Toeing-in and toeing-out are frequently seen at all ages and are caused by a variety of conditions affecting the feet, ankles, legs, knees, and hips. In-toeing is more common than out-toeing and is more likely to be caused by benign conditions. Protective or compensatory shifting of the body weight to the middle or outside of the foot in pronation and knock-knee, both normal developmental stages, is the most common cause of toeing-in and corrects itself in time. Developmental bowing of the legs, also self-correcting, may lead to temporary toeing-in. Talipes equinovarus and metatarsus varus are associated with toeing-in. Spasticity of the internal rotator muscles of the hip, as seen in cerebral palsy, produces toeing-in, as does anterior maldirection of the acetabulum.

Toeing-out is seen with calcaneovalgus and pes planovalgus. Flaccid paralysis of the internal rotator muscles of the hip results in toeing-out. Posterior maldirection of the acetabulum produces toeing-out.

The remaining causes of both conditions are related to internal or external torsion of the tibia and femur. In general, with toeing-in, if the child's patellae are noted to be rotated inward (kissing knees) while walking, then the underlying problem is above the knee; if they face straight forward, then the underlying problem is below the knee.[12]