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Updated: Nov 3 2024

Adult Dysplasia of the Hip

Images
https://upload.orthobullets.com/topic/5008/images/Xray 1 - DDH_moved.jpg
https://upload.orthobullets.com/topic/5008/images/19_moved.jpg
https://upload.orthobullets.com/topic/5008/images/acetabular protrusio..jpg
https://upload.orthobullets.com/topic/5008/images/lateral center edge angle.jpg
https://upload.orthobullets.com/topic/5008/images/lcea.jpg
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  • summary
    • Adult Dysplasia of the Hip is a disorder of abnormal development of the hip joint resulting in a shallow acetabulum with lack of anterior and lateral coverage.
    • Diagnosis is made with plain radiographs of the hip joint. 
    • Treatment typically involves periacetabular osteotomies for those with concentrically reduced hips with congruous joint space and total hip arthroplasty for those presenting with end stage osteoarthritis.
  • Epidemiology
    • Incidence
      • US: 3-5%
      • estimated that 10% of all THA are performed as a result of dysplasia
    • Demographics
      • females > males
      • 2-4x relative risk increase
    • Risk factors
      • breech presentation, female sex, primiparity, and family history
  • Etiology
    • Pathophysiology
      • abnormal movement of the femoral head within the acetabulum due to both osseous and soft tissue abnormalities
      • leads to overload of the acetabular rim leading to secodnary OA
    • Associated conditions
      • increased femoral anteversion, coxa valga, head-neck junction deformitites, femoral head asphericity, hypoplasia of the femoral intramedullary canal, posterior displacement of the greater trochanter
  • Anatomy
    • Acetabulum
      • normal anteversion 15°, abduction 45°
    • Proximal femur
      • femoral head
        • center of the femoral head should be at level of the greater trochanter
      • proximal femur
        • normal femoral neck anteversion: 15° relative to the femoral condyles
        • normal neck shaft angle: 125°
  • Classification 

      • Crowe Classfication
      • Grade
      • Proximal displacement
      • Femoral head subluxation
      • I
      • <10% vertical height of pelvis
      • Proximal migration of head neck junction from inter-teardrop line <50% of femoral head vertical diameter
      • II
      • 10-15%
      • 50-75%
      • III
      • 15-20%
      • 75-100%
      • IV
      • > 20%
      • >100%
      • Hartofilakidis Classification
      • Dysplasia
      • (Type A)
      • Femoral head within acetabulum despite some subluxation.
      • Segmental deficiency of the superior wall.
      • Inadequate depth of true acetabulum.
      • Low dislocation
      • (Type B)
      • Femoral head creates a false acetabulum superior to the true acetabulum.
      • There is a complete absence of the superior wall.
      • Inadequate depth of 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.
  • Presentation
    • Symptoms
      • hip or groin pain with insidious onset
        • exacerbating activitis include hip flexion or external rotation in weight bearing stance
      • lateral hip pain and a limp or Trendelenburg gait may occur with abductor fatigue
    • Physical exam
      • insepction
        • evaluation of gait; abductor fatigue or Trendelnburg sign
        • overall ligamentous laxity; Beighton score
      • motion
        • increased internal rotation with the hip in flexion
          • increased femoral anteversion
      • provocative tests
        • anterior apprehension sign
          • lateral decubitus position, hip placed in extension as examiner applies progressive external rotation and adduction
          • positive with apprehension and/or pain
        • prone external rotation tests
          • anterior-directed force on the posterior greater trochanter
  • Imaging
    • Radiographs
      • recommended views
        • AP
        • lateral
        • false-profile view
      • findings
        • asphericity of the femoral head
        • coxa valga (increase neck-shaft angle)
        • narrow femoral canal
      • measurements
        • lateral center-edge angle (LCEA) of Wiberg
          • assesses superolateral coverage of the femoral head on the AP view
          • angle between a verticle line through the center of the femoral head and the acetabular edge
          • dysplastic: <20°
          • 20-25° "borderline"
          • 25-39° normal
        • Tonnis angle
          • inclination of the weight bearing portion of the acetabulum
          • angle formed between the horizontal and a line along the superior acetabulum
          • evaluated on the AP view
          • dysplastic: >10°
          • normal: <10°
        • anterior center-edge angle of Lequesne
          • assesses anterior coverage of the femoral head
          • angle created between a vertical line through the center of the femoral head and the anterior acetabulum
          • evaluated on the false-profile view
          • dysplastic: <20°
          • normal 25-40°
          • >40° indicative of femoroacetabular impingement (FAI)
        • Femoro-Epiphyseal Acetabular Roof (FEAR) index
          • angle formed between the horizontal portion of the central proximal femoral physeal scar and the acetabular index
          • evaluated on the AP view
          • FEAR index <5° indicative of a stable hip not requiring treatment
    • CT
      • indications
        • preoperative planning
        • should only be ordered by treating surgeon
      • findings
        • adequate assessment of acetabular and proximal femoral osseous morphology including excessive anteversion or retroversion
          • distal femur should be included in patients with clinical signs of femoral anteversion
          • diameter of femoral canal may be over-estimated on AP radiographs and underestimated on lateral radiographs due to rotational mismatch of the metaphysis and diaphysis
  • Prevention
    • Identification and prevention of infantile developmental dysplasia (DDH)
      • Pavlik harness, closed and open reductions, spica casting, proximal femoral osteotomies
  • Treatment
    • Nonoperative
      • supportive measures 
        • role of long-term nonsurgical management in symptomatic dysplasia is limited given premature progression of secondary OA
    • Operative
      • hip arthroscopy
        • indications
          • adjunct procedure to PAO for enhanced visualization and management of chondral, labral and proximal femoral cam-type lesions
          • contraindicated in the setting of moderate to severe dysplasia
        • outcomes
          • chondral and labral pathology is a sequelae of osseous instability and may recur or progress if underlying pathology is not corrected
            • associated with accelerated progression of arthritis, hip subluxation, less functional improvement, as well as increased risk of surgical failure and reoperation
      • periacetabular osteotomy (PAO)
          • symptomatic dysplasia in an adolescent or adult with a concentrically reduced hip and congruous joint space
          • preserved range of motion
          • intraoperative dynamic testing of hip motion is needed to determine the need for femoral osteotomy
            • minimum of 90° flexion and 15° internal rotation to prevent FAI
        • advantages
          • provides hyaline cartilage coverage
          • preserved integrity of the posterior column, which allows patients to weight bear as tolerated postoperatively
          • large multidirectional corrections
          • preserves external rotators
          • delays need for arthroplasty
        • outcomes
          • reliably improves radiographic parameters and symptomatology
          • 92% survivorship at 15 years in avoiding THA
      • salvage pelvic osteotomy (Chiari, Shelf)
        • indications
          • unreduced hip
          • recommended for patients with inadequate femoral head coverage and an incongruous joint (a salvage procedure)
        • outcomes
          • 84% survivorship at 17 years with advanced OA as an endpoint
          • advanced DDH and asphericity of the femoral head associated with poor outcomes
      • hip resurfacing
        • indications
          • can be used for Crowe type I or II disease
        • outcomes
          • unable to address leg-length discrepancy
          • 10% revision rate at 6 years
          • higher revision and complication rate with hip resufracing in patients with DDH compared to general population
      • total hip arthroplasty (THA)
        • indications
          • treatment of choice for patients with end-stage OA secondary to dysplasia
          • may need small acetabular components
        • outcomes
          • improves Harris Hip scores and pain
          • outcomes for Crowe I and II patients are in similar to those of THA for primary OA in the short term
            • revision rates for Crowe III and IV are higher than non-dysplastic hips
          • long term follow up demonstrates a higher revision rate for THA in dysplastic hips
          • increased complication profile: infection, instability and neruovascular injury
            • risk of sciatic nerve injury if limb length changed by >4cm
            • may need to perform femoral shortening (trochanteric or subtrochanteric)
  • Techniques
    • Supportive measures
      • technique
        • weight loss, NSAIDs, activity modification, intra-articular injections
    • Hip arthroscopy
      • technique
        • should not be performed in isolation as it does not treat underlying pathologic cause
        • hip arthroscopy performed concomitantly with PAO to address labral pathology or evaluate for chondral injuries
          • if significant chondral injury is identified, PAO can be abandoned with minimal morbidity
          • continues to be controversial
    • Periacetabular osteotomy (PAO) (Ganz, Bernese)
      • approach
        • modified Smith-Petersen
      • technique
        • involves osteotomies in the pubis, ilium, and ischium near the acetabulum
        • allows significant three-dimensional correction of the acetabulum
        • importantly, the osteotomies avoid disruption to the posterior column
          • posterior column fracture results in pelvic discontinuity and the need for supplemental plate fixation
      • complications
        • hip arthroplasty performed after PAO may lead to increased incidence of a retroverted acetabular cup
    • Salvage Osteotomies
      • Chiari Osteotomy
        • technique
          • make cut above acetabulum to sciatic notch and shift ilium lateral beyond the edge of acetabulum
          • depends on metaplastic bone (fibrocartilge) for successful results.
        • complications
          • shortens limb
      • Shelf Osteotomy
        • approach
          • modified Smith-Petersen
        • technique
          • places extra-articular buttress of bone to the lateral acetabulum over the subluxed femoral head
          • increases weight bearing surface
          • cover femoral head with fibrocartilage (metaplastic bone), not articular cartilage
    • Hip Resurfacing
      • technique
        • posterior approach with release from the piriformis to the gluteus maximus tendon
          • partial gluteus maximus tendon release aids in exposure
        • unable to address limb length
      • complications
        • postoperative femoral neck fracture
    • Total Hip Arthroplasty
      • approach
        • anterior, lateral or posterior based approaches may be used
      • technique
        • trochanteric osteotomy may be needed to improve visualization, especially in Crowe type III or IV dysplastics
        • goal is to place the acetabular component in the true acetabulum to restore normal hip center of rotation and biomechanics
          • this may cause significant leg lengthening, which would subsequently require femoral shortening (trochanteric or subtrochanteric)
        • components may need to be medialized or used with augments to gain adequate coverage and stability of the acetabulum
          • can use uncemented cup if there is less than 30% uncoverage
        • a high hip center can be used to gain adequate bony stability, but is less ideal biomechanically
        • modular femoral components allow for correction of rotational deformities
      • complications
        • increased risk of loosening with a high hip center
        • increased risk of neurovascular injury and infection
  • Complications
    • 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
    • Nonunion
      • 29% nonunion with greater trochanter osteotomy
      • subtrochanteric osteotomy and trochanter advancement lowers nonunion rate
    • Hip Dislocation
      • increased risks of hip dislocation after arthroplasty (5-10%), especially when high hip center is used
    • Component loosening
      • placement of the acetabular component in a high hip position associated with increased risk of loosening
    • Periprosthetic femur fx
    • Infection
  • Prognosis
    • 48% of THA in patients < 50-years-old are a result of dysplasia
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