Understanding Joint Dislocations: Causes and Treatment

Introduction

A dislocation is a separation of the bones in a joint. This injury can result in significant pain and can affect the functioning of the joint, including its strength, movement and the support it can provide.

Most dislocations occur due to significant force, such as impact resulting from a car accident, fall or contact sports. Less frequently, they can occur due to other factors such as abnormally shaped joint surfaces or lack of strength and support provided by connective tissues surrounding joints.

Any joint in the body can dislocate, but the shoulder is the most common site in adults.¹ 

Joint dislocation

Joints are sites where bones meet, part of the body’s musculoskeletal system. They provide support and allow the movement of body parts in different directions. There are hundreds of joints in the body in various shapes and sizes.

A dislocation occurs when a joint moves out of its normal alignment, with the ends of the bones fully separated. For a ball and socket joint such as the shoulder or hip, this would involve the ball fully coming out of the socket. Partial separations of joints are called subluxations.

During a dislocation, damage can occur to components of the joints and surrounding soft tissues, including the ligaments, tendons, muscles, nerves and blood vessels. All of these structures can be stretched or torn.

A fracture (a break or crack in a bone) can also occur at the same time as a dislocation. This is called a fracture-dislocation. 

Causes of dislocation

Dislocations are usually the result of impact involving significant force, although less commonly can occur without trauma. 

Traumatic dislocations

Common causes of traumatic joint dislocations include:

• Injuries incurred through contact during sports such as rugby, ice hockey and basketball, or those which can involve falls such as skiing and gymnastics
• High impact during road traffic accidents and industrial accidents
• Falls

Non-traumatic dislocations

Some individuals will have inherently unstable joints, which increases their risk of non-traumatic joint dislocations. Common causes of this instability include

• Conditions involving abnormalities of connective tissue (which provide support and stability to the joints) which can lead to joint hypermobility (joints with a greater range of movement and flexibility than normal). Examples are Ehlers-Danlos syndromes.
• Abnormally shaped joints, such as the shallow hip sockets, are found in Developmental dysplasia of the hip.

Signs and symptoms of dislocation

The following signs and symptoms may be present with a joint dislocation:

• Pain - possibly intense
• Visible deformity/loss of alignment
• Swelling
• Bruising or discolouration
• Numbness or tingling
• Reduced range of movement
• Loss of strength
• Muscle spasms 
• The sensation of joint moving out of place/audible ‘pop’ sound at the time of injury
• Inability to weight bear (for joints of the lower limb)

Diagnosis of dislocation

The diagnosis of dislocation is made using reported history, physical examination and imaging.

History of injury/onset

Details of the trauma or sudden onset of symptoms can provide valuable diagnostic information for dislocations.² The mechanism of injury and degree of force involved can be used to predict which structures are most likely to have been damaged and to what extent.

Physical examination 

Physical examination is used to check for abnormalities, including loss of alignment, lack of blood supply and damage to soft tissues. 

Imaging

X-rays are commonly used to check for joint displacement. If further information is required regarding damage to bones or surrounding soft tissues, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) may also be used. 

(American Academy of Orthopaedic Surgeons)

Dislocated joints can sometimes restore themselves to normal alignment without medical intervention. X-ray imaging may not be definitive in these cases, as the loss of alignment may no longer be visible. Instead, diagnosis of a suspected dislocation may rely on evidence of soft tissue damage in keeping with this type of injury.³

Treatment for dislocation

Dislocations require urgent medical attention, and treatment should be sought without delay to ensure the best outcomes.⁴ No attempts should be made to restore joint alignment by anyone who is not a healthcare professional.

The immediate aim of dislocation treatment is usually to restore the correct alignment of the joint (called reduction of dislocation). A later aim is to restore the joint to full function. 

If possible, restoration of alignment is achieved through a non-invasive (without surgery) manipulation of the bones of the joint, called a closed reduction. If this is not possible, surgery may be required. 

Surgery can also be necessary to repair stretched or torn soft tissues such as the joint capsule, ligaments, tendons, blood vessels and nerves. The type of procedure required will be determined by the Orthopaedics team in each case.

Once alignment is achieved, the joint may be immobilised to allow the initial stages of healing to occur, for example, with a splint, sling or brace. 

Avoidance of activities that would put the area under stress may be advised during the healing phase. A programme of rehabilitation may then follow to restore full joint function, including movement, strength and stability. 

Recovery time

Recovery time from dislocation injuries ranges from several weeks to several months, depending on which joint is affected and the degree of damage to surrounding tissues. Larger joints often take longer to heal than smaller ones.

Rehabilitation after dislocation varies in duration, depending on the case. 

Treatment of recurrent dislocations

Further treatment may be advised for recurrent dislocations to increase stability at the joint. This often involves a surgical procedure.

Commonly dislocated joints

Any of the joints in the body can dislocate, including peripheral and spinal joints. The British Medical Journal lists common sites for dislocation as the shoulder, elbow, fingers, patella (kneecap) and hip.

Shoulder

The glenohumeral joint is the most commonly dislocated in the body in adults.¹ The vulnerability to dislocation is due to the shallow socket of this ball-and-socket joint, which permits a large range of movement of the upper limb but provides little stability.⁵

Most shoulder dislocations involve trauma. In the majority of cases, the ball of the joint is pushed forward out of the socket. This can result from direct force from behind or from a force applied to an outstretched arm in an externally rotated position, creating a leverage effect that forces the head of the humerus forward.⁶ These injuries commonly arise from contact sports.⁷

The elbow is a complex of joints joining the upper and lower arm. The most frequently dislocated is the humeroulnar joint, often resulting from a fall onto an outstretched hand. This is the most commonly dislocated joint in children.⁸ 

Finger

Finger joint dislocations are the most common injuries incurred during sports and can affect any of the three joints in each finger. The mechanism of injury is often an abrupt force to the end of the finger or when a finger is forcefully bent backwards, for example, during sports such as basketball.⁹

Patella

Patellar (kneecap) dislocation typically results from trauma, such as a direct force to the inside of the knee or a non-contact, twisting movement of the lower limb. Variations in anatomy and muscle imbalance at the knee can influence its stability and contribute to the likelihood of dislocation at this joint.¹⁰

Hip dislocation

The hip is a ball-and-socket joint with a deep socket that encloses a large part of the ball. Due to this stable shape, the hip is relatively difficult to dislocate without significant force. Typical mechanisms of injury include a fall from a height or a car accident. 

There is an increased likelihood of hip dislocation following hip replacement surgery, with the risk highest in the early stages after this procedure.¹¹ 

There is also an increased likelihood in people with developmental dysplasia of the hip, where the hip joint is less stable due to the socket being more shallow than normal.

Complications of dislocation

Many dislocation injuries are treated successfully, and the full function of the joint will be restored. 

However, many different structures can be damaged during a dislocation injury, including the joint capsule, ligaments, tendons, muscles, cartilage, nerves and blood vessels. Severe damage to these tissues can result in loss of function in the long term. 

In addition, many of these soft tissues provide support and stability to joints. Stretches or tears to these structures can, therefore, result in joint instability. This can lead to a greater likelihood of future or recurrent dislocations at the same site. 

The glenohumeral joint of the shoulder, in particular, has a high chance of dislocating again after the first incident. The younger the person at the time of the first dislocation, the greater the risk of recurrence.⁵ Further information about chronic shoulder instability and recurrent dislocation can be found at the American Association of Orthopaedic Surgeons website.

Dislocation prevention

Dislocations often result from high-impact trauma incurred during accidents and contact sports. The risk of dislocation injuries may be reduced through the use of appropriate safety and protective equipment at work, during sports and in cars and by taking measures to prevent falls. Further information on the factors which can contribute to falls can be found on the NHS Falls Prevention webpage. 

FAQs

How do I know if a joint is dislocated?

A dislocated joint may look visibly deformed and may be intensely painful. There may be obvious swelling and/or bruising and clear restriction to movement. Dislocations require urgent medical attention and are usually confirmed through imaging such as X-rays. 

When should I seek medical help for a joint dislocation?

If you suspect you may have a joint dislocation, you should seek medical help immediately. You should not try to re-align the joint yourself. 

Summary

Dislocations are joint injuries involving bones at a joint separating. They are often caused by trauma involving high force, such as accidents, falls and sports injuries. Dislocations can result in significant damage to soft tissues surrounding the joint, including the joint capsule, ligaments, muscles, nerves and blood vessels, and can be intensely painful.

Dislocations are usually diagnosed using imaging such as X-rays. Suspected dislocations should receive urgent medical attention.