Impact of sagittal spine-pelvis-leg alignment and muscle strength on quality of life and low back pain in rural Japanese community- dwelling middle-aged and elderly persons

Background Lower limb compensation for spinal sagittal malalignment and its impact on quality of life (QOL) and low back pain (LBP) have not been well studied. Objective To clarify postural compensation and the impact of spinal and lower limb sagittal alignment and muscle strength on QOL and LBP in persons > 50 years old. Methods In this cross-sectional study, 122 rural community-dwelling, healthy adults (56 males, 66 females; average age 71.1 years; age range, 52-88 years) underwent assessments of QOL (36-Item Short-Form Health Survey; SF-36), LBP (Roland-Morris Disability Questionnaire; RDQ), thoracic kyphosis (TK), lumbar lordosis (LL), sacral inclination (SI), grip strength, lower limb strength, and back extensor strength (BES). On univariate and multivariate analyses, variables that correlated with QOL and the RDQ were identified. Results LL was moderately correlated with SI and weakly correlated with the knee flexion angle (KFA). LL, KFA, C7-L5D, and BES were correlated with SF-36 subscales and the RDQ. KFA contributed to the physical component summary of the SF-36. Female sex and BES contributed to the RDQ. Conclusions Knee flexion compensated for lumbar kyphosis, but affected physical QOL scores negatively; BES was the most reliable contributor to QOL and the RDQ.