The hip joint is where the femoral head (the top of the femur) meets the pelvis. In anatomy, the word “version” refers to the angle or rotation of all or part of an organ, bone or other structure in the body, relative to other structures in the body. Retroversion refers to an abnormal backward rotation of the hip relative to the knee. This condition can affect patients of all ages and  leads to abnormal stress in the low back, hip and knee and abnormal gait. 

Femoral retroversion is a rotational or torsional deformity in which the femur twists backward (outward) relative to the knee. The opposite condition, in which the femur has an abnormal forward (inward) rotation, is called femoral anteversion. 

The condition is usually congenital, meaning children are born with it. In many cases, the child may grow out of it. In cases where the child does not grow out of femoral retroversion, the condition may be mild enough not to cause any significant health challenges. However, in excessive cases, surgery may be needed to correct the rotation. Torsional deformity can also occur after a fracture where the bone heals with deformity or malunion.

What Is Femoral Retroversion?

Femoral retroversion is a condition in which the femoral neck is rotated backward in relation to the femoral shaft. This means the hip is twisted backward (posteriorly) in relation to the knee. Because the lower part of the femur is connected to the knee, this also means that the knee is twisted outward relative to the hip. Femoral retroversion is also often called hip retroversion.

Femoral retroversion can occur in one or both legs. In some cases, hip/femoral retroversion may be combined with a separate torsional deformity, such as a rotation in the tibia.

Causes of Femoral Retroversion

The exact cause of femoral retroversion is unknown. Femoral retroversion is often a congenital condition, meaning it is present from birth and develops in the womb. It also appears to be related to the position of the baby as it grows in the womb.

Femoral retroversion often runs in families, which may indicate that some children have a higher risk of being born with this condition. Femoral retroversion can also occur after a physical trauma such as a femur fracture.

Symptoms of Femoral Retroversion

The first symptom of femoral retroversion is usually a visual recognition of the rotated femur. However, in some cases, this may be difficult to identify, especially if femoral retroversion is combined with a separate rotation deformity such as tibial torsion.

Symptoms of femoral retroversion may include:

• Out-toeing or “duck walk” – walking with the foot pointed outward instead of straight ahead
• Learning to walk late (in children)
• Flat Feet
• Difficulty with running
• Fatigues easily with physical activity
• Poor balance or coordination
• Hip and knee pain
• Low back pain
• Degeneration or arthritis of the hip

Diagnosing Femoral Retroversion 

If the doctor suspects a femoral retroversion, he will conduct a physical examination of the legs and hips in addition to a thorough medical, developmental and family history. The doctor will also observe the patient’s gait (manner of walking) to look for signs of out-toeing or gait compensation. He may also order an X-ray or CT scan to look for possible deformities. Diagnosing femoral retroversion can sometimes be difficult, as the common positioning used for X-ray imaging may not reveal a rotation in the femoral neck. 

If the individual also has a separate rotational bone deformity such as internal tibial torsion – an inward rotation of the tibia (shinbone) – then femoral retroversion becomes even more difficult to diagnose. This is because opposite, incorrect rotations of the femur and tibia often leave the feet parallel during walking, which often makes the misalignment of the hips and knees go unnoticed.

How is femoral retroversion treated?

Many children born with femoral retroversion grow out of it. For those who do not grow out of it, a mild femoral retroversion may not cause any significant issues.

However, an excessive femoral retroversion can place stress on hip and knee joints, often leading to joint pain and abnormal wear. In these situations, a surgical procedure known as a femoral osteotomy may be used. This surgery includes cutting and realigning the femur.

In some cases, the doctor may perform a less invasive version of a femoral osteotomy. In this type of surgery, the femur bone is cut through a portal and an intramedullary rod is inserted into the marrow cavity of the bone.  Thus, a normal rotation between the hip and the knee is established, correcting the torsional deformity. This procedure may be done for children over age 10 and adults and has a quick and reliable recovery.