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http://upload.orthobullets.com/topic/1035/images/dislocate1.jpg
http://upload.orthobullets.com/topic/1035/images/r hip fracture dislocation.jpg
http://upload.orthobullets.com/topic/1035/images/anterior hip dislocation.jpg
http://upload.orthobullets.com/topic/1035/images/AP exray hip dislocation_moved.gif
Introduction
  • Epidemiology
    • rare, but high incidence of associated injuries 
    • mechanism is usually young patients with high energy trauma
  • Hip joint inherently stable due to
    • bony anatomy
    • soft tissue constraints including
      • labrum
      • capsule 
      • ligamentum teres
Classification
  • Simple vs. Complex
    • simple
      • pure dislocation without associated fracture
    • complex
      • dislocation associated with fracture of acetabulum or proximal femur
  • Anatomic classification
    • posterior dislocation (90%)
      • occur with axial load on femur, typically with hip flexed and adducted
        • axial load through flexed knee (dashboard injury
      • position of hip determines associated acetabular injury
        • increasing flexion and adduction favors simple dislocation
      • associated with
        • osteonecrosis
        • posterior wall acetabular fracture
        • femoral head fractures
        • sciatic nerve injuries 
        • ipsilateral knee injuries (up to 25%) 
    • anterior dislocation 
      • associated with femoral head impaction or chondral injury
      • occurs with the hip in abduction and external rotation
      • inferior ("obturator") vs. superior ("pubic")
        • hip extension results in a superior (pubic) dislocation
          • Clinically hip appears in extension and external rotation
        • flexion results in inferior (obturator) dislocation
          • Clinically hip appears in flexion, abduction, and external rotation 
Presentation
  • Symptoms
    • acute pain, inability to bear weight, deformity
  • Physical exam
    • ATLS
      • 95% of dislocations with associated injuries 
    • posterior dislocation (90%) 
      • most common
      • associated with posterior wall and anterior femoral head fracture
      • hip and leg in slight flexion, adduction, and internal rotation 
      • detailed neurovascular exam (10-20% sciatic nerve injury)
      • examine knee for associated injury or instability
      • chest X-ray ATLS workup for aortic injury 
    • anterior dislocation
      • hip and leg in flexion, abduction, and external rotation 
Imaging
  • Radiographs
    • can typically see posterior dislocation on AP pelvis 
      • femoral head smaller then contralateral side
      • Shenton's line broken
      • lesser trochanter shadow reveals internally rotated limb as compared to contralateral side
      • scrutinize femoral neck to rule out fracture prior to attempting closed reduction
      • AP pelvis and Judet views after reduction to evaluate associated acetabular fractures
  • CT
    • helps to determine direction of dislocation, loose bodies, and associated fractures
      • anterior dislocation 
      • posterior dislocation 
    • post reduction CT must be performed for all traumatic hip dislocations to look for  
      • femoral head fractures 
      • loose bodies 
      • acetabular fractures 
  • MRI
    • controversial and routine use is not currently supported 
    • useful to evaluate labrum, cartilage and femoral head vascularity
Treatment
  • Nonoperative
    • emergent closed reduction within 6 hours 
      • indications
        • acute anterior and posterior dislocations
      • contraindications
        • ipsilateral displaced or non-displaced femoral neck fracture
  • Operative
    • open reduction and/or removal of incarcerated fragments
      • indications
        • irreducible dislocation
        • radiographic evidence of incarcerated fragment 
        • delayed presentation 
        • non-concentric reduction
        • should be performed on urgent basis
    • ORIF
      • indications
        • associated fractures of
          • acetabulum 
          • femoral head
          • femoral neck 
            • should be stabilized prior to reduction
    • arthroscopy
      • indications
        • no current established indications
        • potential for removal of intra-articular fragments
        • evaluate intra-articular injuries to cartilage, capsule, and labrum
Techniques
  • Closed reduction 
    • perform with patient supine and apply traction in line with deformity regardless of direction of dislocation
    • must have adequate sedation and muscular relaxation to perform reduction 
    • assess hip stability after reduction
    • post reduction CT scan required to rule out
      • femoral head fractures 
      • intra-articular loose bodies/incarcerated fragments
        • may be present even with concentric reduction on plain films
        • acetabular fractures
    • post-reduction 
      • for simple dislocation, follow with protected weight bearing for 4-6 weeks
  • Open reduction
    • approach
      • posterior dislocation
        • posterior (Kocher-Langenbeck) approach
      • anterior dislocation
        • anterior (Smith-Petersen) approach
    • technique
      • may place patient in traction to reduce forces on cartilage due to incarcerated fragment or in setting of unstable dislocation
      • repair of labral or other injuries should be done at the same time
Complications
  • Post-traumatic arthritis 
    • up to 20% for simple dislocation, markedly increased for complex dislocation
  • Femoral head osteonecrosis
    • 5-40% incidence
    • Increased risk with increased time to reduction
  • Sciatic nerve injury
    • 8-20% incidence
    • associated with longer time to reduction
  • Recurrent dislocations
    • less than 2%
 

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