Lower Limb Phase Angle Correlates Most with Locomotive Syndrome and Walking Function in Patients with Lumbar Spinal Stenosis: A Retrospective Study.

Abstract

Introduction: Locomotive syndrome is characterized by reduced mobility due to musculoskeletal disorders. Lumbar spinal stenosis (LSS) primarily causes locomotive syndrome, and its severity is associated with its progression. The phase angle (PhA) has gained attention as an indicator of physical function and nutritional status. Previous studies indicate associations between whole-body PhA and physical function and quality of life in patients with LSS. However, the relationship between site-specific PhAs and locomotive syndrome remains unaddressed. This study examined the association between regional PhA and locomotive syndrome in patients with LSS.

Methods: We enrolled 133 patients with LSS and assessed their age, sex, body mass index (BMI), prognostic nutritional index (PNI), life space assessment, handgrip strength, timed up-and-go test (TUG), and PhA values (whole body, upper limbs, trunk, and lower limbs). Locomotive syndrome was evaluated using the 25-question Geriatric Locomotive Function Scale (GLFS-25). Spearman's rank correlation analysis was performed to evaluate the relationship between PhA and GLFS-25 scores. Multiple linear regression analysis was conducted to assess independent associations, adjusting for age, sex, BMI, disease duration, type of neurological classification (radicular, cauda equina, and mixed), skeletal muscle mass index, PNI, handgrip, and TUG as covariates.

Results: Lower-limb PhA showed the strongest negative correlation with GLFS-25 (ρ=-0.363, p<0.001). In the multiple regression analysis, lower-limb PhA remained significantly associated with the GLFS-25 score (β=-0.224, 95% confidence interval: -11.69 to -0.224, p=0.044), with a model R² of 0.29. No significant associations were found for the whole-body, upper-limb, or trunk-PhA.

Conclusions: Lower-limb PhA is independently associated with locomotive syndrome severity in patients with LSS and may reflect lower limb function, such as walking speed, and may serve as a useful site-specific indicator for assessing locomotive syndromes.