Version or torsion is when there is a twist in the bone. Femoral anteversion occurs when the thigh bone (known as the femur) turns inward. It is normal to have a larger amount of anteversion at birth, and this slowly improves with growth and development. In infants, the hips naturally turn outwards and the soft tissues are tight in this direction, and so often times the severity of femoral anteversion is not appreciated until about 18 months of age when the soft tissues are loosened by walking motion.
The upper end of the femur is composed of two parts – the shaft or longer part of the bone and the femoral head and neck. As mentioned above, the femoral anteversion changes with time as the child develops. When development is completed, the neck and head are turned in approximately 15 degrees in relationship to the shaft of the bone. When the internal rotation is greater than this (such as if the angle was 30 or 40 degrees), this is labeled as femoral anteversion.
Femoral anteversion can occur before birth when the legs internally rotate to fit in the womb. Femoral anteversion can also occur in combination with other deformities of the thigh bone. Although the focus of this article is when femoral anteversion occurs on its own, it is also a very important factor when it occurs as a component of a more complex deformity.
Femoral anteversion can cause a patient to walk with their toes pointing inward (called in-toeing or “pigeon-toed”) instead of pointing straight ahead. With femoral anteversion, the knees point inward while walking. The feet may also point inward or they may point straight.
In-toeing from femoral anteversion is most often noticed by parents six months or later after walking starts. It is usually painless. Children may appear clumsy, trip often, and run awkwardly. Children with femoral anteversion often sit in the “W” position, with their knees bent and feet next to their hips.
When femoral anteversion is associated with external tibial torsion (outward twist of the tibia or lower leg bone), there can be knee problems such as patellar (knee cap) instability and pain, particularly when the child reaches the adolescent age range. Into adulthood this deformity can cause significant issues in the knee and hip. Patients will often decrease their activity in order to avoid the symptoms that are caused by anteversion.
Doctor Examination (physical exam, imaging studies, tests)
Your doctor will exam your gait or how you walk. They will also examine the lower extremities for range of motion and pain, and they will assess the rotation of the femur and tibia generally with the patient face down.
The majority do not require imaging, but imaging studies such as x-rays can be useful to detect related problems such as knock knees and knee cap positioning issues. Occasionally an MRI or CT scan may be obtained to further evaluate the rotation of the femurs and tibias, particularly in preparation for surgery. This is because rotation of the bones cannot be measured on an x-ray, but they can be measured accurately with these other types of imaging.
Femoral anteversion usually improves on its own as children grow. Special shoes, braces, orthotics or exercises to not help. Most femoral anteversion improvement occurs by the age of 10 or 11 years.
In rare cases, where femoral anteversion does not improve adequately on its own AND there are issues with tripping, walking, or pain, surgery may be suggested. Surgery involves cutting the femur (an osteotomy) and turning it outwards. The bone can be held in position while it heals with wires, plates, screws, a nail, or an external fixator depending on patient age and any other deformities which are present. Surgery is usually reserved for older children and adult patients. Patients can have more trouble with anteversion when they reach adulthood.
Femoral anteversion can also occur in conjunction with other deformities of the thigh bone, or after trauma, and in these instances, it can cause more symptoms and is more likely to be treated with surgery.