Survivorship analysis of adductor surgery to prevent hip displacement in children with cerebral palsy.

Background: Hip adductor soft tissue surgery is the mainstay of so-called 'preventative surgery' in cerebral palsy. This surgery is designed for younger children showing early hip displacement as determined by migration percentage (MP), with the goal of preventing future hip dislocation or the need for reconstructive/salvage surgery. However, most previous studies have short follow-up periods, with the maximum mean in large cohort studies being 39 months. Objective(s): To assess the success rate ofhip adductor surgery in the prevention of hip displacement in children with cerebral palsy, hypothesising success would be related to Gross Motor Function Classification System (GMFCS) level. Study Design: Long term retrospective cohort with Cox proportional hazards survivorship analyses. Study Participants and Setting: This study included children with cerebral palsy (aged 2-10 years, preoperative MP 3050% on satisfactory quality AP hip radiography) whose index adductor release surgery was performed at a tertiary children's hospital between January 1994 and December 2004, and had a minimum 12 month follow-up. Materials/Methods: Age, gender, MP at index surgery, GMFCS level, and type of adductor release surgery (adductor release with or without hip flexor release and obturator nerve phenolisation/division) were analysed. The principal outcome variable was the time to 'failure' (the need for additional operative intervention such as revision soft tissue release, femoral osteotomy, salvage surgery or the development of painful subluxation or dislocation). Result(s): A total of 330 children were reviewed (33 GMFCS level II, 55 level III, 103 level IV and 139 level V). Mean age at index surgery was 4.2 years, MP 43.2%, and mean post-operative follow-up was 7.1 years (range 1-14 years). Eighty-two children had adductor longus and gracilis lengthening, 97 longus/gracilis/iliopsoas lengthening, 97 adductor release with psoas tenotomy and obturator nerve phenolisation, and 54 addu