Kinematic analysis of a multi-segment foot model for research and clinicalapplications: a repeatability analysis

An unbiased understanding of foot kinematics has been difficult to achieve due to the complexity of foot structure and motion. We have developed a pro tocol for evaluation of foot kinematics during barefoot walking based on a multi-segment foot model. Stereophotogrammetry was used to measure retroref lective markers on three segments of the foot plus the tibia. Repeatability was evaluated between-trial, between-day and between-tester using two subj ects and two testers. Subtle patterns and ranges of motion between segments of the foot were consistently detected. We found that repeatability betwee n different days or different testers is primarily subject to variability o f marker placement more than inter-tester variability or skin movement. Dif ferences between inter-segment angle curves primarily represent a shift in the absolute value of joint angles from one set of trials to another. In th e hallux. variability was greater than desired due to vibration of the mark er array used. The method permits objective foot measurement in gait analys is using skin-mounted markers. Quantitative and objective characterisation of the kinematics of the foot during activity is an important area of clini cal and research evaluation. With this work we hope to have provided a firm basis for a common protocol for in vivo foot study. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.