PROPOSAL AND IMPLEMENTATION OF MOTION ANALYSIS OF THE SPINE FOR PREGNANT WOMEN USING INERTIAL MEASUREMENT UNITS

¹Osaka Metropolitan University, Department of Rehabilitation Science, Habikino-shi, Japan

Background: Standing up and sitting down are associated with low back pain (LBP) during pregnancy. An understanding of the relationship focusing on the posture of the spinal column during these motions is required to manage the LBP. Thus, a quantitative evaluation of stationary posture and spinal movement can be useful for understanding the relationship. However, it has been difficult to assess the motion of the spine objectively and quantitatively.

Purpose: To propose a motion analysis system and investigate the relationship between the motion feature of the lumber spine and LBP for pregnant women.

Methods: A following device was proposed to obtain motion data of the spine during motion analysis. The device was a sheet-like device with 20 inertial measurement units (IMUs) connected in a row with an interval of 20 mm. The proposed device was attached to the back of seven pregnant women (30.9 ± 4.8 years) along the spinal column. Then, the participants performed standing up and sitting down. From the data of IMUs, some evaluation index of movement of the spinal column was calculated. The participants were asked about the intensity of LBP by a numerical rating scale (NRS) and divided into two groups based on the intensity of LBP. The difference in each motion index was explored between the groups by comparison analysis. Additionally, Spearman’s rank correlation coefficient was calculated to investigate the association between the number of the most moving sensors and the LBP intensity.

Results: The posture and motion analysis could be conducted by the proposed device. Among the enrolled participants, five pregnant women were categorized in the moderate-severe LBP group and two were categorized in the no–mild LBP group. As the result of the statistical analysis, the pregnant women who had moderate-to-severe LBP tend to not move their upper spine in the forward and also vertical direction significantly (p-values < 0.01). Moreover, a statistically significant positive correlation between the number of sensors on the roll axis, that indicate rotational movement of the spine in the forward direction, in the standing up motion and the NRS score was observed.

Conclusions: In this study, we measured the movement of the spine of the trunk during the standing and sitting motions of pregnant women using a sheet-like device connecting 20 IMUs. The results showed that the pregnant women who had LBP could not use the hip strategy or tilt the body trunk or pelvis forward sufficiently for shifting their body’s center of gravity while sitting down. The results also suggest that they tended to have increased lumbar lordosis in standing up. The results confirmed that it is possible to evaluate the posture and movements of the spine, such as linear movement and rotation, not only at rest but also during motion using the proposed system.

Implications: By determining the effect of the spinal alignment shift during certain motions on LBP by the proposed devise, reflecting the characteristics of pregnancy, effective movement instruction can be formulated for the purpose of improving LBP during pregnancy.

Funding acknowledgements: This study was supported by JSPS KAKENHI, grant number 20K19348.

Keywords:
Assessment system
Motion analysis
Pregnancy

Topics:
Musculoskeletal: spine
Pelvic, sexual and reproductive health
Innovative technology: robotics

Did this work require ethics approval? Yes

Institution: Osaka Prefecture University

Committee: Ethics Committee of the Graduate School of Comprehensive Rehabilitation

Ethics number: 2108-108