Femoral anteversion and neck-shaft angles in hip instability in cerebral palsy.

A consecutive sample of 411 hip roentgenograms in 215 patients with cerebral palsy was evaluated. Femoral anteversion and neck-shaft angles were measured and compared with hip stability indexes to determine which of the two angles is more important in hip instability. The correlation coefficients were higher and statistically significant for femoral anteversion and lower and statistically nonsignificant for neck-shaft angles. These findings suggest that increased femoral anteversion has greater correlation than increased coxa valga with hip instability in cerebral palsy patients and therefore should be addressed primarily when surgically treating these hips.