summary Hip Conditions in Cerebral Palsy are caused by spasticity and present with a constellation of findings such as hip subluxation, hip dislocation, and hip joint degeneration. Diagnosis is made with hip radiographs to assess the percent of femoral head with no acetabular coverage using the Reimers migration index. Treatment can range from surgical soft tissue procedures to bony osteotomies depending age of patient, degree of spasticity and on severity hip subluxation. Epidemiology Incidence progressive hip subluxation occurs in up to 50% of children with spastic quadriparesis (cerebral palsy) incidence of subluxation by age 7 is higher in more severe forms of cerebral palsy GMFCS I: < 10% risk GMFCS II: 10-15% risk GMFCS III: 30-40% risk GMFCS IV: 50-60% risk GMFCS V: 70-80% risk Etiology Cerebral Palsy General Pathoanatomy 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 Classification Stages of Hip Deformity in Cerebral Palsy Characteristics Treatment Hip at risk Hip abduction of < 45° with partial uncovering of the femoral head on radiographs Reimers index < 33% Botox A into spastic muscles (age <3) to delay surgery Attempt to prevent dislocation with adductor release, psoas release, hamstring lengthening (age 3-4) Avoid obturator neurectomy Hip subluxation Reimers index >33% Disrupted Shenton's line Treat with adductor tenotomy if abduction is restricted. If persistent subluxation, proximal femur varus derotational osteotomy (age 5-6) Do pelvic osteotomies if acetabular insufficiency is present Spastic dislocation Frankly dislocated hip Reimers index >100% Open reduction with varus derotational osteotomy, + femoral shortening, and pelvic osteotomies Windswept hips Abduction of one hip with adduction of the contralateral hip Brace adducted hip with or without tenotomy and release abduction contracture of abducted hip Comparison of Spastic Hip Dysplasia and Developmental Dysplasia of the Hip Factor Spastic Developmental Findings at birth Hip usually normal Hip usually abnormal Age at risk Usually normal in 1st year of life; recognized after age 2 yr Most often recognized in 1st year of life Detection Radiographs needed in most cases Physical exam in most cases Etiology Spastic muscles drive femoral head out of normal acetabulum, pelvic obliquity Mechanical factors (breech), ligamentous laxity, abnormal acetabular growth Childhood progression Progressive subluxation common Progressive subluxation rare Natural history Pain in many subluxated/ dislocated hips by 2nd or 3rd decade Pain in many subluxated hips by 4th or 5th decade Acetabular deficiency Usually posterosuperior Usually anterior Early measures Muscle lengthening Pavlik harness or closed reduction Missed or failed early measures Hip osteotomies, often without open reduction Closed or open reduction, often without osteotomies (before 18mth of age) Salvage Castle resection-interposition arthroplasty Usually total hip arthroplasty Presentation Symptoms hip and/or groin pain difficulty with sitting difficulty with perineal care/hygiene Physical exam unreliable diagnostic assessment if used alone decreased hip ROM pain with hip motion gait difficulty due to lever arm dysfunction hip subluxation/dislocation rare in ambulatory patients thigh length discrepancy (hard to evaluate in setting of adductor contracture) may be seen - sometimes referred to as a "pseudogalleazi sign" Evaluation 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 Treatment Nonoperative observation mild cases Physical therapy never shown to prevent hip subluxation Abduction bracing alone does not reduce dislocations and may cause windswept deformity Operative - soft tissue procedures 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 Operative - reconstuctive procedures 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 Operative - salvage procedures 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 Techniques Hip adductor and psoas release with abduction bracing 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 higher rate of treatment failure in patients with >40% hip subluxation percentage Proximal femoral osteotomy and soft-tissue release, possible acetabular osteotomy 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 Valgus support osteotomy (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 Castle resection-interposition arthroplasty 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 Complications Osteonecrosis of femoral head incidence 1-11% Heterotopic Ossification prevention radiation on the second or third postoperative day more effective than anti-inflammatory medications Insufficiency factures incidence ranges from 4-29% may be seen in distal femur following postoperative Spica casting Abduction contracture may occur with neurectomy of anterior branch of obturator nerve during adductor releases Prognosis 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%