Coxa Vara

Coxa vara has been classified by Beals as developmental, congenital, or traumatic. It can result from disturbances to a variety of structures about the growing proximal femur. Infantile or developmental coxa vara is estimated to affect 1:25,000 live births. It is bilateral in about 1/3 of cases. Clinically, there is shortening of the limb in the 2 cm range, with weakness of the abductors and thigh atrophy. Radiographically, developmental coxa vara is characterized by a triangular metaphyseal fragment of the inferior femoral neck. This is in an "inverted Y' pattern and is diagnostic of developmental coxa vara. The natural history of developmental coxa vara is variable, and appears related to the Hilgenreiner physeal angle, or sometimes simply the physeal angle. This is the angle between a line along the physis and the floor line (which Hughes felt was more accurate) or a line between the triradiate cartilages. Obviously, the greater the angle, the more propensity toward shear stress on the physis, and the less chance of spontaneous recovery. Proximal femoral osteotomy is the only effective intervention, and sufficient valgus must be achieved to reduce shear forces along the physis.