Relationship between the morphology and composition of the lumbar paraspinal and psoas muscles and lumbar intervertebral motion in chronic low‐back pain: An exploratory study

Abstract

Muscles of the lumbar spine play an important role in controlling segmental intervertebral motion. This study aimed to evaluate the association between lumbar intervertebral motion and changes in lumbar morphology/composition in people with chronic low-back pain (CLBP). A sample of 183 patients with CLBP participated in this cross-sectional study. Participants underwent lumbar flexion-extension X-rays to determine vertebral motion (translational and/or rotational motion) of lumbar levels (L1-L2 to L5-S1) and lumbar spine magnetic resonance imaging to quantify total and functional cross-sectional areas (CSAs) and asymmetry of the multifidus (MF), lumbar erector spinae (LES), and psoas muscles. The relationship between morphology/ composition of the muscles and lumbar intervertebral motion was investigated. Smaller total and functional CSAs of the MF and greater CSAs of the LES muscle were observed in participants with greater intervertebral motion. Muscle asymmetry was observed at different lumbar vertebral levels. The greatest amount of translational intervertebral motion was observed at the L3-L4 level, while the greatest amount of rotational translation occurred at the L4-L5. Associations were observed between the morphology of the paraspinal muscles at the vertebral levels adjacent to the L3-L4 level and the increased intervertebral motion at this level. Relationships between measures of muscle morphology/composition and increased segmental vertebral motion were observed. The results may provide a plausible biological reason for the effectiveness of rehabilitating deficient paraspinal muscles in a subset of people with CLBP.

Comparison of lumbar muscle morphology in patients with chronic nonspecific low back pain with and without clinical lumbar segmental instability

“…The results of our study showed L4-L5 ES hypertrophy in patients with clinical LSIs, but not in other CNLBPs, which appears to be a compensatory response of an unstable spinal system. Consistent with our findings, a recent study reported a significant increase in erector spinae CSA in patients with positive structural LSI [ 19 ]. Previous studies of spondylolisthesis also showed hypertrophy of ES [ 15 ].…”

“…According to histological studies, the deep fibers of the MF muscle contain a higher percentage of type l fibers compared to other paraspinal muscles, and these slow-twitch fibers are more exposed to the adverse effects of pain and spinal immobility. This problem is one of the causes of the MF atrophy in the present study[ 15 , 19 ]. In this study, both groups of CNLBP with and without LSI showed almost similar MF atrophy.…”

“…A study by Thakar showed that patients with spondylolisthesis had atrophy of the MF muscle and hypertrophy of the ES compared to healthy subjects. In a recent study of LBP, researchers acknowledged that hypertrophy of the ES muscle at the L4–L5 vertebral level may be due to a compensation or anatomical adaptation to the increased motion at the upper lumbar levels [ 19 ]. However, ES hypertrophy may have occurred as a compensatory response to poor stabilization of the lumbosacral spine due to pain, dysfunction, and deeper muscle atrophy.…”

“…A systematic review that was recently conducted by Seyedhoseinpoor et al showed that people with LBP have smaller MF muscles with a significant amount of intramuscular fat infiltration [ 18 ]. And meaningful associations between morphologic changes of the MF and ES with greater intervertebral motion have been reported in people with chronic LBP in a recent exploratory study [ 19 ]. Although the role of lumbar muscles in maintaining stability has been emphasized as an active subsystem of stability; but probable morphological change of lumbar muscle has not been clearly defined by literature in CLBP patients with clinical LSI.…”

Quantifying the stiffness of lumbar erector spinae during different positions among participants with chronic low back pain

“…From 1999 to 2016, its prevalence was reported to have increased 23.5% in China [2]. CLBP is significantly associated with the lumbar muscles [3][4][5]. Various lumbar muscles contribute to maintaining the stability of the low back during trunk movement.…”