Remodeling of the proximal femur after varus osteotomy in children with cerebral palsy.

The purpose of this study was to determine and measure the factors that affect the remodeling of the proximal femur after varus osteotomy in children with spastic cerebral palsy (CP). Seventy-five varus proximal osteotomies were performed on 44 children (26 females, 18 males) for hip dysplasia. Thirty-nine patients had spastic CP and five had spastic diplegia; 35 patients used a wheelchair for mobility and nine could walk. Mean age at time of surgery was 8 years (SD 4 years), range 2 years 6 months to 15 years. Preoperative, immediate postoperative, and follow-up (0 to 6 months, 6 months to <1 year, 1 year to <2 years, 2 years to <4 years, 4 years to <6 years, and 6 years to <8 years) radiographs were reviewed. Neck-shaft angles were measured. Correlations to examine the relationship between age at time of surgery and ambulatory status with postoperative changes in neck-shaft angles were reviewed. Remodeling of the proximal femur does occur after varus osteotomy as long as the physes of the proximal femur show growth potential. Remodeling was quite variable between patients: children younger than 4 years old at the time of surgery remodeled more than children who were older than 4 years. Ambulatory status has little effect on the magnitude of remodeling. This study reinforces the need to follow these patients with periodic hip radiographs until completion of growth.