CP hip

Question 1

Epidemiology

Answer 1

progressive hip subluxation occurs in up to 50% of children with spastic quadriparesis

Question 2

Pathoanatomy

Answer 2

• subluxation
  
  • strong tone in hip adductor and flexors lead to scissoring and predisposes to hip subluxation and dislocation
• dislocation
  
  • dislocation is typically posterior and superior (>95%)
• degeneration
  
  • in time, dysplastic and erosive changes in the cartilage of the femoral head can develop and lead to pain

Question 3

Prognosis

Answer 3

• grade of hip subluxation is correlated with the GMFCS level
  
  • minimal in level I and up to 90% in level V
• natural history studies have shown that hips will dislocate in the absence of treatment if Reimers index >60-70%

Question 4

Classification

Question 5

Comparison of Spastic Hip Dysplasia and Developmental Dysplasia of the Hip

Question 6

Radiographs

Answer 6

• Radiographs
  
  • AP and frog lateral (if possible)
    
    • Hip abduction of <45° with partial uncovering of the femoral head on radiographs represents an at risk hip
  • Reimers migration index
  • • percent of femoral head with no acetabular coverage
      
      • most accurate method to identify and monitor hip stability
      • < 33% = at risk
      • > 33% = subluxated hip
• CT Scan
  
  • More useful for operative planning rather than diagnosis
  • 3d rendering can help plan acetabular correction
  • CT scanogram can be helpful to measure femoral version if planning a derotational osteotomy

Question 7

Nonoperative

Answer 7

• observation
  
  • mild cases
• Physical therapy never shown to prevent hip subluxation
• Abduction bracing alone does not reduce dislocations and may cause windswept deformity

Question 8

Operative

Answer 8

• soft tissue procedures
• reconstuctive procedures
• salvage procedures

Question 9

Operative - soft tissue procedures

Answer 9

Hip adductor and psoas release with abduction bracing

• indications
  
  • children < 4 years and Reimers index > 40%
    
    • Consider for “at risk” hips (see chart above)
  • any evidence of progressive subluxation if less than 8-year-old
  • May also be used as a supplement to bone procedures

Question 10

Operative - reconstuctive procedures

Answer 10

proximal femoral osteotomy with shelf-producing (Dega) osteotomy and soft-tissue release

• indications
  
  • children > 4 years old or Reimers index > 60%
• best to treat all pathology at single stage if the patient has a severely dysplastic CP hip

Question 11

Operative - salvage procedures

Answer 11

• valgus support osteotomy (femoral head resection + valgus subtrochanteric femoral osteotomy (e.g McHale Technique)
  
  • indication
    
    • salvage technique for symptomatic and chronically dislocated hips in cerebral palsy
• Castle resection-interposition arthroplasty
  
  • indications
    
    • chronically dislocated hips, especially in the adult CP population
    • unable to walk, stand to transfer (GMFCS 5)
• total hip arthroplasty
  
  • indications
    
    • ambulatory patients and wheelchair bound who can stand to transfer
  • results
    
    • 85% 10 year survival in CP patients
• hip arthrodesis
  
  • indications
    
    • young patients
    • ambulatory patients and wheelchair bound who can stand to transfer
• Girdlestone procedure
  
  • indications
    
    • no longer performed because uniformly causes pain
      
      • caused by lack of interposition of soft tissue between cut femur and acetabulum leads to proximal femoral migration

Question 12

Hip adductor and psoas release with abduction bracing

Answer 12

• goals of treatment
  
  • prevent hip subluxation and dislocation
  • maintain comfortable seating
  • facilitate care and hygiene
  • >45 degrees of hip abduction after releases
• technique
  
  • begin with tenotomy of the adductor longus, sequentially release gracilis and adductor brevis as needed
  • release the psoas tendon either at the level of the insertion (non-ambulatory patients) or proximally at the pelvic brim in the myotendonous junction (ambulatory patients)
• complications
  
  • careful of obturator nerve if brevis release is needed
    
    • a neurectomy of the obturator nerve can cause an abduction contraction

Question 13

Proximal femoral osteotomy and soft-tissue release, possible acetabular osteotomy

Answer 13

• goals of treatment
  
  • hip containment in the severely dysplastic hip with progressive subluxation
  • single-stage osteotomies may have improved outcome
• technique
  
  • shortening varus derotational osteotomy to correct increased valgus and anteversion
  • may need pelvic osteotomy to correct acetabular dysplasia; the indications to combine pelvic osteotomy at the time of femur osteotomy remain controversial

Question 14

Valgus support osteotomy

Answer 14

(femoral head resection + valgus subtrochanteric femoral osteotomy (e.g McHale Technique)

• non-anatomic arthroplasty that relieves pain and improves hip abduction
• technique
  
  • anterolateral approach to remove femoral head and neck leaving ligamentum teres attached to acetabulum
  • perform a closing wedge subtrochanteric valgus-producing osteotomy and fix with lateral plate
  • attach ligamentum teres to psoas tendon or anterior capsule
  • the lesser trochanter will articulate with the dome of the acetabulum
• successfully relieves pain despite non-anatomic articulation

Question 15

Castle resection-interposition arthroplasty

Answer 15

technique

• resect proximal femur at the level of lesser trochanter (note the difference from a Girdlestone)
• oversew vastus over cut proximal femoral end
• oversew abductors, psoas and hip capsule over acetabulum
• this interposes a large mass of soft tissue between the acetabulum and proximal femur