Do variations in paraspinal muscle morphology and composition predict low back pain in men?

Application of MRI imaging parameters in lumbar spine diseases: a review of the literature

AIM

The purpose of this study is to review the application of MRI imaging parameters in lumbar degenerative diseases (LDD) and related complications after lumbar surgery, and to explore its application scope, advantages and diagnostic value.

MATERIALS AND METHODS

This study provides a comprehensive review of the application of MRI imaging parameters in LDD. The measurement methods of each imaging parameter were described in detail, and the clinical significance of each parameter in LDD and postoperative complications of lumbar spine was summarized.

RESULTS

Studies have shown that reduced paraspinal muscle cross-sectional area (CSA), increased fat infiltration rate (FIR), and smaller lumbar depression value (LIV) are risk factors for the development of LDD and postoperative complications of lumbar spine (vertebral fracture, screw loosening, cage subsidence, etc). The vertebral bone quality (VBQ) score reflects vertebral bone quality and correlates significantly with DXA T-value and QCT BMD value, which can effectively identifying patients with osteopenia or normal bone quality. At the same time,elevated VBQ score is a significant predictor of the occurrence of osteoporosis, postoperative screw loosening and fusion cage subsidence in the lumbar spine.

CONCLUSION

Our study showed that MRI imaging-related parameters are widely used in clinical practice, which can quantitatively reflect the quality of paravertebral muscles, the degree of fat infiltration, and vertebral bone density. They have important guiding significance for the diagnosis, treatment and prognosis of lumbar spine diseases.

A comparative analysis of lumbar paraspinal muscle morphology between two movement system impairment subgroups of chronic nonspecific low back pain

BACKGROUND

Based on the kinesiopathologic model, the Movement System Impairment (MSI) classification of LBP has shown that repetitive movements could contribute to pathoanatomic tissue changes. However, these changes have not been evaluated in different MSI classification subgroups of patients with LBP.

OBJECTIVE

This study compared the grades of fatty infiltration as one of the muscle's pathologic changes in the lower lumbar paraspinal and psoas muscles between the two subgroups of patients diagnosed with MSI syndromes having opposite movement direction impairments.

DESIGN

Observational cross-sectional study.

METHOD

Forty-five participants with chronic LBP were enrolled in the study, with 23 patients in the lumbar flexion-rotation (FlexRot) subgroup and 22 in the lumbar extension-rotation (ExtRot) subgroup of MSI. Magnetic resonance imaging (MRI) and the Goutallier Classification System (GCS) were used for fatty grading of lumbar paraspinal and psoas muscles. After the reliability of this grading scale was evaluated, the results were compared between the two subgroups.

RESULTS

The Mann-Whitney U Test showed significantly higher fat infiltration of lower lumbar multifidus and erector spinae muscles in the lumbar ExtRot subgroup, with no significant difference between the two subgroups in terms of psoas muscles (P ≤ 0.05). Inter-rater reliability of GCS was acceptable to excellent, and intra-rater reliability was good to excellent.

CONCLUSION

The fatty infiltration grade of lumbar paraspinal muscles in L4-L5 and L5-S1 levels are significantly different between the two LBP subgroups of MSI that have two opposite movement direction impairments. The lumbar paraspinal muscles, which contribute to extension, have a higher grade of fat in the ExtRot subgroup, whose symptoms are aggravated by lumbar extension.

Correlation between degeneration of cervical intervertebral disc and degeneration of paravertebral muscle

Objective

To investigate the relationship between degeneration of cervical intervertebral disc and degeneration of paravertebral muscles[multifidus (MF), cervical semispinalis (SCer), semispinalis capitis (SCap) and splenius capitis (SPL)].

Methods

82 patients with chronic neck pain were randomly selected, including 43 males and 39 females, with 50.73 0.7.51 years old. All patients were scanned by 3.0T MRI Philips Ingenia performed conventional MRI sequence scanning and fat measurement sequence mDIXON-Quant scanning of cervical. Fat infiltration (FI) and cross-sectional area (CSA) of cervical paravertebral muscle (MF, SCer, SCap and SPL) at central level of C5-6 disc were measured by Philips 3.0T MRI image post-processing workstation. According to Pfirrmann grading system, there was no grade I in the included cases. The number of grade IIr IV cases were n=16, 40, 19 and 7 respectively. CSA and FI of cervical paravertebral muscles were compared with t test or one-way ANOVA, Spearman correlation analysis was used to evaluate the correlation between age, disc degeneration, and CSA, FI of cervical paravertebral muscles, and multiple linear regression analysis was used to analyze the independent influencing factors of CSA and FI.

Results

CSA of cervical paravertebral muscles in male patients was significantly higher than that in female patients (all P<0.001), but there was no significant difference in FI (all P>0.05). Age was weakly correlated with CSA of MF+SCer, moderately correlated with CSA of SCap and SPL (r=-0.256, -0.355 and -0.361, P<0.05), weakly correlated with FI of SCap and SPL (r= 0.182 and 0.264, P<0.001), moderately correlated with FI of MF+SCer (r=0.408, P<0.001). There were significant differences in FI with disc degeneration (P<0.001, P=0.028 and P=0.005). Further correlation analysis showed that disc degeneration was strongly correlated with FI of MF+SCer (r=0.629, P<0.001), and moderately correlated with FI of SCap and SPL (r=0.363, P=0.001; r=0.345, P=0.002). Multiple linear regression analysis showed that sex and age were the influencing factors of CSA of SCap and SPL, sex was the independent influencing factor of CSA of MF+SCer, and disc degeneration was the independent influencing factor of FI.

Conclusions

Age is negatively correlated with CSA and positively correlated with FI. Disc degeneration was correlated with FI of paravertebral muscles, especially with FI of MF and SCer. Sex and age were the influencing factors of CSA, while disc degeneration was the independent influencing factor of FI.

Spinal degeneration and lumbar multifidus muscle quality may independently affect clinical outcomes in patients conservatively managed for low back or leg pain

Few non-surgical, longitudinal studies have evaluated the relations between spinal degeneration, lumbar multifidus muscle (LMM) quality, and clinical outcomes. None have assessed the potential mediating role of the LMM between degenerative pathology and 12-month clinical outcomes. This prospective cohort study used baseline and 12-month follow-up data from 569 patients conservatively managed for low back or back-related leg pain to estimate the effects of aggregate degenerative lumbar MRI findings and LMM quality on 12-month low back and leg pain intensity (0-10) and disability (0-23) outcomes, and explored the mediating role of LMM quality between degenerative findings and 12-month clinical outcomes. Adjusted mixed effects generalized linear models separately estimated the effect of aggregate spinal pathology and LMM quality. Mediation models estimated the direct and indirect effects of pathology on leg pain, and pathology and LMM quality on leg pain, respectively. Multivariable analysis identified a leg pain rating change of 0.99 [0.14; 1.84] (unstandardized beta coefficients [95% CI]) in the presence of ≥ 4 pathologies, and a disability rating change of - 0.65 [- 0.14; - 1.16] for each 10% increase in muscle quality, but no effect on back pain intensity. Muscle quality had a non-significant mediating role (13.4%) between pathology and leg pain intensity. The number of different pathologies present demonstrated a small effect on 12-month leg pain intensity outcomes, while higher LMM quality had a direct effect on 12-month disability ratings but no mediating effect between pathology and leg pain. The relations between degenerative pathology, LMM quality, and pain-related outcomes appear complex and may include independent pathways.

Fatty Infiltration of Multifidus Muscles: An Easily Overlooked Risk Factor for the Severity of Osteoporotic Vertebral Fractures

OBJECTIVES

Osteoporotic vertebral fractures (OVFs) are a critical public health concern requiring urgent attention, and severe OVFs impose substantial health and economic burdens on patients and society. Analysis of the risk factors for severe OVF is imperative to actively prevent the occurrence of this degenerative disorder. This study aimed to investigate the risk factors associated with the severity of OVF, with a specific focus on changes in the paraspinal muscles.

METHODS

A total of 281 patients with a first-time single-level acute OVF between January 2016 and January 2023 were enrolled in the study. Clinical and radiological data were collected and analyzed. The cross-sectional area (CSA) and degree of fatty infiltration (FI) of the paraspinal muscles, including the multifidus muscles (MFMs), erector spinae muscles (ESMs), and psoas major muscles (PSMs), were measured by magnetic resonance imaging (MRI) of the L4/5 intervertebral discs. According to the classification system of osteoporotic fractures (OF classification) and recommended treatment plan, OVFs were divided into a low-grade OF group and a high-grade OF group. Univariate and multivariate logistic regression analyse s were performed to identify risk factors associated with the severity of OVF.

RESULTS

Ninety-eight patients were included in the low-grade OF group, and 183 patients were included in the high-grade OF group. Univariate analysis revealed a significantly higher incidence of a high degree of FI of MFMs (OR = 1.71, p = 0.002) and ESMs (OR = 1.56, p = 0.021) in the high-grade OF group. Further multivariate logistic regression analysis demonstrated that a high degree of FI of the MFMs (OR = 1.71, p = 0.002) is an independent risk factor for the severity of OVF.

CONCLUSION

A high degree of FI of the MFMs was identified as an independent risk factor for the severity of OVF. Decreasing the degree of FI in the MFMs might lower the incidence of the severity of OVF, potentially reducing the necessity for surgical intervention in OVF patients.

Augmentation of musculoskeletal soft tissue morphology within low back pain patients may suggest the presence of physiological stress shielding: An in vivo study

INTRODUCTION

The pathomechanism of low back pain (LBP) remains unknown. However, changes to mechanical properties of soft tissues affected by LBP may indicate the presence of stress shielding, which may manifest via tissue remodeling. This study investigates the potential for physiological stress shielding within the lumbar spine by examining differences within lumbar soft tissue morphology between control and LBP subjects.

METHODS

Through MRI, the total and functional cross-sectional area (tCSA, fCSA) and fatty infiltration (FI) of the lumbar multifidus (MF), erector spinae (ES), quadratus lumborum (QL), psoas major (PM), and thoracolumbar fascia (TLF) were measured from the L1/L2 to L5/S1 intervertebral disc levels of 69 subjects (36 LBP and 33 control subjects). Statistical analysis was conducted using Mann-Whitney U. P < 0.05 denoted significance.

RESULTS

Comparison of male LBP patients and male healthy controls yielded an increase in tCSA and fCSA within the L4/L5 PM (p < 0.01), and the L4/L5 ES (p = 0.02) and PM (p < 0.01), respectively, of LBP patients. Female LBP patients' FI compared to female controls increased within the L1/L2 MF (p = 0.03), L3/L4 MF (p = 0.04) and ES (p = 0.02), and L4/L5 QL (p = 0.01). The L3/L4 TLF also demonstrated an 8% increase in LBP subjects.

CONCLUSION

Male patients' results suggest elevated tissue loading during motion yielding hypertrophy in the L4/L5 ES and PM fCSA, and PM tCSA. Female LBP patients' MF, ES, and PM at L3/L4 demonstrating elevated FI coupled with TLF tCSA hypertrophy may suggest irregular stress distributions and lay the foundation for stress shielding within musculoskeletal soft tissues.

PILLAR: ParaspInaL muscLe segmentAtion pRoject - a comprehensive online resource to guide manual segmentation of paraspinal muscles from magnetic resonance imaging

BACKGROUND

There is an increasing interest in assessing paraspinal morphology and composition in relation to low back pain (LBP). However, variations in methods and segmentation protocols contribute to the inconsistent findings in the literature. We present an on-line resource, the ParaspInaL muscLe segmentAtion pRoject (PILLAR, https://projectpillar.github.io/ ), to provide a detailed description and visual guide of a segmentation protocol by using the publicly available ITK-SNAP software and discuss related challenges when performing paraspinal lumbar muscles segmentations from magnetic resonance imaging (MRI).

METHODS

T2-weighted and corresponding fat-water IDEAL axial MRI from 3 males and 3 females (2 chronic LBP and 1 control for each sex) were used to demonstrate our segmentation protocol for each lumbar paraspinal muscle (erector spinae, lumbar multifidus, quadratus lumborum and psoas) and lumbar spinal level (L1-L5).

RESULTS

Proper segmentation requires an understanding of the anatomy of paraspinal lumbar muscles and the variations in paraspinal muscle morphology and composition due to age, sex, and the presence of LBP or related spinal pathologies. Other challenges in segmentation includes the presence and variations of intramuscular and epimuscular fat, and side-to-side asymmetry.

CONCLUSION

The growing interest to assess the lumbar musculature and its role in the development and recurrence of LBP prompted the need for comprehensive and easy-to-follow resources, such as the PILLAR project to reduce inconsistencies in segmentation protocols. Standardizing manual muscle measurements from MRI will facilitate comparisons between studies while the field is progressively moving towards the automatization of paraspinal muscle measurements for large cohort studies.

Investigating sources for variability in volunteer kinematics in a braking maneuver, a sensitivity analysis with an active human body model

Occupant kinematics during evasive maneuvers, such as crash avoidance braking or steering, varies within the population. Studies have tried to correlate the response to occupant characteristics such as sex, stature, age, and BMI, but these characteristics explain no or very little of the variation. Therefore, hypothesis have been made that the difference in occupant response stems from voluntary behavior. The aim of this study was to investigate the effect from other sources of variability: in neural delay, in passive stiffness of fat, muscle tissues and skin, in muscle size and in spinal alignment, as a first step towards explaining the variability seen among occupants in evasive maneuvers. A sensitivity analysis with simulations of the SAFER Human Body Model in braking was performed, and the displacements from the simulations were compared to those of volunteers. The results suggest that the head and torso kinematics were most sensitive to spinal alignment, followed by muscle size. For head and torso vertical displacements, the range in model kinematics was comparable to the range in volunteer kinematics. However, for forward displacements, the included parameters only explain some of the variability seen in the volunteer experiment. To conclude, the results indicate that the variation in volunteer vertical kinematics could be partly attributed to the variability in human characteristics analyzed in this study, while these cannot alone explain the variability in forward kinematics. The results can be used in future tuning of HBMs, and in future volunteer studies, when further investigating the potential causes of the large variability seen in occupant kinematics in evasive maneuvers.

Enhanced grading methods for lumbar paraspinal fat infiltration and its prognostic value in predicting lumbar disc herniation

BACKGROUND

The simplified 3-grade system for measuring fat infiltration in the paraspinal muscles is widely utilized. In comparing our proposed 4-grade system to the existing 3-grade system, we evaluated its impact on results and particularly its ability to predict disc herniation, ultimately highlighting deficiencies in the latter. The objective of this investigation was to validate the efficacy of our newly proposed semi-quantitative simplified 4-grade system for assessing fat infiltration, as compared to the existing literature-based simplified 3-grade system, in terms of their predictive value for lumbar disc herniation.

METHODS

Infiltration of the right and left lumbar multifidus and erector spinae muscles were assessed using a semi-quantitative 3- and 4-grade fat infiltration system on axial magnetic resonance imaging sections at the L3-S1 level in all subjects, with comparison of results between groups. The correlation between these grading systems and lumbar disc herniation was investigated.

RESULTS

The simplified 3-degree system for measuring fat infiltration was not effective in predicting lumbar disc herniation (p > 0.05), while the 4-degree system proved to be useful in predicting it (p < 0.05). In both grading systems, females were found to have a higher risk of lumbar disc herniation than males (p < 0.05), and the risk increased with age and body mass index (BMI) (p < 0.001).

CONCLUSIONS

It was observed that using the 4-grade fat infiltration system to determine the level of fat infiltration in the paraspinal muscles is more effective in predicting lumbar disc herniation compared to the 3-grade system. The 4-grade fat infiltration grading system proves to be an efficient semi-quantitative method that can replace the simplified 3-grade system.

The association between morphological characteristics of paraspinal muscle and spinal disorders

BACKGROUND

Spinal disorders affect millions of people worldwide, and can cause significant disability and pain. The paraspinal muscles, located on either side of the spinal column, play a crucial role in the movement, support, and stabilization of the spine. Many spinal disorders can affect paraspinal muscles, as evidenced by changes in their morphology, including hypertrophy, atrophy, and degeneration.

OBJECTIVES

The objectives of this review were to examine the current literature on the relationship between the paraspinal muscles and spinal disorders, summarize the methods used in previous studies, and identify areas for future research.

METHODS

We reviewed studies on the morphological characteristics of the paravertebral muscle and discussed their relationship with spinal disorders, as well as the current limitations and future research directions.

RESULTS

The paraspinal muscles play a critical role in spinal disorders and are important targets for the treatment and prevention of spinal disorders. Clinicians should consider the role of the paraspinal muscles in the development and progression of spinal disorders and incorporate assessments of the paraspinal muscle function in clinical practice.

CONCLUSION

The findings of this review highlight the need for further research to better understand the relationship between the paraspinal muscles and spinal disorders, and to develop effective interventions to improve spinal health and reduce the burden of spinal disorders.

The Effects of Combined Motor Control and Isolated Extensor Strengthening versus General Exercise on Paraspinal Muscle Morphology, Composition, and Function in Patients with Chronic Low Back Pain: A Randomized Controlled Trial

Low back pain (LBP), a globally widespread and persistent musculoskeletal disorder, benefits from exercise therapy. However, it remains unclear which type leads to greater changes in paraspinal muscle health. This study aimed to (1) compare the effects of a combined motor control and isolated lumbar extension exercise (MC+ILEX) versus a general exercise (GE) intervention on paraspinal muscle morphology, composition, and function, and (2) examine whether alterations in paraspinal muscle health were correlated with improvements in pain, function, and quality of life. Fifty participants with chronic LBP were randomly assigned to each group and underwent a 12-week supervised intervention program. Magnetic resonance imaging and ultrasound assessments were acquired at baseline, 6 and 12 weeks to examine the impact of each intervention on erector spinae (ES) and multifidus (MF) muscle size (cross-sectional area, CSA), composition, and function at L4-L5 and L5-S1. Self-reported questionnaires were also acquired to assess participant-oriented outcomes. Our findings indicated that the MC+ILEX group demonstrated greater improvements in MF and ES CSA, along with MF thickness at both levels (all p < 0.01). Both groups significantly improved in pain, function, and quality of life. This study provided preliminary results suggesting that an MC+ILEX intervention may improve paraspinal morphology while decreasing pain and disability.

Comparison of paraspinal muscle composition measurements using IDEAL fat-water and T2-weighted MR images

PURPOSE

The purpose of this study was to evaluate the agreement between paraspinal muscle composition measurements obtained from fat-water images using % fat-signal fraction (%FSF) in comparison to those obtained from T2-weighted magnetic resonance images (MRI) using a thresholding method.

METHODS

A sample of 35 subjects (19 females, 16 males; 40.26 ± 11.3 years old) was selected from a cohort of patients with chronic low back pain (LBP). Axial T2-weighted and IDEAL (Lava-Flex, 2 echo sequence) fat and water MR images were obtained using a 3.0 Tesla GE scanner. Multifidus, erector spinae, and psoas major muscle composition measurements were acquired bilaterally at L4-L5 and L5-S1 using both imaging sequences and related measurement methods. All measurements were obtained by the same rater, with a minimum of 7 days between each method. Intra-class correlation coefficients (ICCs) were calculated to assess intra-rater reliability. Pearson Correlation and Bland-Altman 95% limits of agreement were used to assess the agreement between both measurement methods.

RESULTS

The intra-rater reliability was excellent for all measurements with ICCs varying between 0.851 and 0.997. Strong positive correlations indicating a strong relationship between composition measurements were obtained from fat-water and T2-weighted images for bilateral multifidus and erector spinae muscles at both spinal levels and the right psoas major muscle at L4-L5, with correlation coefficient r ranging between 0.67 and 0.92. Bland-Altman plots for bilateral multifidus and erector spinae muscles at both levels revealed excellent agreement between the two methods, however, systematic differences between both methods were evident for psoas major fat measurements.

CONCLUSION

Our findings suggest that utilizing fat-water and T2-weighted MR images are comparable for quantifying multifidus and erector spinae muscle composition but not of the psoas major. While this suggests that both methods could be used interchangeably for the multifidus and erector spinae, further evaluation is required to expand and confirm our findings to other spinal levels.

A preliminary study on degenerate characteristics of lumbar and abdominal muscles in middle-aged and elderly people with varying bone mass

BACKGROUND

With the wide application of QCT in the clinical assessment of osteoporosis and sarcopenia, the characteristics of musculoskeletal degeneration in middle-aged and elderly people need to be further revealed. We aimed to investigate the degenerate characteristics of lumbar and abdominal muscles in middle-aged and elderly people with varying bone mass.

METHODS

A total of 430 patients aged 40-88 years were divided into normal, osteopenia, and osteoporosis groups according to quantitative computed tomography (QCT) criteria. The skeletal muscular mass indexes (SMIs) of five muscles [abdominal wall muscles (AWM), rectus abdominis (RA), psoas major muscle (PMM), posterior vertebral muscles (PVM), and paravertebral muscles (PM)] included in lumbar and abdominal muscles were measured by QCT. Differences in SMIs among three groups, as well as the correlation between SMIs and volumetric bone mineral density (vBMD) were analyzed. The areas under the curves (AUCs) for SMIs for prediction of low bone mass and osteoporosis were calculated.

RESULTS

In male group, SMIs of RA and PM in osteopenia group were significantly lower than those in the normal group (P = 0.001 and 0.023, respectively). In female group, only SMI of RA in osteopenia group was significantly lower than that in the normal group (P = 0.007). SMI of RA was positively correlated with vBMD with the highest coefficients in male and female groups (r = 0.309 and 0.444, respectively). SMIs of AWM and RA had higher AUCs varying from 0.613 to 0.737 for prediction of low bone mass and osteoporosis in both genders.

CONCLUSIONS

The changes of SMIs of the lumbar and abdominal muscles in patients with varying bone mass are asynchronous. SMI of RA is expected to be a promising imaging marker for predicting abnormal bone mass.

TRIAL REGISTRATION

ChiCTR1900024511 (Registered 13-07-2019).

Evaluation of the degeneration of the multifidus and erector spinae muscles in patients with low back pain and healthy individuals

BACKGROUND

Although several studies have been conducted to determine the cause of low back pain (LBP), a sufficient correlation has not been found between research findings and symptoms. Therefore there seems to be a need for studies to explain the relationship between pain and morphological changes in the paraspinal muscles of patients with LBP through comparisons with healthy control subjects.

OBJECTIVE

The aim of this study was to examine degeneration in the lumbar musculus multifidus (LMF) and lumbar musculus erector spinae (LES) muscles in patients with chronic LBP with non-radiculopathy lumbar disc herniation (LDH), patients with mechanical LBP, and healthy individuals.

METHODS

The study included 35 patients with mechanical LBP, 38 patients with non-radiculopathy LDH, and a control group of 36 healthy participants. In all patients and the control group, evaluations were made on axial magnetic resonance imaging slices at L3-S1 level of the LMF and LES cross-sectional areas (CSA), total CSA (TCSA = LMF+LES), fat infiltrations and asymmetries.

RESULTS

The mean CSA values of the right and left LMF and LES showed significant differences between the groups (p< 0.001, p= 0.002, p= 0.002, p= 0.010, respectively). Fat infiltrations showed a difference between the right-left LMF and left LES groups (p= 0.007, p< 0.001, p= 0.026, respectively). Asymmetry was not observed between the CSA and TCSA of the right and left sides.

CONCLUSION

A correlation was found between fat infiltration in the LMF and mechanical LBP and LDH. However, no significant correlation was determined between LBP and the CSA and TCSA of the LMF and LES. This was thought to be due to an incorrect result of CSA and TCSA in the evaluation of muscle mass. Therefore, for a more accurate evaluation of muscle mass, it can be considered necessary to measure muscle atrophy associated with fat infiltration or functional CSA.

The relationship between the degeneration and asymmetry of the lumbar multifidus and erector spinae muscles in patients with lumbar disc herniation with and without root compression

BACKGROUND

The determination of muscle pathologies in lumbar disc herniation (LDH) and other conditions with low back pain is important for understanding low back problems and determining appropriate treatment methods. In patients with lumbar disc herniation with radiculopathy, elucidating the effect of root compression on the severity of muscle degeneration may predict the importance of alleviating root compression. For this purpose, magnetic resonance imaging (MRI) was used to compare the degeneration and asymmetries of the lumbar musculus multifidus (MF) and lumbar musculus erector spinae (ES) muscles in patients with lumbar discopathy without root compression (radiculopathy) and in patients with lumbar discopathy with root compression (radiculopathy).

METHODS

The patients were examined in two groups: 56 patients with lumbar discopathy and no radiculopathy (Non-rad group) and 51 patients with lumbar discopathy and radiculopathy (Rad group). On axial MRI sections passing through the centre of the disc at the L3-S1 level, the asymmetry, cross-sectional area (CSA), fat infiltration, and total CSA (TCSA = MF + ES) of the MF and ES muscles were measured and compared.

RESULTS

No difference was seen between the groups with respect to the CSA values of the right and left MF and left ES, but a significant difference was found in the right ES CSA (p = 0.021). The CSA and TCSA of the MF and ES showed no asymmetry according to group. Severe fat infiltration of > 50% in the right and left MF and left ES was found in the Rad group at a higher rate than in the Non-rad group. Fat infiltration was significantly positively correlated with age, body mass index, and the duration of pain (p < 0.001, p < 0.001, p = 0.004, respectively).

CONCLUSIONS

The study results showed a correlation between LDH and paraspinal muscle degeneration, while no correlation was found with asymmetry. Severe (> 50%) fat infiltration is associated with root compression, and the severity of fat filtration increases in the presence of root compression. The development of more severe degeneration due to denervation associated with root compression plays a role in the emergence of this situation. Therefore, in patients with lumbar disc herniation with radiculopathy, it can be foreseen that to stop and correct severe fat infiltration and muscle degeneration, first, nerve root compression should be corrected with appropriate medical treatment methods, and in patients in whom there is no response, the pressure should be alleviated with appropriate surgical methods.

A new equation for correlation of clinical and radiological factors affecting multifidus muscle degeneration in magnetic resonance imaging

Background

Multifidus muscle (MF) is one of the back muscles of the spine that is involved in the pathogenesis of low back pain. Its role as a stabilizer of the spine continues to present diagnostic and therapeutic challenges. The degree of MF degeneration is dependent on multiple clinical and radiological factors. We proposed a new equation to predict MF degeneration based upon clinical and radiological changes in magnetic resonance imaging.

Methods

Clinical factors associated with MF degeneration include visual analogue scale (VAS) for pain, body mass index, duration of complaint, age of the patients and the presence of sciatica. Other radiological factors include the number of disc pathologies, neural canal stenosis and facet joint arthropathies, by building a module of a univariate and multivariate linear regression analysis for the parameters affecting MF degeneration score as a dependent variable.

Results

Regarding the univariate and multivariate linear regression for factors affecting MF degeneration, the most common factors associated with increased multifidus score were the duration in years and VAS score in the multivariate analysis model with B value equal to 0.184 according to duration in years and equal to 0.287 with VAS score according to 95% confidence interval.

Conclusion

The equation for multifidus score is a helpful method to predict the degree of MF degeneration in relation to clinical variable.

Investigation of the relationship between the clinical evaluation results of lumbar region muscles with cross-sectional area and fat infiltration

BACKGROUND

The relationship between the endurance of the lumbar paraspinal muscles and morphological changes needs to be clarified. In this context, the importance can be revealed of increasing the endurance level of the paraspinal muscles in the prevention and treatment of low back diseases.

OBJECTIVE

The aim of this study was to examine the relationship between the clinical evaluation results of the cross-sectional area (CSA) and fat infiltration of the lumbar deep paraspinal muscles.

METHODS

The study included 37 patients with mechanical low back pain (mechanical), 41 patients with lumbar hernia without root compression (discopathy) and 36 healthy individuals as a control group. The functional status of the lumbar deep paraspinal muscles was evaluated clinically with muscle endurance tests. The fat infiltration and CSA of the muscles were evaluated on axial MRI sections at the L3-S1 level.

RESULTS

The mean values of the prone bridge, Biering-Sorenson, and trunk flexion tests were seen to be highest in the control group and lowest in the discopathy group (p< 0.001). In all tests, the longest test period was obtained at < 10% fat infiltration and the shortest at > 50% fat infiltration. It was observed that as the amount of fat infiltration of the muscles increased, the test times were shortened. There was no significant relationship between the endurance level and the CSA of the groups.

CONCLUSION

The study results demonstrated that the endurance of the paraspinal muscles is associated with the fat infiltration of the muscles. In patients with chronic low back pain, information about muscle morphology and degeneration can be obtained with simple endurance tests without the need for further measurements. On clinical examination, a weak endurance level of the paraspinal muscles indicates the presence of a low back problem and an increase in the amount of fat infiltration.

Paraspinal Muscle Degeneration: A Potential Risk Factor for New Vertebral Compression Fractures After Percutaneous Kyphoplasty

Background

The paraspinal muscle is essential for maintaining normal spine function and structure, which degeneration is closely related to various spinal diseases. The main objective of this study was to identify the potential role of paraspinal muscle degeneration in the occurrence of new vertebral compression fractures (NVCF) and develop a clinically applicable nomogram for prospective NVCF risk prediction.

Methods

A total of 202 patients with single-level osteoporotic vertebral compression fractures (OVCF) who underwent percutaneous kyphoplasty treatment between January 2016 and March 2019 were included in this study. Demographic, clinical, radiological, and treatment data were collected and analyzed. The paraspinal muscle cross-sectional area (CSA) and fat signal fraction (FSF) were measured to quantify the extent of muscle degeneration. Multivariate binary logistic regression analysis was performed to select risk factors to build a nomogram that predicted the occurrence of NVCF. The concordance index (C-index) and calibration curve were used to evaluate the discriminative capacity and predictive accuracy of the nomogram.

Results

NVCF occurred in 54 of 202 patients (26.7%). The erector spinae FSF (OR = 1.064; P = 0.001), psoas major FSF (OR = 1.326; P < 0.001), and the difference index of the muscle CSA between multifidus and psoas major (OR = 1.048; P < 0.001) were independent risk factors for the occurrence of NVCF. The nomogram performance was good after evaluation using the calibration curves and C-index (95% confidence interval, 0.854–0.943).

Conclusion

Paraspinal muscle degeneration is a potential risk factor for NVCF occurrence. A nomogram was designed to precisely predict the risk of NVCF. This predictive nomogram may help clinicians to make better clinical decisions and provide more accurate functional exercise protocol for OVCF patients.

An externally validated deep learning model for the accurate segmentation of the lumbar paravertebral muscles

PURPOSE

Imaging studies about the relevance of muscles in spinal disorders, and sarcopenia in general, require the segmentation of the muscles in the images which is very labour-intensive if performed manually and poses a practical limit to the number of investigated subjects. This study aimed at developing a deep learning-based tool able to fully automatically perform an accurate segmentation of the lumbar muscles in axial MRI scans, and at validating the new tool on an external dataset.

METHODS

A set of 60 axial MRI images of the lumbar spine was retrospectively collected from a clinical database. Psoas major, quadratus lumborum, erector spinae, and multifidus were manually segmented in all available slices. The dataset was used to train and validate a deep neural network able to segment muscles automatically. Subsequently, the network was externally validated on images purposely acquired from 22 healthy volunteers.

RESULTS

The median Jaccard index for the individual muscles calculated for the 22 subjects of the external validation set ranged between 0.862 and 0.935, demonstrating a generally excellent performance of the network, although occasional failures were noted. Cross-sectional area and fat fraction of the muscles were in agreement with published data.

CONCLUSIONS

The externally validated deep neural network was able to perform the segmentation of the paravertebral muscles in an accurate and fully automated manner, although it is not without limitations. The model is therefore a suitable research tool to perform large-scale studies in the field of spinal disorders and sarcopenia, overcoming the limitations of non-automated methods.

A novel MRI index for paraspinal muscle fatty infiltration: reliability and relation to pain and disability in lumbar spinal stenosis: results from a multicentre study

BACKGROUND

Fatty infiltration of the paraspinal muscles may play a role in pain and disability in lumbar spinal stenosis. We assessed the reliability and association with clinical symptoms of a method for assessing fatty infiltration, a simplified muscle fat index (MFI).

METHODS

Preoperative axial T2-weighted magnetic resonance imaging (MRI) scans of 243 patients aged 66.6 ± 8.5 years (mean ± standard deviation), 119 females (49%), with symptomatic lumbar spinal stenosis were assessed. Fatty infiltration was assessed using both the MFI and the Goutallier classification system (GCS). The MFI was calculated as the signal intensity of the psoas muscle divided by that of the multifidus and erector spinae. Observer reliability was assessed in 102 consecutive patients for three independent investigators by intraclass correlation coefficient (ICC) and 95% limits of agreement (LoA) for continuous variables and Gwet's agreement coefficient (AC1) for categorical variables. Associations with patient-reported pain and disability were assessed using univariate and multivariate regression analyses.

RESULTS

Interobserver reliability was good for the MFI (ICC 0.79) and fair for the GCS (AC1 0.33). Intraobserver reliability was good or excellent for the MFI (ICC range 0.86-0.91) and moderate to almost perfect for the GCS (AC1 range 0.55-0.92). Mean interobserver differences of MFI measurements ranged from -0.09 to -0.04 (LoA -0.32 to 0.18). Adjusted for potential confounders, none of the disability or pain parameters was significantly associated with MFI or GCS.

CONCLUSION

The proposed MFI demonstrated high observer reliability but was not associated with preoperative pain or disability.

The relationships between physical activity, lumbar multifidus muscle morphology, and low back pain from childhood to early adulthood: a 12-year longitudinal study

We investigated the longitudinal associations between physical activity (PA), lumbar multifidus morphology, and impactful low back pain (LBP) in young people. Nine-year-old children were recruited from 25 primary schools and followed up at age 13, 16, and 21 years. We measured PA with accelerometers at age 9, 13, and 16; quantified patterns of lumbar multifidus intramuscular adipose tissue (IMAT) change from 13 to 16 years using magnetic resonance imaging; and recorded LBP and its impact with standardised questionnaires and interviews. Associations were examined with crude and adjusted logistic or multinomial models and reported with odds ratios (OR) or relative risk ratios (RRR). We included data from 364 children (mean[SD] age = 9.7[.4] years). PA behaviour was not associated with LBP. Having persistently high IMAT levels at age 13 and 16 was associated with greater odds of LBP (OR[95% CI] = 2.98[1.17 to 7.58]). Increased time in moderate and vigorous intensity PA was associated with a lower risk of higher IMAT patterns (RRR[95% CI] = .67[.46 to .96] to .74[.55 to 1.00]). All associations became non-significant after adjusting for sex and body mass index (BMI). Future studies investigating the relationships between PA behaviour, lumbar multifidus IMAT, and impactful LBP should account for potential confounding by sex and BMI.

An evaluation of the efficacy of a four-grade fat infiltration classification method, presented for the first time in literature

BACKGROUND

The deficiency of the commonly used 3-grade fat infiltration system is discussed by comparing it with the 4-grade fat infiltration system, newly presented to the literature. The aim of this study was to evaluate the efficacy of a semi-quantitative simplified 4-grade fat infiltration measurement system, described for the first time in literature, through comparison with the existing simplified 3-grade fat infiltration system in the prediction of lumbar disc herniation.

METHODS

The study included 51 patients diagnosed with lumbar disc hernia and 50 healthy individuals as the control group. The patients were evaluated in respect of fat infiltration of the right and left lumbar multifidus and erector spina muscles on axial magnetic resonance imaging slices passing through the centre of the disc at L3-S1 level using the 3 and 4-grade fat infiltration measurement systems.

RESULTS

The 3-grade fat infiltration system was found to be insufficient in the prediction of lumbar disc herniation (p > 0.05) and the 4-grade fat infiltration system was determined to be effective in the prediction of lumbar disc herniation (p < 0.001).

CONCLUSION

The 4-grade fat infiltration system was seen to be more effective than the 3-grade fat infiltration system in the determination of the level of fat infiltration in the paraspinal muscles and the prediction of lumbar disc herniation. The 4-grade fat infiltration system is a more effective semi-quantitative grading system which can be used instead of the simplified 3-grade system.

Association of Paraspinal Muscle CSA and PDFF Measurements With Lumbar Intervertebral Disk Degeneration in Patients With Chronic Low Back Pain

There is an interaction between the lumbar spine and paraspinal muscles, which may play a role in the development of intervertebral disc (IVD) degeneration and may affect CLBP. The study aims to assess the relationship between IVD degeneration and paraspinal muscle fat infiltration in CLBP patients by quantitative MR imaging, and to evaluate the influence of sex and age on CLBP muscle fat infiltration. Sixty CLBP patients (46.3 years ±17.0) and thirty-two healthy subjects (44.9 years ±17.6) were recruited for this study. 3.0 T MRI was used to perform the sagittal and axial T1, T2 of the lumbar spine, and axial paraspinal muscle IDEAL imaging at the L4/5 and L5/S1 levels. Proton density fat fraction (PDFF) of the multifidus and erector spinae at two IVD levels were measured. The Pfirrmann grades of IVD degeneration, Oswestry Disability Index (ODI), and Visual Analog Scale (VAS) were also evaluated. Compare the cross-sectional area (CSA) and PDFF of the paraspinal muscles between CLBP patients and healthy subjects, and analyze the relationship between the muscle PDFF and Pfirrmann grades, gender, and age of CLBP patients. Compared with healthy subjects, the CSA of the multifidus muscle in CLBP patients decreased (1320.2±188.1mm²vs. 1228.7±191.0 mm², p<0.05) at the L4/5 level, the average PDFF increased, (7.7±2.6% vs. 14.79±5.3%, 8.8±4.2% vs. 16.03±5.3%, all p<0.05) at both L4/5 and L5/S1 levels. The PDFF of paraspinal muscles were correlated with adjacent IVD degeneration, ODI and VSA in CLBP patients (all p<0.05). After using age and body mass index (BMI) as control variables, significance was retained (all p<0.05). Multiple regression analysis revealed sex and age also were significantly associated with multifidus PDFF (all p < 0.05). This study confirmed that the CSA decreased and the PDFF increased of the paraspinal muscles in CLBP patients. It reveals a significant correlation between the PDFF of CLBP paraspinal muscles and the grade of IVD degeneration. Sex and age are also important factors influencing CLBP paraspinal muscle infiltration.

Paraspinal muscle imaging measurements for common spinal disorders: review and consensus-based recommendations from the ISSLS degenerative spinal phenotypes group

PURPOSE

Paraspinal muscle imaging is of growing interest related to improved phenotyping, prognosis, and treatment of common spinal disorders. We reviewed issues related to paraspinal muscle imaging measurement that contribute to inconsistent findings between studies and impede understanding.

METHODS

Three key contributors to inconsistencies among studies of paraspinal muscle imaging measurements were reviewed: failure to consider possible mechanisms underlying changes in paraspinal muscles, lack of control of confounding factors, and variations in spinal muscle imaging modalities and measurement protocols. Recommendations are provided to address these issues to improve the quality and coherence of future research.

RESULTS

Possible pathophysiological responses of paraspinal muscle to various common spinal disorders in acute or chronic phases are often overlooked, yet have important implications for the timing, distribution, and nature of changes in paraspinal muscle. These considerations, as well as adjustment for possible confounding factors, such as sex, age, and physical activity must be considered when planning and interpreting paraspinal muscle measurements in studies of spinal conditions. Adoption of standardised imaging measurement protocols for paraspinal muscle morphology and composition, considering the strengths and limitations of various imaging modalities, is critically important to interpretation and synthesis of research.

CONCLUSION

Study designs that consider physiological and pathophysiological responses of muscle, adjust for possible confounding factors, and use common, standardised measures are needed to advance knowledge of the determinants of variations or changes in paraspinal muscle and their influence on spinal health.

Paraspinal muscle pathophysiology associated with low back pain and spine degenerative disorders

Low back pain disorders affect more than 80% of adults in their lifetime and are the leading cause of global disability. The muscles attaching to the spine (ie, paraspinal muscles) are critical for proper spine health and play a crucial role in the functioning of the spine and whole body; however, reports of muscle dysfunction and insufficiency in chronic LBP (CLBP) patients are common. This article presents a review of the current understanding of the relationship between paraspinal muscle pathophysiology and spine-related disorders. Human literature demonstrates a clear association between altered muscle structure/function, most notably fatty infiltration and fibrosis, and low back pain disorders; other associations, including muscle cell atrophy and fiber type changes, are less clear. Animal literature then provides some mechanistic insight into the complex relationships, including initiating factors and time courses, between the spine and spine muscles under pathological conditions. It is apparent that spine pathology can directly lead to changes in the paraspinal muscle structure, function, and biology. It also appears that changes to the muscle structure and function can directly lead to changes in the spine (eg, deformity); however, this relationship is less well studied. Future work must focus on providing insight into possible mechanisms that regulate spine and paraspinal muscle health, as well as probing how muscle degeneration/dysfunction might be an initiating factor in the progression of spine pathology.

Longitudinal study of risk factors for decreased cross-sectional area of psoas major and paraspinal muscle in 1849 individuals

This 10-year retrospective observational study investigated longitudinal losses in psoas major and paraspinal muscle area in 1849 healthy individuals (1690 male, 159 female) screened using computed tomography. Logistic regression analysis revealed significant decreases in psoas major and paraspinal muscle area at 10 years relative to the baseline area regardless of age or sex, starting at 30 years of age. Only aging [≥ 50 s (odds ratio [OR]: 1.72; 95% confidence interval [CI] 1.05–2.84; p = 0.03) and ≥ 60 s (OR: 2.67; 95% CI 1.55–4.60; p < 0.001)] was a risk factor for decreases in psoas major area. Age ≥ 60 years (OR: 2.05; 95% CI 1.24–3.39; p = 0.005), body mass index ≥ 25 kg/m² (OR: 1.32; 95% CI 1.01–1.73; p = 0.04), and visceral fat ≥ 100 cm² (OR: 1.61; 95% CI 1.20–2.15; p = 0.001) were risk factors for decreases in paraspinal muscle area. Physical activity ≥ 900 kcal/week (OR: 0.68; 95% CI 0.50–0.94; p = 0.02) attenuated paraspinal muscle area loss in male. Our study demonstrated that walking > 45 min daily (Calories = METs (walking: 3.0) × duration of time (h) × weight (60 kg) × 1.05) can reduce paraspinal muscle loss, which may in turn decrease the risk of falls, low-back pain, and sarcopenia.

Ultrasound Imaging Analysis of the Lumbar Multifidus Muscle Echo Intensity: Intra-Rater and Inter-Rater Reliability of a Novice and an Experienced Rater

Background and Objectives: Ultrasound echo intensity (EI) of the lumbar multifidus muscle (LMM) could offer valuable insights regarding muscle quality in people with low back pain (LBP). However, whether the rater’s experience noticeably influences the reliability and precision of LMM EI measurements has not been established. The aims of this study were to investigate the intra-rater and inter-rater reliability of LMM EI measurements, and to compare the reliability and SEM between a novice and an experienced rater. Materials and Methods: Twenty athletes (10 females, 10 males) with a history of LBP were included in this study. Transverse ultrasound images of LMM were taken at L5 in prone. LMM EI measurements were obtained bilaterally by tracing the maximum ROI representing the LMM cross-sectional area (CSA), avoiding the inclusion of bone or surrounding fascia. All measurements were performed by two novice raters and an experienced researcher. Each measurement was acquired by each rater three times for each side on three different images, and the average was used in the analyses. Raters were blinded to each other’s measurements and the participant’s clinical information. Intra-class correlation coefficients (ICCs) were obtained to assess the intra-rater and inter-rater reliability. Results: The intra-rater ICC values for the LMM measurements for the experienced rater were excellent (ICC all > 0.997). The inter-rater reliability ICC values showed moderate to excellent reliability (0.614 to 0.994) and agreement between the novice raters and the experienced rater, except for Novice 1 for the right LMM, which revealed lower ICCs and a wider 95% CI. Intra-rater and inter-rater reliability results were similar when separately looking at the right and left side of the muscle and participant gender. Conclusions: Our findings support the clinical use of ultrasound imaging for the assessment of LMM EI in individuals with LBP.

Imaging Evaluation of Fat Infiltration in Paraspinal Muscles on MRI: A Systematic Review with a Focus on Methodology

Purpose

Numerous studies have applied a variety of methods to assess paraspinal muscle degeneration. However, the methodological differences in imaging evaluation may lead to imprecise or inconsistent results. This article aimed to provide a pragmatic summary review of the current imaging modalities, measurement protocols, and imaging parameters in the evaluation of paraspinal muscle fat infiltration (FI) in MRI studies.

Methods

Web of Science, EMBASE, and PubMed were searched from January 2005 to March 2020 to identify studies that examined the FI of paraspinal muscles on MRI among patients with lumbar degenerative diseases.

Results

Intramyocellular lipids measured by magnetic resonance spectroscopy and FI measured by chemical‐shift MRI were both correlated to low back pain and several degenerative lumbar diseases, whereas results on the relationship between FI and degenerative lumbar pathologies using conventional MRI were conflicting. Multi‐segment measurement of FI at the lesion segment and adjacent segments could be a prognostic indicator for lumbar surgery. Most studies adopted the center of the intervertebral disc or endplate as the level of slice to evaluate the FI. Compared with visual semiquantitative assessment, quantitative parameters appeared to be precise for eliminating individual or modality differences. It has been demonstrated that fat CSA/total CSA (based on area) and muscle–fat index (based on signal intensity) as quantitative FI parameters are associated with multiple lumbar diseases and clinical outcomes after surgery.

Conclusion

Having a good command of the methodology of paraspinal muscle FI on MRI was effective for diagnosis and prognosis in clinical practice.

Assessing lumbar paraspinal muscle cross-sectional area and fat composition with T1 versus T2-weighted magnetic resonance imaging: Reliability and concurrent validity

Purpose

Studies using magnetic resonance imaging to assess lumbar multifidus cross-sectional area frequently utilize T1 or T2-weighted sequences, but seldom provide the rationale for their sequence choice. However, technical considerations between their acquisition protocols could impact on the ability to assess lumbar multifidus anatomy or its fat/muscle distinction. Our objectives were to examine the concurrent validity of lumbar multifidus morphology measures of T2 compared to T1-weighted sequences, and to assess the reliability of repeated lumbar multifidus measures.

Methods

The lumbar multifidus total cross-sectional area of 45 patients was measured bilaterally at L4 and L5, with histogram analysis determining the muscle/fat threshold values per muscle. Images were later re-randomized and re-assessed for intra-rater reliability. Matched images were visually rated for consistency of outlining between both image sequences. Bland-Altman bias, limits of agreement, and plots were calculated for differences in total cross-sectional area and percentage fat between and within sequences, and intra-rater reliability analysed.

Results

T1-weighted total cross-sectional area measures were systematically larger than T2 (0.2 cm²), with limits of agreement <±10% at both spinal levels. For percentage fat, no systematic bias occurred, but limits of agreement approached ±15%. Visually, muscle outlining was consistent between sequences, with substantial mismatches occurring in <5% of cases. Intra-rater reliability was excellent (ICC: 0.981–0.998); with bias and limits of agreement less than 1% and ±5%, respectively.

Conclusion

Total cross-sectional area measures and outlining of muscle boundaries were consistent between sequences, and intra-rater reliability for total cross-sectional area and percentage fat was high indicating that either MRI sequence could be used interchangeably for this purpose. However, further studies comparing the accuracy of various methods for distinguishing fat from muscle are recommended.

Age-related degeneration of lumbar muscle morphology in healthy younger versus older men

AIM

The aim of this study was to evaluate age-related changes in lumbar paravertebral muscle (LPM) morphology in healthy younger and older adult men.

METHODS

T2-weighted axial MRI of the lumbar spine were obtained for 12 healthy older (67.3 ± 6.0 years) and younger (24.7 ± 3.1 years) men. Normalised muscle volume (NMV) and muscle fat infiltrate (MFI) were determined bilaterally for the psoas (PS), quadratus lumborum (QL), erector spinae (ES) and multifidus (MF). MANOVA was used to compare NMV and MFI between age groups. Follow-up ANOVA compared NMV and MFI for each muscle between age groups, with physical activity (PA) as a covariate. Stepwise regression was used to explore the association between muscle morphology.

RESULTS

NMV of the ES and QL were significantly lower in the older group (OG) (p = 0.040 and p < 0.001, respectively). MFI across all muscles was significantly greater in the OG (p < 0.001). PA did not moderate the relationship between aging and muscle degeneration. Non-dominant handgrip strength was associated with NMV (p = 0.003).

CONCLUSIONS

Age-related atrophy is muscle specific in the lumbar spine; changes in lumbar musculature is independent of PA, handgrip strength may reflect morphological changes in the postural muscles with age. This study supports establishing effective targeted exercise interventions in the lumbar musculature.

LUMINOUS database: lumbar multifidus muscle segmentation from ultrasound images

BACKGROUND

Among the paraspinal muscles, the structure and function of the lumbar multifidus (LM) has become of great interest to researchers and clinicians involved in lower back pain and muscle rehabilitation. Ultrasound (US) imaging of the LM muscle is a useful clinical tool which can be used in the assessment of muscle morphology and function. US is widely used due to its portability, cost-effectiveness, and ease-of-use. In order to assess muscle function, quantitative information of the LM must be extracted from the US image by means of manual segmentation. However, manual segmentation requires a higher level of training and experience and is characterized by a level of difficulty and subjectivity associated with image interpretation. Thus, the development of automated segmentation methods is warranted and would strongly benefit clinicians and researchers. The aim of this study is to provide a database which will contribute to the development of automated segmentation algorithms of the LM.

CONSTRUCTION AND CONTENT

This database provides the US ground truth of the left and right LM muscles at the L5 level (in prone and standing positions) of 109 young athletic adults involved in Concordia University's varsity teams. The LUMINOUS database contains the US images with their corresponding manually segmented binary masks, serving as the ground truth. The purpose of the database is to enable development and validation of deep learning algorithms used for automatic segmentation tasks related to the assessment of the LM cross-sectional area (CSA) and echo intensity (EI). The LUMINOUS database is publicly available at http://data.sonography.ai .

CONCLUSION

The development of automated segmentation algorithms based on this database will promote the standardization of LM measurements and facilitate comparison among studies. Moreover, it can accelerate the clinical implementation of quantitative muscle assessment in clinical and research settings.

Age-related fatty infiltration of lumbar paraspinal muscles: a normative reference database study in 516 Chinese females

Background

Fatty infiltration, as a result of aging, is an essential biomarker of muscle degeneration. This research aimed to investigate the age-dependent change of fatty degeneration in the paraspinal muscles of healthy Chinese women. This study also explores the effect of body size on fatty infiltration of paraspinal muscles.

Methods

Cross-sectional area of paraspinal muscles (CSA_muscle) and intermuscular adipose tissue (CSA_IMAT) were measured at the L3 mid-vertebral level of 516 healthy females, who underwent abdomen quantitative computed tomography (QCT) scans. Subsequently, IMAT% [CSA_IMAT / (CSA_IMAT + CSA_muscle)] were calculated. The relationship between basic information and measurements was evaluated using Spearman correlations. Comparisons of QCT results among different BMI subgroups in different age groups were analyzed with the Kruskal-Wallis H test and LSD, post-hoc correction. Age-related changes were calculated after the adjustment of height and weight.

Results

The mean CSA_IMAT of 20-29 years group (n=69) and 70-79 years group (n=25) were 3.00 cm² and 11.06 cm², respectively. While the mean CSA_muscle of 20-29 years group was 38.46 cm² and 70-79 years group was 30.86 cm². The mean IMAT% difference between 20-29 years group and 70-79 years group was -18.55%. Strong, positive non-linear associations were observed between ageing and CSA_IMAT, along with IMAT% (r=0.656, P<0.01; r=0.714, P<0.01). However, CSA_muscle was shown to decrease with age in a weak, negative linear fashion (r=-0.265, P<0.01). Positive relationships between BMI and CSA_IMAT, CSA_muscle, along with IMAT%, were found. Significant differences were observed between obesity and normal BMI subgroup for all variables in three age groups. CSA_IMAT showed a larger age-related difference compared to CSA_muscle.

Conclusions

Fatty infiltration in paraspinal muscles increased with age and BMI, while muscle loss may be associated with aging. The present study provided standardized reference data for the fatty degeneration of paraspinal muscles across the adult lifespan of Chinese females, which will play a critical role in future studies.

Inconsistent descriptions of lumbar multifidus morphology: A scoping review

BACKGROUND

Lumbar multifidus (LM) is regarded as the major stabilizing muscle of the spine. The effects of exercise therapy in low back pain (LBP) are attributed to this muscle. A current literature review is warranted, however, given the complexity of LM morphology and the inconsistency of anatomical descriptions in the literature.

METHODS

Scoping review of studies on LM morphology including major anatomy atlases. All relevant studies were searched in PubMed (Medline) and EMBASE until June 2019. Anatomy atlases were retrieved from multiple university libraries and online. All studies and atlases were screened for the following LM parameters: location, imaging methods, spine levels, muscle trajectory, muscle thickness, cross-sectional area, and diameter. The quality of the studies and atlases was also assessed using a five-item evaluation system.

RESULTS

In all, 303 studies and 19 anatomy atlases were included in this review. In most studies, LM morphology was determined by MRI, ultrasound imaging, or drawings - particularly for levels L4-S1. In 153 studies, LM is described as a superficial muscle only, in 72 studies as a deep muscle only, and in 35 studies as both superficial and deep. Anatomy atlases predominantly depict LM as a deep muscle covered by the erector spinae and thoracolumbar fascia. About 42% of the studies had high quality scores, with 39% having moderate scores and 19% having low scores. The quality of figures in anatomy atlases was ranked as high in one atlas, moderate in 15 atlases, and low in 3 atlases.

DISCUSSION

Anatomical studies of LM exhibit inconsistent findings, describing its location as superficial (50%), deep (25%), or both (12%). This is in sharp contrast to anatomy atlases, which depict LM predominantly as deep muscle. Within the limitations of the self-developed quality-assessment tool, high-quality scores were identified in a majority of studies (42%), but in only one anatomy atlas.

CONCLUSIONS

We identified a lack of standardization in the depiction and description of LM morphology. This could affect the precise understanding of its role in background and therapy in LBP patients. Standardization of research methodology on LM morphology is recommended. Anatomy atlases should be updated on LM morphology.

Assessment of the association between paraspinal muscle degeneration and quality of life in patients with degenerative lumbar scoliosis

The present study aimed to determine the characteristics of multifidus, erector spinae and psoas major degeneration in elderly patients with degenerative lumbar scoliosis (DLS) and the correlation between asymmetric changes and patient quality of life. A total of 49 patients with lumbar scoliosis (DLS group) and 38 healthy individuals (control group) were prospectively examined. The functional cross-sectional area, cross-sectional area difference index (CDI) and fat infiltration rate (FIR) of the multifidus, erector spinae and psoas major at the apical vertebral level were measured using MRI. The visual analogue scale (VAS) score, Oswestry Disability Index (ODI) and 36-item Short Form Health Survey (SF-36) score were used to evaluate patient quality of life. Correlations between the degree of asymmetric muscular degeneration and quality of life were analysed. The CDI of the multifidus, erector spinal and psoas major was higher in the DLS group compared with that in the control group. The CDI of the multifidus was found to be positively associated with the Cobb angle of lumbar scoliosis. Similar results were obtained for fat infiltration between the two groups. In addition, the CDI and FIR difference index of the multifidus was positively correlated with the VAS score and ODI but negatively correlated with the SF-36 score. The quality of life significantly decreased with increasing asymmetric atrophy and fat infiltration in the multifidus. Thus, strategies to enhance the function of the multifidus may have a positive impact on quality of life (Chinese Clinical Trial Registry, registration date, 2018.11.12; registration no. ChiCTR1800019459.).

Effect of different exercise programs on non-specific chronic low back pain and disability in people who perform sedentary work

BACKGROUND

This study compared the short- and long-term effects of different exercise programs on lumbar muscle function, cross-sectional area of the multifidus muscle, functional disability and low back pain in people who perform sedentary work.

METHODS

A total of 70 volunteer women with sedentary occupations suffering from low back pain were randomized to either the lumbar stabilization exercise program group or the lumbar muscle strengthening exercise program group. All subjects entered the 20-week exercise programs. The measurement of the cross-sectional area of the multifidus muscle was executed by using an ultrasound system, isokinetic peak torque was measured applying an isokinetic dynamometer.

FINDINGS

The results indicated that the 20-week exercise programs reduced low back pain and functional disability. Positive effects for the cross-sectional area of the multifidus muscle, functional disability and low back pain lasted for 4 weeks after the application of lumbar muscle strengthening exercise program and for 12 weeks after the application of lumbar stabilization exercise program. The lumbar muscle strength increased and lasted for 8 weeks after both exercise programs.

INTERPRETATION

The 20-week lumbar stabilization exercise and muscle strengthening exercise programs were efficacious in decreasing LBP and functional disability in people performing sedentary work, however the lumbar stabilization exercise program was more effective, and this effect lasted for 12 weeks after completion of the program.

The effect of low back pain and lower limb injury on lumbar multifidus muscle morphology and function in university soccer players

Background

The lumbar multifidus muscle (LMM) plays a critical role to stabilize the spine. While low back pain (LBP) is a common complaint in soccer players, few studies have examined LMM characteristics in this athletic population and their possible associations with LBP and lower limb injury. Therefore, the purpose of this study was to 1) investigate LMM characteristics in university soccer players and their potential association with LBP and lower limb injury; 2) examine the relationship between LMM characteristics and body composition measurements; and 3) examine seasonal changes in LMM characteristics.

Methods

LMM ultrasound assessments were acquired in 27 soccer players (12 females, 15 males) from Concordia University during the preseason and assessments were repeated in 18 players at the end of the season. LMM cross-sectional area (CSA), echo-intensity and thickness at rest and during contraction (e.g. function) were assessed bilaterally in prone and standing positions, at the L5-S1 spinal level. A self-reported questionnaire was used to assess the history of LBP and lower limb injury. Dual-energy x-ray absorptiometry (DEXA) was used to acquire body composition measurements.

Results

Side-to-side asymmetry of the LMM was significantly greater in males (p = 0.02). LMM thickness when contracted in the prone position (p = 0.04) and LMM CSA in standing (p = 0.02) were also significantly greater on the left side in male players. The LMM % thickness change during contraction in the prone position was significantly greater in players who reported having LBP in the previous 3-months (p < 0.001). LMM CSA (r = − 0.41, p = 0.01) and echo-intensity (r = 0.69, p < 0.001) were positively correlated to total % body fat. There was a small decrease in LMM thickness at rest in the prone position over the course of the season (p = 0.03).

Conclusions

The greater LMM contraction in players with LBP may be a maladaptive strategy to splint and project the spine. LMM morphology measurements were correlated to body composition. The results provide new insights with regards to LMM morphology and activation in soccer players and their associations with injury and body composition measurements.

The relationship between cross-sectional area of multifidus muscle and disability index in patients with chronic non-specific low back pain

BACKGROUND

Nonspecific low back pain (NSLBP) is a common problem that may have an effect on the level of functional ability. Imaging techniques indicated the degeneration of multifidus muscles in patients with low back pain. But its relationship with disability in NSLBP is unclear.

OBJECTIVE

To assess the relationship between changes in multifidus muscle morphology in MRI as paraclinical data with changes in the level of disability as clinical data in patients with CNLBP, whose MRI studies are normal. Moreover, the relationship between multifidus CSA and its thickness was determined.

DESIGN

Cross-sectional study.

METHODS

A total of 45 subjects with CNLBP participated in this study. Multifidus muscle thickness and cross-sectional area (CSA) for both sides in L4-L5 and L5-S1 levels were measured with MRI and Image J software. Level of disability was assessed with Roland-Morris disability index.

RESULTS

There was no significant relationship between multifidus muscle's CSA or thickness variations among the L4-L5 and L5-S1 levels and disability index score. Furthermore, Pearson's test showed significant positive relationship between thickness and CSA of muscles (p˂0.05).

CONCLUSION

The relationship between lumbar multifidus Thickness and disability in CNLBP with normal MRI study, is not proven in this study. Multifidus muscle thickness in L4-L5 or L5-S1 level can be representative of its CSA in patients with CNLBP and normal MRI.

Paraspinal muscle cross-sectional area predicts low back disability but not pain intensity

BACKGROUND AND CONTEXT

The lumbar paraspinal muscles, including the erector spinae and multifidus, play an important role in movement and control of the spine. However, our understanding of their contribution to low back pain and disability is unclear. Systematic reviews have reported conflicting evidence for an association between paraspinal muscle size and low back pain, and a paucity of data examining muscle cross-sectional area (CSA) and low back disability.

PURPOSE

To investigate the relationship between paraspinal muscle CSA and both low back pain intensity and disability.

STUDY DESIGN/SETTING

One-year longitudinal cohort study.

PATIENT SAMPLE

Participants were selected from the SpineData Registry (Denmark), which enrolls people with low back pain of 2 to 12 months duration without radiculopathy and a satisfactory response to primary intervention.

OUTCOME MEASURES

Current, typical, and worst pain in the prior 2 weeks were assessed by 11-point numeric rating scales and an average pain score was calculated, and disability was measured using the 23-item Roland-Morris Disability Questionnaire. CSA (cm²) of the lumbar paraspinal muscles was measured at levels L3-L5 from magnetic resonance images.

METHODS

Participants completed the study questionnaires and underwent the lumbar spine magnetic resonance images at baseline and were followed up 12 months later to repeat the questionnaires. Statistical analyses involved multivariable linear regression (cross-sectional analysis) and linear mixed-models (longitudinal analysis) with adjustment for confounders. Multiple imputation was conducted to account for missing data.

RESULTS

A total of 962 participants were included and 588 (65.8%) were followed up at 12-months. Multivariable analysis showed that greater paraspinal muscle CSA was associated with lower levels of disability, after adjusting for confounders (right mean CSA: baseline beta -0.16, 95% CI -0.26 to -0.06, p<.01; longitudinal beta -0.11, 95% CI -0.21 to -0.01, p=.03). This was evident at all levels, except L5 which was marginal at baseline (beta -0.08, 95% CI -0.15 to -0.001, p=.045) and not significant longitudinally (beta -0.05, 95% CI -0.12 to 0.02, p=.18). However, there were no associations between muscle CSA and pain intensity (baseline beta -0.02, 95% CI -0.06 to 0.02, p=.29; longitudinal beta -0.02, 95% CI -0.06 to 0.02, p=.34). Results were similar for both complete case and multiple imputation analyses.

CONCLUSIONS

This study found an inverse relationship between lumbar paraspinal muscle CSA and low back disability, but not pain intensity. While further investigation is needed, these findings suggest that treatment strategies directed at increasing paraspinal muscle size may be effective in reducing low back disability.

Are Magnetic Resonance Imaging Technologies Crucial to Our Understanding of Spinal Conditions?

Persistent spinal (traumatic and nontraumatic) pain is common and contributes to high societal and personal costs globally. There is an acknowledged urgency for new and interdisciplinary approaches to the condition, and soft tissues, including skeletal muscles, the spinal cord, and the brain, are rightly receiving increased attention as important biological contributors. In reaction to the recent suspicion and questioned value of imaging-based findings, this paper serves to recognize the promise that the technological evolution of imaging techniques, and particularly magnetic resonance imaging, is allowing in characterizing previously less visible morphology. We emphasize the value of quantification and data analysis of several contributors in the biopsychosocial model for understanding spinal pain. Further, we highlight emerging evidence regarding the pathobiology of changes to muscle composition (eg, atrophy, fatty infiltration), as well as advancements in neuroimaging and musculoskeletal imaging techniques (eg, fat-water imaging, functional magnetic resonance imaging, diffusion imaging, magnetization transfer imaging) for these important soft tissues. These noninvasive and objective data sources may complement known prognostic factors of poor recovery, patient self-report, diagnostic tests, and the "-omics" fields. When combined, advanced "big-data" analyses may assist in identifying associations previously not considered. Our clinical commentary is supported by empirical findings that may orient future efforts toward collaborative conversation, hypothesis generation, interdisciplinary research, and translation across a number of health fields. Our emphasis is that magnetic resonance imaging technologies and research are crucial to the advancement of our understanding of the complexities of spinal conditions. J Orthop Sports Phys Ther 2019;49(5):320-329. Epub 26 Mar 2019. doi:10.2519/jospt.2019.8793.

Cross-sectional area of the paraspinal muscles and its association with muscle strength among fighter pilots: a 5-year follow-up

Background

A small cross sectional area (CSA) of the paraspinal muscles may be related to low back pain among military aviators but previous studies have mainly concentrated on spinal disc degeneration. Therefore, the primary aim of the study was to investigate the changes in muscle CSA and composition of the psoas and paraspinal muscles during a 5-year follow up among Finnish Air Force (FINAF) fighter pilots.

Methods

Study population consisted of 26 volunteered FINAF male fighter pilots (age: 20.6 (±0.6) at the baseline). The magnetic resonance imaging (MRI) examinations were collected at baseline and after 5 years of follow-up. CSA and composition of the paraspinal and psoas muscles were obtained at the levels of 3–4 and 4–5 lumbar spine. Maximal isometric strength tests were only performed on one occasion at baseline.

Results

The follow-up comparisons indicated that the mean CSA of the paraspinal muscles increased (p < 0.01) by 8% at L3–4 level and 7% at L4–5 level during the 5-year period. There was no change in muscle composition during the follow-up period. The paraspinal and psoas muscles’ CSA was positively related to overall maximal isometric strength at the baseline. However, there was no association between LBP and muscle composition or CSA.

Conclusions

The paraspinal muscles’ CSA increased among FINAF fighter pilots during the first 5 years of service. This might be explained by physically demanding work and regular physical activity. However, no associations between muscle composition or CSA and low back pain (LBP) experienced were observed after the five-year follow-up.

Ultrasonography of multifidus muscle morphology and function in ice hockey players with and without low back pain

OBJECTIVES

To examine the relationship between lumbar multifidus (LM) morphology, function, echo-intensity (EI) and body composition among a group of university level ice hockey players with and without low back pain (LBP).

DESIGN

Cross-sectional study.

SETTING

University Research Centre.

PARTICIPANTS

Thirty-two hockey players (18 females, 14 males) participated in this study.

MAIN OUTCOME MEASURES

Resting LM cross-sectional area (CSA) was assessed bilaterally at the L5 level in prone and standing using ultrasound imaging. The LM thickness at rest and during contraction was evaluated in addition to LM EI. Body composition measures were acquired using dual-energy X-ray absorptiometry (DEXA) and LBP history was acquired using a self-reported questionnaire.

RESULTS

LM muscle CSA was significantly associated with body composition measurements. LM EI was strongly associated with total % body fat and significantly greater in females. Resting LM muscle CSA and thickness (prone) was significantly smaller in players with LBP 4-weeks prior. LM side-to-side asymmetry (standing) was also significantly greater in players with LBP 3-months prior.

CONCLUSION

The results provide new insights with regards to LM morphology and activation in ice hockey players and revealed specific deficits in LM morphology in athletes with LBP. LM morphology was strongly associated with body composition measurements.

Electrical Impedance Myography for Assessing Paraspinal Muscles of Patients with Low Back Pain

The objective of this study was to determine the potential value of electrical impedance myography (EIM) for assessing lumbosacral paraspinal muscle (LPM) condition in lower back pain (LBP) patients. Standard methods for assessing the condition of LPMs, such as magnetic resonance imaging, are inconvenient and expensive. One tool that could be useful for this purpose is electrical impedance myography (EIM) a technique that can be performed rapidly at the bedside. After undergoing a screening history and examination, subjects were studied with the mView EIM device (Myolex, Inc, Boston). Bilateral LPMs were measured three times each and the two closest sets of measurements averaged on each side. Data analysis included non-parametric two-group comparisons between healthy subjects and back pain patients, receiver-operating curve analyses, and correlation analyses to age and body mass index. A total of 86 healthy individuals (median age (interquartile range) (IQR), 45.5 years (30.3-56.0 years), 42 men, 44 women) and 47 LBP (median age 51.0 year (39.5-57.5) years, 21 men, 26 women) were enrolled. Median EIM 100kHz phase was lower in the LBP patients (9.3°(IQR 8.4°-10.6°) versus 11.4°(IQR 9.4°-13.0°), p = 0.0007). Significantly increased normalized side-to-side differences were present for all three EIM variables (e.g., median 100 kHz phase 0.15 (IQR 0.07-0.31 in LBP patients versus 0.09 (IQR 0.04-0.17) in healthy individuals). A significant correlation between 100 kHz EIM phase and reactance was found with age (Rspearman=-0.46, P=0.0002 and Rspearman=-0.440, P=0.0003) but not for resistance. This study provides early evidence supporting that EIM has the potential to serve as a useful tool for evaluating the condition of LPMs.

Severe Lumbar Intervertebral Disc Degeneration Is Associated with Modic Changes and Fatty Infiltration in the Paraspinal Muscles at all Lumbar Levels, Except for L1-L2: A Cross-Sectional Analysis of 50 Symptomatic Women and 50 Age-Matched Symptomatic Men

BACKGROUND

Low back pain is a common public health problem associated with lumbar intervertebral disc degeneration. It is still unclear, however, whether intervertebral disc degeneration is an isolated process or accompanied by other degenerative events. We analyzed whether disc degeneration was associated with vertebral end-plate changes and fatty infiltration in the paraspinal muscles. We also aimed to identify whether the severity of disc degeneration influenced this association.

METHODS

Intervertebral disc degeneration, vertebral end-plate changes, and fatty infiltration in the multifidus, erector spinae, and psoas muscles at all lumbar intervertebral disc levels were evaluated on lumbar spine magnetic resonance images of 50 symptomatic women and 50 age-matched symptomatic men.

RESULTS

The women had greater lumbar intervertebral disc degeneration scores at L4-L5 and L5-S1 and in total. The women had more fatty infiltration in the multifidus and erector spinae muscles at L4-L5 and L5-S1. The men had more fatty infiltration in the psoas muscle at L5-S1. Patients with severe intervertebral disc degeneration were more likely to have increased fatty infiltration in the multifidus and erector spinae muscles. The rate of vertebral end-plate changes was also greater in the patients with severe intervertebral disc degeneration.

CONCLUSIONS

Severe disc degeneration in the lumbar spine is closely associated with Modic changes and fatty infiltration in the multifidus and erector spinae muscles. We suggest that disc degeneration is not an isolated event but, rather, a continuum of events that could more clearly be shown in future prospective, large sample-size studies.

Severe Lumbar Disability Is Associated With Decreased Psoas Cross-Sectional Area in Degenerative Spondylolisthesis

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

Alterations in lumbar paraspinal muscle cross-sectional area (CSA) may correlate with lumbar pathology. The purpose of this study was to compare paraspinal CSA in patients with degenerative spondylolisthesis and severe lumbar disability to those with mild or moderate lumbar disability, as determined by the Oswestry Disability Index (ODI).

METHODS

We retrospectively reviewed the medical records of 101 patients undergoing lumbar fusion for degenerative spondylolisthesis. Patients were divided into ODI score ≤40 (mild/moderate disability, MMD) and ODI score >40 (severe disability, SD) groups. The total CSA of the psoas and paraspinal muscles were measured on preoperative magnetic resonance imaging (MRI).

RESULTS

There were 37 patients in the SD group and 64 in the MMD group. Average age and body mass index were similar between groups. For the paraspinal muscles, we were unable to demonstrate any significant differences in total CSA between the groups. Psoas muscle CSA was significantly decreased in the SD group compared with the MMD group (1010.08 vs 1178.6 mm², P = .041). Multivariate analysis found that psoas CSA in the upper quartile was significantly protective against severe disability (P = .013).

CONCLUSIONS

We found that patients with severe lumbar disability had no significant differences in posterior lumbar paraspinal CSA when compared with those with mild/moderate disability. However, severely disabled patients had significantly decreased psoas CSA, and larger psoas CSA was strongly protective against severe disability, suggestive of a potential association with psoas atrophy and worsening severity of lumbar pathology.

Does a Better Perfusion of Deconditioned Muscle Tissue Release Chronic Low Back Pain?

Non-specific chronic low back pain (nsCLBP) is a multifactorial condition of unknown etiology and pathogenesis. Physical and genetic factors may influence the predisposition of individuals to CLBP, which in many instances share a musculoskeletal origin. A reduced pain level in low back pain patients that participate in exercise therapy highlights that disuse-related muscle deconditioning may predispose individuals to nsCLBP. In this context, musculoskeletal pain may be the consequence of capillary rarefaction in inactive muscle as this would lower local tissue drainage and washing out of toxic waste. Muscle activity is translated into an angio-adaptative process, which implicates angiogenic-gene expression and individual response differences due to heritable modifications of such genes (gene polymorphisms). The pathophysiologic mechanism underlying nsCLBP is still largely unaddressed. We hypothesize that capillary rarefaction due to a deconditioning of dorsal muscle groups exacerbates nsCLBP by increasing noxious sensation, reducing muscle strength and fatigue resistance by initiating a downward spiral of local deconditioning of back muscles which diminishes their load-bearing capacity. We address the idea that specific factors such as angiotensin-converting enzyme and Tenascin-C might play an important role in altering susceptibility to nsCLBP via their effects on microvascular perfusion and vascular remodeling of skeletal muscle, inflammation, and pain sensation. The genetic profile may help to explain the individual predisposition to nsCLBP, thus identifying subgroups of patients, which could benefit from ad hoc treatment types. Future therapeutic approaches aimed at relieving the pain associated with nsCLBP should be based on the verification of mechanistic processes of activity-induced angio-adaptation and muscle-perfusion.

Muscle Atrophy Measurement as Assessment Method for Low Back Pain Patients

Low back pain is one of the most common pain disorders defined as pain, muscle tension, or stiffness localized below the costal margin and above the inferior gluteal folds, sometimes with accompanying leg pain. The meaning of the symptomatic atrophy of paraspinal muscles and some pelvic muscles has been proved. Nowadays, a need for new diagnostic tools for specific examination of low back pain patients is posited, and it has been proposed that magnetic resonance imaging assessment toward muscle atrophy may provide some additional information enabling the subclassification of that group of patients.

Muscle Control and Non-specific Chronic Low Back Pain

Objectives

Chronic low back pain (CLBP) is the most prevalent of the painful musculoskeletal conditions. CLBP is a heterogeneous condition with many causes and diagnoses, but there are few established therapies with strong evidence of effectiveness (or cost effectiveness). CLBP for which it is not possible to identify any specific cause is often referred to as non‐specific chronic LBP (NSCLBP). One type of NSCLBP is continuing and recurrent primarily nociceptive CLBP due to vertebral joint overload subsequent to functional instability of the lumbar spine. This condition may occur due to disruption of the motor control system to the key stabilizing muscles in the lumbar spine, particularly the lumbar multifidus muscle (MF).

Methods

This review presents the evidence for MF involvement in CLBP, mechanisms of action of disruption of control of the MF, and options for restoring control of the MF as a treatment for NSCLBP.

Results

Imaging assessment of motor control dysfunction of the MF in individual patients is fraught with difficulty. MRI or ultrasound imaging techniques, while reliable, have limited diagnostic or predictive utility. For some patients, restoration of motor control to the MF with specific exercises can be effective, but population results are not persuasive since most patients are unable to voluntarily contract the MF and may be inhibited from doing so due to arthrogenic muscle inhibition.

Conclusions

Targeting MF control with restorative neurostimulation promises a new treatment option.

Are the size and composition of the paraspinal muscles associated with low back pain? A systematic review

BACKGROUND CONTEXT

Although previous studies have investigated the association between paraspinal muscle morphology and low back pain (LBP), the results are conflicting.

PURPOSE

This systematic review examined the relationship between size and composition of the paraspinal muscles and LBP.

STUDY DESIGN/SETTING

A systematic review was carried out.

PATIENT SAMPLE

No patient sample was required.

OUTCOME MEASURES

This review had no outcome measures.

METHODS

A systematic search of electronic databases was conducted to identify studies investigating the association between the cross-sectional area or fatty infiltration of the paraspinal muscles (erector spinae, multifidus, psoas, and quadratus lumborum) and LBP. Descriptive data regarding study design and methodology were tabulated and a risk of bias assessment was performed.

RESULTS

Of the 119 studies identified, 25 met the inclusion criteria. Eight studies were reported as having low to moderate risk of bias. There was evidence for a negative association between cross-sectional area (CSA) of multifidus and LBP, but conflicting evidence for a relationship between erector spinae, psoas, and quadratus lumborum CSA and LBP. Moreover, there was evidence to indicate multifidus CSA was predictive of LBP for up to 12 months in men, but insufficient evidence to indicate a relationship for longer time periods. Although there was conflicting evidence for a relationship between multifidus fat infiltration and LBP, there was no or limited evidence for an association for the other paraspinal musculature.

CONCLUSIONS

This review found evidence that multifidus CSA was negatively associated with and predictive of LBP up to 12 months but conflicting evidence for an association between erector spinae, psoas, and quadratus lumborum CSA and LBP. To further understand the role of the paraspinal musculature in LBP, there is a need for high-quality cohort studies which extend over both the short and longer term.

Measurements of the trapezius and erector spinae muscles using virtual touch imaging quantification ultrasound-Elastography: a cross section study

Background

This study uses virtual touch imaging quantification (VTIQ) technology for the first time to conduct measurements of the trapezius and erector spinae muscles in a large study population. The significance of various influencing factors, such as age and sex, are also examined.

Method

The study population comprised 278 subjects. The Siemens Acuson S3000 and VTIQ technology were used for measurements of the trapezius and erector spinae muscles (Siemens Healthcare, Erlangen, Germany).

Results

The following mean values ± standard deviation were calculated: left trapezius: males 2.89 ± 0.38 m/s, females 2.71 ± 0.37 m/s; right trapezius: males 2.84 ± 0.41 m/s, females 2.70 ± 0.38 m/s; left erector spinae: males 2.97 ± 0.50 m/s, females 2.81 ± 0.57 m/s; right erector spinae: males 3.00 ± 0.52 m/s, females 2.77 ± 0.59 m/s. A significant difference between male and female subjects was demonstrated both for the shear wave velocities of the trapezius and erector spinae as well as for the thickness of the trapezius muscle (p < 0.05). There was also a significant difference in muscle elasticity between subjects over 60 years of age and those under 60 (p < 0.05). Furthermore, the results indicate that regular physical activity has an effect on muscle elasticity.

Conclusions

Our results demonstrate significantly different results between male and female subjects and between under- and over-sixty-year-old subjects. This means that sex-related and age-adapted considerations are obviously needed for further studies.

Change in fatty infiltration of lumbar multifidus, erector spinae, and psoas muscles in asymptomatic adults of Asian or Caucasian ethnicities

PURPOSE

Fatty infiltration (FI) is a feature of degenerating muscle that predominates in the low lumbar spine, associates with pain, and is confounded by age, spinal degeneration, and curvature. We determined rates for decline of lumbar muscle quality according to ethnicity, muscle, and spinal level in asymptomatic subjects.

METHODS

Cross-sectional simulation study assessing aggregated data; 650 Asians aged 20-89 years versus 80 Caucasians aged 20-62 years. Change in lumbar multifidus, erector spinae (ES), and psoas fat content were computed using synthetic data and Monte Carlo simulations. General linear regression models and multivariate adaptive regression splines enabled estimation of yearly decline rates [with 95% confidence intervals (CI)].

RESULTS

ES at L1-5 (total) shows steeply reduced density (rate; CI) for Asians in older (>53.3 years) adulthood (-0.32; -0.27 to -0.36/year). For Asians, multifidus (-0.18; -0.15 to -0.20/year) and psoas (-0.04; -0.03 to -0.06/year) also decline, while ES in younger ≤53.3 years) adults does not (0.06; 0.01-0.12/year). Caucasian multifidus declines (increasing FI % rate; CI) insignificantly faster (L1-5; 0.23; 0.10-0.36%/year) than ES (0.13; 0.04-0.22%/year). Multifidus decline does not differ between ethnicities. ES in older Asians generally declines fastest across ethnicities and muscles, and particularly in the low lumbar levels. Low lumbar levels show higher rates of decline in Asians, with mixed level-dependencies apparent in Caucasians.

CONCLUSIONS

Decline in lumbar muscle composition may differ between ethnicities and muscles. ES and low lumbar levels appear increasingly susceptible in Asians. Longitudinal studies examining rate of change to muscle composition may provide distinction between spinal conditions.