Relationship between the Medial Longitudinal Arch Movement and the Pattern of Rearfoot Motion during the Stance Phase of Walking.

The purpose of this study was firstly to investigate the pattern of the rearfoot (RF) motion, and secondly to determine any in vivo relationship between the medial longitudinal arch (MLA) movement as a measure of the windlass mechanism and the RF motion during the normal stance phase of walking. Seventeen healthy subjects between the ages of 22 and 33 years old were studied. The timing and magnitude of the RF motion and the first metatarsophalangeal (FMTP) joint extension were assessed using a six-camera Vicon motion analysis system. In addition, the MLA angle was recorded. The results indicate that the timing and magnitude of the RF motion were significantly associated with dynamic windlass function. Subjects could be divided into two groups (EARLY and LATE EVERSION ONSET) based upon the time when the RF motion began the maximum eversion during the stance phase of walking. The LATE EVERSION ONSET group had a greater magnitude of the RF eversion and the maximum MLA angle. In addition, this group had delayed onset of the FMTP joint extension.