Femoral torsion is the rotation of the proximal portion of the femur on its longitudinal axis in relation to the transverse plane of the knee. Femoral anteversion is the extreme twisting of the femoral neck anteriorly relative to the femoral condyles. Femoral retroversion is the extreme twisting of the femoral neck posteriorly relative to the femoral condyles.

In utero and postnatal positioning of the legs and hips produces stresses that bring about these rotational deformities of the femoral neck. The true incidence of anteversion and retroversion is not known, but the former is much more common and occurs twice as frequently in girls as in boys.

Femoral anteversion produces kissing knees, toeing-in, and a clumsy gait. With the patella in neutral position, the greater trochanter of the femur lies posterior to the lateral, longitudinal midthigh line. External rotation is decreased and internal rotation of the hip in extension is increased (normally 35 to 45 degrees for both). External rotation of the hip in flexion is normal, however. The findings in retroversion are the opposite of those found in anteversion of the femoral neck. Imaging is only required in cases of extreme anteversion or retroversion.

A simple measure that can be employed by the primary care physician early on for parental concern over toeing-in is to have the child learn to sit in the tailor, modified lotus, or Indian-style sitting position. The use of Denis Browne splints is contraindicated, and corrective shoes are of no value.

Most femoral torsion deformities correct themselves by 7 years of age. If they do not follow the typical pattern of improvement with growth, then an orthopedist should be consulted because the persistence of these deformities may lead to degenerative arthritis of the hip joint. Referral for evaluation should also be made if a child has extreme rotation, especially when associated with difficulty walking or running, or when significant asymmetry of the anteversion exists. Orthopedic treatment consists of the use of a bivalve lower-trunk and leg cast during sleeping hours or, in rare cases, a derotation osteotomy of the middle or lower femoral shaft.