PAPER 010: A TOE OUT FOOT PROGRESSION ANGLE DURING GAIT AFFECTS THE CHARACTERISTICS OF THE KNEE ADDUCTION MOMENT IN KNEE OSTEOARTHRITIS

Abstract

Purpose: To test the null hypotheses that no significant differences in the net external knee adduction moment waveform captured during gait exist between neutral, toe in and toe out foot progression angle (FPA) modifications and between those with mild to moderate knee OA and asymptomatic control subjects.

Method: Ten patients with mild to moderate knee OA (age 45±7 years) and 16 asymptomatic control subjects (age 54±8 years) participated. Informed consent was obtained for all participants. Three-dimensional (3D) motion and ground reaction force data were recorded during gait. Five trials of each condition,

1. Self-selected walking (Neutral),

2. Toe out walking (10o> self-selected, velocity +/− 0.1 m/s of self-selected) and

3. Toe in walking (10o

Results: There was a significant condition effect for FPA (Neutral=7o, Toe out=24o and Toe in=−9o) and a significant group effect for walking velocity (Asymptomatic=1.46m/s, Knee OA=1.27m/s). In both groups, a toe out FPA produced

1. a reduction in the overall knee adduction moment (captured by PC1),

2. a reduction in the late stance magnitude of the knee adduction moment magnitude (captured by PC2 and PC3) and

3. an increase in the early stance knee adduction moment magnitude (captured by PC2) (p< 0.05).

Conclusion: The knee adduction moment is considered an indicator of medial tibio-femoral compressive loading. In this study, a toe out FPA modification during gait altered the characteristics of the knee adduction moment. A reduction in the overall magnitude, more specifically during late stance was found with the toe out gait modification. An increased initial stance peak magnitude was also found during toe out gait. This finding is novel, indicating that a greater peak medial compartment load is produced