Varus knee or bow-leggedness is a deformity marked by medial angulation of the leg in relation to the thigh, an outward bowing of the legs, giving the appearance of a bow. It is also known as bandy-leg, bowleg, bow-leg, and tibia vara. Usually there is an outward curvature of both femur and tibia.
If a child is sickly, either with rickets or suffering from any ailment that prevents the due ossification of the bones, or is improperly fed, the bowed condition may remain persistent. Thus the chief cause of this deformity is rickets. Skeletal problems, infection, and tumors can also affect the growth of the leg, sometimes giving rise to a one-sided bow-leggedness. The remaining causes are occupational, especially among jockeys, and from physical trauma, the condition being very likely to supervene after accidents involving the condyles of the femur.