Dislocation
A dislocation occurs when the bones forming a joint separate due to excessive stretching of the ligament that connects them.
Symptoms and causes
Dislocation, also called luxation, is the separation of the bones in a joint, causing the loss of their anatomical relationship. It usually results from excessive force on the ligament connecting the bony components, leading to ligamentous stretching and loosening.
The name of a dislocation is typically derived from the bone farthest from the area where the dislocated bone has been repositioned or from the damaged joint. The most common types are knee dislocation with patellar displacement, shoulder dislocation in which the clavicle separates from the scapula (acromioclavicular dislocation), and elbow dislocation, involving displacement of the humerus and forearm bones (ulna and radius).
Depending on the severity of the dislocation, it can be classified as:
- Complete dislocation: the bones are fully separated.
- Subluxation: there is partial displacement of the articulating bones, causing loss of their usual alignment, but they remain in contact.
The prognosis of dislocation is generally favorable, as appropriate treatment usually resolves the condition without complications within six to twelve weeks. More severe cases may require longer recovery times. In individuals under 20 years old, there is a higher risk of recurrence.
Symptoms
The most characteristic symptoms of a dislocation are:
- Severe pain.
- Tingling or numbness of the joint.
- Swelling.
- Bruising.
- Limited range of motion.
- Visible deformity, which may vary depending on the direction of the dislocation:
- Previous dislocation: the bone moves forward; commonly observed in the shoulder.
- Posterior dislocation: the bone moves backward; more frequent in the hip.
- Inferior dislocation: the bone is positioned lower than usual; less common than anterior dislocation but also occurs in the shoulder.
- Superior dislocation: the bone is positioned above its normal location; typically occurs in the acromioclavicular joint.
- The skin covering the affected joint may appear altered, allowing dislocations to be classified as:
- Open dislocation: the skin is torn because the displaced bones pierce through, resulting in an exposed wound that constitutes a medical emergency.
- Closed dislocation: no open wound is present; the skin remains intact.
Causes
The causes of dislocation include:
- Traumatic dislocation: caused by an impact or fall.
- Congenital dislocation: present from birth due to interrupted intrauterine development. The most common example is developmental dysplasia of the hip, in which the femoral head does not fit properly into the pelvic acetabulum.
- Pathological dislocation: results from an underlying disease that weakens the joints.
- Recurrent dislocation: chronic recurrence due to ligament or joint capsule damage.
Risk Factors
Dislocation risk increases in the following situations:
- Experiencing falls or traffic accidents.
- Practicing contact sports, especially in young adults.
- Joint hyperlaxity: ligaments are more flexible than usual, allowing a greater range of motion.
- Muscle weakness.
- Joints with shallow cavities, which are less stable.
- Advanced age: aging causes muscle weakness and decreased bone density, increasing joint instability.
- Diseases that weaken the joints:
- Osteoarthritis: chronic cartilage degeneration.
- Arthritis: joint inflammation.
- Septic arthritis: joint infection.
- Rheumatoid arthritis: the immune system attacks the synovial membrane, causing tendon inflammation and joint weakening.
- Severe ligamentous laxity: excessively relaxed ligaments.
- Bone tumors.
Complications
Dislocations rarely lead to complications, but possible consequences include:
- Compartment syndrome: if associated with a bone fracture, swelling may obstruct blood flow, causing tissue necrosis.
- Vascular damage: similar to compartment syndrome, preventing blood supply to tissues.
- Internal bleeding: open dislocations can perforate the skin and blood vessels, causing significant blood loss.
- Peripheral nerve injury: nerves may be compressed or stretched. Recovery is common, but total rupture requires surgical intervention.
- Infections: open dislocations create a wound, increasing infection risk. If the infection spreads to bone (osteomyelitis), it becomes severe and difficult to treat.
Prevention
Dislocations can be prevented through simple measures:
- Strengthening muscles and improving flexibility with targeted exercises.
- Using protective equipment (helmet, knee pads, elbow pads, wrist guards) for high-impact sports.
- Avoiding joint overstrain by adopting proper posture and technique during physical activity.
- Warming up before exercise and stretching afterward.
Which Physician Treats Dislocation?
Dislocation is managed in the specialties of Traumatology and Orthopedic surgery, Family and community medicine, and Sports medicine.
Diagnosis of dislocation typically includes:
- Medical history: gathering information about prior medical conditions, lifestyle, mechanism of injury, and symptoms.
- Physical examination:
- Observing for bruising, swelling, deformity, or open wounds.
- Palpating the joint to identify swelling and tender points.
- Assessing range of motion.
- Checking distal pulses to evaluate vascular integrity.
- Evaluating muscle function and skin sensation to detect neurological damage.
- X-ray: produces images of bones and surrounding soft tissues, revealing abnormal positioning and associated fractures, as well as displacement type (anterior, posterior, inferior, superior).
- Computed tomography (CT): X-rays taken from multiple angles provide a 3D view of the joint; useful for detecting fractures not visible on conventional X-rays or complex injuries.
- Magnetic resonance imaging (MRI): uses radio waves and a magnetic field to obtain detailed images of the joint, including bones, tendons, and ligaments, unlike X-rays or CT.
Typical management of a dislocation includes:
- Immediate first aid: can be administered by anyone until medical care is reached. Do not attempt to reduce the joint without proper technique, as this may worsen the injury.
- Immobilize the joint in its current position.
- Apply ice to reduce swelling.
- Closed reduction: the specialist uses local anesthesia to reposition the joint, usually with manual techniques.
- Surgery: required for dislocations that cannot be managed with closed reduction, involving repositioning bones surgically.
- Post-reduction immobilization: the joint must remain immobilized until ligament repair is complete. Typically a sling is used, but a splint or cast may be applied in some cases.
- Rehabilitation: physiotherapy is essential to restore full mobility. Treatment begins with gentle movements, progressing to specific exercises to strengthen muscles.
