A Method of Determining the Angular Malalignments of the Knee and Ankle Joints Resulting from a Tibial Malunion

Malalignments of the knee and ankle joints resulting from tibial angular malunion can be determined using mathematical analysis. The angular deformity of the tibia is equal to the sum of the angular malalignments formed by the knee and ankle joints in relation to the horizontal plane. These malalignments are not equal. A larger percentage of the deformity is reflected inferiorly as the deformity approaches the ankle joint. A table was formulated to provide the corresponding degrees of joint malalignment (knee and ankle) for tibial angular deformities at different positions along the tibia. The analysis provides a useful tool to quantify the knee and ankle joint malalignments secondary to tibial angular malunion. Although designation of prognosis at different degrees of angular deformity is beyond the scope of this study, it does provide improved correlation between tibial angular deformities and the clinical outcome, e.g., degenerative arthroses of the adjacent joints, in future studies on tibial fractures.