Fig 1.

Schematic representation of a right knee showing the methodology for measurement of both varus malalignment and proposed correction for a medial opening wedge osteotomy. To evaluate the amount of deformity in the mechanical axis, a line is drawn from the center of the femoral head to the center of the talar dome. Planning for surgical correction is made by measuring the angle created by a line drawn from the center of the femoral head to the center of the lateral tibial eminence and a line down the anatomic axis of the tibia. This angle is then transposed to the medial proximal tibia at the level of the desired correction. An anteriorly or posteriorly placed plate can later result in a biplanar correction by increasing or decreasing the tibial slope respectively.