2021 年 59 巻 1 号 p. 14-23
Walking ability plays a major role in being healthy. Assessment of the walking ability of cane users in daily life will assist in rehabilitation implementation and health maintenance. We are developing a system for evaluating the walking ability of a cane user based on the motion of the cane. The purpose of this study was to analyze the correlation between the walking ability and the cane motion indicators that can be measured using an inertial measurement unit (IMU), and to identify the indicators that can be used to evaluate the walking ability. Twelve postoperative patients who had undergone total knee arthroplasty, uni-compartmental knee arthroplasty, total hip arthroplasty or bipolar hip arthroplasty were video recorded while walking along a 6m long straight line with a cane, and the resulting IMU data were recorded. We detected the timing of the initial contact and the terminal contact of the cane based on the jerk norm and the absolute angular jerk, calculated using the IMU data. We used gait velocity and step length as the walking ability indicators, and analyzed the correlation between these two indicators and the indicators detected using the IMU. These indicators were the angles in the sagittal and coronal planes of the cane at the initial contact and terminal contact, the acceleration and the jerk norms at the initial contact and terminal contact, the time of the cane touching the ground, and the maximum angular velocity while swinging the cane. Gait velocity was related to the acceleration and the jerk norm of the cane at the terminal contact and the time of the cane touching the ground. Step length was related to the cane angle in the sagittal plane at the initial contact and terminal contact, the acceleration norm and the jerk norm at the terminal contact, and the maximum angular velocity while swinging the cane. These findings proved that the IMU attached to the cane could measure the indicators related to walking ability.