A shoulder subluxation refers to a partial dislocation of the shoulder joint. This occurs when the ball of the upper arm bone, called the humerus, partly comes out of the glenoid socket in the shoulder.
In a complete dislocation, the humerus is knocked totally out of the socket.
The shoulder is the most mobile joint in the body. It contains a number of bones, ligaments, and muscles that work together to keep it stable. Because the shoulder is so mobile, it is very susceptible to dislocation.
A shoulder subluxation is often the result of trauma, injury, or a stroke that weakens the arm muscles.
In this article, we discuss the symptoms and treatments of a shoulder subluxation. We also describe the recovery process and exercises that can help.
A subluxation can be more difficult to identify than a complete dislocation. However, in some cases, the partially dislocated humerus is visible under the skin.
A person may be able to feel the ball of the humerus moving in and out of the shoulder socket, which is usually uncomfortable and can be painful.
Symptoms of a shoulder subluxation can include:
- a visibly deformed or out-of-place shoulder
- numbness or tingling, also called paresthesia, along the arm
- trouble moving the joint
Also, a person may also notice a clicking or catching sensation in the shoulder while performing daily activities, especially those that involve reaching overhead.
Because the shoulder moves in several directions, it can dislocate forward, backward, or downward. This is also true for subluxations.
When a dislocation is partial, the shoulder capsule can be stretched or torn, which may complicate the dislocation.
Typically, only a forceful blow or fall can cause the humerus to pop out of place. Extreme rotation can also pull the arm from its socket.
Once a shoulder is dislocated, the joint can become unstable and prone to future dislocations or subluxations.
A shoulder subluxation is often caused by:
- Trauma. Subluxation can result from accidents or injuries that damage the shoulder's joint or other structures that provide stability. Common examples include falls and motor vehicle accidents.
- A sports injury. Contact sports, including hockey and football, often cause shoulder subluxations, as do sports that involve falling, such as skiing and gymnastics.
- A stroke. Strokes often cause muscle weakness, which can lead to destabilization of the shoulder joint, followed by a subluxation. One review found that 80 percent of participants who had experienced a stroke also had a shoulder subluxation.
Younger men and other highly physically active groups have the greatest risk of a subluxation.
Treatment aims to reposition the humerus back into the socket and ensure that it stays in place.
A doctor can diagnose a shoulder subluxation using an ultrasound. A correct diagnosis is key in determining the best course of treatment.
Treatment can include the following:
- Closed reduction. This involves a doctor attempting to gently maneuver the bone back into position. When this is achieved, severe pain should improve almost immediately.
- Surgery. This may be recommended when dislocations recur. It may also be the preferred treatment when nerves, blood vessels, or ligaments in the shoulder have been damaged.
- Shoulder brace. A person may need to wear a splint, brace, or sling for a few days or weeks to prevent the shoulder from moving. The length of time will depend on the extent of the dislocation.
- Medication. This may involve a muscle relaxant and an anti-inflammatory agent, such as ibuprofen, for pain and swelling.
- Rehabilitation. Following surgery or time spent in a sling, a doctor may recommend a rehabilitation program. The goal is to restore the range of motion, strength, and stability of the shoulder joint.
The strengthening exercises below may help to increase the stability of the shoulder joint. However, a physical therapist can prescribe a home exercise regimen tailored to each person's needs.
The following exercises may help to increase shoulder stability:
- Shoulder flexors. Stand facing a wall with the arms hanging loose. Raise the forearm and bend the elbows at a 90-degree angle. Make a fist with the palm facing the floor, and gently try to push the fist into the wall.
- Shoulder extensors. Stand with the back to a wall and the arms hanging loose. Raise the forearms with the elbows bent at a 90-degree angle. Attempt to press the back of the elbows into the wall.
- Shoulder abductors. Stand with the injured side against a wall. Raise the arm, with the elbow bent, and attempt to move the entire arm sideways, into the wall.
Speak with a physical therapist or doctor before attempting any exercises at home. Appropriate exercises vary, depending on the injury. Certain exercises can make some people's symptoms worse.
Beyond exercises, a physical therapist may recommend the following:
- therapeutic massage
- avoiding certain movements or activities
- joint mobilization
When an injured person has a subluxation with no major nerve or tissue damage, the shoulder joint should improve quickly. However, if a person becomes active too soon, they are likely to experience a future dislocation.
Following surgery for a dislocated shoulder, a doctor will often recommend that a person wears a sling for several weeks. Gradually introducing physical therapy can help an individual to regain strength and range of motion. It is best to avoid intense movements of the shoulder to prevent complications.
The shoulder contains strong connective tissue, muscles, and ligaments that work to keep the humerus centered in its socket. These structures can become overstretched or injured, which may complicate a subluxation or dislocation.
Some complications of a shoulder subluxation include:
- damage to blood vessels and nerves in the shoulder
- other shoulder injuries, such as ligament or muscle tears
- a loss of movement and flexibility
- shoulder instability resulting in recurring subluxations
A shoulder subluxation shares some symptoms with similar injuries. Misdiagnosis is common.
A subluxation may be mistaken for the following:
This refers to inflammation of the biceps tendon. Due to the position of the tendon, biceps tendinopathy is a common cause of shoulder pain.
Fracture or injury to the clavicle, commonly called the collarbone, may lead to pain in the shoulder and trouble moving the joint.
Rotator cuff injury
Injuries to the rotator cuff tendon are often responsible for shoulder pain in people of all ages. Minor injuries may heal on their own, while severe injuries tend to require surgery.
A dislocation involves a complete separation of the upper arm bone from the shoulder socket. Symptoms are similar to those of a subluxation, and only a medical professional may be able to distinguish the two.
Shoulder pain in competitive swimmers is often called swimmer's shoulder. Because swimming requires a high level of shoulder flexibility and range of motion, swimmers are often likely to have hypermobility of the joint and an increased risk of injury.
When a person seeks medical attention promptly and receives a correct diagnosis, a shoulder subluxation is treatable.
When no surgery is recommended, several months may pass before a person can tell how well the treatment is working.
Recovery time varies, depending on the extent of the subluxation and whether or not a person has undergone surgery.
In the aftermath of a subluxation, a person should avoid strenuous activity, to prevent a recurrence.