Treatment for proximal femoral focal deficiency
Depending on the severity of the deformities, the treatment may include the amputation of the foot or part of the leg, lengthening of the femur, extension prosthesis, or custom shoe lifts. Amputation usually requires the use of prosthesis. Another alternative is a rotationplasty procedure, also known as Van Ness surgery. In this situation, the foot and ankle are surgically removed, then attached to the femur. This creates a functional “knee joint”. This allows the patient to be fit with a below knee prosthesis vs a traditional above knee prosthesis.
In less severe cases, the use of an Ilizarov apparatus can be successful in conjunction with hip and knee surgeries (depending on the status of the femoral head/kneecap) to extend the femur length to normal ranges. This method of treatment can be problematic in that the Ilizarov might need to be applied both during early childhood (to keep the femur from being extremely short at the onset of growth) and after puberty (to match leg lengths after growth has ended). The clear benefit of this approach, however, is that no prosthetics are needed and at the conclusion of surgical procedures the patient will not be biologically or anatomically different from a person born without PFFD.
Children with severe PFFD may require a prosthetic to walk. Because of this, treatment is geared toward improving how your child’s body works with the prosthetic. The goal is to improve your child’s overall function, so they can move and develop at a pace similar to their peers. While the timing of treatment varies from child to child, in most cases it begins when your child turns 3 years old — allowing time for early bone to harden — and is completed by the end of high school, when most children have finished growing.
The first important treatment decision that must be made is whether your child could benefit from limb-lengthening procedures. The most likely candidates to benefit are children with a congenital short femur (Type A PFFD). To be eligible for limb lengthening, a child must have:
- A femur with a predicted discrepancy at skeletal maturity of usually less than 40 percent of the contralateral femur
- A stable hip, or one that can be made stable
- Good function and stability in the knee, ankle, and foot
- Limb lengthening typically includes surgery to cut the bone, and placement of an internal rod or external fixator to slowly stretch the limb as new bone forms. While traditional treatment includes external fixators, orthopedic surgeons at CHOP are using a new internal technique for limb lengthening that eliminates the need for pins and bulky external fixation frames. Depending on how fast your child’s bone grows; this limb-lengthening procedure can take months and may need to be repeated.
If limb lengthening is not appropriate for your child — either because their leg-length discrepancy is too great or because they will not tolerate the procedures — prostheses should be considered. While most children with proximal femoral focal deficiency will need an above-the-knee prosthesis with a mechanical knee, others with a stable biologic knee may only need a below-the-knee prosthesis. Determining which type of prosthetic device is best for your child’s condition — as well as the best approach to properly fit the device — is the next important decision in your child’s treatment plan.
Initial treatment for children with PFFD should mirror normal development and begin when a toddler is ready to stand. The child is fitted with a custom-molded prosthesis that equalizes leg lengths but does not require surgical correction. In most cases, these prostheses are not large enough to accommodate flexing at both the knee and foot, so developmental growth can be slower. However, a custom-molded prosthesis that accommodates the child’s lower extremity is effective at allowing young children to move around and explore their space.
Additional surgical procedures
As your child grows, the importance of having both a functional knee and foot becomes more important. At this time, decisions must be made about which prosthetic type is most appropriate and which surgical approach will allow the prosthetic to fit optimally.
Additional surgical options include:
In which the knee joint is fused to adjacent bones (femur and tibia) allowing for a longer and more stable leg that can be more easily contained within the prosthesis. Foot amputation, in which the leg is shortened to accommodate a mechanical knee and the end of the leg, can be more easily contained within a prosthesis.
In which the ankle assumes the function of a knee. To accomplish this, the limb is surgically cut, rotated 180 degrees and reattached. This allows for improved function due to the use of a biologic knee instead of a mechanical one, and the need for a below-the-knee prosthetic.
In which the hip socket (acetabulum) and femoral head are surgically corrected to address varus deformity (outwardly turned legs) and bone fractures that won’t mend without intervention (pseudoarthrosis). This procedure is only appropriate for children with Type A or B deficiencies. Iliofemoral arthrodesis, in which the knee assumes the function of the hip. In this procedure, the femur is fused to the pelvis so when the child extends their anatomic knee, they are effectively moving their hip. This procedure, which is most often used for children with Type C and D PFFD, is often performed as part of a staged reconstruction with rotationplasty or foot amputation to allow for improved prosthesis fit and enhanced function.
In which a shallow hip socket is reshaped to create better coverage of the ball of the thigh-bone. This procedure is often used to treat acetabular dysplasia. During surgery, the surgeon cuts the bones in the hip joint, reorients them, and secures them in a new position.
Safety in surgery
Surgery can dramatically improve the long-term outcomes for your child with proximal femoral focal deficiency, but it can also be a stressful experience for you and your child. At CHOP, we offer a wealth of resources that can help you and your child prepare for surgery. Additionally, we follow many best practices before, during and after surgery to decrease the risk of infection and increase positive outcomes. Our safety protocols have been so successful that many other institutions have adopted them.