The Association of Lumbar Paraspinal Muscle Size and Quality With Physical Function, Disability, and Pain in Adults With Chronic Low Back Pain

Objective: Chronic low back pain (LBP) is linked to reduced lumbar paraspinal muscle size and quality. Given their role in spinal stabilization, this study examined associations between lumbar paraspinal muscle morphology and physical function, disability, and pain in chronic LBP. Design: Cross-sectional study. Methods: Cross-sectional area (CSA) and attenuation of the erector spinae and multifidi (upper: L1-L3; lower: L4-S1), psoas and quadratus lumborum (L3) were measured from computed tomography images. Performance-based physical function was assessed using the Five Times sit-to-stand, 2-minute walk, 4-meter walk, active sit-up, and single-leg stance tests. Disability and symptoms were evaluated using the Oswestry Disability Index, Numerical Pain Rating Scale, and PainDETECT. Linear and logistic regression analyses were conducted, adjusting for age, sex, and body mass index (BMI). Results: We analyzed data from 193 adults (age 55.0 ±16.0 years; BMI 27.2 ±4.0; 55% female). Regarding CSA, lower erector spinae was associated with walking speed (β:.0001, p:.021), upper erector spinae with balance (β:.002, p:.039), lower multifidi with neuropathic symptoms (β:-.010, p:.030), and quadratus lumborum with abdominal endurance (β:-.006, p:.012). For attenuation, upper erector spinae was associated with abdominal endurance (β:.046, p:.047) and quadratus lumborum with balance (β:.046, p:.030). Conclusions: Lumbar paraspinal muscle morphology was associated with physical function and neuropathic symptoms in chronic LBP.