Toe-in gait reduces the first peak knee adduction moment in patients with medial compartment knee osteoarthritis

The first peak of the knee adduction moment has been linked to the presence, severity, and progression of medial compartment knee osteoarthritis. The objective of this study was to evaluate toe-in gait (decreased foot progression angle from baseline through internal foot rotation) as a means to reduce the first peak of the knee adduction moment in subjects with medial compartment knee osteoarthritis. Additionally, we examined whether the first peak in the knee adduction moment would cause a concomitant increase in the peak external knee flexion moment, which can eliminate reductions in the medial compartment force that result from lowering the knee adduction moment. We tested the following hypotheses: (a) toe-in gait reduces the first peak of the knee adduction moment, and (b) toe-in gait does not increase the peak external knee flexion moment. Twelve patients with medial compartment knee osteoarthritis first performed baseline walking trials and then toe-in gait trials at their self-selected speed on an instrumented treadmill in a motion capture laboratory. Subjects altered their foot progression angle from baseline to toe-in gait by an average of 5° (p<0.01), which reduced the first peak of the knee adduction moment by an average of 13% (p<0.01). Toe-in gait did not increase the peak external knee flexion moment (p=0.85). The reduced knee adduction moment was accompanied by a medially-shifted knee joint center and a laterally-shifted center of pressure during early stance. These results suggest that toe-in gait may be a promising non-surgical treatment for patients with medial compartment knee osteoarthritis.