back into position. Depending on the amount of pain and swelling, a muscle relaxant or sedative or, rarely, a general anesthetic might be given before moving the shoulder bones. When the shoulder bones are back in place, severe pain should improve almost immediately.
• Surgery. Surgery might help those with weak shoulder joints or ligaments who have repeated shoulder dislocations despite strengthening and rehabilitation. In rare cases, damaged nerves or blood vessels might require surgery. Surgical treatment might also reduce the risk of re-injury in young athletes.
• Immobilization. After closed reduction, wearing a special splint or sling for a few weeks can keep the shoulder from moving while it heals.
• Medication. A pain reliever or a muscle relaxant might provide comfort while the shoulder heals.
• Rehabilitation. When the splint or sling is no longer needed, a rehabilitation program can help restore range of motion, strength and stability to the shoulder joint.

A fairly simple shoulder dislocation without major nerve or tissue damage likely will improve over a few weeks. Having full range of motion without pain and regained strength are necessary before returning to regular activities. Resuming activity too soon after shoulder dislocation may cause re-injury of the shoulder joint.

Try these steps to help ease discomfort and encourage healing after being treated for a dislocated shoulder:

• Rest the shoulder. Don't repeat the specific action that caused the shoulder to dislocate. Try to avoid painful movements. Limit heavy lifting or overhead activity until the shoulder feels better.
• Apply ice then heat. Putting ice on the shoulder helps reduce inflammation and pain. Use a cold pack, a bag of frozen vegetables or a towel filled with ice cubes for 15 to 20 minutes at a time. Do this every couple of hours the first day or two.
• Take pain relievers. Medications such as aspirin, ibuprofen (Advil, Motrin IB, others), naproxen sodium (Aleve) or acetaminophen (Tylenol, others) might help relieve pain. Follow label directions and stop taking the drugs when the pain improves.
• Maintain the range of motion of the shoulder. After one or two days, your health care provider might have you do some gentle exercises to help maintain the shoulder's range of motion. Being inactive can cause joints to stiffen.

Once the injury heals and the shoulder has good range of motion, keep exercising. Daily shoulder stretches and a shoulder-strengthening and stability program might help prevent another dislocation. Your health care provider can help plan an appropriate exercise routine.

Depending on the severity of the injury, your primary care provider or the emergency room doctor might recommend that an orthopedic surgeon examine the injury.

What you can do

You may want to be ready with:

• Detailed descriptions of the symptoms and the cause of the injury
• Information about past medical problems
• The names and doses of all medications and dietary supplements you take
• Questions to ask the provider

For a dislocated shoulder, some basic questions might include:

• Is my shoulder dislocated?
• What tests do I need?
• What treatment approach do you recommend? Are there alternatives?
• How long will it take my shoulder to heal?
• Will I have to stop playing sports? For how long?
• How can I protect myself from re-injuring my shoulder?

What to expect from your doctor

Be prepared to answer questions, such as:

• How severe is your pain?
• What other symptoms do you have?
• Can you move your arm?
• Is your arm numb or tingling?
• Have you dislocated your shoulder before?
• What, if anything, seems to improve your symptoms?
• What, if anything, appears to worsen your symptoms?