Hip Dislocation

Definition: Separation of the femoral head from the acetabulum of the pelvis in either a posterior or anterior direction.

Classification and Mechanism

• Anatomic
  • Anterior Dislocation (10%)
    • Occurs with axial loading of hip in extension and abduction or from a significant posterior force on the joint forcing the femoral head anteriorly.
    • Can be shifted inferiorly (extension > flexion) or superiorly (flexion > extension)
  • Posterior Dislocation (90%)
    • Occurs with axial loading of hip in flexion and adduction. dashboard injury where the patient’s knee hits the dashboard/steering wheel in flexion and forces the femoral head posteriorly.
• Complexity: Stewart-Milford System (Egol, 2010)

Type I	Simple dislocation without a fracture.
Type II	Dislocation with one or more rim fragments but with sufficient socket to ensure stability after reduction.
Type III	Dislocation with fracture of the rim producing gross instability
Type IV	Dislocation with fracture of the head or neck of the femur

Mechanistic Considerations

• As the femoral head dislocates, it can injure the femoral neurovascular bundle
• Diminishes blood supply to the femoral head leading to avascular necrosis
• Avascular necrosis can develop within 6 hours stressing the need for prompt identification and reduction (Hougaard 1986)
  • Reduction < 6 hours: 4.8% avascular necrosis
  • Reduction > 6 hours: 52.9% avascular necrosis

Epidemiology

• Uncommon injury, typically secondary to trauma or in non-native joints
  • Traumatic
    • 70% of all hip dislocations are dunne to motor vehicle collisions
    • Relatively rare in younger individuals, with only 5% occurring in individuals less than 14 years old (typically sports or fall- related). (Goodwin, 2011)
  • Post-Hip Arthroplasty
    • Dislocation one of the most common complications after arthroplasty, occurring due to laxity, implant positioning, improper implant choice and impingement. (Kendoff, 2013)
    • Frequency: (Eysel 2014) (Weatherford, 2011)
      • 2% after primary total hip arthroplasty
      • 28% after revision and implant exchange surgeries
      • 70% of dislocations occur within the first month and 75-90% posterior
• Associated with other injuries in up to 95% of traumatic cases (Goulet, 1999)
  • Acetabular fractures (70%)
  • Other extremity fractures (39%)
  • Closed head injuries (24%)
  • Craniofacial injuries (21%)
  • Thoracic injuries (21%)
  • Femoral head fractures (14%)

Physical Exam

• General
  • Severe pain
  • Inablity to move the affected lower extremity
• Hip Exam
  • Anterior Dislocation: mildly flexed, abducted and externally rotated
  • Posterior Dislocation: flexed, adducted and internally rotated
• Special Considerations
  • Complete a full trauma survey given frequency of associated injuries
  • Direct particular attention to ipsilateral joints given the large force transmitted through the lower extremity to cause the dislocation
    • Ipsilateral knee, patellar and femur fractures are common co-injuries
    • Meniscal and PCL injuries are common with dashboard type injuries
  • Complete a full neurovascular exam
    • Sciatic nerve injuries occur in up to 10% of cases.
    • Check dorsiflexion of the ankle and large toe (will be weak in anterior and posterior dislocations)

Imaging Modalities

• Initial imaging should include a plain hip with AP pelvis
  • If suspicion for associated fracture, subsequent CT is recommended to fully characterize the injury .
  • If a fracture is present, your orthopedics colleagues may prefer to manage the injury operatively and any closed manipulation may cause injury to surrounding neurovascular structures.
• Posterior Dislocation

• Anterior Dislocation

• Concomitant Fracture
  • Common in traumatic dislocations but may be difficult to visualize with X-rays
  • CT scan superior imaging modality if concern for fracture
    • Fracture of the anterior articular surface of the femoral head (black arrow)
    • Fracture of the posterior margin of the acetabulum (green arrow)
    • Fragment of bone (grey arrow) in the soft tissues posterior to the acetabulum, which had arisen from the posterosuperior femoral head

Management

• Closed Reduction
  • Urgent reduction (<6 hours) should be performed in most cases to reduce the risk of osteonecrosis
  • If there is an associated hip/femoral neck fracture, the patient may require closed reduction under anesthesia or an open reduction in the OR
• 

  Allis Maneuver (Waddell 2016)

  Closed Reduction Techniques (Meyer, 2016)

  • Allis Maneuver
    • Place the patient supine in the bed with the physician either on the bed (as shown) or standing beside the patient
    • While an assistant stabilizes the pelvis, hold the ipsilateral leg just below the knee, flex it to 90 degrees and apply traction in line with the femur
    • As the hip begins to reduce, extend the hip and externally rotate to allow the femoral head to slide back into the acetabulum
• 

  Bigelow Maneuver (Waddell 2016)

  Bigelow Maneuver

  • Place the patient in the supine position with the physician standing beside the bed
  • Place your forearm beneath the patients knee and grasp the ankle with your opposite hand (as shown)
  • While an assistant stabilizes the pelvis, flex the hip to 90 degrees and apply traction in line with the femur while abducting, externally rotating and extending the hip until reduced
• 

  Rochester Maneuver (Waddell 2016)

  Rochester/Whistler Maneuver

  • Place the patient in the supine position with both legs flexed and the physician at the standing beside the bed
  • Slide your arm beneath the knee of the affected side and then hold the knee of the contralateral side
  • Place your hand on the ankle of the affected leg and apply downward traction at the ankle, internally and externally rotating as needed
• 

  Stimson Gravity Maneuver (Waddell 2016)

  Stimson Gravity Maneuver

  • Place the patient in a prone position with the legs over the side of the bed in 90 degrees flexion
  • Place one hand on the patient’s ipsilateral calf, just below the knee, and the under beneath the ipsilateral ankle (as shown)
  • Apply downward force on the lower extremity using the hand on the calf and use the hand on the ankle to apply internal/external rotation until the hip is reduced
• Captain Morgan
  • Place the patient in a supine position with the pelvis stabilized by and assistant or strapped to the bed
  • Stand on the side of the patients bed and place your knee, flexed at 90 degrees, beneath the patients ipsilateral leg, just distal to their knee (as shown)
  • Place your forearm beneath the patients knee and grasp the ankle with your opposite hand (as shown)
  • Apply upward traction with the hand behind the patient’s knee and internally/externally rotate at the ankle until the hip is reduced

• Open Reduction
  • Reduction in the OR
  • Consider in cases of irreducible dislocation, evidence of incarcerated fragments, unstable fracture-dislocation, delayed presentation (>6-12 hrs) or if the reduction is not concentric. (Bhandari, 2012)
• Post-Reduction Management
  • Imaging
    • A post-reduction X-ray should be obtained in all cases (native or non-native) and  a CT is recommended in traumatic cases of dislocation to rule out fracture.
  • Post-Discharge Care
    • Exercise Precautions (non-fractured):
      • Controlled passive range-of-hip motion exercises and early mobilization
      • Extremes of motion should be avoided for 4-6 weeks to allow for capsular and soft-tissue healing
      • Anterior: avoid hyperextension of the hip with external rotation
      • Posterior: avoid flexion of the hips past 45 degrees
    • Weight-bearing
      • Institution specific
      • No associated fracture: Generally full weight-bearing as tolerated
      • Associated fracture: depends on surgical vs. non-surgical management by orthopedics
    • Immobilization
      • Anterior: an abduction pillow may be helpful
      • Posterior: use a simple knee immobilizer
• Complications:
  • Osteonecrosis resulting from avascular necrosis
  • Chronic Pain/Arthritis
    • Post-traumatic arthritis can occur in up to 37.5% of patients with traumatic hip dislocation. (Srikrishnamurthy, 1983)

Take Home Points

• Early identification and reduction is key to prevent complications
• Always perform a full trauma and neuro exam, particularly of ipsilateral joints as concomitant injuries are common with traumatic dislocations
• Don’t be reassured by negative post-reduction XRs as small fractures can occur. You should always consider CT

Read More

ALiEM: PV Card: Hip Injuries

Orthobullets: Hip Dislocation

EMin5.com: Hip Dislocations

Radiopedia: Hip Dislocation

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Kovacevix D et al. Injuries about the hip in the adolescent athlete. Sports Med Arthrosc. 2011 Mar. 19 (1): 64-74. PMID: 21293240

Zahar A et al. Dislocation after total hip arthroplasty. Current Reviews in Musculoskeletal Medicine. 2013;6(4):350-356. PMID: 24170479

Dargel J et al. Dislocation Following Total Hip Replacement. Deutsches Ärzteblatt International. 2014;111(51-52):884-890. PMID: 25597367

Weatherford, B (2011, November). Hip Dislocation. Retrieved from http://www.orthobullets.com/recon/5012/tha-dislocation

Hak DJ1, Goulet JA. Severity of injuries associated with traumatic hip dislocation as a result of motor vehicle collisions. J Trauma. 1999 Jul;47(1):60-3. PMID: 10421188

Hougaard K, Thomsen PB. Traumatic posterior dislocation of the hip – prognostic factors influencing the incidence of avascular necrosis of the femoral head. Arch Orthop Trauma Surg. 1986;106:32-35. PMID: 3566493

Upadhyay SS et al. An analysis of the late effects of traumatic posterior dislocation of the hip without fractures. J Bone Joint Surg Br. 1983 Mar;65(2):150-2. PMID: 6826619

Waddell BS et al. A Detailed Review of Hip Reduction Maneuvers: A Focus on Physician Safety and Introduction of the Waddell Technique. Orthopedic Reviews. 2016;8(1):6253.  PMID: 27114811

Bhandari, M. Evidence-based Orthopedics. Chichester: Wiley Blackwell, 2012. Web.