Motion analysis of 3D multi-segmental spine during gait in symptom remission people with low back pain: a pilot study

Low back pain (LBP) is a long-lasting condition with a variable course rather than pain episodes of unrelated occurrences. Thus, the remission stage between the symptom recurrence is critical. This study aimed to investigate the trunk control of the symptom remission people with low back pain (LBP-R) during gait based on a multi-segmental spine model, including the musculoskeletal factors of lumbar muscle activity and regional thoracic and lumbar kinematics.

Twenty-one males (10 LBP-R, age 23-37, height 165-185 cm, weight 60-74 kg; 11 controls, age 23-38, height 164-183 cm, weight 55-80 kg) were evaluated using 3D motion analysis and surface electromyography (sEMG). The thoracic (T) and lumbar (L) spine were divided into upper and lower portions separately (T3-T7; T7-T12; T12-L3; L3-L5). This pilot study investigated the segmental redundancy with the cross-correlation analyses of spine kinematic time series (R_xy) and correlation analyses of the range of motion between adjacent segments (R_ROM) during gait. Meanwhile, the bilateral lumbar erector spinae (ES) and multifidus (MF) muscle activation during the stance and swing phases were calculated respectively.

The Upper Thoracic/Lower Thoracic pairing in the sagittal plane significantly showed a very strong correlation (R_xy:0.93) in the LBP-R group, while the controls displayed a weak correlation (R_xy:0.22). In addition, the Lower Thoracic/Upper Lumbar and Lower Lumbar/Pelvis pairings in the sagittal plane for the LBP-R group significantly showed very weak to weak correlations (R_xyrange: 0.17-0.24), while the healthy controls displayed moderate correlations (R_xyrange: 0.49-0.52). Most R_ROM values demonstrated very weak to moderate correlations (Number of pairings: 21/24). Compared with healthy controls, left-side ES muscle activation in the LBP-R group was significantly greater during the ipsilateral swing phase and smaller during the ipsilateral stance phase (P < 0.05).

Compared with healthy controls, the LBP-R group exhibited higher lumbar ES activation during the swing phase and altered movement redundancy between adjacent spinal segments in the sagittal plane. As effectively mechanical biomarkers, such findings may help establish a new approach to rehabilitation and self-management for LBP experiencers. A larger sample size is required to generalize these findings to the broader population.