The correction of genu varum for patients with medial compartment osteoarthritis is a well established treatment with the goals of reducing knee pain and slowing the progression of knee arthritis. A full correction of the varus and even overcorrection are needed to achieve these goals. The use of osteotomy in patients with genu varum to prevent arthritis from ever occurring is more controversial. The following case will present the story of an elite soldier whose job requires him to be in top physical condition. His experience with realignment surgery and ability to recover and surpass his pre op athleticism will be described.
This is a 33 year old male who is part of the United Sates special forces who began experiencing medial knee pain with running and other high impact activities. He had bilateral genu varum since childhood and attributed the pain to this deformity. He was found to have varus deformity limited to the coronal plane involving the right proximal tibia and the left proximal tibia and distal femur. He was keen anatomic reduction of the deformities with external fixation with the goal of return to high impact activities surpassing his pre op function.
The plan was to correct the left side first including both femoral and tibial osteotomy. The femur osteotomy was done with an acute correction method using static external fixation. Osteoplasty of the ipsilateral tibia with external fixation was performed simultaneously. The tibia deformity was corrected gradually to ensure a perfect mechanical axis alignment. The right side was corrected 6 weeks later. This gave the left side adequate time to heal. The left side then became the strong side and supported the newly operated right side. Right side correction required only the tibial osteotomy and a uniplanar fixator.
Femoral osteotomy with external fixation can be done percutaneously, with minimal blood loss and allows immediate post op weight bearing. Femoral osteotomy with a plate requires an open approach to the femur, is associated with greater blood loss, and requires protective weight bearing. Opening wedge osteotomy with plating also requires bone grafting.
Gradual correction of the tibial deformity is accomplished with external fixation. Uniplanar deformity is addressed with a monolateral frame, whereas, multiplanar and oblique plane deformities are more effectively corrected with circular fixation. Hydroxyapatite coated, tapered, 6mm half pins provide excellent fixation. Patients perform adjustments at home after a short latency period. Deformity correction proceeds at 1mm per day and takes from 10-21 days. The alignment is adjusted until the desired mechanical axis is achieved as measured on 51” standing radiographs.
The use of cannulated half pin insertion technique has made the application of unilateral external fixators more accurate. A wire is used to find the ideal insertion point for the first half pin. A cannulated drill is slid over the wire and both cortices are drilled. The half pin is then placed into the drill hole. Monolateral fixators are extremely unforgiving and this method has made application easier.
In active patients tibial fracture through a pin hole is a concern as is collapse of the newly formed regenerate bone. Although these complications are extremely rare they remain a concern immediately post frame removal. The protocol used after frame removal includes the use of a hinged knee brace with maximum of 50% weight bearing for 2 weeks. Patients are then allowed to discontinue the brace and progress to full weight bearing after obtaining a new x-ray. Patient can then resume low impact exercises. Running and sports are allowed 3 months after frame removal.
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