Kinematic Analysis of Pelvic and Lower Limb Joints during Stand-to-sit Movement in Individuals with Chronic Low Back Pain: A cross-sectional study.

Objectives: It is crucial to investigate the daily functions commonly utilized by individuals with low back pain (LBP) due to their implications for recurrence and chronicity. Stand-to-sit (StTS) task is one of the more repetitive functions in human daily life. This study aims to evaluate pelvic and lower limb joint kinematics during the StTS task in individuals with Non-Specific Chronic Low Back Pain (NSCLBP) compared to a healthy control group. Methods: Pelvic and lower limb joint kinematic data in all three planes were recorded from 20 individuals with LBP and 20 healthy individuals using a Qualisys motion capture system during the StTS task. A Functional Data Analysis statistical approach was employed to compare the kinematic data between the two groups. Results: In the initial phase of the movement, we observed a greater anterior pelvic tilt (P=0.028) and an altered pelvic frontal plane motion pattern (P=0.029) in the LBP compared to the healthy group. The only significant differences between the lower limb joint kinematics of the two groups were a less hip external rotation position (P=0.025) and a more knee adduction pattern (P=0.002) on the right side in the LBP subjects compared to the healthy group. Conclusion: Considering a few differences noted between the two groups across various joints and planes evaluated, it appears that the kinematic pattern of the lower limbs does not significantly differ between the NSCLBP and healthy groups during the StTS task in most comparisons. However, distinct kinematic patterns have been observed in the pelvic region, particularly in the sagittal and frontal planes, between the two groups.