The windlass mechanism during normal walking and passive first metatarsalphalangeal joint extension

OBJECTIVE: To assess the relationship between passive first metatarsophalangeal extension and rearfoot motion during walking on the windlass mechanism. DESIGN: An in vivo study of the windlass mechanism during passive extension of the first metatarsophalangeal joint and walking. BACKGROUND: Despite theoretical work regarding the windlass mechanism in cadavers, there is little research concerning its in vivo role. METHODS: The amount of first metatarsophalangeal extension and medial longitudinal arch movement of the right foot in 20 subjects between the age of 22 and 55 years was recorded as they sat with their right hip, knee and ankle in 90 degrees and their great toe passively extended. In addition, movement of the rearfoot was recorded while they walked. RESULTS: The results of this study showed that the windlass mechanism is active during passive extension of the great toe. In addition, subjects could be divided into two groups (IMMEDIATE and DELAYED) based upon the timing of when the windlass mechanism began relative to passive extension of their first metatarsophalangeal joint. During walking, the DELAYED group was more inverted at heel strike and had a greater magnitude of rearfoot eversion. CONCLUSIONS: Two distinct subpopulations of individuals can be identified by when the windlass mechanism is initiated relative to passive first metatarsalphalangeal extension.