Shoulder instability occurs when the arm’s ball joint moves in and out of the shoulder socket joint. Chronically unstable shoulders can lead to loose shoulder joints that slip out of place repeatedly.

The shoulder is the most flexible joint in the body, but it can often become unstable. Repeated dislocations can damage the ligaments and tendons supporting the joint, making the joint more prone to looseness and slipping. Shoulder instability is relatively rare and is typically more common in younger and more active individuals.

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Three connected bones make up the shoulder joint:

  • The collarbone connects the shoulder to the body.
  • The ball-shaped top of the upper arm fits into the glenoid.
  • The glenoid is the socket of the shoulder.

Shoulder joint dislocation affects the glenohumeral joint. The ball at the top of the arm connects to the socket joint of the shoulder here. The shapes of these bones support flexibility in the shoulder, but this can also mean that the glenohumeral joint loses stability.

Shoulder instability can present in several forms and may occur for a range of reasons.

Dislocation and subluxation

Shoulder dislocation can occur when the arm’s ball joint slips out of the socket joint, often due to trauma from sports injuries, falls, or motor accidents. Sometimes, this involves a complete dislocation that causes the bone to separate from the tendons or ligaments completely. Dislocations show obvious physical changes, cause pain and swelling, and require immediate medical treatment.

Other dislocations are partial, known as subluxations, meaning they are less obvious. They may cause pain but can slip back into the socket without assistance. The joint can remain unstable and may cause more partial dislocations in the future. According to a 2023 review, around 85% of shoulder instability events are subluxation episodes.

If a joint remains unstable due to dislocation, there is a high risk of future dislocations. One 2017 study reported that 85–92% of young people with a dislocated shoulder go on to experience another dislocation in the shoulder.

Labral tear

The labrum is an area of tissue that covers the rim of the shoulder joint. It makes the joint 50% deeper, helping the ball of the arm fit better. Several ligaments also attach to the labrum. If the labrum tears, it can make the joint less stable.

Several types of labral tears can affect the joint:

  • A superior labrum, anterior to posterior tear: This often affects the top of the socket. It can also include the start of the tendon connecting the bicep to the labrum.
  • A Bankart lesion: This is a tear at the bottom and front of the labrum that usually occurs due to an anterior shoulder dislocation. This type of dislocation causes the arm to slip forward out of the shoulder socket.
  • A posterior labral tear: This refers to a tear at the back of the socket. It occurs due to trauma or wear and tear on the joint over time.

Genetic hyperlaxity

Joint hyperlaxity or hypermobility refers to joints with an atypically larger range of motion. It does not always cause health problems. Some people, such as gymnasts or ballet dancers, benefit from the improved flexibility hypermobility can provide.

However, others with hyperlaxity can experience pain, clicking, and dislocation in their joints, as well as recurrent injuries. Hyperlaxity can be present from birth or develop due to repeated traumas or instability events in the joints.

In people who have shoulder instability due to hyperlaxity, the shoulder may move out of the socket to the front, back, or bottom of the joint.

Looseness and dislocations are the main symptoms of shoulder instability. This might involve the following symptoms in the shoulders and arms:

  • repeated complete or partial dislocations
  • a sense of the shoulder giving out
  • looseness
  • arms that keep slipping in and out of the socket
  • arms that seem to “hang” in place
  • pain, often due to shoulder injury

A doctor will discuss a person’s medical history and physical symptoms. They will also carry out examinations that test general ligament looseness, such as touching the underside of the forearm with the thumb. This may help them check for hyperlaxity.

They may request X-ray and MRI scans to check for ligament, tendon, or bone damage.

A physician will first recommend nonsurgical treatment to see how shoulder instability responds. If a person experiences repeated dislocations, surgery may be necessary to repair the soft tissue around the joint. This can provide more stability over time.

Nonsurgical treatment

These treatment options might include:

  • Changes to activities: Changes to daily activities can help protect the shoulder from injury. This could include avoiding activities or exercises that involve lifting the arms above the head. A person might need to avoid contact sports for around 3 months after an instability-related injury such as dislocation.
  • Nonsteroidal anti-inflammatory drugs (NSAIDs): Medications such as NSAIDs may help reduce the pain and swelling of shoulder instability. Options include ibuprofen, aspirin, and naproxen.
  • Physical therapy: Exercises to improve shoulder strength and control may help support stability. A physical therapist can guide an individual through bespoke courses and provide home exercises to help recovery.

Several months of nonsurgical treatment may be necessary to start seeing results.

Surgical treatment

Depending on the extent of tissue damage and which ligaments or tendons have sustained damage, two types of procedures can help address severe shoulder instability or repeated dislocations.

This might involve arthroscopy, a procedure in which a surgeon uses a tiny camera to look inside the shoulder and repairs tissues with extremely thin instruments. People can leave the clinic or hospital on the same day they undergo surgery.

More intensive open surgery may be necessary for more severe damage or instability. The surgeon may make a wider cut and observe the surgery directly.

After surgery, the doctor stops the joint from moving by requesting that the affected arm stay in a sling. They may combine this with an ice pack to relieve pain for around 1–2 weeks before the sling can come off.

The individual will then undergo a rehabilitation program to restore the unstable arm to a range of motion and strength similar to the other arm. This usually includes several joint-strengthening exercises that gradually get harder as stability returns.

The recovery time depends on both the injury and how many times the injury has occurred.

A first-time instability event, such as a dislocation, may fully recover in 3–6 months if the surrounding tendons and ligaments have not sustained damage.

People with physically demanding jobs may not be able to return to work for 2–4 weeks. Doctors usually recommend avoiding heavy lifting and contact sports involving the shoulders for between 6 weeks and 3 months.

Shoulder instability refers to shoulder joints that have a high risk of slipping out of place. It can occur as dislocation, subluxation, laxity, or a labral tear. It is most common in highly active people. Certain activities, such as playing contact sports, also increase the risk. However, some individuals are born with more flexible, less stable shoulder joints.

Treatment may involve lifestyle modifications or pain relief medications. If these do not have an effect after 3 months, a doctor may recommend arthroscopy or open surgery to make the joint more stable. Rehabilitation with a sling and physical therapy can support recovery. Full healing can take 6 months or longer, depending on the instability event.