What is Proximal Femoral Focal Deficiency?
The femur or thighbone is the long bone present in your leg. It connects the hip and the knee joint. Proximal femoral focal deficiency is a rare birth defect of the lower limbs affecting young children. It is characterized by partial absence of the proximal femur which is the upper part of the thighbone. The proximal femur articulates with the socket of the hip joint called the acetabulum.
Proximal femoral focal deficiency results in shortening of the entire lower limb and a prominent leg length discrepancy. It typically affects only one of the lower limbs.
What are the Causes of Proximal Femoral Focal Deficiency?
The exact cause of proximal femoral focal deficiency is not known. Consumption of certain drugs during pregnancy may lead to a birth deformity in the baby.
Some other causes that may contribute to proximal femoral focal deficiency may include:
- Abnormal fetal development
- Genetic defect
- Bone infection
- Trauma
- Severe burn
- Exposure to toxic radiation
What are the Signs and Symptoms of Proximal Femoral Focal Deficiency?
The signs and symptoms of proximal femoral focal deficiency may include:
- Femur is short and possibly twisted or bent since birth
- Leg length discrepancy
- Unstable hip and/or knee joint
- Abnormal gait (walking style)
- Tripping during walking or running activities
- Lack of free movement or limited range of motion
How is Proximal Femoral Focal Deficiency Diagnosed?
You should consult an orthopedic surgeon specializing in knee or hip disorders or a specialist in lower limbs. The doctor will review your child’s medical history, family history, and examine your child’s external symptoms such as bone deformity, leg length discrepancy, and abnormal gait. In addition, strength of the muscles in the lower limbs and range of motion will also be checked. Imaging tests such as X-ray, ultrasonography, and MRI (magnetic resonance imaging) scan may also be recommended to confirm the diagnosis and develop a treatment plan best suited for your child.
What are the Treatment Options for Proximal Femoral Focal Deficiency?
Proximal femoral focal deficiency can be treated with timely diagnosis and a customized treatment plan. The choice and length of treatment will depend on your child’s age and leg condition. Each child is unique and will benefit from a customized multidisciplinary approach that combines non-operative and surgical treatment to maximize joint function.
The first choice of treatment is usually the conservative approach. If non-surgical methods do not yield desired results, then your doctor would recommend surgery.
Non-Surgical Treatments
- Orthotic devices such as insoles, knee braces, and crutches to provide walking support
- Physical therapy in the form of exercises and massage
- Pain relief injections into the affected joint to suppress the pain and inflammation
- Immobilization by a cast or splint to allow the affected leg to rest
Surgical Treatment
The first step is to ensure that your child is old enough to undergo surgical treatment. The different surgical options may include:
- Limb-lengthening,
- Knee arthrodesis
- Femoral arthrodesis
- Rotationplasty
- Partial amputation
Limb Lengthening
Limb lengthening is a reconstructive procedure where the deformed bone is straightened or missing bone is replaced. The process of increasing the bone length depends on tissue and bone regeneration. When the bone is pulled apart, it tends to regenerate at the rate of approximately 1 mm per day.
Femoral Arthrodesis
Femoral arthrodesis involves fusion of the proximal femur with the pelvis. The surgeon makes a small incision in your child’s leg and may remove some portion from the femur and the surrounding muscles. The prepared bone is then connected to the pelvis using rods, screws, plates, or pin. This provides stability to the hip joint and improves mobility.
Knee Arthrodesis
Knee arthrodesis involves the fusion of the thigh bone (femur) to the shin bone (tibia). This results in a stable knee joint and better coordination of the knee muscles with the hip joint. It is performed for children aged 2-3 years.
Rotationplasty
Rotationplasty also called Van Nes rotationplasty, is a kind of limb salvage procedure. In this surgery, the lower leg and foot are rotated 180 degrees backwards, so the child’s foot is positioned where the knee used to be, with the heel portion in front and the toes pointing backwards. Placing the ankle joint in the position of the knee creates a functional knee for your child. And the knee joint acts as the hip joint. Then, a prosthesis is placed beneath the functional knee. This significantly improves limb mobility compared to the traditional above-the-knee amputation and prosthesis.
Partial Amputation
Partial amputation is a type of limb salvage surgery. It involves debridement- removal of the injured bone and surrounding tissues and reconstructing them into a functional limb. This may be done using an allograft, a bone graft from a donor, a metal implant, or a combination of a metal implant and bone graft called an allograft-prosthetic composite. Your surgeon may remove a part of the foot or a knee bone to allow for placement of the prosthesis.
