Adult Dysplasia of the Hip

Topic updated on 06/07/16 11:01pm
  • Hip dysplasia is a disorder of abnormal development or dislocation of the hip secondary to capsular laxity and mechanical factors
  • Adult and adolescent dysplasia can come in two forms
    • dysplasia that was previously treated
    • dysplasia that was not treated
      • if left untreated it can progress to early arthritis
  • Pathoanatomy
    • acetabular retroversion is most common factor
  • Epidemiology
    • dysplasia is attributable to 1/3rd of all cases of hip osteoarthritis
Crowe Classification
Grade Proximal displacement  Femoral head subluxation
I Less than 10%  • Less than 50%
II 10-15%  • 50-75%
III 15-20%  • 75-100%
IV  Greater than 20%  • Greater than 100%
Hartofilakidis Classification
Dysplasia (Type A) Femoral head within acetabulum despite some subluxation. Segmental deficiency of the superior wall. Inadequate true acetabulum depth.
Low dislocation (Type B) Femoral head creates a false acetabulum superior to the true acetabulum. There is complete absence of the superior wall. Inadequate depth of the true acetabulum.
High dislocation (Type C) Femoral head is completely uncovered by the true acetabulum and has migrated superiorly and posteriorly. There is a complete deficiency of the acetabulum and excessive anteversion of the true acetabulum.

  • Symptoms
    • hip or groin pain, especially in flexion activities
    • often insidious onset
  • Physical exam
    • increased internal rotation before arthritis sets in
      • due to increased femoral anteversion
    • decreased internal rotation may represent osteoarthritis
    • increased external rotation with ambulation
    • positive anterior impingement test (pain with passive flexion, internal rotation and adduction)
    • may have instability with extension, abduction and external rotation
  • Radiographs
    • recommended views
      • standard a/p and lateral radiographs
    • findings
      • abnormalities with the femoral head
        • decreased sphericity
        • decreased head:neck offset
      • abnormalities with the pelvis
        • increased retroversion (Crossover sign) 
        • acetabular protrusio 
      • false profile view 
      • lateral center edge angle 
        • angle formed by a vertical line and a line connecting the center of the femoral head with the lateral edge of the acetabulum
        • <20 degrees associated with dysplasia
    • measurements
      • Tonnis angle
        • measures inclination of weight bearing zone
        • angle greater than 10 is abnormal
  • CT
    • useful in accessing structural abnormalities of the femoral head and neck
  • Nonoperative
    • supportive measures
      • indicated as first line of treatment
  • Operative
    • periacetabular osteotomy +/- a femoral osteotomy
      • indications 
        • symptomatic dysplasia in an adolescent or adult with
        • concentrically reduced hip
        • congruous joint with good joint space
      • advantages
        • provides hyaline cartilage coverage
        • posterior column remains intact and patients can weight bear
        • preserves external rotators
        • delays need for arthroplasty
    • salvage pelvic osteotomy (chiari, shelf)
      • indications
        • unreduced hip
        • recommended for patients with inadequate femoral head coverage and an incongruous joint (a salvage procedure)
    • hip resurfacing
      • indications
        • can be used for Crowe type I or II disease
    • total hip arthroplasty (THA)
      • indications
        • treatment of last resort for those with severe arthritis
        • preferred treatment for older patients (>50) and those with advanced structural changes
        • in a patient with bilateral hip dysplasia, there are significant technical challenges that need to be addressed to ensure a successful total hip arthroplasty.
Surgical Techniques
  • PAO (Ganz, Bernese)  
    • technique
      • involves multiple osteotomies in the pubis, ilium, and ischium near the acetabulum. This allows improved three-dimensional correction of the acetabulum configuration. It is technically the most challenging
    • complication
      • complication rate as high as 15% in experienced hands
      • hip arthroplasty performed after PAO may lead to increased incidence of a retroverted acetabular cup
  • Shelf Osteotomy 
    • goal
      • to increase the weight bearing surface by placing extra-articular buttress of bone over the subluxed femoral head
      • cover femoral head with fibrocartilage (NOT articular cartilage)
    • technique
      • add bone to the lateral aspect of acetabulum. Depends on metaplastic (fibrocartilage) for successful results.
  • Chiari Osteotomy   
    • technique
      • make cut above acetabulum to sciatic notch and shift ileum lateral beyond edge of acetabulum. Depends on metaplastic bone (fibrocartilge) for successful results.
  • Total Hip Replacement
    • technique
      • may need trochanteric osteotomy to improve visualization in Crowe type III or IV patients
      • in a patient with bilateral hip dysplasia, there are significant technical challenges that need to be addressed to ensure a successful total hip arthroplasty
      • acetabular cup is ideally placed where the center of the true acetabulum would be
      • restoring the center of the hip may cause significant lengthening and require femoral shortening.
      • a high hip center can be used when there is inadequate bone stock in the acetabulum to achieve adequate host bone coverage. 
      • a modular femoral implant may be used for a dysplastic hip with significant rotational deformity. 
      • can use uncemented cup if it can be 80% or more covered with the acetabulum
  • Sciatic nerve palsies
    • 10 times increased incidence of sciatic nerve palsy (5-15%)
    • lengthening of greater than 4 cm can lead to sciatic nerve palsy that will present clinically as a foot drop. 
  • Hip Dislocation
    • increased risks of hip dislocation after arthroplasty (5-10%)
  • Periprosthetic femur fx
  • Infection


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