Gait characterization of pre- and postoperative patients with lumbar spinal stenosis utilizing a body-mounted inertial measurement unit

This report presents a quantitative evaluation of gait characteristics in patients with lumbar spinal stenosis (LSS). Our method used a miniature three-dimensional inertial measurement unit (IMU) attached on the cervical back of the upper trunk. Our experiment examined 18 LSS subjects (70±8 years) before surgery and after surgery at three months. Their gait performance was examined using a six-minute walking test shuttling between 30 m straight walkways in a hospital. Spatiotemporal gait factors including step counts, cadence, and mean step lengths were estimated from the IMU measures for every walking path. Transition periods of walking around turns were excluded from the data. Subsequently, three-dimensional rotation angles of the upper body were calculated to evaluate the degree of postural sway during walking. It was assumed that variations in gait factors or postural performance involving consecutive walking time were observed as an expression of pain or intermittent claudication of LSS. Experimental results showed remarkable changes in the maximum walking distance and walking time postoperatively. Postoperative subjects walked with greater step length, fewer steps, and less step interval variety on a walking path. Moreover, analysis of postural sway revealed that postoperative subjects had decreased sway range mainly in an anterior-posterior direction, maintaining their upper body steadiness and their walking smoothness. Results show that our method of gait characterization, combining validated clinical walking test with the use of wearable IMU, is useful for evaluating the curative effects on LSS patients before and after surgery in terms of their walking performance.