Proximal Femoral Geometry Before and After Varus Rotational Osteotomy in Children With Cerebral Palsy and Neuromuscular Hip Dysplasia

BACKGROUND:Surgical management of hip dysplasia in children with cerebral palsy (CP) usually includes varus rotational osteotomy (VRO) of the proximal femur. Several techniques of VRO (end-to-end, EE; end-to-side, ES) have been designed to maximize correction and minimize associated deformities. The goals of the current study were to establish the prevalence and contribution of caput valgum to coxa valga deformity in children with CP, compare the geometry of the proximal femur after EE and ES techniques of VRO, and document the response of the proximal femur to subsequent growth after VRO. METHODS:The records of 75 children with CP (Gross Motor Function Classification System, levels IV and V) with 137 surgically treated hips were retrospectively reviewed. Outcomes were limited to the technical domain (eg, radiographic measurements and surgical complications). Measurements made for each hip (preoperative, operative, and follow-up) included the neck-shaft angle (NSA), head-shaft angle (HSA), and the medialization index. RESULTS:The mean age at the time of surgery was 7 years. The mean follow-up was 5 years and 6 months. Caput valgum was present in all hips, increasing the actual geometric valgus by a mean of 10%. The ES technique was more effective at medializing the femoral shaft; however, this benefit was lost with growth (P=0.891). The ES technique was more effective at achieving and maintaining correction of the NSA (P=0.026). Maintenance of correction of the HSA was comparable for both ES and EE surgical techniques (P=0.099). Subsequent growth of the proximal femur resulted in loss of correction of the NSA (mean 29%) and HSA (mean 21%). DISCUSSION:Caput valgum is usually present in children with CP who are undergoing surgical hip reconstruction. The ES technique is a reasonable alternative for the correction of neuromuscular hip dysplasia associated with extreme coxa valga and long femoral necks. Recurrence of coronal plane deformity with growth after VRO is common, and further study is required to determine how best to control this phenomena. LEVEL OF EVIDENCE:Level IV—therapeutic.