The relationship of lumbar multifidus muscle morphology to previous, current, and future low back pain: a 9-year population-based prospective cohort study

Relationship between Abnormal Spontaneous Brain Activity and Altered Neuromuscular Activation of Lumbar Paraspinal Muscles in Chronic Low Back Pain

OBJECTIVE

To investigate the neural mechanism underlying functional reorganization and motor coordination strategies in patients with chronic low back pain (cLBP).

DESIGN

A case-control study based on data collected during routine clinical practice.

SETTING

This study was conducted at the the First Affiliated Hospital of Sun Yat-sen University.

PARTICIPANTS

Fifteen patients with cLBP and fifteen healthy controls.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Whole brain blood oxygen level-dependent signals were measured using functional magnetic resonance imaging and amplitude of low-frequency fluctuation (ALFF) method to identify pain-induced changes in regional spontaneous brain activity. A novel approach based on the surface electromyography (EMG) system and fine-wire electrodes was used to record EMG signals in the deep multifidus, superficial multifidus, and erector spinae.

RESULTS

In cLBP, compared with healthy groups, ALFF was higher in the medial prefrontal, primary somatosensory, primary motor, and inferior temporal cortices, whereas it was lower in the cerebellum and anterior cingulate and posterior cingulate cortices. Furthermore, the decrease in the average EMG activity of three lumbar muscles in the cLBP group was positively correlated with the ALFF values of the primary somatosensory cortex, motor cortex, precuneus, and middle temporal cortex but significantly negatively correlated with the ALFF values of the medial prefrontal and inferior temporal cortices. Interestingly, the correlation between the functional activity in the cerebellum and the EMG activity varied in the lumbar muscles.

CONCLUSIONS

These findings suggest a functional association between changes in spontaneous brain activity and altered voluntary neuromuscular activation patterns of the lumbar paraspinal muscles, providing new insights into the mechanisms underlying pain chronicity as well as important implications for developing novel therapeutic targets of cLBP.

Fibro-adipogenic progenitors in physiological adipogenesis and intermuscular adipose tissue remodeling

Excessive accumulation of intermuscular adipose tissue (IMAT) is a common pathological feature in various metabolic and health conditions and can cause muscle atrophy, reduced function, inflammation, insulin resistance, cardiovascular issues, and unhealthy aging. Although IMAT results from fat accumulation in muscle, the mechanisms underlying its onset, development, cellular components, and functions remain unclear. IMAT levels are influenced by several factors, such as changes in the tissue environment, muscle type and origin, extent and duration of trauma, and persistent activation of fibro-adipogenic progenitors (FAPs). FAPs are a diverse and transcriptionally heterogeneous population of stromal cells essential for tissue maintenance, neuromuscular stability, and tissue regeneration. However, in cases of chronic inflammation and pathological conditions, FAPs expand and differentiate into adipocytes, resulting in the development of abnormal and ectopic IMAT. This review discusses the role of FAPs in adipogenesis and how they remodel IMAT. It highlights evidence supporting FAPs and FAP-derived adipocytes as constituents of IMAT, emphasizing their significance in adipose tissue maintenance and development, as well as their involvement in metabolic disorders, chronic pathologies and diseases. We also investigated the intricate molecular pathways and cell interactions governing FAP behavior, adipogenesis, and IMAT accumulation in chronic diseases and muscle deconditioning. Finally, we hypothesize that impaired cellular metabolic flexibility in dysfunctional muscles impacts FAPs, leading to IMAT. A deeper understanding of the biology of IMAT accumulation and the mechanisms regulating FAP behavior and fate are essential for the development of new therapeutic strategies for several debilitating conditions.

Prediction of Subsequent Vertebral Fracture After Acute Osteoporotic Fractures from Clinical and Paraspinal Muscle Features

To construct a nomogram based on clinical factors and paraspinal muscle features to predict vertebral fractures occurring after acute osteoporotic vertebral compression fracture (OVCF). We retrospectively enrolled 307 patients with acute OVCF between January 2013 and August 2022, and performed magnetic resonance imaging of the L3/4 and L4/5 intervertebral discs (IVDs) to estimate the cross-sectional area (CSA) and degree of fatty infiltration (FI) of the paraspinal muscles. We also collected clinical and radiographic data. We used univariable and multivariable Cox proportional hazards models to identify factors that should be included in the predictive nomogram. Post-OVCF vertebral fracture occurred within 3, 12, and 24 months in 33, 69, and 98 out of the 307 patients (10.8%, 22.5%, and 31.9%, respectively). Multivariate analysis revealed that this event was associated with percutaneous vertebroplasty treatment, higher FI at the L3/4 IVD levels of the psoas muscle, and lower relative CSA of functional muscle at the L4/5 IVD levels of the multifidus muscle. Area under the curve values for subsequent vertebral fracture at 3, 12, and 24 months were 0.711, 0.724, and 0.737, respectively, indicating remarkable accuracy of the nomogram. We developed a model for predicting post-OVCF vertebral fracture from diagnostic information about prescribed treatment, FI at the L3/4 IVD levels of the psoas muscle, and relative CSA of functional muscle at the L4/5 IVD levels of the multifidus muscle. This model could facilitate personalized predictions and preventive strategies.

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.

Paravertebral Muscular Neurophysiological Function as an Independent Outcome Predictor of Recurring Herniation/Low Back Pain after Radiofrequency Ablation: A Prospective Follow-Up and Case-Control Study Based on Surface Electromyography

OBJECTIVE

Spinal endoscopy radiofrequency is a minimally invasive technique for lumbar disc herniation (LDH) and low back pain (LBP). However, recurring LDH/LBP following spinal endoscopy radiofrequency is a significant problem. Paravertebral musculature plays a crucial role in spine stability and motor function, and the purpose of the present study was to identify whether patients' baseline lumbar muscular electrophysiological function could be a predictor of recurring LDH/LBP.

METHODS

This was a prospective follow-up and case-control study focusing on elderly patients with LDH who were treated in our department between January 1, 2018, and October 31, 2021. The end of follow-up was recurring LBP, recurring LDH, death, missing to follow-up or 2 years postoperation. The surface electromyography test was performed before the endoscopy C-arm radiofrequency (ECRF) operation to detect the flexion-relaxation ratio (FRR) of the lumbar multifidus (FRRLM ) and the longissimus erector spinae (FRRES ), and the other baseline parameters included the general characteristics, the visual analogue scale, the Japanese Orthopaedic Association score, and the Oswestry Disability Index. Intergroup comparisons were performed by independent t-test and χ2 -test, and further binary logistic regression analysis was performed.

RESULTS

Fifty-four patients completed the 2-year follow-up and were retrospectively divided into a recurring LDH/LBP group (Group R) (n = 21) and a no recurring group (Group N) (n = 33) according to their clinical outcomes. FRRLM and FRRES in Group N were much higher than those in Group R (p < 0.001, p = 0.009). Logistic regression analysis showed that only the FRRLM (odds ratio [OR] = 0.123, p = 0.011) and FRRES (OR = 0.115, p = 0.036) were independent factors associated with the ECRF outcome.

CONCLUSIONS

Lumbar disc herniation patients' baseline FRRLM and FRRES are independent outcome predictors of recurring LDH/LBP after ECRF. For every unit increase in baseline FRRLM , the risk of recurring LDH/LBP is decreased by 87.7%, and for every unit increase in baseline FRRES , the risk of recurring LDH/LBP is decreased by 88.5%.

Risk Factors in Patients with Low Back Pain Under 40 Years Old: Quantitative Analysis Based on Computed Tomography and Magnetic Resonance Imaging mDIXON-Quant

Purpose

While low back pain (LBP) constitutes a global life disorder cause, the contribution of paraspinal muscles to its pathogenicity remains elusive. We characterized the paraspinal muscles of patients with LBP using lumbar three-dimensional computed tomography (CT) and magnetic resonance imaging (MRI) mDIXON-Quant, and evaluated the risk factors combined with clinical data.

Methods

A retrospective study involving 181 patients (10-40 years) who underwent lumbar 3D-CT and MRI mDIXON from January 1, 2021 to December 31, 2022, and divided into normal, non-chronic LBP [non-CLBP], and CLBP groups. Clinical data, paraspinal muscle cross-sectional area, Hounsfield unit for CT values, and fat fraction derived from mDIXON-Quant were compared. Three readers analyzed the images independently; intra- and interobserver agreement was measured. Spearman analysis and multiple logistic regression were used to analyze the correlation between clinical data, radiologic and paraspinal muscle parameters. A nomogram was constructed for individualized prediction.

Results

Correlation analysis revealed that body mass index, visual analog scale score, Pfirrmann grade, annulus fibrosus tear, lumbar lordosis (LL), and Modic changes correlated with LBP (all P<0.05). The Pfirrmann grade and annulus fibrosus tear showed positive correlation (r=0.673, 0.559), whereas LL was negatively correlated (r=-0.469). The multifidus CT values were negatively correlated with LBP at L4-5/L5-S1; the multifidus fat fraction was positively correlated at L4-5/L5-S1 (r=0.734, r=0.584, P<0.001). The multiple logistic regression showed that L4-5 multifidus fat fraction (P=0.046, OR=1.167), Pfirrmann grade (P=0.017, OR=0.063), LL (P=0.002, OR=0.828) and annulus fibrosus tear (P=0.005, OR=0.024) were risk factors for predicting LBP in the non-CLBP group; in the CLBP group, BMI (P=0.048 OR=1.225), L4-5 multifidus fat fraction (P=0.001 OR=1.299), LL (P=0.003, OR=0.841) and Pfirrmann classification (P=0.009, OR=0.046) were risk factors.

Conclusion

BMI, L4-5 multifidus fat fraction, LL, and Pfirrmann grade are risk factors for CLBP in patients under 40; whereas annulus fibrosus tear is an independent risk factor for non-CLBP, nomograms derived from these parameters can help predict LBP and MRI mDIXON-Quant is recommended for quantitatively analyzing paraspinal muscle fat infiltration.

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.

Changes of the posterior paraspinal and psoas muscle in patients with low back pain: a 3-year longitudinal study

PURPOSE

This study aimed to investigate the changes of the posterior paraspinal muscles (PPM) and psoas muscle in patients with low back pain (LBP) over time.

METHODS

Patients with LBP who had a repeat lumbar MRI with a minimum of 3-years apart at a tertiary referral center were analyzed. MRI-based quantitative assessments of the PPM and the psoas muscle were conducted for the baseline and follow-up MRI. The cross sectional area (CSA), the functional cross sectional area (fCSA) and the fat area (FAT) were calculated using a dedicated software program. The fatty infiltration (FI,%) of the regions of interest was calculated. Differences between the 1st and 2nd MRI were calculated for all assessed muscular parameters.

RESULTS

A total of 353 patients (54.4%female) with a median age of 60.1 years and BMI of 25.8 kg/m2 at baseline were analyzed. The mean time between the 1st and 2nd MRI was 3.6 years. The fCSAPPM declined in both sexes significantly from the 1st to the 2nd MRI, whereas the FATPPM increased. In line with this result, the FIPPM increased in both males (29.9%) and females (19.4%). Females had a higher FIPPM and FIPsoas than males in both MRIs. In females, no significant changes were found for the psoas muscle. The CSAPsoas and fCSAPsoas in males were significantly smaller in the 2nd MRI. With increasing age, a significant trend in a decrease in ∆FIPPM was observed for both sexes.

CONCLUSION

The study revealed significant quantitatively muscular changes in males and females, especially in the posterior paraspinal muscles in only three years' time.

Paraspinal Muscle in Chronic Low Back Pain: Comparison Between Standard Parameters and Chemical Shift Encoding-Based Water-Fat MRI

BACKGROUND

Paraspinal musculature (PSM) is increasingly recognized as a contributor to low back pain (LBP), but with conventional MRI sequences, assessment is limited. Chemical shift encoding-based water-fat MRI (CSE-MRI) enables the measurement of PSM fat fraction (FF), which may assist investigations of chronic LBP.

PURPOSE

To investigate associations between PSM parameters from conventional MRI and CSE-MRI and between PSM parameters and pain.

STUDY TYPE

Prospective, cross-sectional.

POPULATION

Eighty-four adults with chronic LBP (44.6 ± 13.4 years; 48 males).

FIELD STRENGTH/SEQUENCE

3-T, T1-weighted fast spin-echo and iterative decomposition of water and fat with echo asymmetry and least squares estimation sequences.

ASSESSMENT

T1-weighted images for Goutallier classification (GC), muscle volume, lumbar indentation value, and muscle-fat index, CSE-MRI for FF extraction (L1/2-L5/S1). Pain was self-reported using a visual analogue scale (VAS). Intra- and/or interreader agreement was assessed for MRI-derived parameters.

STATISTICAL TESTS

Mixed-effects and linear regression models to 1) assess relationships between PSM parameters (entire cohort and subgroup with GC grades 0 and 1; statistical significance α = 0.0025) and 2) evaluate associations of PSM parameters with pain (α = 0.05). Intraclass correlation coefficients (ICCs) for intra- and/or interreader agreement.

RESULTS

The FF showed excellent intra- and interreader agreement (ICC range: 0.97-0.99) and was significantly associated with GC at all spinal levels. Subgroup analysis suggested that early/subtle changes in PSM are detectable with FF but not with GC, given the absence of significant associations between FF and GC (P-value range: 0.036 at L5/S1 to 0.784 at L2/L3). Averaged over all spinal levels, FF and GC were significantly associated with VAS scores.

DATA CONCLUSION

In the absence of FF, GC may be the best surrogate for PSM quality. Given the ability of CSE-MRI to detect muscle alterations at early stages of PSM degeneration, this technique may have potential for further investigations of the role of PSM in chronic LBP.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2.

Relationship between sarcopenia/paravertebral muscles and the incidence of vertebral refractures following percutaneous kyphoplasty: a retrospective study

Background

This study aimed to reveal the associations of osteoporotic vertebral compression refracture (OVCRF) incidence with sarcopenia and paravertebral muscles (PVM).

Methods

A total of 214 elderly patients who underwent percutaneous kyphoplasty in our hospital between January 2017 and December 2019 were analyzed. Data on possible risk factors, including sex, age, weight, height, diabetes, treated vertebral levels (thoracolumbar junction [(T10–L2]), vacuum clefts, and body mass index (BMI), were collected. Preoperative bone mineral density (BMD) and appendicular muscle mass were evaluated using dual-energy X-ray absorptiometry. Nutritional status was evaluated using the Mini Nutritional Assessment. Magnetic resonance imaging was performed to evaluate the physiological cross-sectional area of the PVM.

Results

Overall, 74 (15 men and 59 women) and 60 (55 women and 14 men) patients developed OVCRF and sarcopenia, respectively. Sarcopenia is related to advanced age, ower BMD and BMI values. Sarcopenia-related indicators (PVM fat rate, appendicular muscle mass index, grip strength) were significantly lower in the sarcopenia group. Univariate analysis showed a correlation between OVCRF and BMD, BMI, diabetes, sarcopenia, and age. Multivariate analysis suggested that fatty infiltration of the PVM, BMD, sarcopenia, diabetes, BMI, and treated vertebral level remained as the independent predictors of OVCRF (p < 0.05).

Conclusions

The association between sarcopenia and PVM as independent risk factors for OVCRF was established in this study; therefore, sarcopenia should be greatly considered in OVCRF prevention.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05832-6.

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.

Reliability and agreement of lumbar multifidus volume and fat fraction quantification using magnetic resonance imaging

INTRODUCTION

Magnetic resonance imaging (MRI) is the standard to quantify size and structure of lumbar muscles. Three-dimensional volumetric measures are expected to be more closely related to muscle function than two-dimensional measures such as cross-sectional area. Reliability and agreement of a standardized method should be established to enable the use of MRI to assess lumbar muscle characteristics.

OBJECTIVES

This study investigates the intra- and inter-processor reliability for the quantification of (1) muscle volume and (2) fat fraction based on chemical shift MRI images using axial 3D-volume measurements of the lumbar multifidus in patients with low back pain.

METHODS

Two processors manually segmented the lumbar multifidus on the MRI scans of 18 patients with low back pain using Mevislab software following a well-defined method. Fat fraction of the segmented volume was calculated. Reliability and agreement were determined using intra-class correlation coefficients (ICC), Bland-Altman plots and calculation of the standard error of measurement (SEM) and minimal detectable change (MDC).

RESULTS

Excellent ICCs were found for both intra-processor and inter-processor analysis of lumbar multifidus volume measurement, with slightly better results for the intra-processor reliability. The SEMs for volume were lower than 4.1 cm³. Excellent reliability and agreement were also found for fat fraction measures, with ICCs of 0.985-0.998 and SEMs below 0.946%.

CONCLUSION

The proposed method to quantify muscle volume and fat fraction of the lumbar multifidus on MRI was highly reliable, and can be used in further research on lumbar multifidus structure.

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.

Alteration of lumbar muscle morphology and composition in relation to low back pain: a systematic review and meta-analysis

BACKGROUND CONTEXT

Previous studies have proposed that there is a relationship between low back pain (LBP) and morphology and composition of paraspinal muscles. However, results have been conflicting, especially regarding fatty infiltration of muscles.

PURPOSE

The primary goal of this study was to review and analyze results from imaging studies which investigated morphological and composition changes in the multifidus, erector spinae and psoas major muscles in people with LBP.

STUDY DESIGN/SETTING

Systematic review with meta-analysis.

PATIENT SAMPLE

A patient sample was not required OUTCOME MEASURES: This review did not have outcome measures.

METHODS

PubMed, Scopus, Web of Sciences, EMBASE and ProQuest were searched for eligible studies up to 31st July 2020 (all languages). A systematic search of electronic databases was conducted to identify studies investigating the association between the morphology and fat content of lumbar muscles in people with LBP compared with a (no LBP) control group. 13,795 articles were identified. Based on the screening for inclusion/ exclusion, 25 were included. The quality of the studies was evaluated using the Newcastle-Ottawa Scale. From the 25 articles, 20 were included in the meta-analysis.

RESULTS

Results showed that the total cross-sectional area of the multifidus was smaller in people with LBP (Standardized mean difference, SMD = -0.24, 95% CI = -0.5 to 0.03). Combined SMDs showed a medium effect of LBP on increasing multifidus muscle fat infiltration (SMD = 0.61, 95% CI = 0.30 to 0.91). There were no LBP related differences identified in the morphology or composition of the lumbar erector spine and psoas major muscles.

CONCLUSIONS

People with LBP were found to have somewhat smaller multifidus muscles with a significant amount of intramuscular fat infiltration. Varying sample size, age and BMI of participants, quality of studies and the procedures used to measure fat infiltration are possible reasons for inconsistencies in results of previous studies.

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.

Intermittent pain in patients with chronic low back pain is associated with abnormalities in muscles and fascia

We investigated the relationship between paravertebral muscles and perimuscular connective tissues of the thoracolumbar fascia region and the four types of pain in patients suffering from chronic low back pain. A total of 17 patients with chronic low back pain participated in this study. Ultrasound imaging method was used to measure the thickness and echogenicity of the paravertebral muscles and perimuscular connective tissues. The measurement site considered in this study was located lateral to the midpoint between L2-3 and L4-5 spines. In addition, age, gender, BMI, numerical rating scale and the short-form McGill pain questionnaire 2 (includes questions with respect to continuous pain, intermittent pain, neuropathic pain and affective descriptors) were used for assessment. Statistical analysis was performed using correlation analysis and multiple regression analysis. A significant association was observed between paravertebral muscle echogenicity at L2-3 and the numerical rating scale (r = 0.499), between paravertebral muscle echogenicity at L4-5 with numerical rating scale (r = 0.538) and intermittent pain (r = 0.594), and between perimuscular connective tissue thickness at L2-3 and numerical rating scale (r = 0.762). We observed that the factor influencing perimuscular connective tissue thickness at L2-3 and L4-5 was intermittent pain (β = 0.513, β = 0.597, respectively). It was also observed that some of the imaging findings were associated with age and BMI. In conclusion, we observed that paravertebral muscle echogenicity and perimuscular connective tissue thickness in patients with chronic low back pain were associated with pain, especially intermittent pain.

Formulation of Japanese Orthopaedic Association (JOA) clinical practice guideline for the management of low back pain- the revised 2019 edition

BACKGROUND

The latest clinical guidelines are mandatory for physicians to follow when practicing evidence-based medicine in the treatment of low back pain. Those guidelines should target not only Japanese board-certified orthopaedic surgeons, but also primary physicians, and they should be prepared based entirely on evidence-based medicine. The Japanese Orthopaedic Association Low Back Pain guideline committee decided to update the guideline and launched the formulation committee. The purpose of this study was to describe the formulation we implemented for the revision of the guideline with the latest data of evidence-based medicine.

METHODS

The Japanese Orthopaedic Association Low Back Pain guideline formulation committee revised the previous guideline based on a method for preparing clinical guidelines in Japan proposed by Medical Information Network Distribution Service Handbook for Clinical Practice Guideline Development 2014. Two key phrases, "body of evidence" and "benefit and harm balance" were focused on in the revised version. Background and clinical questions were determined, followed by literature search related to each question. Appropriate articles were selected from all the searched literature. Structured abstracts were prepared, and then meta-analyses were performed. The strength of both the body of evidence and the recommendation was decided by the committee members.

RESULTS

Nine background and nine clinical qvuestions were determined. For each clinical question, outcomes from the literature were collected and meta-analysis was performed. Answers and explanations were described for each clinical question, and the strength of the recommendation was decided. For background questions, the recommendations were described based on previous literature.

CONCLUSIONS

The 2019 clinical practice guideline for the management of low back pain was completed according to the latest evidence-based medicine. We strongly hope that this guideline serves as a benchmark for all physicians, as well as patients, in the management of low back pain.

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.

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.

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.

New MR-based measures for the evaluation of age-related lumbar paraspinal muscle degeneration

PURPOSE

Although signal intensity on T2W axial images is sensitive in detection of fatty infiltration to assess paraspinal muscle degeneration, it is affected by inhomogeneities of magnetic fields and individual variabilities. The purpose of this study was to propose reference adjusted signal measures on T2W axial images and determine their capacities in reflecting age-related lumbar paraspinal muscle degeneration.

METHODS

Lumbar MR images of 421 population-based subjects (177 men and 244 women, mean age 53.1 years, range 19.8-87.9 years) were studied. A custom software Spine Explore (Tulong 2.0) was used to automatically obtain paraspinal measurements of multifidus, erector spinae and psoas major. FCSA/TCSA was defined as functional cross-sectional area relative to total cross-sectional area of paraspinal muscle. Two new signal measures were canal-adjusted and cerebrospinal fluid (CSF)-adjusted signal, defined as the ratio between mean signal measurements and the mean signal of the canal and CSF.

RESULTS

The raw signal measurements of the paraspinal muscles were weakly correlated to age (r = 0.28-0.39, P < 0.001). When the signal of canal (r = 0.43-0.59, P < 0.001) or CSF (r = 0.45-0.61, P < 0.001) was used as reference, the correlations substantially increased. Signal measurements of three paraspinal muscles, adjusted or not, were strongly associated with Goutallier score (ρ = 0.60-0.65, P < 0.001) and FCSA/TCSA (r = -0.64 to -0.82, P < 0.001). Greater Goutallier score was associated with greater age (r = 0.38-0.60, P < 0.001), while Lumbar indentation value (LIV) not.

CONCLUSION

On routine T2W axial MR images the adjusted signal measurements using an internal reference of CSF or canal can better reflect age-related degenerative changes in the paraspinal muscles.

Trunk Muscle Mass Measured by Bioelectrical Impedance Analysis Reflecting the Cross-Sectional Area of the Paravertebral Muscles and Back Muscle Strength: A Cross-Sectional Analysis of a Prospective Cohort Study of Elderly Population

Trunk muscles play an important role in supporting the spinal column. A decline in trunk muscle mass, as measured by bioelectrical impedance analysis (TMM-BIA), is associated with low back pain and poor quality of life. The purpose of this study was to determine whether TMM-BIA correlates with quantitative and functional assessments traditionally used for the trunk muscles. We included 380 participants (aged ≥ 65 years; 152 males, 228 females) from the Shiraniwa Elderly Cohort (Shiraniwa) study, for whom the following data were available: TMM-BIA, lumbar magnetic resonance imaging (MRI), and back muscle strength (BMS). We measured the cross-sectional area (CSA) and fat-free CSA of the paravertebral muscles (PVM), including the erector spinae (ES), multifidus (MF), and psoas major (PM), on an axial lumbar MRI at L3/4. The correlation between TMM-BIA and the CSA of PVM, fat-free CSA of PVM, and BMS was investigated. TMM-BIA correlated with the CSA of total PVM and each individual PVM. A stronger correlation between TMM-BIA and fat-free CSA of PVM was observed. The TMM-BIA also strongly correlated with BMS. TMM-BIA is an easy and reliable way to evaluate the trunk muscle mass in a clinical setting.

Impact of paravertebral muscle in thoracolumbar and lower lumbar regions on outcomes following osteoporotic vertebral fracture: a multicenter cohort study

We investigated the effect of paravertebral muscle (PVM) on poor prognosis in osteoporotic vertebral fracture (OVF) and remaining lower back pain (LBP) in the thoracolumbar and lower lumbar regions. Additional OVF occurrence in the thoracolumbar and remaining LBP in the lumbar region was significantly related to PVM fat infiltration percentage.

PURPOSE

Paravertebral muscle (PVM) is an important component of the spinal column. However, its role in the healing process after osteoporotic vertebral fracture (OVF) is unclear. This study aimed to clarify the effect of PVM in thoracolumbar and lower lumbar regions on OVF clinical and radiological outcomes.

METHODS

This was a multicenter prospective cohort study from 2012 to 2015. Patients ≥ 65 years old who presented within 2 weeks after fracture onset were followed up for 6 months. PVM was measured at the upper edge of the L1 and L5 vertebral body in the magnetic resonance imaging (MRI) T2-axial position at registration. The cross-sectional area (CSA), relative CSA (rCSA), and fat infiltration percentage (FI%) were measured. Severe vertebral compression, delayed union, new OVF, and remaining low back pain (LBP) were analyzed.

RESULTS

Among 153 patients who were followed up for 6 months, 117 with measurable PVM were analyzed. Their average age was 79.1 ± 7.2 years, and 94 were women (80.3%). There were 48 cases of severe vertebral compression, 21 delayed unions, 11 new OVF, and 27 remaining LBP. Among all poor prognoses, only the FI% of the PVM was significantly associated with new OVF (p = 0.047) in the thoracolumbar region and remaining LBP (p = 0.042) in the lumbar region.

CONCLUSION

The occurrence of additional OVF in the thoracolumbar region and remaining LBP in the lumbar region was significantly related to the FI% of the PVM. Physicians should be aware that patients with such fatty degeneration shown in acute MRI may require stronger treatment.

Computed tomography evaluation of fat infiltration ratio of the multifidus muscle in chronic low back pain patients

Background and objectives

Fat infiltration of multifidus muscle is an important parameter to assess the efficacy of spinal stabilization training in chronic low back pain (LBP) patients. As a CT scan shows a specific attenuation value for fat, it can be used as a ratio to evaluate fat infiltration of the muscle relative to its cross-sectional area. This study aims to compare the fat infiltration ratio of multifidus muscle between subjects with and without chronic LBP in Indonesia.

Methods

Comparative cross-sectional study of 20 subjects with chronic LBP and 20 subjects without LBP. Fat infiltration ratio calculation of the multifidus muscle was obtained from the database of abdominal CT at the level of the superior and inferior endplate of L4 and L5 vertebral body.

Results

The fat infiltration ratio of multifidus muscle in the chronic LBP subjects group was significantly higher than the subjects group without NPB (p < 0.05). The cut-off value of the fat infiltration ratio at the level of the inferior endplate of L4 was 0.125 (75 % sensitivity and 80 % specificity).

Conclusion

The calculation of the multifidus muscle fat infiltration ratio at the inferior endplate L4 using CT is a potential method to evaluate multifidus muscle quality in chronic LBP patients.

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.

Lumbar Muscle Fat Content Has More Correlations with Living Quality than Sagittal Vertical Axis in Elderly Patients with Degenerative Lumbar Disorders

Purpose

As the most poorly tolerated and debilitating form of spinal malalignment, sagittal imbalance is becoming an increasingly recognized cause of pain and disability in adults. However, there is evidence showing that sagittal imbalance has a weak or no correlation with health-related quality-of-life (HRQoL) outcomes. The objective of this study was to describe the direct factor associated with HRQoL in terms of Oswestry Disability Index (ODI) assessment.

Patients and Methods

This study retrospectively evaluated the clinical and radiographic information of 179 elderly patients with degenerative lumbar disorders and suboptimal sagittal standing posture (sagittal vertical axis>50 mm). Patient-reported outcomes were assessed using ODI. Patients with ODI≥40% were assigned to Group D (disability), while those with ODI<40% were assigned to Group ND (non-disability).

Results

Compared with Group ND (n=104), patients in Group D (n=75) had greater thoracolumbar kyphosis, pelvic incidence-lumbar lordosis (PI-LL), sagittal vertical axis (SVA), T1 pelvic angle, and fat infiltration, and smaller LL and muscle mass ratio. Pearson analysis revealed a high correlation between the percentage of fat infiltrated and ODI (r=768, P<0.01) and moderate correlation between SVA and ODI (r=0.408, P<0.001). Linear regression results indicated that fat infiltration was an independent factor associated with ODI. ODI significantly correlated with SVA in patients with major fat infiltration (r=0.328, P=0.001), while having no correlation with SVA in those with moderate or minor fat infiltration (r=0.083, P=0.464).

Conclusion

Lumbar muscle fat infiltration is an independent factor associated with the living quality in terms of ODI assessment in the elderly population with degenerative lumbar disorders, which has more correlations with ODI scores than the sagittal imbalance. The relationship between HRQoL outcomes and sagittal imbalance depends on the quality of lumbar muscle.

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.

Impact of nonsurgical spinal decompression on paraspinal muscle morphology and mechanical properties in young adults with low back pain

Objective

The mechanism underlying the benefit of nonsurgical spinal decompression (NSSD) on low back pain is unclear. This study was performed to investigate the immediate impact of NSSD on the mechanical properties and morphology of the paraspinal muscles.

Methods

Participants with low back pain were recruited. NSSD therapy was provided on one occasion. A myotonometer was placed perpendicularly on the skin surface over the paraspinal muscle at the level of L₃/L₄ to measure the mechanical muscle properties. The multifidus thickness was measured using B-mode ultrasound and defined as the distance between the transverse process and subcutaneous tissue fascia. The difference between before and after NSSD was analyzed by a paired t-test.

Results

Thirty participants (mean age, 20.9 ± 0.8 years; 9 male, 21 female) were recruited. No significant difference was observed in the muscle mechanical properties or morphology between before and after the intervention.

Conclusions

NSSD intervention did not induce immediate changes in the paraspinal muscle mechanical properties or multifidus thickness in young adults with low back pain. NSSD might produce benefits by stimulating mechanical receptors rather than inducing morphological changes or mechanical property alterations of the muscle fibers. These parameters may not be suitable outcome measures for NSSD intervention.

Automatic Characterizations of Lumbar Multifidus Muscle and Intramuscular Fat with Fuzzy C-means based Quantization from Ultrasound Images

BACKGROUND

Low Back Pain (LBP) is a common disorder involving the muscles and bones and about half of the people experience LBP at some point of their lives. Since the social economic cost and the recurrence rate over the lifetime is very high, the treatment/rehabilitation of chronic LBP is important to physiotherapists, both for clinical and research purposes. Trunk muscles such as the lumbar multifidi is important in spinal functions and intramuscular fat is also important in understanding pain control and rehabilitations. However, the analysis of such muscles and related fat require many human interventions and thus suffers from the operator subjectivity especially when the ultrasonography is used due to its cost-effectiveness and no radioactive risk.

AIMS

In this paper, we propose a fully automatic computer vision based software to compute the thickness of the lumbar multifidi muscles and to analyze intramuscular fat distribution in that area.

METHODS

The proposed system applies various image processing algorithms to enhance the intensity contrast of the image and measure the thickness of the target muscle. Intermuscular fat analysis is done by Fuzzy C-Means (FCM) clustering based quantization.

RESULTS

In experiment using 50 DICOM format ultrasound images from 50 subjects, the proposed system shows very promising result in computing the thickness of lumbar multifidi.

CONCLUSION

The proposed system have minimal discrepancy(less than 0.2 cm) from human expert for 72% (36 out of 50 cases) of the given data. Also, FCM based intramuscular fat analysis looks better than conventional histogram analysis.

The natural course of the paravertebral muscles after the onset of osteoporotic vertebral fracture

This study revealed the change in the paravertebral muscles in patients with osteoporotic vertebral fracture. Increased pain is likely to be the driver for reduced activity, reduced activities of daily living, and consequent increase in fat infiltration of the paravertebral muscles, assumed to be secondary to reduced activity level or, conversely, partial immobilization.

INTRODUCTION

To reveal the time courses and impact of the paravertebral muscles (PVMs) on the healing process of osteoporotic vertebral fractures and risk factors for PVM decrease.

METHODS

Consecutive patients with symptomatic osteoporotic vertebral fractures were enrolled in 11 hospitals. At enrollment and 3- and 6-month follow-up, PVMs, including the multifidus and erector spinae, were examined using magnetic resonance imaging (MRI). The PVM cross-sectional area (CSA) and fat signal fraction (FSF) were measured at L3. Low back pain (LBP), activities of daily living (ADLs), and risk factors for PVM decrease at the 6-month follow-up were investigated. PVM decrease was defined as > 1 standard deviation decrease of the CSA or > 1 standard deviation increase of the FSF.

RESULTS

Among 153 patients who completed the 6-month follow-up, 117 (92 women, 79%) had MRI of L3 at enrollment and 3- and 6-month follow-up (mean age at enrollment, 78.5 years). The CSA did not change 6 months from onset (p for trend = 0.634), whereas the FSF significantly increased (p for trend = 0.033). PVM decrease was observed in 30 patients (26%). LBP was more severe, and delayed union was more frequent in patients with PVM decrease (p = 0.021 mixed-effect model and p = 0.029 chi-square test, respectively). The risk factors for PVM decrease were ADL decline at the 3-month follow-up (adjusted odds ratio = 5.35, p = 0.026).

CONCLUSION

PVM decrease was significantly related to LBP and delayed union after osteoporotic vertebral fracture onset. ADL decline at the 3-month follow-up was a risk factor for PVM decrease. Therefore, restoring ADLs within 3 months after onset is important.

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.

Does pre-operative multifidus morphology on MRI predict clinical outcomes in adults following surgical treatment for degenerative lumbar spine disease? A systematic review

Aim

Low back pain (LBP) resulting from degenerative lumbar spine disease is a leading contributor to global disability. Changes in the morphology of the lumbar multifidus muscle on magnetic-resonance imaging (MRI) are associated with worse LBP and disability, but the association between multifidus morphology and post-operative outcomes is not known. The purpose of this systematic review is to examine the relationship between pre-operative multifidus morphology and post-operative changes in pain and disability.

Methods

We performed a systematic search using the Cochrane Library, EMBASE, MEDLINE, CINAHL and Scopus databases covering the period from January 1946 to January 2018. The literature was searched and assessed by independent reviewers according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. All relevant papers were assessed for risk of bias according to the Quality in Prognosis Studies tool.

Results

The initial search yielded 436 studies, of which 6 studies were included in the analysis. Four studies were at a low risk of bias. These studies included a total of 873 patients undergoing spinal surgery. An association between low fat infiltration and greater improvement in LBP and disability following surgery was identified. There was insufficient evidence to identify a relationship between cross-sectional area (CSA) and LBP or disability.

Conclusions

This systematic review found evidence for an association between low multifidus fat infiltration on MRI at baseline and greater reductions in measures of LBP and disability following surgical treatment. There is also limited evidence for an association between larger pre-operative multifidus CSA and improvements in disability, but not pain. The findings of this review should be interpreted with caution due to the small quantity of the available literature.

Longitudinal Analysis of Paraspinal Muscle Cross-Sectional Area During Early Adulthood - A 10-Year Follow-Up MRI Study

Only a few previous studies have investigated paraspinal musculature (i.e., multifidus (MF), psoas major (PSM), erector spinae (ES)) in longitudinal, population-based settings. This study aimed to evaluate changes in the cross-sectional area (CSA) of the paraspinal muscles between the ages of 20 and 30 years. The study population consisted of a sub-cohort from the Northern Finland Birth Cohort 1986 (n = 298; 156 men, 142 women). Baseline magnetic resonance imaging was performed at a mean age of 21.3 years and follow-up imaging at 30.6 years. The CSA measurements were performed by tracing the paraspinal muscle outlines individually (MF, ES, PM) and all combined (total muscle area (TMA)) at the L4 cranial endplate level. The longitudinal data analysis was performed using generalized estimating equations modelling. The CSA of MF and ES increased during the follow-up among both sexes (men: MF + 5.7%, p < 0.001; ES + 2.7%, p = 0.001; and women: MF + 10.5%, p < 0.001; ES 9.2%, p = 0.001). The CSA of PM decreased among men (PM −4.0%, p < 0.001) but not among women (PM + 0.5%, p = 0.553). TMA increased significantly only among women (men: +0.5%, p = 0.425; women: +6.5%, p < 0.001). The increases in ES and TMA were more distinct among women than men (p < 0.001). Our study demonstrated clear age- and sex-related changes in paraspinal muscle size in early adulthood.

Age- and sex-specific effects in paravertebral surface electromyographic back extensor muscle fatigue in chronic low back pain

The impact of aging on the back muscles is not well understood, yet may hold clues to both normal aging and chronic low back pain (cLBP). This study sought to investigate whether the median frequency (MF) surface electromyographic (SEMG) back muscle fatigue method—a proxy for glycolytic muscle metabolism—would be able to detect age- and sex-specific differences in neuromuscular and muscle metabolic functions in individuals with cLBP in a reliable way, and whether it would be as sensitive as when used on healthy individuals. With participants seated on a dynamometer (20° trunk anteflexion), paraspinal SEMG activity was recorded bilaterally from the multifidus (L5), longissimus (L2), and iliolumbalis (L1) muscles during isometric, sustained back extensions loaded at 80% of maximum from 117 younger (58 females) and 112 older (56 female) cLBP individuals. Tests were repeated after 1–2 days and 6 weeks. Median frequency, the SEMG variable indicating neuromuscular fatigue, was analyzed. Maximum back extensor strength was comparable between younger and older participants. Significantly less MF-SEMG back muscle fatigue was observed in older as compared to younger, and in older female as compared to older male cLBP individuals. Relative reliability was excellent, but absolute reliability appeared large for this SEMG-fatigue measure. Findings suggest that cLBP likely does not mask the age-specific diagnostic potential of the MF-SEMG back extensor fatigue method. Thus, this method possesses a great potential to be further developed into a valuable biomarker capable of detecting back muscle function at risk of sarcopenia at very early stages.

Geography of Lumbar Paravertebral Muscle Fatty Infiltration: The Influence of Demographics, Low Back Pain, and Disability

STUDY DESIGN

Cross-sectional.

OBJECTIVE

We quantified fatty infiltration (FI) geography of the lumbar spine to identify whether demographics, temporal low back pain (LBP), and disability influence FI patterns.

SUMMARY OF BACKGROUND DATA

Lumbar paravertebral muscle FI has been associated with age, sex, LBP, and disability; yet, FI accumulation patterns are inadequately described to optimize interventions.

METHODS

This cross-sectional study employed lumbar axial T1-weighted magnetic resonance imaging in 107 Southern-Chinese adults (54 females, 53 males). Single-slices at the vertebral inferior end-plate per lumbar level were measured for quartiled-FI, and analyzed against demographics, LBP, and disability (Oswestry Disability Index).

RESULTS

Mean FI% was higher in females, on the right, increased per level caudally, and from medial to lateral in men (P < 0.05). FI linearly increased with age for both sexes (P < 0.01) and was notably higher at L 4&5 than L1, 2&3 for cases aged 40 to 65 years. BMI and FI were unrelated in females and inversely in males (P < 0.001). Females with LBPweek and males with LBPyear had 1.7% (each) less average FI (P < 0.05) than those without pain at that time-point. Men locating their LBP in the back had less FI than those without pain (P < 0.001). Disability was unrelated to FI for both sexes (P > 0.05).

CONCLUSION

Lumbar paravertebral muscle FI predominates in the lower lumbar spine, notably for those aged 40 to 65, and depends more on sagittal than transverse distribution. Higher FI in females and differences of mean FI between sexes for BMI, LBP, and disabling Oswestry Disability Index suggest sex-differential accumulation patterns. Our study contradicts pain models rationalizing lumbar muscle FI and may reflect a normative sex-dependent feature of the natural history of lumbar paravertebral muscles.

LEVEL OF EVIDENCE

2.

Fat Infiltration in the Multifidus Muscle as a Predictor of Prognosis After Decompression and Fusion in Patients with Single-Segment Degenerative Lumbar Spinal Stenosis: An Ambispective Cohort Study Based on Propensity Score Matching

OBJECTIVE

To determine whether fat infiltration in the multifidus muscle would predict surgical prognosis in patients with degenerative lumbar spinal stenosis (DLSS).

METHODS

This ambispective cohort study enrolled 118 consecutive patients undergoing surgery for L4-5 single-segment DLSS. Fat infiltration rate (FIR) on magnetic resonance images of the multifidus muscle at L5-S1 were measured using ImageJ software. The enrolled patients were divided into FIR <25% and FIR ≥25% groups according to their FIR of the multifidus muscle at L5-S1. The 2 groups of patients who finished follow-up were further matched for the baseline covariates based on propensity scores. Patients' reported outcomes including the visual analog scale score for back pain and leg pain, and the Oswestry Disability Index (ODI) score were compared between groups at follow-up and further adjusted using generalized linear models.

RESULTS

Patients in the FIR <25% group showed statistically significantly greater reduction in ODI at 6 and 18 months after surgery than did patients in the FIR ≥25% group in either cohort regardless of adjustment; however, the 2-point between-group difference was smaller than the predefined minimum clinically important difference. In addition, more patients in the FIR <25% group achieved clinically significant improvement in ODI than those in the FIR ≥25% group in either complete cohort or matching cohort (63.8% vs. 21.1%, P < 0.001; 70.3% vs. 24.1%, P < 0.001, respectively) before and after adjustment (63.3% vs. 27.8%, P < 0.001; 69.1% vs. 31.0%, P < 0.001, respectively).

CONCLUSIONS

Fat infiltration in multifidus muscle at L5-S1 could be a potential predictor of functional improvement after surgery in patients with L4-5 single-segment DLSS.

Height loss but not body composition is related to low back pain in community-dwelling elderlies: Shimane CoHRE study

Background

Low back pain (LBP) is a common complaint in the elderly Japanese population. Although previous studies showed that height loss was associated with LBP, it remains unclear whether LBP is associated with body composition. The objective of the present study was to investigate whether body composition and physical characteristics, including height loss, were associated with LBP.

Methods

The present study is retrospectively registered, and the participants were 2212 community-dwelling Japanese people aged over 60 years who participated in the Shimane CoHRE study in 2016. We investigated the presence of LBP, body composition parameters (muscle, fat, body weight, and bone mass), physical characteristics (body height and height loss), chronic diseases, history of fall, smoking, and drinking habits. We examined the relationships of body composition parameters and physical characteristics with point prevalence of LBP using multivariate logistic regression.

Results

The point prevalence of LBP was 43.2% in women and 39.5% in men. Logistic regression models showed that body height and body composition were not significantly associated with LBP; however, height loss was associated significantly with LBP in women and men (OR: 1.14, 95% CI: 1.08–1.20 and OR: 1.13, 95% CI: 1.06–1.21, respectively). Hypertension (OR: 1.32, 9 5% CI: 1.04–1.69) and chronic heart disease (OR: 1.57, 95% CI: 1.01–2.43) in women and history of fall (OR: 1.70, 95% CI: 1.13–2.56) and cerebrovascular disease (OR: 1.88, 95% CI: 1.05–3.34) in men were significantly associated with LBP. However, body composition was not associated with LBP in either gender.

Conclusions

The present study demonstrated that height loss, but not body composition, was related to LBP in community-dwelling elderly people. To elucidate the cause of LBP, it is important to consider the relationship with height loss.

Electronic supplementary material

The online version of this article (10.1186/s12891-019-2580-6) contains supplementary material, which is available to authorized users.

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.

Fear-avoidance beliefs are associated with a high fat content in the erector spinae: a 1.5 tesla magnetic resonance imaging study

Background

Intramuscular adipose tissue (IMAT) is a feature of degenerative muscle composition and is a common feature in populations with chronic low back pain (CLBP). Avoidance behavior is a possible cause of morphological muscle composition due to disuse of the paraspinal muscles. Therefore it is of clinical interest to determine the association between fear-avoidance beliefs and IMAT of the paraspinal muscles in populations with CLBP.

Methods

In this cross-sectional study, we examined twenty-four adults, featuring a mean age of 48.63 years (SD ± 14.73), with CLBP. Axial T2-weighted Magnetic Resonance Imaging (MRI) images were selected on the same level as the intervertebral disc of segments L4-L5 and L5-S1. After determine the region of interest, the amount of IMAT was measured by an automatic-threshold method to distinguish fat from muscle tissue. Fear-avoidance beliefs were measured with the Fear-Avoidance Beliefs Questionnaire, with regard to Physical Activity (FABQ-PA). Bivariate correlation and multiple regression analysis were used to determine the association between IMAT of the paraspinal muscles and fear-avoidance beliefs.

Results

There is a significant bivariate association between the FABQ-PA and ES IMAT (r = 0.484, P = 0.017), but not for LMM (r = 0.228, P = 0.284). The association between the FABQ-PA and ES IMAT remained moderate after adjusting for covariates (β = 0.381, P = 0.028).

Conclusion

Fear-avoidance beliefs are moderately associated with ES IMAT and poorly associated with LMM IMAT in a population with CLBP. Results should be interpreted with caution due to a small and selected study population.

Dual-Energy X-ray Absorptiometry and Bioelectrical Impedance Analysis are Beneficial Tools for Measuring the Trunk Muscle Mass of Patients with Low Back Pain

Introduction

Limb muscle mass measurement using dual-energy X-ray absorptiometry (DXA) is considered the gold standard for the diagnosis of sarcopenia. Moreover, bioelectrical impedance analysis (BIA) is also recognized as a beneficial tool considering its high correlation with DXA. However, it remains to be elucidated whether DXA and BIA can accurately measure trunk lean mass.

The aim of this study was to investigate the correlation between DXA and BIA measurements of trunk muscle mass and the cross-sectional area (CSA) of trunk muscles measured using magnetic resonance imaging (MRI) and to compare measures of trunk muscle mass obtained using DXA and BIA in patients with low back pain (LBP).

Methods

In total, 65 patients participated in the study. The correlation between DXA and BIA measurements and the CSA of trunk and paraspinal muscles at the L4-5 level were calculated. In addition, the correlation between DXA and BIA measurements of trunk muscle mass and the differences between these two measurements were determined.

Results

The correlation coefficient between DXA and BIA trunk muscle mass measurement and trunk muscle CSA was 0.74 and 0.56 for men and 0.69 and 0.44 for women, respectively. DXA and BIA measurement values showed a significantly moderate correlation with the CSA of the erector spinae (ES) and psoas major (PM). The multifidus (MF) CSA did not correlate with measurements of DXA and BIA in both men and women. Although DXA and BIA measurements were significantly correlated, a significant difference between these two measurements was found. BIA overestimated the trunk muscle mass significantly compared with DXA.

Conclusions

Trunk muscle mass measured with DXA and BIA was correlated with the CSA of most trunk muscles. Although the measurement of DXA and BIA showed a high correlation, BIA overestimated trunk muscle mass compared with DXA. Both DXA and BIA are beneficial for measuring trunk muscle mass.

ISSLS PRIZE IN CLINICAL SCIENCE 2019: clinical importance of trunk muscle mass for low back pain, spinal balance, and quality of life-a multicenter cross-sectional study

STUDY DESIGN

A multicenter cross-sectional study.

OBJECTIVES

To clarify the relationship of trunk muscle mass with low back pain, spinal sagittal balance, and quality of life. Few reports have investigated the relationship of trunk muscle mass with lumbar spine function and spinal balance, and the clinical significance of trunk muscle mass remains unclear.

METHODS

Patients attending spinal outpatient clinics at 10 different medical institutions were enrolled in this study. Patient demographics, trunk muscle mass and appendicular skeletal muscle mass (ASM) measured by bioelectrical impedance analysis (BIA), body mass index (BMI), Charlson Comorbidity Index (CCI), the Oswestry Disability Index (ODI), visual analog scale (VAS) for low back pain, sagittal vertical axis (SVA), and EuroQol 5 Dimension (EQ5D) score were investigated. Multivariate nonlinear regression analysis was used to investigate the association of trunk muscle mass with the ODI, VAS score, SVA, and EQ5D score.

RESULTS

Of 2551 eligible patients, 1738 (mean age 70.2 ± 11.0 years; 781 men and 957 women) were enrolled. Trunk muscle mass was significantly correlated with the ODI, VAS score, SVA, and EQ5D score (P < 0.001) when adjusted for age, sex, BMI, ASM, CCI, and history of lumbar surgery. Patient deterioration was associated with a decrease in trunk muscle mass, and the deterioration accelerated from approximately 23 kg.

CONCLUSIONS

Trunk muscle mass was significantly associated with the ODI, VAS score, SVA, and EQ5D score. Trunk muscle mass may assume an important role to elucidate and treat lumbar spinal dysfunction and spinal imbalance. These slides can be retrieved under Electronic Supplementary Material.

Predictors of clinical success with stabilization exercise are associated with lower levels of lumbar multifidus intramuscular adipose tissue in patients with low back pain

Purpose: Investigate the construct validity of prognostic factors purported to predict clinical success with stabilization exercise for low back pain by exploring their associations with lumbar multifidus composition.Methods: Patients with low back pain were recruited from a hospital imaging department. The presence of fivepredictors (age <40 years, positive prone instability test, aberrant trunk flexion movements, straight leg raise range of motion >91°, spinal hypermobility) were identified by standardized physical examination. Predictors were grouped by total positive findings and status on a clinical prediction rule. The proportion of lower lumbar multifidus intramuscular adipose tissue was measured with 3.0 T magnetic resonance imaging. Univariate and multivariate associations were examined with linear regression and reported with standardized beta coefficients (β) and 95% confidence intervals.Results: Data from 62 patients (11 female) with mean (SD) age of 45.2 (11.8) years were included. Total number of predictors (β[95% CI] = -0.37[-0.61,-0.12]; R² = 0.12), positive prediction rule status (β[95% CI] = -0.57[-0.79,-0.35]; R² = 0.30), and age <40 years were associated with lower intramuscular adipose tissue (β[95% CI] = -0.55[-0.77,-0.33]; R² = 0.27). No other individual factors were associated with lumbar multifidus intramuscular adipose tissue.Conclusions: These findings support the construct validity of the grouped prognostic criteria. Future research should examine the clinical utility of these criteria. Implications for RehabilitationLow back pain is the single largest cause of disability worldwide and exercise therapy is recommended by international low back pain treatment guidelines.Lower levels of lumbar multifidus intramuscular adipose tissue were associated with predictors of clinical success with stabilization exercise.Higher proportions of lumbar multifidus intramuscular adipose tissue may help identify patients who require longer duration exercise training, or those who are unlikely to respond to stabilization exercise.

Advancing imaging technologies for patients with spinal pain: with a focus on whiplash injury

BACKGROUND CONTEXT

Radiological observations of soft-tissue changes that may relate to clinical symptoms in patients with traumatic and non-traumatic spinal disorders are highly controversial. Studies are often of poor quality and findings are inconsistent. A plethora of evidence suggests some pathoanatomical findings from traditional imaging applications are common in asymptomatic participants across the life span, which further questions the diagnostic, prognostic, and theranostic value of traditional imaging. Although we do not dispute the limited evidence for the clinical importance of most imaging findings, we contend that the disparate findings across studies may in part be due to limitations in the approaches used in assessment and analysis of imaging findings.

PURPOSE

This clinical commentary aimed to (1) briefly detail available imaging guidelines, (2) detail research-based evidence around the clinical use of findings from advanced, but available, imaging applications (eg, fat and water magnetic resonance imaging and magnetization transfer imaging), and (3) introduce how evolving imaging technologies may improve our mechanistic understanding of pain and disability, leading to improved treatments and outcomes.

STUDY DESIGN/SETTING

A non-systematic review of the literature is carried out.

METHODS

A narrative summary (including studies from the authors' own work in whiplash injuries) of the available literature is provided.

RESULTS

An emerging body of evidence suggests that the combination of existing imaging sequences or the use of developing imaging technologies in tandem with a good clinical assessment of modifiable risk factors may provide important diagnostic information toward the exploration and development of more informed and effective treatment options for some patients with traumatic neck pain.

CONCLUSIONS

Advancing imaging technologies may help to explain the seemingly disconnected spectrum of biopsychosocial signs and symptoms of traumatic neck pain.

[Risk factors for surgical site infection following posterior lumbar intervertebral fusion]

OBJECTIVE

To analyze the risk factors of surgical site infection (SSI) following posterior lumbar intervertebral fusion.

METHODS

This retrospective case-control study was conducted in 2904 patients undergoing posterior lumbar intervertebral fusion from 2011 to 2016. Forty-three patients with SSI within 30 days after the operation served as the case group, and 334 randomly selected patients without infection served as the control group. Age, gender, diabetes, body mass index (BMI), albumin level, multilevel procedures, subcutaneous fat thickness, surgery duration and the percentage of lumbar multifidus muscle fat infiltration were analyzed, and univariate and multivariate logistic regression analyses were performed to identify the risk factors of SSI.

RESULTS

Multivariate logical regression analysis identified a female gender, subcutaneous fat thickness, multilevel surgery, and lumbar multifidus muscle fat infiltration as significant risk factors for SSI (P < 0.05). BMI was not correlated with fat infiltration in the lumbar multifidus muscle (P > 0.05).

CONCLUSIONS

A female gender, multilevel surgery, subcutaneous fat thickness and fat infiltration in the multifidus muscle are related to SSI following posterior lumbar intervertebral fusion. Fat infiltration in the multifidus muscle was a spine-specific risk factor for SSI independent of BMI.

Functional and Morphological Changes in the Deep Lumbar Multifidus Using Electromyography and Ultrasound

Surface electromyography (sEMG) studies have indicated that chronic low back pain (cLBP) involves altered electromyographic activity and morphological structure of the lumbar multifidus (LM) beyond pain perception; however, most studies have evaluated the superficial lumbar multifidus. It is difficult to record electromyography (EMG) signals from the deep multifidus (DM) to determine the neuromuscular activation patterns, making it difficult to determine the relationship between functional and structural changes in cLBP. We developed a novel method to record intramuscular EMG signals in the DM based on the sEMG system and fine-wire electrodes. We measured EMG signals of the DM in 24 cLBP patients and 26 pain-free healthy controls to identify changes in neuromuscular activation. We also used ultrasound to measure DM muscle thickness, cross-sectional area, and contraction activity to identify potential relationships between EMG activity and structural damage. cLBP patients had decreased average EMG and root mean square, but increased median frequency and mean power frequency. Average EMG was positively correlated with contractile activity, but not statistically correlated with noncontractile anatomical abnormalities. Our results suggest that cLBP alters the neuromuscular activation patterns and morphological structure of the contractile activity of the DM, providing insights into the mechanisms underlying pain perception.