It has previously been reported that individuals with varus knee alignment are at an increased risk for the development of medial knee osteoarthritis. In individuals with established medial knee osteoarthritis, varus knee alignment has been shown to be related to the knee external adduction moment (KEAM) during gait. This moment has been associated with medial compartment loading and disease progression. Preliminary data suggests that the knee external adduction moment is also increased in asymptomatic, varus knees. Therefore, reducing the knee external adduction moment in these individuals may reduce their risk for the development of knee OA later in life.

Three studies were undertaken studying young individuals with asymptomatic, varus knees. The purpose of the first study was to compare the gait mechanics of seventeen asymptomatic, varus-aligned individuals to those of asymptomatic, normally-aligned individuals. We hypothesized there would be group differences in frontal plane mechanics, but no differences in the sagittal plane data. The results largely supported our hypotheses, demonstrating group differences in the frontal plane of the knee and rearfoot. Notably, the knee external adduction moment was significantly higher in the varus-aligned individuals, and was similar in magnitude to that of symptomatic medial knee osteoarthritis. This finding suggests that high medial knee joint loads contribute to the increased risk of developing medial compartment disease in this population. The second study assessed static and dynamic measures of the lower extremity as predictors of the knee external adduction moment using correlation and hierarchical regression techniques. Tibial mechanical axis as measured by an inclinometer, and kinematic knee adduction angle during gait, were the strongest predictors. Rearfoot eversion was also a significant dynamic predictor. In the third study, the effectiveness of a gait retraining program aimed at reducing the knee external adduction moment was examined. In this study, varus-aligned individuals underwent a retraining program utilizing real-time visual feedback to improve dynamic knee alignment during gait. The knee adduction moment was reduced after systematic training, and also at a one month follow-up. The kinematics responsible for the reductions in the knee adduction moment were increased hip adduction and internal rotation, as well as decreased knee adduction.

These studies are the first investigation into the gait mechanics of individuals with asymptomatic, varus knees. The results suggest that varus knee structure is associated with altered movement patterns and increased dynamic knee joint loads. Also, we found that static and dynamic variables associated with frontal plane alignment relate well to the KEAM. Finally, we introduced a novel gait modification aimed at reducing the KEAM. If utilized, medial knee joint loading may be reduced, potentially lowering the risk for incident medial knee OA.