Definition

A shoulder joint dislocation occurs when one of the bones that make up the shoulder joint shifts out of or separates from its normal position. The shoulder joint is a ball-and-socket joint composed of the scapula (shoulder blade) and the humerus (upper arm bone). In the case of dislocation, the ball-shaped end of the upper arm bone moves out of the cup-shaped socket of the shoulder blade.

The shoulder joint is prone to dislocation due to its flexibility, wide range of motion, and susceptibility to injury in contact sports such as rugby or football. It usually requires significant force or impact to cause the shoulder bone to dislocate. Dislocation can cause the joint to move forward, backward, or downward.

Shoulder dislocation is a common joint injury, accounting for about 50% of all large joint dislocations. Most cases involve anterior dislocation (the bone dislocates forward), with around 97% of shoulder dislocations being anterior. Additionally, connective tissues around the joint may stretch or tear, worsening the dislocation.

Causes

The shoulder joint is the most frequently dislocated joint in the body. Since the shoulder has a wide range of motion, it can dislocate forward, backward, or downward. Most cases occur with anterior shoulder dislocation. Posterior dislocation (backward) is rare, making up only 2-4% of cases, while inferior dislocation (downward) is the rarest, accounting for less than 1% of all shoulder dislocations.

Dislocations typically occur when the shoulder experiences sudden pressure or impact that pulls or pushes the bones out of place. For example, when the arm is extended and hit with force, the shoulder joint can dislocate. Twisting the shoulder joint may also cause the upper arm bone to pop out of the socket.

Ligaments around the shoulder joint connect the bones. When dislocation occurs, these ligaments can stretch to their maximum capacity and tear, worsening the dislocation.

Risk Factor

Anyone can experience a shoulder joint dislocation, but it is most common among teenagers and young adults, particularly athletes in contact sports.

Common causes include:

• Traffic accidents that result in strong impact to the shoulder
• Falling awkwardly from a height
• Sports injuries, especially in contact sports like hockey or football. Sports with a high risk of falls, like skiing, gymnastics, or volleyball, can also lead to shoulder dislocations
• Severe muscle contractions, such as during seizures or electric shocks

Symptoms

A dislocated shoulder joint often presents immediate symptoms following an injury from sports, a fall, or an accident. Symptoms of a shoulder dislocation may include:

• Severe, sudden pain, sometimes accompanied by a “pop” sound as the shoulder dislocates
• Visible changes in the shape of the shoulder compared to the unaffected side
• Other signs of inflammation, such as swelling or bruising
• Reduced range of motion, making it difficult to move the shoulder due to intense pain or nerve impairment
• Numbness, weakness, or tingling around the shoulder, neck, or arm
• Excessive muscle contractions, such as spasms, that increase pain

Diagnosis

Diagnosing a shoulder dislocation involves a medical interview, physical examination, and supporting tests.

Medical Interview

The doctor may ask about your symptoms and how the injury occurred. They might also ask about your medical history.

Physical Examination

The doctor will examine the shoulder and entire body, checking for reduced range of motion, pain, and changes in shoulder shape. They will also assess any nerve or blood vessel issues around the shoulder. Injury to the axillary nerve, which runs through the shoulder and armpit, occurs in up to 40% of shoulder dislocation cases.

Imaging Tests

X-rays and MRIs help confirm the diagnosis. X-rays can reveal whether the upper arm bone has shifted out of the shoulder socket, while MRIs can check for damage to surrounding tissues, such as nerves and blood vessels.

Management

Treatment for a shoulder dislocation depends on:

• The severity of the injury
• The complications
• The type of dislocation

Treatment options include:

• Closed Reduction

The dislocated bone is manually repositioned through specific maneuvers. The doctor may use anesthesia or muscle relaxants depending on the pain and swelling before performing the procedure. The pain usually subsides after the procedure.

• Surgery

Surgery may be necessary for people who experience recurrent shoulder dislocations due to weak joints or ligaments or when the shoulder joint cannot be repositioned with manual techniques. Surgery may also address nerve, blood vessel, muscle, or tendon damage.

Afterward, the shoulder is typically immobilized with a brace or sling for several weeks to prevent further injury. Avoid movement until the doctor advises it, as premature activity can cause recurrent dislocations. Cold compresses can help reduce swelling and pain during the initial days of recovery.

The doctor may prescribe pain medication, and a rehabilitation program will help restore the shoulder’s range of motion, strength, and stability.

Complications

Complications associated with shoulder dislocations may include:

• Fractures of the collarbone (clavicle) or upper arm bone (humerus)
• Tears in the muscles, ligaments, or tendons around the shoulder
• Nerve damage near the shoulder joint, leading to numbness, weakness, or paralysis
• Chronic shoulder instability, increasing the risk of recurrent dislocations

Prevention

When participating in contact sports, take precautions by using protective equipment. Avoid situations that could cause falls or forceful impacts on the shoulder. Drive carefully to avoid accidents.

Regular exercise helps maintain the strength and flexibility of the joints and muscles. Those who have had a shoulder dislocation before are at risk of experiencing it again. To prevent re-injury, strengthening and stability exercises for the affected shoulder are recommended.

When to See a Doctor?

If you experience a shoulder joint injury, seek medical attention immediately. While waiting for treatment, avoid moving the dislocated shoulder. Use a sling to keep the shoulder in place. Do not attempt to reposition the bone yourself, as improper techniques could damage surrounding muscles, ligaments, nerves, or blood vessels.

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