Mechanism of Knee Adduction Moment Reduction Through Contralateral Cane Use in Healthy Subjects

The use of a contralateral cane has demonstrated a reduction in the external knee adduction moment (KAM) in patients with knee osteoarthritis. However, the underlying mechanism remains unclear. This study aimed to investigate the specific mechanism in healthy young subjects. Sixteen healthy young participants were included in this study. They walked on a floor under three loading conditions: no cane and with cane loads equivalent to 5% and 10% of body weight. Change in posture and kinetic features of ipsilateral leg were examined at two instants of ground reaction force (GRF) peaks. The results revealed a substantial decrease (40–55%) in both KAM and moment arm, whereas only 12% decrease was observed in GRF with 10% cane loading. Furthermore, KAM was strongly correlated with moment arm (r = 0.97, p < 0.01), but not with GRF (p > 0.05). The reduction in moment arm could be attributed to a medial shift of knee joint and/or a lateral shift of GRF. At the maximum cane loading, medial shift in the knee joint center was significant (p < 0.001), while any shift in GRF was insignificant (p > 0.80). The results suggest that the primary factor contributing to the reduction in KAM is the decrease in moment arm among healthy young subjects. Importantly, the reduction in moment arm was primarily induced by a medial shift of the knee joint center, emphasizing the significance of postural changes.