Many patients with fibular hemimelia will also require knee reconstruction as part of their treatment plan, including valgus deformity correction and knee ligament reconstruction.
Valgus Deformity Correction
The valgus deformity of the knee should be corrected with the first treatment. Valgus of the knee can negatively impact the correction of the foot. The knee valgus most commonly manifests in the lower femur. Even though fibular hemimelia primarily consists of deformities and deficiencies below the knee, there is usually an associated deformity above the knee, at the lower femur.
The valgus deformity is corrected by tethering of the growth plate of the lower femur on the inside of the knee using a procedure called hemiepiphysiodesis. Small metal staples (also referred to as an 8-plate, peanut plate, or hinge-plate device) are applied at one side the growth plate near the knee. Hemiepiphysiodesis temporarily prevents growth on one side of the growth plate while not impeding growth in the rest of the growth plate. This forces the growth plate to grow towards the tether. Therefore, if the knee is a knocked knee, the leg will grow to become straight, and if the plate is not removed, it will actually become bow-legged. It is critical to follow this correction every three months with an x-ray and remove the plate early enough to prevent overcorrection. A slight amount of overcorrection is acceptable because some rebound valgus can occur. An 8-plate hemiepiphysiodesis can be repeated more than once throughout the child’s growth years if the valgus deformity recurs, which may occur in some cases. It is a very minor outpatient procedure when carried out on its own and can be combined with a lengthening and superankle procedure as early as 12 to 18 months of age.
Knee Ligament Reconstruction
Knee ligament reconstruction is rarely required for patients with fibular hemimelia. Patients with combined femoral shortening and fibular hemimelia are more likely to require knee ligament reconstruction. Knee ligament reconstruction is performed using the Paley SUPERknee procedure. The SUPERknee can be performed as young as 18 months of age.