Association of the Cross-Sectional Area, Muscularity, and Muscle-Fat Ratio of the Paraspinal Muscles with Chronic Low Back Pain

It is now a well-established fact that paraspinal muscle integrity plays a critical role in low back pain. We aimed  to determine the association of the cross-sectional area (CSA), muscle disc ratio (muscularity), and muscle fat ratio of the paraspinal muscles with chronic low back pain (CLBP) of varied pathologies, and  the effect of aging and BMI.

The CSAs of the muscles did not differ significantly between the two groups except for multifidus (p<0.05) and psoas (p<0.001) at L1-L2, and psoas (p<0.001) at L2-L3. There was significant difference in CSA of disc at L3-L4, L4-L5, L5-S1 (p<0.05), muscle fat ratio (p<0.01) and muscularity of multifidus and psoas (p<0.05) from L1 to L5 levels. There was no correlation of age and BMI with the CSA. Aging led to fatty infiltration in both the groups. The CSAs of muscles and discs were comparable (p>0.05) among subgroups except at few spinal levels. Muscularity among the subgroups varied at different levels. The muscle fat ratio were comparable (p>0.05).

Muscularity and composition rather than overall CSA of important spinal stabilizers  are associated with CLBP. Age and BMI has no correlation to CSA of paraspinal muscles. Various disc and muscle parameters do not differ much among common lumbar pathologies.