Traumatic dislocation of the hip

Types

Clinical signs

General

• Severe hip or groin pain and inability to stand or bear weight
• Obvious deformity and fixed abnormal position of the leg
• Shortening of the affected limb, particularly in posterior dislocation
• Painful or absent hip movements
• Muscle spasm
• Examine for open wounds, pelvic instability, and associated limb injuries.

Posterior dislocation

• Hip flexed, adducted, internally rotated
• Limb shortened
• Prominence of femoral head may be felt in buttock
• Bruising or laceration over the anterior knee can suggest a dashboard mechanism.
• Sciatic nerve injury is a key complication, especially affecting the common peroneal division:
  • weak ankle/toe dorsiflexion
  • numbness over dorsum of foot
  • foot drop

Anterior dislocation

• Hip abducted and externally rotated
• Femoral head may be palpable in groin
• Assess femoral pulse and distal vascular status carefully because femoral vessels may be at risk.

Diagnosis

1. Initial trauma assessment

• Airway, breathing, circulation
• Control life-threatening bleeding
• Assess other injuries before and during hip management
• Provide analgesia and immobilize the limb in its position of comfort.

2. Neurovascular examination

• Distal pulses, capillary refill
• Motor: ankle dorsiflexion, plantarflexion, toe movement
• Sensation: especially common peroneal and tibial nerve distributions
• Sciatic nerve status in posterior dislocation
• Femoral nerve and vascular status in anterior dislocation.

3. Imaging

• AP pelvis and hip radiographs are the initial investigation.
• Cross-table lateral or other appropriate lateral views help determine direction of dislocation.
• Look for associated fractures of:
  • posterior wall/column of acetabulum
  • femoral head
  • femoral neck
  • greater trochanter
• CT scan after reduction is generally required to confirm a concentric reduction and identify intra-articular fragments, femoral-head fracture, acetabular fracture, or an occult fracture.
• MRI is not routine acutely but can be useful later for suspected osteonecrosis, labral/cartilage injury, or persistent symptoms.

Treatment

Emergency principle: urgent reduction

Immediate management

1. Resuscitation and assessment for multiple trauma.
2. Strong analgesia.
3. Urgent orthopedic involvement.
4. Procedural sedation or general anesthesia with adequate muscle relaxation.
5. Closed reduction if there is no contraindication and the dislocation is reducible.
6. Recheck and document neurovascular status immediately afterward.
7. Obtain post-reduction radiographs and CT.

Closed reduction

• Allis maneuver
• Stimson gravity technique
• Captain Morgan/Whistler-type techniques

Indications for open reduction or surgery

• Failed closed reduction
• Irreducible dislocation due to soft tissue or bony interposition
• Nonconcentric reduction or intra-articular loose fragment
• Associated femoral-head or acetabular fracture requiring fixation
• Femoral-neck fracture
• Persistent instability or recurrent dislocation
• Progressive sciatic nerve deficit
• Major vascular injury
• Open injury

Post-reduction care

• Repeat neurovascular assessment and imaging.
• CT to exclude retained fragments and define fractures.
• Protected weight bearing, commonly toe-touch or non-weight bearing initially when a fracture, instability, or significant soft-tissue injury is present.
• Early supervised range-of-motion and rehabilitation according to stability and associated injuries.
• Thromboprophylaxis when indicated by trauma severity, immobilization, and institutional protocol.
• Serial follow-up radiographs; monitor for avascular necrosis and post-traumatic osteoarthritis.

Complications

Early

• Sciatic nerve palsy
• Femoral nerve or vascular injury in anterior dislocation
• Associated acetabular, femoral-head, femoral-neck, or knee injury
• Failure of reduction or recurrent dislocation
• Iatrogenic femoral-neck fracture during reduction

Late

• Avascular necrosis of femoral head
• Post-traumatic osteoarthritis
• Heterotopic ossification
• Chronic pain, stiffness, reduced hip motion
• Recurrent instability
• Osteonecrosis-related collapse of the femoral head

Exam-focused summary

• Posterior dislocation: dashboard injury; shortened, adducted, internally rotated leg; sciatic nerve risk.
• Anterior dislocation: abducted, externally rotated leg; assess femoral vessels.
• Obtain AP pelvis/hip radiographs, but do not delay urgent reduction unnecessarily.
• Reduce under adequate sedation/anesthesia, preferably within 6 hours.
• Perform and document neurovascular examination before and after reduction.
• CT after reduction is important for occult fractures, fragments, and confirmation of concentric reduction.
• Failed, unstable, fracture-associated, or nonconcentric reductions require operative management.