Cerebral Palsy — Adductor Release for Hip Subluxation

Indication. Symptomatic, progressive hip displacement in a child with cerebral palsy, shown by a rising migration percentage (Reimers) on serial AP pelvis radiographs and/or loss of functional abduction, that has not responded to optimised tone management (oral baclofen, botulinum toxin). The classic trigger is a migration percentage greater than 30 to 40 percent, or functional abduction less than 20 to 30 degrees with the hip extended that compromises seating, perineal hygiene or transfers. Absolute indications

• Progressive hip subluxation with migration percentage greater than 30 to 40 percent on serial surveillance radiographs despite optimised tone management.
• Abduction less than 20 to 30 degrees with the hip extended, producing inability to maintain seating or perform perineal hygiene.
• Painful spastic hip with radiographic displacement that limits quality of life or nursing care.
• Established dislocation in a non-ambulatory patient when reduction and containment are still feasible, usually before skeletal maturity. Relative indications
• Borderline migration (25 to 35 percent) with rapidly increasing tone or loss of abduction on serial examinations.
• Ambulatory patient with deteriorating Trendelenburg gait and abduction less than 20 degrees.
• Pre-operative optimisation before planned femoral or pelvic osteotomy in a child with established displacement.
• Severe adductor spasticity interfering with orthotic wear or therapy participation. Contraindications. Absolute: a fixed abduction contracture greater than 30 degrees (release would worsen function); active infection or untreated pressure sores in the groin or perineum; a non-reducible dislocation with severe acetabular deficiency where containment is no longer possible. Relative: very young age (less than 3 to 4 years) unless migration is rapidly progressive — trial tone management first; severe osteopenia with high fracture risk during positioning; medical comorbidities that preclude safe anaesthesia for a combined procedure. The one decision that matters — soft tissue alone, or add bone? Every plan begins with the same medial groin release; the real choice is whether the displacement is advanced enough to need bony containment at the same sitting:

Consent specifically for incomplete abduction gain, over-release with abduction contracture, obturator or medial femoral cutaneous nerve injury, wound dehiscence, heterotopic ossification, recurrent subluxation needing bony reconstruction, and the frequent need for combined femoral and pelvic osteotomy in established displacement. Setup. Supine on a radiolucent table with both hips prepared and draped free (to compare abduction and allow bilateral release). A small sandbag under the ipsilateral buttoick opens the medial groin; the image intensifier is set for AP pelvis views to confirm migration percentage. General anaesthesia with muscle relaxation, with caudal or epidural analgesia for bilateral cases, and routine antibiotic prophylaxis.

The goal is to restore a painless, stable hip with enough abduction for seating and hygiene by selectively releasing the spastic adductors and lengthening the iliopsoas through the medial groin approach — protecting the anterior obturator nerve, the medial femoral circumflex artery and the hip capsule throughout, and stopping the instant the target abduction is reached. The exposure is laid out in full as the first steps of the sequence below (and in depth on the medial approach to the hip page).

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Rehabilitation | Phase | Timing | Weight-bearing | Therapy | |-------|--------|----------------|---------| | 1 | 0-2 weeks | As tolerated for isolated release; non or partial for 6 weeks if combined with femoral osteotomy | Abduction positioning 30 to 40 degrees at all times; finger active motion only | | 2 | 2-6 weeks | Continue | Gentle passive and active-assisted abduction and flexion within the safe range; wound check at 48 hours | | 3 | 6-12 weeks | Progress, or protected per fixation | Strengthening, gait training and sitting balance; transition to night abduction brace | | 4 | 3-6 months | Full | Return to therapy and orthotic programme; surveillance radiographs at 3, 6 and 12 months | Maintain 30 to 40 degrees of abduction with pillows or a brace whenever the child is not mobilising, but avoid forced abduction greater than 40 degrees — it risks obturator nerve stretch and wound dehiscence. Use multimodal analgesia (caudal or epidural infusion for 48 to 72 hours, paracetamol, NSAIDs if renal function permits, opioids as needed) and optimise nutrition early, especially in gastrostomy-dependent children. Continue surveillance radiographs every 6 months until skeletal maturity. Special cases. Perform bilateral release in a single sitting when the child is medically stable to avoid two anaesthetics; stage 2 to 4 weeks apart if there is significant respiratory or nutritional compromise. When bony reconstruction is combined, do the adductor release first to allow safe positioning, close the medial incision, then turn to the lateral approach for the femoral varus derotation osteotomy and pelvic osteotomy, and protect with a spica cast or abduction brace for 6 to 12 weeks depending on fixation stability. Complications

Why the hip subluxes. Spastic hip displacement in cerebral palsy is driven by sustained adductor and flexor spasticity overpowering the immature acetabulum, with the femoral head migrating laterally and proximally. Early identification of a migration percentage greater than 30 percent allows soft-tissue release before irreversible acetabular dysplasia develops; delaying surgery until migration exceeds 50 percent or dislocation occurs significantly reduces the success of containment procedures.

Evidence for soft-tissue release. Isolated adductor release reduces migration percentage by 10 to 20 percent in early subluxation (less than 40 percent) and improves abduction by 15 to 25 degrees in most series; success is highest when performed before 5 to 6 years of age and when combined with iliopsoas lengthening and post-operative abduction positioning. In established displacement greater than 40 percent, soft-tissue release alone fails to maintain containment in greater than 60 percent of cases at 5 years, so bony reconstruction is required. Adding femoral varus derotation osteotomy achieves stable containment in 70 to 85 percent of children with migration 40 to 60 percent, and adding a pelvic osteotomy (Dega, Salter or Pemberton) further improves acetabular coverage and reduces the redislocation risk to less than 15 percent at 10 years. The consistent message across series — release early, release selectively, preserve the anterior obturator nerve, and add bone when displacement is established — is why nerve-sparing selective release is the standard and a perennial viva favourite.