The influence of walking mechanics and time on the results of proximal tibial osteotomy

The current study describes the influence of the passage of time on the original findings. The mechanisms used by some patients to reduce loading at the knee (adduction moment) also were analyzed. We evaluated the gait of twenty-seven patients (thirty-two knees) who had had a proximal tibial osteotomy for a varus gonarthrosis. Twenty-four patients (twenty-eight knees) returned for follow-up at three to 8.9 years after the osteotomy. This is a follow-up to our original study (Prodromos et al.), which described a relationship between the magnitude of the adduction moment at the knee during walking and the outcome of proximal tibial osteotomy. The patients were divided into low and high adduction-moment groups on the basis of the magnitude of the adduction moment at the knee as measured preoperatively during walking. All fourteen patients in the low adduction-moment group and nine of the fourteen patients in the high adduction-moment group had a good or excellent result. The varus deformity recurred in ten patients in the high adduction-moment group and in three patients in the low adduction-moment group. All of the results degenerated over time. The adaptive mechanism that was used to lower the adduction moment during gait included shortening the stride and toeing-out. The significant correlation between the magnitudes of the inversion moment at the ankle and the adduction moment at the knee suggested that the toe-out gait reduced the adduction moment at the knee. One year after the osteotomy, the adduction moment at the knee and the inversion moment at the ankle were reduced significantly in both groups, but the mean adduction moment in the high adduction-moment group remained higher than that in the low adduction-moment group.