Proximal femoral deformity is common in children with cerebral palsy (CP), contributing to hip instability and ambulation difficulties. This population-based cohort study investigates the prevalence and significance of these deformities in relation to Gross Motor Function Classification System (GMFCS) level. Children with a confirmed diagnosis of CP born within a three-year period were identified from a statewide register. Motor type, topographical distribution and GMFCS level were obtained from clinical notes. Neck Shaft Angle (NSA) and Migration Percentage (MP) were measured from an anteroposterior pelvis x-ray with the hips internally rotated. Measurement of FNA was by the Trochanteric Palpation Test (TPAT) or during fluoroscopic screening of the hip with a guide wire in the centre of the femoral neck. Linear regression analysis was performed for FNA, NSA and MP according to GMFCS level. 292 children were eligible. FNA was increased in all GMFCS levels. The lowest measurements were at GMFCS levels I and II p<0.001. GMFCS levels III, IV, and V were uniformly high p<0.001. Neck shaft angle increased sequentially from GMFCS levels I to V (p<0.001). This study confirms a very high prevalence of increased FNA in children with CP in all GMFCS levels. In contrast, NSA and MP progressed step-wise with GMFCS level. We propose that increased FNA in children with CP represents failure to remodel normal fetal alignment because of delay in ambulation and muscle imbalance across the hip joint. In contrast, coxa valga is an acquired deformity and is largely related to lack of weight bearing and functional ambulation. The high prevalence of both deformities at GMFCS levels IV and V explain the high rate of displacement in these hips and the need for proximal femoral realignment surgery in the prevention and management of hip displacement.
This study evaluates outcomes of hip adductor surgery in children with cerebral palsy in preventing hip displacement. This review is from the perspective of an extended follow-up (beyond 3 years in contrast to currently available literature) and the Gross Motor Function Classification System (GMFCS). A retrospective audit was performed of children with cerebral palsy aged 2 to 10 years who had primary adductor surgery at the Royal Children’s Hospital Melbourne between January 1994 and December 2004. These children had hip migration percentages (MP) greater than 30% and been followed up for a minimum 12 months post-operatively.
There is much debate about the nature and extent of deformities in the proximal femur in children with cerebral palsy. Most authorities accept that increased femoral anteversion is common, but its incidence, severity and clinical significance are less clear. Coxa valga is more controversial and many authorities state that it is a radiological artefact rather than a true deformity. We measured femoral anteversion clinically and the neck-shaft angle radiologically in 292 children with cerebral palsy. This represented 78% of a large, population-based cohort of children with cerebral palsy which included all motor types, topographical distributions and functional levels as determined by the gross motor function classification system. The mean femoral neck anteversion was 36.5° (11° to 67.5°) and the mean neck-shaft angle 147.5° (130° to 178°). These were both increased compared with values in normally developing children. The mean femoral neck anteversion was 30.4° (11° to 50°) at gross motor function classification system level I, 35.5° (8° to 65°) at level II and then plateaued at approximately 40.0° (25° to 67.5°) at levels III, IV and V. The mean neck-shaft angle increased in a step-wise manner from 135.9° (130° to 145°) at gross motor function classification system level I to 163.0° (151° to 178°) at level V. The migration percentage increased in a similar pattern and was closely related to femoral deformity. Based on these findings we believe that displacement of the hip in patients with cerebral palsy can be explained mainly by the abnormal shape of the proximal femur, as a result of delayed walking, limited walking or inability to walk. This has clinical implications for the management of hip displacement in children with cerebral palsy.
