Study on Improvement in Estimation Accuracy of Lumbar Disc Load Considering Pelvic Tilt

Abstract

So far, the method to quantitatively evaluate the load applied to the lumbar intervertebral disc using the body surface shape of the waist has been proposed. This report clarifies effects of pelvis on lumbar disc load. Therefore, we investigate the relationship between pelvic angle and load ratio in forward/backward pelvic tilt, upper body bending motion, and static forward tilt posture. These experiments are conducted in standing and sitting postures. As results, it was confirmed that the load ratio was decreased due to the pelvic tilt and that the effect of pelvis was greater in sitting posture. Additionally, the load ratio increased with increase of the forward tilt angle in standing posture, but the load ratio fluctuation was not so much seen in sitting posture. This is considered to be because the load compensation due to the pelvic tilt in sitting posture is large. From these, it was found that forward tilt of pelvis plays a role in compensating for lumbar disc load and that it has a greater effect in sitting posture. Thus, it became possible to divide the load ratio into the effects of upper body flexion and pelvic tilt, and it became possible to examine the relationship between posture and lumber load in more detail.