The kinematics of the subtalar joint during the contact phase of walking : a novel measurement strategy
Movement at the subtalar joint is believed to be a fundamental contributor to foot function during walking. The complex structure and movement, and inaccessibility of the joint have resulted in limited published data with which to substantiate or refute theories regarding its movement during walking. This study investigated the use of the CODA M PX30 three d imensional motion analysis system and a purpose designed marker placement model as a strategy for measuring the movement of the subtalar joint during the contact phase of walking. The in vitro reliability of the measurement strategy was tested and the combination of the CODA M PX30 and the marker placement model shown to be reliable. The effect of skin movement on surface marker location was investigated. Although markers were shown to move relative to the bones, angular orientations calculated from marker positions were shown to be representative of those calculated directly from the bones. The in vivo reliability of the measurement strategy was tested using multiple data sets from a single subject. Results showed the measurement strategy to be reliable and to produce results comparable to previous published data. Subsequent testing on m u ltiple subjects produced a similar outcome. The novel measurement strategy described in this study was shown to be a valid non-invasive, i n vivo method of assessing the movement of the subtalar joint during the contact phase of walking.