Dr. Kevin Yip

Dr Kevin Yip
Orthopaedic Surgeon
MBBS(UK), FRCS(EDIN), FAM(SING), FHKCOS(ORTHO)

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Dislocation in the Adult

Basics
Description
  • Dislocation occurs when a force across a joint disrupts the restraining capsule, ligaments, and muscles.
  • Dislocated joints may reduce spontaneously or remain unreduced.
  • Dislocations can be associated with periarticular fractures, ruptured ligaments, capsular damage, and cartilage damage.
  • The dislocation may result in stretch or injury to the arteries or nerves that cross the joint.
  • Dislocation may occur after prosthetic joint replacement, particularly of the hip.
General Prevention
Use of protective devices and equipment during sporting activity
 
Epidemiology
Incidence
  • In 1 study, the rate of shoulder dislocation was 17 in 100,000 per year.
  • In another study, the rate of dislocation after hip replacement was 3.9%.
Risk Factors
  • Sports
  • Car accidents
  • Falls
  • Trauma
  • Joint replacement
  • Skateboarding and in-line skating
Pathophysiology
  • The vector of force on a limb results in particular patterns of injury to the joint.
    • When a hip is flexed, a force on the axis of the femur results in a posterior hip dislocation.
    • Force on a hip in an extended position results in an anterior dislocation.
Etiology
Associated Conditions
  • Periarticular fractures
  • Nerve and vessel injury
  • Osteonecrosis
  • Cartilage damage
Diagnosis
Signs and Symptoms
  • Pain and deformity of the joint
  • Inability to bear weight on the affected limb
  • Neurologic compromise
History
Traumatic injury, as from a fall or car accident
  
Physical Exam
  • A complete neurologic examination is important, and the strength and sensation distally should be noted.
  • Pulses should be palpated and, if not found, Doppler ultrasound should be performed.
  • The remainder of the extremity should be evaluated for swelling or deformity.
Tests
Imaging
  • Radiography:
    • Plain radiographs of the joint should be taken in 2 planes to show the direction of dislocation.
    • Radiographs are repeated after reduction.
  • CT is used to evaluate intra-articular fracture patterns.
  • MRI is used to evaluate ligament and soft-tissue damage around the joint.
Differential Diagnosis
  • Fracture
  • Joint effusion
  • Joint infection
Treatment
Initial Stabilization
  • All joint dislocations should be reduced as soon as possible.
  • Radiographs should be taken 1st to confirm the dislocation and to show fractures.
General Measures
  • Depending on the nature of the injury, reduction may require no anesthesia, intra-articular joint injection, conscious sedation, or full anesthesia.
    • The hip joint often requires sedation or a full anesthetic with muscle relaxant because the muscle forces around the joint can be great.
  • After reduction, joint stability should be confirmed by taking the joint through its ROM.
  • Unstable joints should be braced or placed in traction after reduction and usually require surgical stabilization.
  • Plain radiographs should be taken in 2 views to confirm reduction.
  • CT is used in dislocations of the hip and shoulder to assess for fractures or intra-articular fragments.
Activity
  • Dislocations that are stable after reduction and do not have fractures usually should be mobilized quickly.
  • Immobilization for a week may help with soft-tissue pain and swelling.
Special Therapy
Physical Therapy
Patients with stable dislocations should begin an assisted program in ROM and joint strengthening.
 
Surgery
  • Indications for surgery include:
    • Unstable joint dislocations
    • Periarticular fractures:
      • Joint injuries do best when ROM exercises can be started early.
      • Fractures must be stabilized to allow for early ROM.
      • Fractures also must be reduced anatomically to decrease the risk of posttraumatic arthritis.
    • In some cases, ruptured or torn periarticular soft tissue may be treated with surgery.
      • Acute shoulder dislocations in young adults have a high risk of recurrent instability.
    • Irreducible joint dislocations:
      • Soft tissues such as tendons, nerves, or arteries may be caught in the joint.
      • Open reduction is required.
    • Intra-articular osteochondral fragments
Follow-up
  • Confirmation should be made after reduction, taking care to assure joint congruity.
  • Patients should be reassessed in 1-2 weeks.
    • If the joint is stable, early ROM should be started.
  • Dislocation may put the patients at risk for instability, osteonecrosis, or posttraumatic arthritis.
Prognosis
  • Prognosis depends on the particular joint dislocated and the injuries to surrounding tissues.
  • Injuries to nerves and arteries around the joint have a poor prognosis.
  • Periarticular fractures are at risk for posttraumatic arthritis and the need for later joint replacement.
  • Missed joint dislocations have a poor prognosis.
  • Shoulder dislocations have a high rate of redislocation in young adults.
  • In active patients, early surgery may be helpful in preventing chronic instability.
Complications
  • Stiffness
  • Osteonecrosis:
    • Most common after hip dislocations.
    • Thought to be secondary to damage to the blood supply of the femoral head.
    • The length of time to reduction is directly related to the risk of osteonecrosis.
      • Hips should be reduced within 6 hours.
  • Posttraumatic arthritis:
    • Depends on the reduction of the fracture and the amount of chondral damage to the joint at the time of injury
      • In 1 study of the outcomes after posterior fracture-dislocations of the hip, poor outcome was seen in 18% of patients.
    • Common after hindfoot subtalar dislocation
  • Joint instability:
    • The presence of fracture and damage to surrounding supportive structures of the joint increases the risk of late instability.
    • Joints with less innate stability, such as the shoulder, have a higher risk of late instability than do joints with more stable bony structures, such as the elbow.
  • Nerve damage:
    • Early reduction reduces the amount of time that nerves are stretched.
    • After hip dislocation, patients with longer times to reduction have worse nerve injuries.
Patient Monitoring
  • Patients should be monitored with radiographs to check that the joint is reduced concentrically.
  • Additional follow-up is based on the individual injury.
    • Patients with hip dislocations should be followed radiographically for the 1st year to assess for posttraumatic arthritis and osteonecrosis.
Miscellaneous
Codes
ICD9-CM
  • 718.3 Recurrent dislocation
  • 831.00 Shoulder dislocation
  • 832.00 Elbow dislocation
  • 833.00 Wrist dislocation
  • 835.00 Hip dislocation
  • 836.50 Knee dislocation
  • 837.1 Ankle dislocation
Patient Teaching
Activity
Early ROM is started for stable joint dislocations.
 
Prevention
  • Design of skate parks may reduce the risk of injuries.
  • Use of protective equipment may reduce the risk of injuries after falls during sporting events.
FAQ
Q: When should a joint be reduced?
A: Joint dislocations should be reduced as quickly as possible to reduce the risk of osteonecrosis, joint damage, and stretch to nerves and blood vessels.

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