Congenital coxa vara: Computed tomographic analysis of femoral retroversion and the triangular metaphyseal fragment

Three patients with congenital coxa vara studied with two- and three-dimens ional computed tomographic (2DCT and 3DCT) methods are reported. In all cas es, the femoral retroversion was documented and subsequently corrected by p roximal femoral osteotomy. In two patients with isolated coxa vara, the phy seal-femoral neck angle was decreased as seen in slipped capital femoral ep iphysis in adolescents. Our studies suggest that the triangular metaphyseal fragment reflects a Salter-Harris type II separation pattern through the d efective femoral neck. The epiphysis and attached triangular fragment slip from the normal superoanterior portion of the neck in an inferior-posterior direction. The treating surgeon should be aware of the often marked femora l retroversion component present in severe congenital coxa vara. This knowl edge allows surgical planning for corrective osteotomies that will better n ormalize hip mechanics. A combination of marked valgus and flexion with int ernal rotation of the distal fragment are required to fully correct the def ormity.