# DDH and Cerebral Palsy Hip - Complex Reconstruction ## Clinical Scenario An 8-year-old girl with spastic diplegic cerebral palsy (GMFCS level IV) presents with progressive right hip pain and difficulty with sitting. X-rays show bilateral hip subluxation with migration percentage 60% on the right and 40% on the left. The right hip has early signs of femoral head deformity. ## Questions & Model Answers Natural history of hip displacement in CP: 1) Incidence - overall 30-35% develop hip displacement, GMFCS IV-V up to 70-90%, 2) Progression - migration percentage increases approximately 5-7% per year if untreated, 3) Consequences - pain (most common indication for surgery), sitting difficulties, perineal hygiene problems, scoliosis, 4) Surveillance - hip surveillance programs recommend annual X-rays for at-risk patients. Intervention thresholds: Soft tissue release (adductor/psoas) - MP 33-40% in young child, Reconstructive surgery - MP >40-50% or progressive, Salvage surgery - established dislocation with significant head deformity. This patient with MP 60% and pain requires reconstruction. **Key Points:** - GMFCS IV-V highest risk (70-90%) - MP increases ~5-7%/year untreated - Reconstruction indicated MP >40-50% - Surveillance programs reduce need for salvage surgery Hip reconstruction in CP - combined procedure: 1) Soft tissue releases - adductor longus +/- brevis tenotomy, psoas lengthening (at lesser trochanter to preserve hip flexion power), 2) Femoral osteotomy - varus derotation shortening osteotomy (VDRO), correct valgus (aim neck-shaft 120-130°), correct anteversion (aim 10-15°), shortening reduces tension on repair, fixed with blade plate or locking plate, 3) Pelvic osteotomy - Dega or San Diego acetabuloplasty (periacetabular osteotomies), redirect acetabulum laterally and anteriorly, bone graft to hold position, 4) Consider bilateral surgery if both hips displaced - reduces total anaesthetics in medically complex patient. Post-operative: spica cast 6 weeks, then bracing/seating optimisation. **Key Points:** - Combined femoral + pelvic osteotomy most effective - VDRO corrects valgus and anteversion - Dega/San Diego periacetabular osteotomies - Consider bilateral single-stage if appropriate Salvage options for established CP hip dislocation with head deformity: 1) Proximal femoral resection (Girdlestone) - remove proximal femur, interposition (capsule/tensor fascia), allows decompression and easier positioning, 2) Valgus osteotomy (McHale) - converts painful abducted hip to painless abducted position, maintains femoral head contact, 3) Total hip arthroplasty - rarely indicated, only for higher functioning patients (GMFCS I-II), high complication rates in CP, 4) Hip arthrodesis - rarely performed, limits positioning, 5) Subtrochanteric resection with interpositional arthroplasty. Selection based on: patient function (GMFCS level), pain location, family/caregiver expectations. Proximal femoral resection most common salvage in GMFCS IV-V - provides pain relief in 80-90%. **Key Points:** - Proximal femoral resection most common salvage - 80-90% pain relief with resection - THA only for high-functioning CP patients - Goal is comfort and positioning, not mobility Hip surveillance in CP: Rationale: Early detection allows preventive soft tissue surgery, avoiding need for complex reconstruction or salvage. Key components: 1) Regular clinical examination - hip ROM (especially abduction <30° concerning), pain assessment, 2) Radiographic monitoring - AP pelvis X-rays at regular intervals, measure migration percentage (MP), Reimers index. Surveillance protocols (Australian CP Hip Surveillance - CPIPS): GMFCS I - baseline at 24 months, discharge if normal, GMFCS II - annual X-rays until 7 years, GMFCS III - 6-monthly X-rays until 7 years then annually, GMFCS IV-V - 6-monthly X-rays ongoing (highest risk). Intervention thresholds: MP >30% - consider soft tissue release, MP >40% - consider reconstruction, MP increasing >10%/year - urgent review. Evidence for surveillance: Australian data shows surveillance programs reduce rate of salvage surgery from 10% to <1%. This patient's bilateral subluxation highlights need for systematic surveillance. **Key Points:** - GMFCS IV-V require 6-monthly X-rays - Migration percentage key measurement - Surveillance reduces salvage surgery rate - MP >40% indicates need for reconstruction Postoperative management: Immediate: 1) Pain management - epidural or regional block beneficial, multimodal analgesia, 2) Spica cast immobilisation for 6 weeks (maintains correction, protects osteotomies), 3) DVT prophylaxis not routinely needed in children, 4) Early nutrition optimisation. Rehabilitation: 1) Post-cast physiotherapy for ROM and strengthening, 2) Seating optimisation - appropriate wheelchair positioning, 3) Standing frame programs, 4) Bracing considerations. Complications: 1) Residual hip dysplasia/subluxation (may need further surgery), 2) AVN of femoral head (5-10%) - especially with excessive shortening, 3) Implant prominence requiring removal, 4) Wound complications (higher in non-ambulatory patients), 5) Heterotopic ossification, 6) Stiffness/decreased ROM, 7) Recurrent displacement (5-15%) - may need revision, 8) Pelvic obliquity from residual contractures. Success defined as: MP <33%, pain relief, improved seating/positioning. **Key Points:** - Spica cast for 6 weeks standard - AVN risk 5-10% - Seating and positioning goals paramount in GMFCS IV-V - Recurrence 5-15% - surveillance continues GMFCS influence on management: GMFCS I-II (ambulatory): Goal is pain-free, mobile hip for walking, THA may be considered in adulthood for secondary OA, tendon transfers may help gait pattern. GMFCS III (limited ambulation): Balance between walking function and positioning, reconstruction strongly favoured over salvage, may transition to wheelchair use over time. GMFCS IV-V (non-ambulatory): Primary goals are comfort, positioning, and hygiene, reconstruction preferred to prevent pain and hip displacement, salvage procedures (proximal femoral resection) acceptable if reconstruction fails. Long-term outcomes: After hip reconstruction: 85-90% maintained reduction at 5 years, 80-85% pain-free, Quality of life improvement in non-ambulatory patients with maintained hip position. Factors predicting success: 1) Earlier intervention (MP <60% at surgery), 2) Younger age, 3) Adequate acetabular coverage achieved, 4) Good postoperative positioning. For this patient (GMFCS IV): goal is comfortable, contained hip for seating, reconstruction indicated to avoid progression to painful dislocation. **Key Points:** - GMFCS level determines functional goals - Non-ambulatory: comfort and positioning primary goals - 85-90% maintain reduction at 5 years - Earlier intervention = better outcomes ## Exam Tips **Opening Statement:** This child with spastic diplegic CP (GMFCS IV) has bilateral hip subluxation requiring intervention. The right hip with MP 60% and pain requires reconstruction with combined femoral and pelvic osteotomy. **Common Pitfalls:** - Don't delay reconstruction until salvage is only option - Hip surveillance programs essential in CP - Consider both hips - bilateral surgery may be appropriate