Pelvic and lower limb gait pattern differ between sex but not between chronic low back pain patients and pain-free individuals under strict inclusion criteria.

Abstract

Gait kinematics research in chronic low back pain (cLBP) is inconsistent due to variable subgrouping, lack of sex-specific analysis, and focus on discrete measures. This study compared pelvic and lower limb gait patterns in a well-defined cLBP subgroup and a pain-free control group, stratified by sex, using functional data analysis. Participants had no prior spinal or lower limb diagnoses, injuries, or surgeries. Magnetic resonance imaging was used to exclude individuals with relevant lumbar spine pathologies. CLBP participants reported lumbar pain almost daily for ≥ 12 weeks. Pain-free individuals scored above the 25th percentile in the SF-36. Gait data were collected via 3D motion capture at self-selected speed and 4 km/h. Kinematic waveforms were analyzed via functional regression. Included were 44 cLBP (29 females, 15 males) and 55 pain-free individuals (36 females, 19 males). Substantial differences in pelvic obliquity, hip ab-/adduction and rotation, and ankle angles between sexes (mean difference standard deviation ratio (RMS) = 0.26-0.84, p = < 0.001-0.035) and in ankle dorsi-/plantarflexion between pain-free and cLBP females (RMS = 0.24-0.41, p = 0.020-0.030) were found. The findings underline the relevance of sex-specific analysis in cLBP gait research. No major gait differences were found between cLBP and pain-free individuals, except for minor ankle kinematic changes in cLBP females. The functional impact of these small changes remains unclear. Future research should investigate how such variations in ankle kinematics affect gait efficiency and contribute to cLBP, while controlling for other factors like sex.