Hip adduction/abduction deformity and apparent leg-length inequality.

The amount of apparent leg-length inequality attributable to given angles of hip adduction/abduction has been expressed quantitatively. The inequality is related to the sine of the angle of adduction/abduction and the distance between the centers of the femoral heads. In a study of 50 adults, the mean figure for this distance in men and women was 18.6 cm. As a rough guide, each 10 degrees of deformity up to 40 degrees produce approximately 3 cm of inequality.