Association Between Multifidus Intramyocellular Lipids and Pain-Related Disorders, Lumbar Spine Dysfunction, Gait Disturbance in Patients with Chronic Low Back Pain: A Cross-Sectional Study Using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire

Background and aims: Fat degeneration in the multifidus muscle (Mm) was more common than in other trunk muscles. We hypothesised that the lipid contents of the Mm and patient-reported quality of life (QOL) are related. However, there are no papers examining the association between fatty degeneration of the Mm and patient-reported QOL using magnetic resonance spectroscopy (MRS). This cross-sectional study aimed to investigate the association between patient-reported QOL, evaluated with the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), and the intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) contents of the Mm and psoas major (PM) by MRS in patients with chronic low back pain (CLBP). Materials and Methods: Forty-eight patients (mean age, 64.2 ± 13.2 years; age range, 41–79 years) with nonspecific CLBP underwent MRS for the quantification of IMCL and EMCL of the right Mm and PM in a volume of interest at L4/L5. All subjects underwent MRS and completed the JOABPEQ in the same day. We performed multiple linear regression analysis of the IMCL and EMCL contents of the Mm and PM with the five domains of the JOABPEQ adjusted for age, sex, and body mass index. Results: The IMCL content of the Mm was correlated with pain-related disorders (standardised partial regression coefficient (β)=−0.59, p<0.01), lumbar spine dysfunction (β=−0.64, p<0.01), and social life dysfunction (β=−0.31, p<0.01) which showed moderate negative correlation, but not with psychological disorders. The EMCL content of the Mm was not correlated with the five domains of the JOABPEQ. The IMCL and EMCL contents of the PM was not correlated with the five domains of the JOABPEQ. Conclusions: IMCL content of the Mm was significantly correlated with the pain-related disorders, lumbar spine dysfunction, gait disturbance, and social life dysfunction domain scores of the JOABPEQ. Future studies using magnetic resonance spectroscopy of the Mm in patients with CLBP may help optimize exercise strategies using IMCL as an index to enhance patient-reported quality of life.