3-DIMENSIONAL KINEMATICS OF THE REARFOOT DURING THE STANCE PHASE OF WALKING IN NORMAL YOUNG-ADULT MALES

Three-dimensional video analysis was used to quantify three-dimensiona l motion of the rearfoot in 14 normal young adult males during the sta nce phase of walking. A stringent calibration procedure enabled standa rdization of the neutral position of the rearfoot. Surface markers wer e placed on the calcaneus and lower tibia, and a joint coordinate syst em was used to determine the relative displacement between the calcane us and lower leg as representative of rearfoot motion. Confirmation wa s made of the assumption of a mechanical coupling between the rearfoot displacements of abduction/ adduction and eversion/inversion. However , there were several findings which contrasted with commonly held assu mptions. For example, the rearfoot was found to evert gradually, rathe r than rapidly, from heel contact to just prior to heel rise. Also the conventional descriptions of the composite movements of pronation and supination were not applicable to rearfoot movement in this study, an d it was therefore concluded that pronation and supination are not val id descriptors of three-dimensional rearfoot motion du ring the stance phase of walking. Relevance-Abnormal rearfoot motion has been recogni zed as a significant factor in many musculoskeletal disorders. Until r ecently it was not possible to quantify accurately the three-dimension al kinematics of the rearfoot during walking. This paper presents a re liable and valid method to quantify rearfoot kinematics during walking , and provides a description of three-dimensional rearfoot motion in t he specified population. Using the method described, it may be possibl et to determine normal rearfoot motion in other populations and provid e a quantitative description of abnormal rearfoot motion. It could be expected that the method would enable identification of the relationsh ip between rearfoot motion and musculoskeletal disorders, and facilita te the prescription, design and evaluation of footwear, foot orthoses, and other forms of therapy utilized in the management of people with abnormal rearfoot motion.