Recurrent Dislocation

Why a joint keeps dislocating

Joints are held in place by three things: the shape of the bones, the soft tissues (ligaments, joint capsule and, in the shoulder and hip, a rim of cartilage called the labrum), and the muscles around them. A first dislocation often damages one or more of these:

• Torn labrum or ligaments: in the shoulder, a forward dislocation often tears the front of the labrum off the socket (a Bankart lesion). In the knee, an outward kneecap dislocation tears the medial patellofemoral ligament (MPFL).
• Bone damage: a dent in the back of the ball of the shoulder (Hill-Sachs lesion) or a chip off the front of the socket (bony Bankart). These reduce the bony "fit" and make further dislocations easier.
• Stretched capsule: the joint lining becomes loose.

Each new dislocation can enlarge these injuries, so the joint becomes progressively less stable.

Risk factors

• Young age at first dislocation: the most important factor. Studies have found that a large majority of people under about 20 who dislocate a shoulder will dislocate again if treated without surgery. The risk falls sharply after age 30 to 40.
• Male sex and contact or collision sports such as football, rugby, hockey and wrestling
• Overhead sports: volleyball, swimming, throwing, climbing
• Bone loss in the shoulder socket or ball on imaging
• Generalized joint laxity: hypermobility spectrum disorders or Ehlers-Danlos syndrome
• For the kneecap: a shallow groove at the end of the thighbone (trochlear dysplasia), a high-riding kneecap (patella alta), knock knees, and a kneecap that sits off to the side

People over 40 have fewer recurrences after a shoulder dislocation but are more likely to have torn the rotator cuff, which can cause weakness and needs its own assessment.

Recurrent shoulder dislocation

The shoulder is the most commonly dislocated large joint, because the shallow socket allows wide movement. About 95% of dislocations are anterior, where the ball slips forward and down, usually when the arm is raised and rotated outward (like throwing or blocking a tackle).

Symptoms of recurrent shoulder instability include:

• the shoulder slipping out with less and less force, sometimes during sleep or reaching
• partial slips (subluxations) with a "dead arm" feeling
• apprehension: fear or muscle guarding when the arm is placed in the throwing position
• aching and weakness between episodes

See dislocated shoulder for first-time dislocations and their immediate care.

Recurrent kneecap dislocation

The kneecap usually dislocates outward when twisting on a bent knee, for example in netball, soccer, basketball or dance. It is most common in teenagers, especially girls. After a first dislocation, a substantial minority have further episodes, with the risk higher in young people with anatomical risk factors.

Symptoms include the knee giving way, a feeling of the kneecap shifting, pain at the front of the knee and swelling. Cartilage chips knocked off during dislocation can float in the joint and cause locking. See patellar instability for more detail.

Other joints

Recurrent dislocation of the elbow, ankle tendons, finger joints, jaw and hip occurs less often. Repeated dislocation in several joints, or dislocations with minimal force, suggest an underlying connective tissue condition.

Diagnosis

• History: how the first dislocation happened, how many times since, how much force it takes, sports and work demands.
• Examination: range of motion, strength, apprehension and relocation tests for the shoulder, kneecap tracking and apprehension for the knee, nerve checks, and the Beighton score for general joint looseness.
• X-rays: confirm the joint is in place and show fractures, bone loss and kneecap position.
• MRI or MR arthrogram: shows labral tears, ligament injuries, cartilage damage and rotator cuff tears.
• CT scan: measures bone loss from the shoulder socket or ball, which guides the choice of surgery.

Treatment

Non-surgical treatment

• Physical therapy: strengthens the muscles that hold the joint in place (rotator cuff and shoulder blade muscles for the shoulder; quadriceps and hip muscles for the knee) and retrains movement control. It works best for people with looseness rather than a large structural tear, and for those with lower activity demands.
• Activity changes to avoid high-risk positions.
• Braces and taping, particularly for the kneecap and for finishing a sports season.

Surgery

Surgery is usually recommended after two or more dislocations, after a first dislocation in young athletes in high-risk sports, or when there is significant bone loss.

Shoulder:

• Arthroscopic Bankart repair: keyhole surgery to reattach the torn labrum and tighten the capsule with small anchors. A "remplissage" procedure may be added to fill a Hill-Sachs dent.
• Latarjet procedure: moves a small piece of bone with an attached tendon to the front of the socket. It is preferred when there is substantial bone loss or after a failed repair, and has low recurrence rates.

Kneecap:

• MPFL reconstruction: replaces the torn ligament with a tendon graft. This is the most common operation for recurrent kneecap dislocation.
• Tibial tubercle osteotomy: shifts the bony attachment of the kneecap tendon to improve tracking.
• Trochleoplasty: deepens a shallow groove, used in selected severe cases.

Recovery after surgery

A sling or brace is used for several weeks, followed by months of physical therapy. Return to contact sport is typically around 4 to 6 months after shoulder stabilization and 6 to 9 months after kneecap reconstruction, depending on the procedure and progress.

Complications of repeated dislocation

• progressive damage to cartilage, the labrum and bone
• early osteoarthritis of the joint
• nerve injury, such as the axillary nerve in the shoulder
• loss of confidence and reduced activity

Frequently asked questions

Why does my shoulder keep dislocating?

The first dislocation often tears the labrum and stretches the ligaments at the front of the shoulder, and may dent the bone. These rarely heal fully, especially in young, active people, so the ball slips out more easily each time. Loose joints and contact or overhead sports increase the risk.

How many dislocations before surgery is needed?

There is no fixed number. Surgeons often recommend stabilization after a second dislocation, or after the first in young athletes who play contact or overhead sports and have a high chance of recurrence. Bone loss on scans also favors surgery. Discuss your goals and risks with an orthopedic surgeon.

Can physical therapy fix recurrent dislocation?

Physical therapy can reduce episodes, especially for people with general joint looseness, lower activity demands, or kneecap instability without major anatomical problems. When a torn labrum, torn ligament or bone loss is the main cause, strengthening alone often cannot prevent further dislocations, and surgery is more reliable.

Does recurrent dislocation cause arthritis?

It can. Each dislocation can damage the joint surface and supporting structures, and people with many dislocations have a higher rate of osteoarthritis later. Stabilizing the joint aims to reduce further damage, although surgery itself does not completely remove the long-term arthritis risk.

What is the difference between dislocation and subluxation?

A dislocation means the joint surfaces have completely separated. A subluxation is a partial slip, where the joint shifts out of place and then goes back by itself. Repeated subluxations are part of the same instability problem and are assessed and treated in the same way.