Yoshio Tsuchiya

Estimation of lumbar load by 2D reconstruction of spine line using wearable sensor system

Anteflexion is essential for many physical activities ranging from carrying objects through snow shoveling to farm work. However, lumbago is a common cause of anteflexion, in which lumbar disks are under a heavy load due to changes in lumbar spine shape. With the aim to reduce lumbago risk, in this study we developed a motion sensor system that can estimate the shape, posture and load on the lumbar spine from measuring the lumbar in the lumbar region when the lumbar spine shape changes and the pelvis posture angle changes. We present a wearable version of this sensor system, and propose an estimation method of the lumbar shape using the pelvis posture angle and lumbar region skin curvature from this system. In addition, we measure the anteflexion using this system and study the change in load of the lumbar spine caused by changes in posture.

Calibration method for lumbosacral dimensions in wearable sensor system of lumbar alignment

Anteflexion of the spine is essential for many physical activities in everyday life. However, this motion places the lumbar disks under heavy load due to changes in the shape of the lumbar spine and can lead to low back pain. With the aim of reducing low back pain, here we developed a wearable sensor system that can estimate lumbosacral alignment and lumbar load by measuring the shape of the lumbar skin when the lumbosacral alignment changes. In addition, we used this system to measure the parameters of anteflexion and studied the change in dimensions of the lumbar spine from changes in posture. By determining the dimensions of the lumbosacral spine on an X-ray image, a lumbosacral dimensions calibration method based on body surface area and height was developed. By using this method, lumbosacral alignment and lumbar load could be accurately estimated using the wearable sensor system.

Wearable Sensor System for Lumbosacral Load Estimation by Considering the Effect of External Load

Anteflexion of the spine is a crucial motion in performing many tasks during work and daily life. It is particularly important in tasks such as providing care to others and carrying objects. To devise measures for preventing back pain, it is necessary to determine the postures associated with high risk of low back pain. Postures that increase lumbosacral load should be identified to reduce the risk of low back pain. In previous work, the relationship between posture and intervertebral loading was clarified, and the centers of gravity in the upper body and the waist shape were estimated. Moreover, individual differences were considered to improve the accuracy of the estimation. This method can estimate the lumbosacral load with sufficient accuracy. However, lumbosacral loading was examined in relation to posture and increases with external load. Therefore, the external load should be included in lumbosacral load estimation. In this study, we developed a back muscle exertion estimation method by using stiffness sensors to measure back muscle exertion, because the back muscle exertion changes with the external load. We conducted experiments in which participants wore the sensor system and the lumbosacral load was estimated from the external load. Estimation using the muscle stiffness sensors was better than previous estimation methods.

A Calibration Method for Interbody Distance in Lumbosacral Alignment Estimation

Anteflexion of the spine is essential for many physical activities of daily living. However, this motion places the lumbar discs under heavy loading because of changes in the shape of the lumbar spine, possibly leading to low back pain. With the aim of reducing low back pain, here we developed a wearable sensor system that can estimate lumbosacral alignment and lumbar load by measuring the shape of the lumbar skin as the lumbosacral alignment changes. The shape of the lumbar skin and posture angle are measured by using curvature sensors and accelerometers. In addition, the wearers physique must be considered for the system to be usable by a variety of people. We developed this system by measuring the body parameters associated with anteflexion and studied the changes in the dimensions of the lumbar spine with changes in posture. By measuring the dimensions of the lumbosacral spine on X-ray images, the posture angle, body surface area, and the dimensions of the lumbosacral spine have relevance. A calibration method for lumbosacral dimensions was developed using this relation. However, the estimation method for lumbosacral alignment could not maintain good calibration of interbody distance. Therefore, we further developed the estimation to include a calibration method for interbody distance, thereby improving the estimation accuracy.

Lumbar load estimation using a musculoskeletal model in consideration of vertebral body displacement: Lumbar load simulation under static conditions

In this study, we propose an estimation model of lumbar load, which is a factor in lumbar disorders. Our proposed method uses a musculoskeletal model with elastic elements between the vertebral bodies, and simulates the inter- vertebral disk pressure and the displacement of the vertebral bodies simultaneously.