Influence of the windlass mechanism on arch-spring mechanics during dynamic foot arch deformation

Abstract

The function of the human foot is described dichotomously as a compliant structure during mid-stance and a stiff lever during push-off. The arch-spring and the windlass mechanisms, respectively, describe each of these behaviours; however, their interaction has not been quantified to date. We hypothesized that by engaging the windlass mechanism with metatarsophalangeal joint (MTPJ) dorsiflexion, we would observe stiffening of the arch and reduced energy absorption and dissipation during dynamic compressions of the foot. Using a custom apparatus, the MTPJ angle was fixed at 30 degrees of plantarflexion, neutral or 30 degrees of dorsiflexion for nine participants, with the shank positioned similarly to the end of mid-stance. The arch was compressed at two speeds, with the faster speed comparable to walking around 1.5 m s Six cameras captured the compression and elongation of the arch, along with other kinematic variables, synchronously with the ground reaction force. Combining these measures, we computed the energy absorbed, returned and dissipated in the arch. Contrary to our hypothesis, when the windlass mechanism was engaged, the arch elongated more, and absorbed and dissipated more energy than when it was not engaged. This engagement of the windlass altered the rotational axis of the mid-foot, which probably oriented the arch-spanning structures closer to their resting length, increasing their compliance. This study provides novel evidence for an interplay between the windlass and arch-spring mechanisms that aids in regulation of energy storage within the foot.

Effect of the upward curvature of toe springs on walking biomechanics in humans

“…However, the small increases in MTP joint dorsiflexion angles caused by toe springs in this study did not affect measured arch stiffness. This result corresponds to the findings of Welte et al 14 , who used static loading to compress the arches of sitting participants at different toe dorsiflexion angles, and found that engaging the windlass mechanism did not increase arch stiffness. A possible explanation might be the flexibility of the plantar aponeurosis, which stretches as the arch is loaded 44 – 46 .…”

“…Recent research, however, challenges this traditional perspective of the windlass mechanism. In a static in vivo loading experiment, Welte et al 14 found that raising the longitudinal arch by dorsiflexing the toes actually decreases the longitudinal arch’s stiffness. In another static in vivo experiment, Farris et al 15 found that the windlass mechanism has little effect on longitudinal arch motion while the arch is experiencing the high loads associated with push-off.…”

Number of Segments Within Musculoskeletal Foot Models Influences Ankle Kinematics and Strains of Ligaments and Muscles

“…The similarity may arise from the fact that both models include the MTP joint, because hopping requires a considerable MTP joint range of motion, which is captured by the 3MFM and 5MFM. An additional, albeit slightly unrelated consideration, is that the presence of the MTP joint may also better capture intrinsic foot mechanics such as the windlass mechanism, which occurs with dorsiflexion of the MTP joint, increases plantar fascia tension, and transitions the arch from compliant to rigid and generates propulsion . Thus, the MTP joint in 3MFM and 5MFM may better capture the range of motion and perhaps other intrinsic muscle mechanisms.…”

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“…For instance, if the patient is standing, the longitudinal medial arch may flatten, but it can also increase with extension of the metacarpophalangeal (MTP) joints. 22 In case of the ICFSG score, cavus deformity is evaluated with the foot dorsiflexed and depending on the appearance of the medial longitudinal arch it can be rated moderate or severe. This method is subjective and might have contributed to the increased rate of cavus deformities reported in this study, particularly if there is some degree of associated extension of the first MTP joint during ankle dorsiflexion.…”