Joint dislocation
A joint dislocation, also called luxation, occurs when there is an abnormal separation in the joint, where two or more bones meet. A partial dislocation is referred to as a subluxation. Dislocations are commonly caused by sudden trauma to the joint like during a car accident or fall. A joint dislocation can damage the surrounding ligaments, tendons, muscles, and nerves. Dislocations can occur in any major joint or minor joint. The most common joint dislocation is a shoulder dislocation.
The treatment for joint dislocation is usually by closed reduction, that is, skilled manipulation to return the bones to their normal position. Only trained medical professionals should perform reductions since the manipulation can cause injury to the surrounding soft tissue, nerves, or vascular structures.
Signs and symptoms
The following symptoms are common with any type of dislocation.- Intense pain
- Joint instability
- Deformity of the joint area
- Reduced muscle strength
- Bruising or redness of the joint area
- Difficulty moving joint
- Stiffness
Complications
In the shoulder, vessel and nerve injuries are rare, but can cause many impairments and requires a longer recovery process. Knee dislocations are rare, but can be complicated by injuries to arteries and nerves, leading to limb-threatening complications. Degenerative changes following injury to the wrist are common, with many developing arthritis. Persistent nerve pain years after the initial trauma is not uncommon. Most finger dislocations occur in the middle of the finger and are complicated by ligamentous injury. Since most dislocations involving the joint near the fingertip are due to trauma, there is often an associated fracture or tissue injury. Hip dislocations are at risk for osteonecrosis of the femoral head, femoral head fractures, the development of osteoarthritis, and sciatic nerve injury. Given the strength of ligaments in the foot and ankle, ankle dislocation-fractures can occur.
Causes
Joint dislocations are caused by trauma to the joint or when an individual falls on a specific joint. Great and sudden force applied, by either a blow or fall, to the joint can cause the bones in the joint to be displaced or dislocated from their normal position. With each dislocation, the ligaments keeping the bones fixed in the correct position can be damaged or loosened, making it easier for the joint to be dislocated in the future.Risk factors
A variety of risk factors can predispose individuals to joint dislocation. They can vary depending on location of the joint. Genetic factors and underlying medical conditions can further increase risk. Genetic conditions, such as hypermobility syndrome and Ehlers-Danlos syndrome put individuals at increased risk for dislocations. Hypermobility syndrome is an inherited disorder that affects the ligaments around joints. The loosened or stretched ligaments in the joint provide less stability and allow for the joint to dislocate more easily. Dislocation can also occur because of conditions such as rheumatoid arthritis. In Rheumatoid arthritis the production of synovial fluid decreases, gradually causing pain, swollen joints, and stiffness. A forceful push causes friction and can dislocate the joint. Notably, joint instability in the neck is a potential complication of rheumatoid arthritis.Participation in sports, being male, variations in the shape of the joint, being older, and joint hypermobility in males are risk factors associated with an increased risk of first time dislocation. Risk factors for recurrent dislocation include participation in sports, being a young male, a history of a previous dislocation with an associated injury, and any history of previous dislocation.
Diagnosis
Initial evaluation of a suspected joint dislocation begins with a thorough patient history, including mechanism of injury, and physical examination. Special attention should be focused on the neurovascular exam both before and after reduction, as injury to these structures may occur during the injury or during the reduction process. Imaging studies are frequently obtained to assist with diagnosis and to determine the extent of injury.Imaging Types
[X-ray], usually a minimum of 2-views
- Generally, pre- and post-reduction X-rays are taken. Initial X-ray can confirm the dislocation and evaluate for any fractures. Post-reduction x-rays confirm successful joint alignment and can identify any injuries that may have been caused during the reduction procedure.
- If initial X-rays are normal but additional injury is suspected, there may be a benefit of obtaining stress/weight-bearing views to look for injury to ligamentous structures and/or need for surgical intervention. One example is with AC joint separations.
[Ultrasound]
- Ultrasound may be useful in an acute setting, and is a bedside test that can be performed in the Emergency Department. Ultrasound accuracy is dependent on user ability and experience. Ultrasound is nearly as effective as x-ray in detecting shoulder dislocations. Ultrasound may also have utility in diagnosing AC joint dislocations.
- In infants <6 months of age with suspected developmental dysplasia of the hip, ultrasound is the imaging study of choice. This is due to the lack of ossification at this age, which will not be apparent on x-rays.
Cross-sectional imaging (CT">CT scan">CT or MRI">Magnetic resonance imaging">MRI)
- X-rays are generally sufficient in confirming a joint dislocation. However, additional imaging can be used to better define and evaluate abnormalities that may be missed or unclear on plain X-rays. CT and MRI are not routinely used for simple dislocation, however CT is useful in certain cases such as hip dislocation where an occult femoral neck fracture is suspected. CT angiogram may be used if vascular injury is suspected. In addition to improved visualization of bony abnormalities, MRI permits for a more detailed inspection of the joint-supporting structures in order to assess for ligamentous and other soft tissue injury.
Classification
Prevention
Preventing joint dislocations can be difficult since most are caused by an unexpected injury. If participating in activities such as contact sports, where there is a risk for dislocation, wearing appropriate protective equipment can be helpful. Similarly, avoiding positions that place the joint in a vulnerable position can reduce the risk of experiencing a dislocation. Strengthening the muscles surrounding joints can effectively reduce the risk of a joint dislocation and recurrent dislocations.Treatment
Non-operative
Reduction/Repositioning
X-rays are taken to confirm the diagnosis and detect any associated fractures. A dislocation is easily seen on an X-ray. Once X-rays are taken, the joint is usually manipulated back into position. This can be a very painful process. This is typically done either in the emergency department under sedation or in an operating room under a general anaesthetic. A dislocated joint should be reduced into its normal position only by a trained medical professional. Trying to reduce a joint without any training could worsen the injury.It is important to reduce the joint as soon as possible. Delaying reduction can compromise the blood supply to the joint. This is especially true in the case of a dislocated ankle, due to the anatomy of the blood supply to the foot. On field reduction is crucial for joint dislocations. As they are extremely common in sports events, managing them correctly at the game at the time of injury, can reduce long term issues. They require prompt evaluation, diagnosis, reduction, and post-reduction management before the person can be evaluated at a medical facility. After a dislocation, injured joints are usually held in place by a splint or a bandage.