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Traumatic Hip Dislocation - Pediatric

Topic updated on 01/15/16 2:10pm
Introduction
  •  Epidemiology
    • location
      • 80% are traumatic posterior dislocations
      • more common than hip fracture
  • Pathophysiology
    • mechanism of injury
      • age <10
        • may have low energy sporting injury, or trip and fall
      • age >10
        • mostly high energy (e.g. MVA)
  • Associated injuries
    • femoral head or neck fracture 
    • acetabular fractures
      • lesser incidence of acetabular fractures compared with adults
      • due to cartilaginous acetabulum and ligamentous laxity
  • Prognosis
    • typically associated with good long-term outcomes when treated promptly
      • most have mild or no pain
      • most return to high-demand activities
Presentation
  • Symptoms
    • pain, inability to bear weight
  • Physical exam
    • posterior dislocation (most common)
      • slight flexion, adduction, and internal rotation of the limb
      • clinical limb length discrepancy
      • if large posterior wall acetabular fracture, can appear shortened without malalignment
    • anterior dislocation
      • flexion, abduction, and external rotation
    • neurovascular exam
      • check for sciatic or gluteal nerve palsy (rare)
Imaging
  • Radiographs
    • recommended views
      • ap and lateral
        • most can be diagnosed on AP pelvis films
        • lateral hip radiographs will confirm anterior vs posterior dislocation
      • post reduction films
        • post-reduction radiographs are necessary to confirm concentric reduction   
    • findings
      • radiographs must be scrutinized in order to inspect for joint incongruity or nonconcentric reduction
  • CT
    • indications
      • post-reduction CT scan is utilized to further evaluate for any entrapped osteochondral fragment   
    • findings
      • inspect for joint incongruity or nonconcentric reduction
      • entrapped labrum or capsule can produce a subtle asymmetry 
      • interposed soft-tissue can be difficult to appreciate on CT scan  
      • osteochondral fragments can be seen in older children and are easily detected by CT 
      • a non-concentric reduction requires exploration to remove entrapped labrum, capsule, osteochondral fragment or ligamentum teres
  • MRI
    • best for evaluating interposed soft tissue 
Treatment
  • Nonoperative
    • closed reduction
      • indications
        • urgent attempt at closed reduction is first line treatment
        • most are successful reduced with closed means (85%)
  • Operative
    • open reduction
      • indications
        • nonconcentric reduction 
        • intra-articular fragment
        • unstable acetabular rim fracture
        • irreducible by closed means
      • technique
        • surgical approach is typically performed in direction of dislocation (most commonly posterior) 
Techniques
  • Closed reduction technique
    • reduction
      • adequate anesthesia or sedation during reduction is mandatory in order to decrease the risk of displacing the proximal femoral epiphysis 
      • reduction under fluoroscopy has been recommended to decrease risk of displacement
    • post-reduction
      • test hip stability before weaning sedation
      • obtain post-reduction imaging
      • some advocate spica cast in younger children or bracing in older children with 6 weeks protected weight-bearing on crutches
Complications
  • Osteonecrosis
    • reported in 3-15%
    • less frequent than in adults if there is an absence of an associated femoral neck fracture
    • if present, thought to be related to delayed reduction  
  • Coxa magna
    • common radiographic finding (20%)
    • not associated with functional limitation
  • Redislocation
    • rare sequela
    • treatment
      • prolonged immobilization
      • if recurrent and recalcitrant to immobilization: capsulorrhaphy
      • treatment based on age of patient and time elapsed since injury
  • Nerve injury
    • sciatic or gluteal nerve injury can occur, usually resolves with prompt reduction

 

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Qbank (3 Questions)

TAG
(OBQ13.56) A 3-year-old male is an unrestrained backseat passenger in a car involved in a head-on collision. An injury radiograph is seen in Figure A. A delay in achieving a concentric reduction has been shown to increase the risk of Topic Review Topic
FIGURES: A          

1. Coxa magna deformity
2. Recurrent post-traumatic dislocation of the hip
3. Chondrolysis
4. Heterotopic ossification
5. Avascular necrosis

PREFERRED RESPONSE ▶
TAG
(OBQ12.97) An 18-year-old male sustains a right hip injury after being tackled on the football field. Figure A shows his radiograph upon presentation to the emergency room three hours later. On physical exam, he is noted to have a foot drop and decreased sensation globally throughout his entire lower leg. Closed reduction under conscious sedation is immediately performed, and the hip is able to be ranged through a stable arc of motion following reduction. A post-reduction radiograph is shown in Figure B. Shortly after the reduction, the patient continues to have a foot drop, but his sensation is slightly improved. Which of the following is the most appropriate next step in management? Topic Review Topic
FIGURES: A   B        

1. Exploration of his sciatic nerve
2. EMG
3. CT scan of his right hip
4. Touch-down weight bearing of his right leg and observation of his sciatic nerve palsy
5. Skeletal traction on the distal femur to relax tension on the sciatic nerve

PREFERRED RESPONSE ▶
TAG
(OBQ06.152) A 10-year-old boy sustained an isolated injury shown in Figure A. Immediate closed reduction was performed in the emergency room with conscious sedation. Post-reduction radiographs are shown in Figure B and post-reduction CT scan in Figure C. What is the next appropriate step in management? Topic Review Topic
FIGURES: A   B   C      

1. Repeat closed reduction
2. Skeletal traction for 1 month
3. Hip arthrotomy via posterior approach
4. Hip arthrotomy via anterior approach
5. Weight-bearing as tolerated with close follow-up and serial radiographs

PREFERRED RESPONSE ▶




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