A dislocated shoulder occurs when the ball of your upper arm bone pops out of the cup-shaped socket in your shoulder blade. It’s one of the most frequently dislocated joints in the body, happening at a rate of about 24 per 100,000 people each year in the United States. The result is immediate, intense pain and a shoulder that visibly looks wrong and won’t move.
How the Shoulder Joint Works
Your shoulder is a ball-and-socket joint. The rounded top of the upper arm bone (the humerus) sits inside a shallow socket on the shoulder blade called the glenoid. Unlike the hip, which has a deep socket that holds the leg bone snugly in place, the glenoid is relatively flat. This design gives the shoulder its remarkable range of motion, letting you reach overhead, behind your back, and across your body, but it also makes the joint inherently less stable and more vulnerable to dislocation.
A ring of cartilage and a network of ligaments surround the socket to help keep the ball in place. When enough force is applied in the wrong direction, these soft tissues tear or stretch, and the ball slips out.
Types of Shoulder Dislocation
About 85 to 97 percent of shoulder dislocations are anterior, meaning the arm bone slides forward out of the socket. This typically happens when the arm is forced into a position of extreme rotation and extension, like winding up for a volleyball spike, blocking a fall with an outstretched hand, or getting tackled with the arm away from the body.
Posterior dislocations, where the ball slips backward, account for only 2 to 4 percent of cases. They’re associated with seizures, electrocution, and direct blows to the front of the shoulder. Because they’re uncommon and don’t always produce the dramatic deformity of an anterior dislocation, they can be harder to recognize.
Inferior dislocations, where the arm bone is forced downward, are rare (less than 1 percent). They usually result from a powerful force on an arm that’s already raised overhead, such as during a high-speed motorcycle crash.
What It Feels Like
The most obvious sign is a shoulder that looks visibly deformed or “squared off” instead of rounded. People often describe feeling a pop followed by severe pain. The joint locks up almost immediately, and you won’t be able to move the arm. Muscle spasms around the shoulder kick in quickly, which intensifies the pain and makes it even harder to move.
Some people also notice numbness or tingling running down the outside of the upper arm. This happens because the nerve that runs just below the shoulder joint can get stretched or pinched when the bone shifts out of place. That nerve controls the large muscle on the outside of your shoulder, so weakness in lifting the arm to the side is another warning sign of nerve involvement.
Damage That Often Comes With It
A dislocation is rarely just a bone slipping out of place. The force that displaces the joint almost always damages surrounding structures. Bone bruises or dents on the back of the humeral head occur in 40 to 90 percent of first-time dislocations, and that number approaches 100 percent in people who’ve dislocated more than once. Tears to the cartilage ring around the socket (called Bankart lesions) are present in roughly 74 percent of cases with associated injuries.
Nerve damage is more common than many people realize. Studies using electrical nerve testing find some degree of nerve injury in 40 to 65 percent of dislocations, though many of these are mild stretch injuries that recover on their own. The nerve most frequently affected controls the deltoid muscle at the top of your shoulder, so difficulty lifting your arm to the side or a patch of numbness over the outer shoulder after reduction are signs your doctor will watch for.
How Doctors Put It Back in Place
The priority after a shoulder dislocation is getting the bone back into the socket, a procedure called reduction. This is done in an emergency room, usually after you’ve been given pain medication and a muscle relaxant (or sometimes light sedation) to help the surrounding muscles release their grip.
Several techniques exist, and your doctor will choose one based on the situation. In one common approach, you lie face down on a raised bed with your injured arm hanging straight down while a small weight attached to your wrist provides gentle, steady traction for 15 to 20 minutes until the muscles relax enough for the bone to slide back. In another, the doctor gradually moves your arm into a fully overhead position while applying gentle traction until the ball drops back into the socket. These methods rely on slow, steady force rather than any dramatic yanking.
Before and after reduction, X-rays are taken from multiple angles to confirm the bone is back in position and to check for fractures. If fractures are present or the joint won’t stay in place, surgery may be needed.
Recovery and Rehabilitation Timeline
After the shoulder is back in the socket, you’ll wear a sling to keep the joint still. For the first two weeks, the goal is simply protecting the injured tissues: no reaching, lifting, or rotating the arm. Most people stay in the sling for two to four weeks total, depending on the severity of the injury.
Rehabilitation generally follows three phases. In the first few weeks, the focus is on controlling pain and swelling while allowing the torn ligaments and cartilage to begin healing. Starting around weeks three to five, you’ll begin gentle range-of-motion exercises to prevent the joint from getting stiff. Strengthening exercises for the rotator cuff and the muscles around the shoulder blade begin around week six and may continue through week 12 or beyond, depending on how you’re progressing.
Return to full activity, including contact sports, typically takes three to four months. Rushing the process increases the risk of re-injury, so the timeline should be guided by actual strength and stability rather than a calendar.
Why Age Affects Your Risk of Re-Dislocation
The single biggest predictor of whether your shoulder will dislocate again is how old you were the first time it happened. People under 30 at the time of their first dislocation are roughly 20 times more likely to experience a repeat dislocation compared to older adults. For those under 20, the odds are still about 7 times higher than average. Young people tend to be more active and have more elastic tissues, which means the joint is both more likely to be stressed and less likely to scar into a stable position on its own.
Interestingly, very young children (under 10) have a lower recurrence risk, likely because their injuries tend to involve different mechanisms and their tissues heal differently.
For young, active people with a high recurrence risk, especially athletes in overhead or contact sports, doctors may recommend surgical repair of the torn cartilage and ligaments rather than relying on rehabilitation alone. The goal of surgery is to restore the structural restraints that keep the ball in the socket, reducing the chance of chronic instability that leads to repeated dislocations and progressive joint damage over time.