The effects of toe-out gait on the knee flexion moment in runners with and without medial compartment knee osteoarthritis

![CDATA[Rationale/ Objectives: Emerging evidence suggests that external knee flexion moment (EKFM) can affect overall knee loading. Previous studies suggested that walking with toe-out gait might reduce external knee adduction moment (EKAM) in people with and without medial compartment knee osteoarthritis (MCKOA), while another recent study reported that running with toe-out gait increased knee contact forces. In addition, no previous study has examined the effect of toeout running gait on the EKFM in runners with MCKOA. Hence, the aim of this study is to compare such effects between runners with and without knee osteoarthritis. Methods: The kinematic and kinetic data were collected from eight runners with early MCKOA (55.0 ± 5.5 years, four males and four females) and eight healthy age-matched controls (55.4±7.5 years, two males and six females). A 2x2 (group × running gait pattern) mixed ANOVA was conducted to analyse the between-groups and within-groups differences (p<0.05). Results: Peak EKFM was greater in healthy runners than runners with MCKOA, regardless of the running pattern (P<0.038). For runners with MCKOA, toe-out gait increased peak EKFM (12.5%, P=0.042). When compared with running with normal and toe-out gait, we did not find a significant difference in the peak knee flexion during stance in healthy runners; but a slight increase of the peak knee flexion in runners with MCKOA (4.2%, P=0.014). Conclusion: Unlike walking with toe-out gait, there is no biomechanical benefit to perform toe-out gait during running. Instead, toe-out running gait may lead to greater knee joint loading by increasing the EKFM.]]