Hip dislocation

Background

Hip anatomy.

• Orthopedic emergency
  • Reduction of native hip should occur within 6hr due to high risk of avascular necrosis
  • Hip prosthetic dislocation is more common and less emergent
• High-energy trauma is primary mechanism for native hip dislocation
  • Dashboard impact, fall from height, sports injury
• Low-energy trauma can cause hip prosthetic dislocation
  • Tying shoes, sitting on toilet or low seat

Types

• Posterior
  • 90% of hip dislocations
  • Often associated with acetabular fracture
• Anterior
  • 10% of hip dislocations
  • Can be superior (pelvic) or inferior (obturator)
  • Neurovascular compromise is unusual

Clinical Features

Posterior Dislocation

• Extremity is shortened, internally rotated, adducted
• Neurovascular exam may review sciatic nerve compromise

Anterior Dislocation

• Extremity is extended (superior) or flexed (inferior), externally rotated, abducted

Differential Diagnosis

Hip pain

Acute Trauma

• Femur fracture
  • Proximal
    • Intracapsular
      • Femoral head fracture
      • Femoral neck fracture
    • Extracapsular
      • Intertrochanteric femur fracture
      • Trochanteric femur fracture
  • Shaft
    • Mid-shaft femur fracture (all subtrochanteric)
• Hip dislocation
• Pelvic fractures
  • Acetabular pelvic fractures
  • Open book pelvic fracture
  • Straddle pelvic fracture
  • Pelvic avulsion fracture

Chronic/Atraumatic

• Hip bursitis
• Psoas abscess
• Piriformis syndrome
• Meralgia paresthetica
• Septic arthritis
  • Septic arthritis of the hip (peds)
• Obturator nerve entrapment
• Avascular necrosis of hip

Evaluation

Workup

Post-surgical hip dislocation

• Hip AP and lateral views
  • Posterior Dislocation: AP view femoral head posterior and superior to acetabulum
  • Anterior Dislocation: AP view shows femoral head in obturator foramen (inferior to acetabulum)
  • If associated femoral neck fracture, will likely need orthopedics
• Consider Judet views
• Consider knee xray
• Consider CT to evaluate acetabulum for subtle fractures (esp for posterior dislocation)

Diagnosis

• Diagnosed typically via radiograph (see above)

Management

• Reduction recommended within 6 hours to prevent avascular necrosis of the femoral head
• Femoral neck fracture is a contraindication to closed reduction
• Procedural sedation

Posterior

Allis Maneuver

Allis maneuver.

• Supine patient on table: deeper sedation (propofol helps with tissue relaxation); firm distal traction at flexed knee to pull head back into acetabulum; assistant stabilizes pelvis by pushing on ASISs

Captain Morgan Hip Reduction

• See figure here
• See video here
• Provider's knee behind supine patients flexed knee with anterior force lifting (via provider plantar flexing foot) and rotation as needed
• Successful in patients with prosthetic hips as well
• Poses less risk of knee injury since most force is applied by lifting leg rather than applying leverage at knee
• Less risk to provider who does not have to stand on top of gurney, and requires only one provider

The Waddell Technique

The Waddell technique

• A modified Allis Maneuver that allows the provider to follow back safety recommendations provided by OSHA
• Provider hovers over patient on the bed and places their forearm under the patient's knee
• The provider squats down, draping their forearm over their knees with the elbow on one knee and wrist/hand over the other knee
• Provider then leans back, pivoting on feet and holding the patient's leg close to their chest, while an assistant stabilizes the pelvis

Anterior

• Reduction: traction, internal rotation, and then external rotation once the femoral hip clears the acetabular rim

Disposition

• If reduced, outpatient with ortho follow up

Post Reduction Care

• Maintain dislocation precautions:
  • Do not bend the operated hip past 90 degrees
    • Zimmer splint or other knee immobilizer can help with this as most individuals cannot flex hip without flexing knee
  • Do not cross the midline of the body with operated leg (use hip abduction pillow)
  • Do not rotate the operated leg inward
  • In bed, toes and knee cap should point toward ceiling
• Toe-touch or feather weight-bearing

Complications

• Post-traumatic arthritis
  • 20% in simple dislocations
  • Common in complex dislocations
• Femoral head osteonecrosis
  • 5-40%
  • Delay in reduction >6 hours increases risk
• Sciatic nerve injury (check EHL function - toe extension)
  • 8-20% incidence
  • Delay in reduction increases risk
• Recurrent dislocations: <2%