The femoral head is the top part of the thighbone (femur), the largest bone in the leg. The femoral head may be twisted (called torsion) either internally (the knees point toward each other with toes in) or externally (the knees point in opposite directions). The twisting appears to be related to the position the baby is in while it is growing in the uterus. Because it often runs in families, some people may be genetically predisposed to this condition. Twisting of the femoral head is common among newborns.
Doctors can detect this birth defect by laying the infant on an examining table and rotating the hips in different directions, noting whether movement is limited.
By adolescence, internal torsion tends to gradually decrease without treatment. Consultation with an orthopedist and surgery are usually needed for children who have a spinal defect, such as spina bifida, or those in whom the torsion interferes with the ability to walk.
External torsion typically corrects itself, especially after the child begins to stand and walk. However, consultation with an orthopedist is needed if external torsion persists after age 8 because at that point the child may need surgery to correct it.