Fig 1.
Graphical illustration of the windlass mechanism.
(A) depicts the windlass mechanism as a mechanical model that helps explain the foot’s ability to act as an effective and efficient lever. Dorsiflexion of the toes creates tension in the plantar aponeurosis that tends to pull the calcaneus towards the metatarsal heads. This motion creates an upward force in the longitudinal arch. (B) During gait, the windlass mechanism acts at the end of stance when the metatarsal heads and the distal phalanges are the only points of contact with the ground on the trailing leg. Aside from the passive windlass mechanism, however, active plantar intrinsic foot muscles might also be a source of late-stance arch rising.
Fig 2.
Experimental setup and data analysis.
(A) Reflective surface markers were attached at five anatomical landmarks of the right Foot: CAL = posterior calcaneus, MET1 = first metatarsal head, MET5 = fifth metatarsal head, NAV = talo-navicular tuberosity, HLX = medial hallux. (B) A self-built lever arm was used to dorsiflex the first toe. The MTP joint of the toe had to align with the rotational axis of the lever arm. The MTP joint angle was defined by two vectors, which were spanned by the markers CAL, MET1, and HLX. The navicular height was defined as the distance of the NAV marker from the x-y plane (defined by CAL, MET1, and MET5 markers). (C) During walking, change in MTP joint angle and navicular height were recorded between heel-rise and toe-off when the metatarsal heads and the distal phalanges were the only points of contact with the ground on the trailing leg.
Fig 3.
Graphical summary of the results.
The results suggest that static windlass effects (sitting and standing) poorly predict the relationship between arch dynamics and metatarsophalangeal joint motion during dynamic load scenarios (walking). (A-C) show the mean changes in navicular height (mm) in relation to toe dorsiflexion (°). (D-F) display the changes in navicular height relative to the toe dorsiflexion (mm/°). Black dots represent the mean value. (G-I) show the linear regression between changes in navicular height (mm) and maximum toe dorsiflexion (°). Each circle represents one participant. The regression line is colored in black. Grey shaded area represents the corresponding confidence interval.