Association between paraspinal muscle morphology, clinical symptoms and functional status in patients with lumbar spinal stenosis

Aquatic exercise versus standard care on paraspinal muscle morphology and function in chronic low back pain patients: a randomized controlled trial

Low back pain (LBP) is a disabling disease and a public health concern. Aquatic exercise is an alternative form of exercise with less spinal loading and difficulty performing movements, benefiting those with pain-related fear. This study aimed to investigate the effect of an aquatic exercise program (SwimEx) versus standard care (SC) on lumbar paraspinal muscle volume and composition, strength and patient outcomes in individuals with chronic LBP. This randomized controlled trial included 34 participants with chronic LBP. Participants were randomly allocated to each group (SwimEx, n = 18; SC, n = 16) and underwent a 10-week supervised intervention program twice per week. Magnetic resonance imaging was performed at baseline and 10-weeks to examine the impact of each intervention on multifidus (MF) and erector spinae (ES) muscle volume (cm3) and fatty infiltration (% FI) at L1-L2, L2-L3, L3-L4, L4-L5, and L5-S1. Mixed model repeated measures ANCOVA revealed no significant time*group interactions for MF and ES volume and %FI. SwimEX had significant increases in MF volume at L2-L3 and L3-L4, and ES volume at L1-L2. Furthermore, SwimEX also had a significant increase in MF %FI at L2-L3. Both groups displayed significant increases in lumbar strength. Correlations between muscle morphology and patient outcomes showed improvements in MF volume were moderately correlated with an increase in physical quality of life and decrease in anxiety/depression. Interestingly, improvements in MF volume, MF %FI, and ES %FI, were each moderately correlated with a decrease in sleep disturbance. In conclusion, aquatic therapy may help increase lumbar paraspinal muscle volume and strength in participants with chronic LBP. Our findings support the notion that improvements in paraspinal muscle health are related to improvements in patient-reported outcomes. More imaging studies are required to examine the impact of exercise on overall paraspinal muscle health in chronic LBP and investigate these associations.

Impact of myosteatosis on prognosis in multiple myeloma patients: A subgroup analysis of 182 cases and development of a nomogram

Background

This study aims to explore the prognostic value of myosteatosis in multiple myeloma (MM) and to analyze the factors influencing myosteatosis.

Methods

A retrospective analysis was conducted on 182 patients treated for MM at our institution from 2009 to 2020 who underwent MRI examinations. The fatty infiltration rate (FIR) of the erector spinae and multifidus muscles at the L3 level was measured to assess the degree of myosteatosis. Patients were grouped based on fracture presence and median FIR, and group differences were compared, with P < 0.05 considered statistically significant. Survival and fractures were used as prognostic indicators, and regression analysis was performed to determine the impact of FIR on these outcomes in MM patients. The factors influencing FIR were analyzed, and the relationship between myosteatosis and MM prognosis was further analyzed within its sensitive subgroups. Finally, a nomogram based on FIR was established and validated.

Results

Significant differences were observed between the fracture and non-fracture groups in lactate dehydrogenase, serum phosphorus, visual analogue scale, oswestry disability index and FIR (P < 0.05). When patients were grouped based on the median FIR (28.89 %), there were significant differences in age, sex, body mass index (BMI), red blood cell (RBC) count, hemoglobin, hematocrit, albumin, visual analogue scale, oswestry disability index, and fracture incidence (P < 0.05). Univariate COX regression analysis indicated that myosteatosis had no significant impact on survival prognosis in MM patients (HR = 0.999, P = 0.852), with a log-rank test P value of 0.11 when grouped by the cut-off FIR value of 33.67 %. Multivariate logistic regression indicated that FIR is an independent predictor of fractures (OR = 1.054, P = 0.000). Multivariate linear regression revealed that age, sex, RBC count, and BMI are independent factors influencing FIR (P < 0.05). When not grouped, FIR's prediction of fractures showed no significant interaction with age, sex, RBC count, or BMI (P for interaction > 0.05). In subgroups with BMI ≥ 25 kg/m2 or RBC count > 3.68 × 10^12/L, FIR lost its predictive significance for fractures. The FIR nomogram model had a C-index of 0.777, and the calibration curve, decision curve analysis, and clinical impact curve all validated its effectiveness.

Conclusions

Myosteatosis characterized by FIR is not a reliable predictor of survival in MM patients but is effective in predicting fractures and is closely related to back pain and functional impairment. FIR is significantly associated with age, sex, RBC count, and BMI.

Comparison of Combined Motor Control Training and Isolated Extensor Strengthening Versus General Exercise on Lumbar Paraspinal Muscle Health and Associations With Patient-Reported Outcome Measures in Chronic Low Back Pain Patients: A Randomized Controlled Trial

Study DesignProspective Randomized Controlled Trial.ObjectivesTo investigate the effect of combined motor control and isolated lumbar strengthening exercise (MC + ILEX) vs general exercise (GE) on upper lumbar paraspinal muscle volume and composition, strength and patient outcomes in individuals with chronic low back pain (LBP).Methods50 participants with nonspecific chronic LBP were randomly allocated (1:1) to each group (MC + ILEX or GE) and underwent a 12-week supervised intervention program 2 times per week. Magnetic resonance imaging was performed at baseline, 6-weeks and 12-weeks to examine the impact of each intervention on multifidus (MF) and erector spinae (ES) muscle volume (cm3) and fatty infiltration (%FI) at L1-L2, L2-L3 and L3-L4.ResultsOur results revealed no significant between-groups findings for MF and ES %FI and volume, and patient-reported psychosocial measures. However, both groups had significant within-groups decreases in MF %FI at L1-L2, L2-L3 and L3-L4, with concomitant decreases in MF volume at L1-L2 and L2-L3, and at L3-L4 in the GE group. Each group displayed significant improvements in Kinesiophobia, while only MC + ILEX had significant improvements in pain catastrophizing, anxiety, depression and sleep. Lastly, significant correlations were found between change in Kinesiophobia and upper lumbar MF %FI, and between change in strength and lower lumbar MF and ES size.ConclusionsBoth exercise interventions may help reduce upper lumbar MF %FI in individuals with chronic LBP, while MC + ILEX could significantly improve important patient outcomes. Our results support the idea that improvements in paraspinal muscle health associate with better patient outcomes. Further high-quality imaging studies are needed to explore these relationships.

Are paraspinal muscle morphology and composition associated with lumbar spinal stenosis? A systematic review

BACKGROUND

There has been increasing interest in associations between paraspinal muscle phenotypes and common spinal disorders, including lumbar spinal stenosis (LSS). However, the relation of paraspinal muscle morphology and composition with LSS is unclear.

OBJECTIVES

To provide a systematic overview and synthesis of current evidence on the association of paraspinal muscle morphology and composition with LSS presence, pain and disability or function.

DESIGN

Systematic review.

METHODS

Relevant studies were identified from a search of EMBASE, PubMed, SPORTDiscuss, Cinahl, Web of Science and PEDro. Relevant studies were selected, data were extracted, and risk of bias was assessed by 2 independent reviewers prior to conducting a narrative synthesis to summarize evidence using GRADE considerations. The study protocol was prospectively registered (Prospero: CRD42021246492).

RESULTS

Of 33 studies included in the review, multifidus (n=22) was most frequently studied, followed by psoas (n=10). Fatty infiltration (20 studies), CSA (n=11) and relative CSA (n=10) were the most studied paraspinal phenotypes. Most studies (n=31) had low risk of bias, with selection and confounding bias (n=13) most common. High variability in approaches used to measure muscle morphology and composition and LSS disability and pain, and variable control of confounding factors, created challenges in synthesizing findings. The only association identified for which there was moderate certainty of evidence was between increased multifidus fatty infiltration and the presence of LSS (4 of 6 studies). All other associations studied with high or moderate strength of evidence demonstrated no association, including no association between multifidus fatty infiltration and pain severity (8 studies), multifidus CSA and LSS disability (7 studies), psoas morphology and LSS anatomical severity (4 studies), or psoas composition and LSS pain severity (4 studies) for which there was high certainty. There was moderate certainty of no association between multifidus morphology and LSS pain severity (5 of 7 studies), and erector spinae morphology and pain severity (3 studies), and erector spinae composition and LSS pain severity (3 studies) and function (3 studies). Other associations remain more unclear.

CONCLUSION

Largely consistent results suggest multifidus fatty infiltration is associated with the presence of LSS. However, other specific associations examined with high or moderate certainty of evidence demonstrated no association, and others remain largely undetermined. Although interest has grown in paraspinal muscle morphology and composition for improved phenotyping, prognosis and treatment of common spinal disorders, the clinical utility of paraspinal muscle imaging in LSS remains unclear.

Thoracolumbar spine muscle size and composition changes in long-duration space missions

Muscle atrophy occurs with extended exposure to microgravity. This study quantified the overall muscle size, lean muscle area and fat infiltration changes pre- to post-flight that occur in the thoracic and lumbar spine with long-duration spaceflight. Pre- and post-flight magnetic resonance imaging (MRI) scans were obtained from 9 crewmembers on long-duration (≥6 months) International Space Station (ISS) missions. Muscle size was measured by the cross-sectional area (CSA) and lean muscle tissue by the functional cross-sectional area (FCSA). Muscle-fat infiltration (MFI) was measured by the mean pixel intensities of the MRI in fat and water phases. A mixed model with random subject effect was used to analyze pre- to post-flight changes. Significant decreases were seen in the quadratus lumborum muscle size (-1.8 ± 0.6% per month, p = 0.002) and lean muscle tissue content in the paraspinal muscles (-0.7 ± 0.2% per month, p ≤ 0.001). Fat infiltration increased significantly in the transversospinalis (+4.1 ± 1.0% per month, p ≤ 0.01) muscle. Treadmill exercise had a tendency to reduce fat content in the paraspinal and quadratus lumborum muscles, while counteracting muscle build-up only in the paraspinal muscles. Cycle ergometer exercise suggested benefits for the psoas muscle. Resistance training appeared to benefit lean muscle mass of most thoracolumbar muscles. Our findings highlight the need for countermeasures to prevent muscle atrophy and detrimental effects in muscle composition during long-duration spaceflight.

Spinopelvic malalignment correlates to lumbar instability and lumbar musculature in chronic low back pain-an exploratory study

As PI-LL mismatch is an effective index for spinal surgery and PI-LL less than 10 probably indicates better quality of life, this study aimed to assess spinopelvic parameters, lumbar instability, and lumbar muscle morphology in patients with chronic low back pain (CLBP) with different PI-LL mismatches. This cross-sectional study included 158 CLBP patients. The association between lumbar extensor muscle morphology (measured from magnetic resonance imaging) and spinopelvic parameters (measured from standing lateral radiographs) and lumbar instability (measured from lumbar flexion/extension radiographs) was compared between two groups of patients with different PI-LL mismatch. PI-LL mismatch showed a significant medium association with lumbar spine stability (χ2 = 8.06, p-value = 0.005, OR = 0.26, 95% CI = 0.10 to 0.69). Total cross-sectional area (TCSA) (OR = < 0.001, 95% CI = < 0.001 to < 0.001), functional cross-sectional area (FCSA) (OR = < 0.001, 95% CI = < 0.001 to < 0. 001) of the multifidus, psoas major TCSA (OR = < 0.001, 95% CI = < 0.001 to < 0.001) and its FCSA (OR = < 0.001, 95% CI = < 0.001 to 0.009) showed a strong negative association with PI-LL mismatch. Patients with lower PI-LL mismatch are younger and have less spinopelvic deviation. They have more local spinal compensatory mechanisms such as increased lumbar lordosis. They have better lumbar musculature and less disability but more lumbar instability.

Multifidus atrophy and/or dysfunction following lumbar radiofrequency ablation: A systematic review

BACKGROUND

Lumbar medial branch nerve radiofrequency ablation (LRFA) is an interventional procedure used to treat chronic lumbar facet joint pain. Because the medial branch nerves also innervate the multifidus muscle, it has been proposed that LRFA may pose a risk of multifidus atrophy and/or dysfunction. However, the quality and level of evidence to answer this clinical question have not been established. Therefore, this review aimed to systematically appraise the literature to discern whether the prevailing evidence substantiates the hypothesis in question.

METHODS

A systematic review compliant with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed to evaluate the quality and level of evidence of studies reporting functional and/or structural changes in the multifidus muscle following LRFA.

RESULTS

Only five cohort studies met inclusion criteria. Two studies assessed changes in multifidus function following LRFA with confirmed denervation at electromyography and significant reduction in multifidus shear modulus with ultrasound shear wave elastography. Of the four studies that evaluated changes in multifidus structure with magnetic resonance imaging following LRFA, two demonstrated a decrease in cross-sectional area or an increase in fat infiltration, one demonstrated no change, and one revealed an apparent increase. Given the destructive nature attributed to LRFA, some degree of multifidus atrophy and/or dysfunction may be plausible, albeit with a very low certainty that relies on a restricted body of literature of modest quality and with a presence of high bias.

CONCLUSION

There is a paucity of studies discussing the potential association between LRFA and multifidus atrophy and/or dysfunction. In light of the shortage of high-quality studies and the absence of standardized protocols to assess both changes in the structure and function of the multifidus subsequent to LRFA, there is a pressing need for more prospective studies with a high methodological rigor to comprehensively address and answer this enduring debate in clinical practice.

Investigation of lumbar multifidus muscle, pain, and fear of falling in patients with lumbar spinal stenosis with poor balance

BACKGROUND

This study aimed to compare the muscle thickness and cross-sectional area (CSA), pain, disability, and fear of falling in patients with lumbar spinal stenosis (LSS) with and without balance problems.

METHODS

Sixty-four patients diagnosed with LSS by magnetic resonance imaging (MRI) were included in this cross-sectional study. The patients were divided into poor (n=31) and normal balance (n=33) groups according to the single leg standing test. Low back pain (Numeric rating scale), dynamic balance (Time up and go test), disability (Oswestry disability index) and fear of falling (International fall efficacy scale) in patients with LSS levels were evaluated. Lumbar (L4/5) multifidus muscle thickness and CSA were obtained from MRI images.

RESULTS

The poor balance group had a lower L4/5 multifidus thickness (p<0.05) and CSA (p<0.05) than the normal balance group. It was determined that an increase in left L4/5 multifidus muscle CSA was associated with decreased impaired balance (p=0.036). Also, a significant correlation was detected between static balance and muscle thickness and CSA (p<0.01). In addition, low back pain, disability, and fear of falling were significantly higher in LSS patients in the poor balance group (p<0.05).

CONCLUSION

Muscle atrophy and decrease in CSA are more common in LSS patients with poor balance. Decreased L4/5 multifidus muscle CSA may increase the risk of balance impairment. Also, LSS patients with poor balance are more likely to experience pain, disability, and fear of falling. Strategies to improve lumbar muscle stability, mass, and pain may reduce impaired balance in LSS.

Walking stress-induced changes in gait patterns and muscle activity: Patients with lumbar spinal stenosis versus asymptomatic controls

INTRODUCTION

Patients with symptomatic lumbar spinal stenosis (sLSS) are often limited in their walking range because of worsening symptoms, which is thought to induce changes in the gait pattern. The aim of this study was to determine whether changes in gait pattern and muscle activity in these patients are elicited by a walking stress and differ from asymptomatic controls.

METHODS

Twenty patients with sLSS and 19 asymptomatic controls performed a 30-minute walking stress. Gait was assessed using seven inertial sensors and sagittal joint range of motion (ROM) was calculated during different phases of gait. Muscle activation of the gluteus medius, erector spinae and multifidus muscles was measured by surface electromyography (EMG) and integrated EMGs (normalized to the maximum during gait) were calculated. Differences between groups and time points (beginning and end) were assessed using mixed factorial analysis of variance.

RESULTS

Patients had less knee extension ROM in terminal stance, less knee flexion ROM in swing and less overall hip flexion/extension ROM than controls (p ≤ 0.03). There were no functionally relevant changes in these parameters during the walking stress. The integrated EMG was greater in all muscles in patients than in controls and increased in both groups during the walking stress in the paraspinal but not in the gluteus medius muscle. There was no interaction between group and time for any of the parameters.

CONCLUSION

Differences in gait pattern and muscle activity between patients with sLSS and controls are generally present, but are not amplified by a walking stress.

Evaluation of the reliability of measuring lower back muscles cross-sectional area based on manual segmentation within multi-level MRI images

INTRODUCTION

Manual segmentation of paraspinal muscle cross-sectional area (CSA) is widely used to assess related health disorders. This study aimed to evaluate the reliability of this segmentation process for each paraspinal region of interest across the three intervertebral levels commonly used for segmentation (L3/4, L4/5, and L5/S1).

METHODS

Axial-T2-weighted MRI images for 238 patients were divided among five raters (47 ± 1 cases each). To conduct the intra-rater reliability study, the CSA of each paraspinal lumber muscle (psoas major (PM), multifidus (MF), and erector spinae (ES)) and the intervertebral disc (ID) were manually segmented twice on all targeted levels before being assessed for each region per rater. The Inter-rater reliability was determined by comparing the results of different readers who segmented the same dataset. The Intraclass Correlation (ICC) and Coefficient-of-Variation percentage (CV%) were reported for each analysis.

RESULTS

Low intra- and inter-rater variability (CV%<11) was found for each reader in each region and intervertebral level. The inter-rater reliability was excellent (ICC>0.9) for the PM, ID, and ES at L3/4. However, it was very good for MF at all levels and ES at L4/5, L5/S1 (ICC range: 0.82-0.88) affected by the fat-infiltration nature of the ES and MF muscles, their proximity to each other, and their smaller size (correlation between muscle size and ICC = 0.6, P < 0.01). The ID segmentation has the lowest CV (<3 %) and excellent ICC (>0.93).

CONCLUSION

Manual paraspinal muscle segmentation using axial-T2-weighted MRI is reliable at all commonly segmented intervertebral levels. However, the reliability level can be degraded by the presence of high-fat infiltrate, unclear muscle boundaries, and muscle size.

IMPLICATIONS FOR PRACTICE

Following consistent guidelines can help improve segmentation results. The IDs can be used as reliable internal references.

Investigating cervical flexion-relaxation ratio in subjects with cervical lateral spinal stenosis compared with asymptomatic controls: A case control study

INTRODUCTION

The cervical flexion-relaxation ratio (FRR) is known as a quantitative measure of the ability of the cervical extensor muscles to relax during the full flexion of the cervical spine. Compared with subjects suffering from non-specific neck pain, the changes occurring in the pattern of the neck muscles' functions in cases with cervical spinal stenosis are not yet well understood. Therefore, this study aimed to compare cervical FRR in subjects with cervical lateral spinal stenosis and asymptomatic controls.

METHODS

In total, 25 subjects with cervical lateral spinal stenosis (aged 44.7 ± 10.4) and 25 asymptomatic individuals (aged 44.3 ± 10.8) were included in this study. These participants performed full-neck flexion, and at the same time, the electrical activity of the cervical erector spinae (CES) muscles was recorded bilaterally. Cervical FRR was further calculated by analyzing the electromyographic data recorded for each muscle.

RESULTS

The mean cervical FRR was significantly lower (P = 0.015) and the FRR asymmetry (ΔFRR) was significantly higher (P = 0.003) in the patients than asymptomatic controls. In addition, the cervical FRR of the involved side was significantly lower in the subjects with cervical pain compared with that in the non-involved one (P = 0.004). There was also a significant difference in the cervical extension (CE) angle between both study groups (P < 0.001), while the cervical flexion (CF) angle was not different (P = 0.25).

CONCLUSION

According to the study results, FRR and its asymmetry in the subjects with cervical lateral spinal stenosis were significantly different from that in asymptomatic controls and the CE angle declined in these subjects.

Fatty Infiltration in Paraspinal Muscles: Predicting the Outcome of Lumbar Surgery and Postoperative Complications

Lumbar spine disorders often cause lower back pain, lower limb radiating pain, restricted movement, and neurological dysfunction, which seriously affect the quality of life of middle-aged and older people. It has been found that pathological changes in the spine often cause changes in the morphology and function of the paraspinal muscles (PSMs). Fatty infiltration (FI) in PSMs is closely associated with disc degeneration and Modic changes. And FI causes inflammatory responses that exacerbate the progression of lumbar spine disease and disrupt postoperative recovery. Magnetic resonance imaging can better distinguish between fat and muscle tissue with the threshold technique. Three-dimensional magnetic resonance imaging multi-echo imaging techniques such as water-fat separation and proton density are currently popular for studying FI. Muscle fat content obtained based on these imaging sequences has greater accuracy, visualization, acquisition speed, and utility. The proton density fat fraction calculated from these techniques has been shown to evaluate more subtle changes in PSMs. Magnetic resonance spectroscopy can accurately reflect the relationship between FI and the degeneration of PSMs by measuring intracellular and extracellular lipid values to quantify muscle fat. We have pooled and analyzed published studies and found that patients with spinal disorders often exhibit FI in PSMs. Some studies suggest an association between FI and adverse surgical outcomes, although conflicting results exist. These suggest that clinicians should consider FI when assessing surgical risks and outcomes. Future studies should focus on understanding the biological mechanisms underlying FI and its predictive value in spinal surgery, providing valuable insights for clinical decision-making.

Preoperative fatty infiltration of paraspinal muscles assessed by MRI is associated with less improvement of leg pain 2 years after surgery for lumbar spinal stenosis

PURPOSE

Fatty infiltration (FI) of the paraspinal muscles may associate with pain and surgical complications in patients with lumbar spinal stenosis (LSS). We evaluated the prognostic influence of MRI-assessed paraspinal muscles' FI on pain or disability 2 years after surgery for LSS.

METHODS

A muscle fat index (MFI) was calculated (by dividing signal intensity of psoas to multifidus and erector spinae) on preoperative axial T2-weighted MRI of patients with LSS. Pain and disability 2 years after surgery were assessed using the Oswestry disability index, the Zurich claudication questionnaire and numeric rating scales for leg and back pain. Multivariate linear and logistic regression analyses (adjusted for preoperative outcome scores, age, body mass index, sex, smoking status, grade of spinal stenosis, disc degeneration and facet joint osteoarthritis) were used to assess the associations between MFI and patient-reported clinical outcomes. In the logistic regression models, odds ratios (OR) and 95% confidence intervals (CI) were calculated for associations between the MFI and ≥ 30% improvement of the outcomes (dichotomised into yes/no).

RESULTS

A total of 243 patients were evaluated (mean age 66.6 ± 8.5 years), 49% females (119). Preoperative MFI and postoperative leg pain were significantly associated, both with leg pain as continuous (coefficient - 3.20, 95% CI - 5.61, - 0.80) and dichotomised (OR 1.51, 95% CI 1.17, 1.95) scores. Associations between the MFI and the other outcome measures were not statistically significant.

CONCLUSION

Preoperative FI of the paraspinal muscles on MRI showed statistically significant association with postoperative NRS leg pain but not with ODI or ZCQ.

Association of Preoperative Osteoporotic Vertebral Compression Fractures with Muscle Atrophy in Lumbar Spinal Stenosis: A Retrospective Cohort Study

Objectives

Osteoporotic vertebral compression fractures (OVCFs) are common in older individuals and lead to pain, spinal deformities, and limited mobility. Paraspinal muscle function correlates with fracture severity, and this association may be more significant in patients with lumbar spinal stenosis (LSS). However, studies on the effects of OVCFs are lacking. This study aimed to investigate the relationship between OVCFs, fat infiltration, and muscle atrophy in patients with LSS.

Methods

This study included 177 patients with preoperative LSS, of whom 16 had OVCFs and 161 did not. Lumbar lordosis angle, fat infiltration, and paraspinal muscle atrophy were evaluated in these patients. Information on patient characteristics such as smoking, diabetes, hemodialysis, steroid use, American Society of Anesthesiologists score, and bladder or bowel dysfunction were obtained from medical records. Logistic regression analysis was conducted to identify factors independently associated with OVCF.

Results

Patients in the OVCF group were significantly older (P=0.006) than those without fractures, and a higher proportion of the OVCF group showed muscle atrophy (P=0.034). Significant variables and those with moderate effect sizes were included in the logistic regression analysis. Muscle atrophy (P=0.028) was independently associated with OVCF.

Conclusions

Muscle atrophy was associated with preoperative OVCFs in patients with LSS. Identifying OVCFs in these patients may underscore the importance of tailored treatment and rehabilitation strategies for the paraspinal muscles.

Preoperative Multifidus Muscle Quality is Associated With Patient Reported Outcomes After Lateral Lumbar Interbody Fusion

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

Lateral lumbar interbody fusion (LLIF) commonly involves a transpsoas approach. Despite the association between LLIF, postoperative iliopsoas weakness, and iatrogenic neuropraxia, no study has yet examined the effect of psoas or multifidus muscle quality on patient-reported outcomes (PROs).

METHODS

This study retrospectively reviewed patients who underwent LLIF with 1-year minimum follow-up. Psoas and multifidus muscle qualities were graded on preoperative magnetic resonance imaging using two validated classification systems for muscle atrophy. Average muscle quality was calculated as the mean score from all levels (L1-2 through L5-S1). Univariate and multivariate statistics were utilized to investigate the relationship between psoas/multifidus muscle quality and preoperative, 6-weeks postoperative, and final postoperative PROs.

RESULTS

74 patients (110 levels) with a mean follow-up of 18.71 ± 8.02 months were included for analysis. Greater multifidus atrophy was associated with less improvement on ODI, SF12, and VR12 (P < .05) on univariate analysis. On multivariate analysis, worse multifidus atrophy predicted less improvement on SF12 and VR12 (P < .05).

CONCLUSION

Despite the direct manipulation of the psoas muscle inherent to LLIF, preoperative psoas muscle quality did not affect postoperative outcomes. Rather, the extent of preoperative multifidus fatty infiltration and atrophy was more likely to predict postoperative pain and disability. These findings suggest that multifidus atrophy may be more pertinent than psoas atrophy in its association with patient-reported outcome measures after LLIF.

Importance of Lumbar Instability in the Study of Associations Between Muscle Morphology, Pain, and Disability in Chronic Low Back Pain

OBJECTIVE

The purpose of this study was to (1) evaluate the relationship between lumbar extensor muscle morphology, with pain and disability in patients with chronic low back pain and (2) compare these relationships in subgroup of chronic low back pain with and without lumbar structural segmental instability.

DESIGN AND METHODS

This cross-sectional study included 183 patients with chronic low back pain. Standing lateral lumbar flexion/extension radiographs were used to assess lumbar structural segmental instability. Lumbar multifidus, erector spinae, and psoas major morphology were determined from axial magnetic resonance imaging. Associations between lumbar muscle morphologies and patient pain and disability were evaluated in two groups with and without lumbar instability.

RESULTS

Patients' disability was negatively associated with psoas major total cross-sectional area (beta = -22.82, 95% CI = -37.05 to -8.59) and functional cross-sectional area (beta = -23.45, 95% CI = -37.81 to -9.09). Multifidus morphology was negatively associated with disability in the lumbar instability group. Pain intensity was only associated to psoas major total cross-sectional area (beta = -3.33, 95% CI = -6.43 to -2.24) and functional cross-sectional area (beta = -3.22, 95% CI = -6.40 to -0.05) only in the lumbar instability group.

CONCLUSIONS

Psoas major atrophy was associated with greater disability and pain in chronic low back pain, but multifidus atrophy was associated with greater disability in chronic low back pain patients with lumbar structural segmental instability.

Psoas muscle index and psoas muscle density are associated with functional status in patients with degenerative lumbar spinal stenosis

BACKGROUND

The factors affecting lumbar spinal function in patients with degenerative lumbar spinal stenosis (DLSS) are still unclear.

OBJECTIVE

This study explored psoas major muscle morphology in patients with DLSS and its association with their functional status.

METHODS

A retrospective study was conducted on 288 patients with DLSS and 260 control subjects. Psoas major muscle evaluation included three morphometric parameters at the L3/4 disc level: psoas major index (PMI), muscle attenuation, and psoas major morphological changes (MPM). The association between psoas major morphology and functional status was assessed using the Oswestry disability index (ODI).

RESULTS

Both female and male patients with DLSS had a higher PMI and lower muscle attenuation. PMI and muscle attenuation were inversely correlated with age in the DLSS group. After multivariable analyses, the PMI and psoas major muscle attenuation were positively correlated with patients' functional status.

CONCLUSION

The PMI and muscle attenuation were positively correlated with functional status in patients with DLSS. These findings have important implications for physiotherapy programs of postoperative rehabilitation and conservative management of DLSS.

The assessment of paraspinal muscle epimuscular fat in participants with and without low back pain: A case-control study

It remains unclear whether paraspinal muscle fatty infiltration in low back pain (LBP) is i) solely intramuscular, ii) is lying outside the epimysium between the muscle and fascial plane (epimuscular) or iii) or combination of both, as imaging studies often use different segmentation protocols that are not thoroughly described. Epimuscular fat possibly disturbs force generation of paraspinal muscles, but is seldomly explored. This project aimed to 1) compare epimuscular fat in participants with and without chronic LBP, and 2) determine whether epimuscular fat is different across lumbar spinal levels and associated with BMI, age, sex and LBP status, duration or intensity. Fat and water lumbosacral MRIs of 50 chronic LBP participants and 41 healthy controls were used. The presence and extent of epimuscular fat for the paraspinal muscle group (erector spinae and multifidus) was assessed using a qualitative score (0-5 scale; 0 = no epimuscular fat and 5 = epimuscular fat present along the entire muscle) and quantitative manual segmentation method. Chi-squared tests evaluated associations between qualitative epimuscular fat ratings and LBP status at each lumbar level. Bivariate and partial spearman's rho correlation assessed relationships between quantitative and qualitative epimuscular fat with participants' characteristics. Epimuscular fat was more frequent at the L4-L5 (X2 = 13.781, p = 0.017) and L5-S1 level (X2 = 27.825, p < 0.001) in participants with LBP compared to controls, which was not found for the higher lumbar levels. The total qualitative score (combined from all levels) showed a significant positive correlation with BMI, age, sex (female) and LBP status (r = 0.23-0.55; p < 0.05). Similarly, the total area of epimuscular fat (quantitative measure) was significantly correlated with BMI, age and LBP status (r = 0.26-0.57; p < 0.05). No correlations were found between epimuscular fat and LBP duration or intensity. Paraspinal muscle epimuscular fat is more common in chronic LBP patients. The functional implications of epimuscular fat should be further explored.

Risk Factors for Distal Junctional Problems Following Long Instrumented Fusion for Degenerative Lumbar Scoliosis: Are they Related to the Paraspinal Muscles

PURPOSE

Although the incidence of distal junctional problems (DJPs) following long construct-based treatment for degenerative lumbar scoliosis (DLS) is lower, affected patients are more likely to require revision surgery when they occur. So the aim of this study is to identify risk factors associated with DJPs to avoid its occurrence by at least 1-year follow-up.

METHODS

A total of 182 DLS patients undergoing long instrumented fusion surgery (≥4 levels) between February 2011 and March 2022 were retrospectively analyzed. Patients were placed into the DJP group if a DJP occurred at the final follow-up; patients without mechanical complications were matched 1:2 according to age, sex and BMI as the control group. Patient characteristics, surgical variables, radiographic parameters, lumbar muscularity and fatty degeneration were analyzed statistically. The statistical differences in the results between the two groups (p values <0.05) and other variables selected by experts were entered into a multivariate logistic regression model, and the forwards likelihood ratio method was used to analyze the independent risk factors for DJPs.

RESULTS

Twenty-four (13.2%) patients suffered a DJP in the postoperative period and the reoperation rate was 8.8%. On univariate analysis, the lowest instrumented vertebra (LIV) CT value (p = 0.042); instrumented levels (p = 0.030); preoperative coronal vertical axis (CVA) (p = 0.046), thoracolumbar kyphosis (TLK) (p = 0.006), L4-S1 lordosis (p = 0.013), sacral slop (SS) (p = 0.030), pelvic tilt (PT) classification (p = 0.004), and sagittal vertical axis (SVA) (p = 0.021); TLK correction (p = 0.049); post-operative CVA (p = 0.029); Overall, There was no significant difference in the paraspinal muscle parameters between the two groups. On multivariate analysis, instrumented levels (OR = 1.595; p = 0.035), preoperative SVA (OR = 1.016; p = 0.022) and preoperative PT (OR = 0.873; p = 0.001) were identified as significant independent risk factors for DJP.

CONCLUSION

Longer instrumented levels, a greater preoperative SVA and a smaller PT were found to be strongly associated with the presence of DJPs in patients treated for DLS. The degeneration of the paraspinal muscles may not be related to the occurrence of DJPs. For DLS patients, the occurrence of DJP can be reduced by selecting reasonable fusion segments and evaluating the patient's sagittal balance and spino-pelvic parameters before operation.

Multifidus dysfunction and restorative neurostimulation: a scoping review

OBJECTIVE

Chronic low back pain (CLBP) is multifactorial in nature, with recent research highlighting the role of multifidus dysfunction in a subset of nonspecific CLBP. This review aimed to provide a foundational reference that elucidates the pathophysiological cascade of multifidus dysfunction, how it contrasts with other CLBP etiologies and the role of restorative neurostimulation.

METHODS

A scoping review of the literature.

RESULTS

In total, 194 articles were included, and findings were presented to highlight emerging principles related to multifidus dysfunction and restorative neurostimulation. Multifidus dysfunction is diagnosed by a history of mechanical, axial, nociceptive CLBP and exam demonstrating functional lumbar instability, which differs from other structural etiologies. Diagnostic images may be used to grade multifidus atrophy and assess other structural pathologies. While various treatments exist for CLBP, restorative neurostimulation distinguishes itself from traditional neurostimulation in a way that treats a different etiology, targets a different anatomical site, and has a distinctive mechanism of action.

CONCLUSIONS

Multifidus dysfunction has been proposed to result from loss of neuromuscular control, which may manifest clinically as muscle inhibition resulting in altered movement patterns. Over time, this cycle may result in potential atrophy, degeneration and CLBP. Restorative neurostimulation, a novel implantable neurostimulator system, stimulates the efferent lumbar medial branch nerve to elicit repetitive multifidus contractions. This intervention aims to interrupt the cycle of dysfunction and normalize multifidus activity incrementally, potentially restoring neuromuscular control. Restorative neurostimulation has been shown to reduce pain and disability in CLBP, improve quality of life and reduce health care expenditures.

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.

Lumbar Degenerative Disease and Muscle Morphology Before and After Lower Limb Loss in Four Military Patients

INTRODUCTION

Low back pain (LBP) is highly prevalent after lower limb amputation (LLA). Reports describing longitudinal changes in spine health before and after amputation are rare. This study describes lumbar spine pathology, muscle morphology, and the continuum of care for LBP before and after LLA.

MATERIALS AND METHODS

We queried electronic medical records of patients who sought care for LBP before and after unilateral LLA between January 2002 and April 2020 and who had documented lumbar imaging pre- and post-LLA. Patient demographics, muscle morphology, spinal pathology, premorbid and comorbid conditions, self-reported pain, and treatment interventions were assessed.

RESULTS

Four patients with LBP and imaging before and after LLA were identified. Intervertebral disc degeneration progressed after amputation in three patients, whereas facet arthrosis progressed in both female patients. The fat content of lumbar musculature generally increased after amputation. Conservative management of LBP before and after amputation was standard, with progression to steroidal injections.

CONCLUSIONS

Lumbar spine health may degrade after amputation. Here, lumbar muscle size did not change after LLA, yet the fat content increased in combination with increases in facet and intervertebral disc degeneration.

Lumbar paraspinal muscle morphology is associated with spinal degeneration in patients with lumbar spinal stenosis

BACKGROUND CONTEXT

Lumbar spinal stenosis (LSS) has been reported to induce changes in paraspinal muscle morphology, but objective physical function and degenerative spine conditions are rarely assessed.

PURPOSE

To identify factors associated with paraspinal muscle morphology using objective physical and degenerative spine assessments in patients with LSS.

STUDY DESIGN/SETTING

Cross-sectional design.

PATIENT SAMPLE

Seventy patients with neurogenic claudication caused by LSS, receiving outpatient physical therapy.

OUTCOME MEASURES

Cross-sectional area (CSA) and functional CSA (FCSA) of the multifidus, erector spinae, and psoas muscles, the severity of stenosis, disc degeneration, and endplate abnormalities were evaluated by magnetic resonance imaging, as well as sagittal spinopelvic alignment by X-ray. Objective physical assessments included pedometry and claudication distance. Patient-reported outcomes included the numerical rating scale of low back pain, leg pain, and leg numbness, and the Zurich Claudication Questionnaire.

METHODS

To assess the impact of LSS on paraspinal muscles, FCSA and FCSA/CSA were compared between the dominant and nondominant sides based on the patients' neurogenic symptoms, and multivariable regression analyses adjusted for age, sex, height, and weight were performed; p<.05 was considered significant.

RESULTS

Seventy patients were analyzed. At one level below the maximum stenotic level, erector spinae FCSA on the dominant side was significantly lower than that on the nondominant side. In the multivariable regression analyses, at one level below the symptomatic level, disc degeneration, endplate abnormalities, and lumbar spinopelvic alignment, such as decreased lumbar lordosis and increased pelvic tilt, were negatively associated with multifidus FCSA and FCSA/CSA ratio. A significant association was observed between dural sac CSA and erector spinae FCSA. Throughout L1/2 to L5/S, disc degeneration, endplate abnormalities, and lumbar spinopelvic alignment were negatively associated with multifidus and erector spinae FCSA or FCSA/CSA.

CONCLUSIONS

Lumbar paraspinal muscle asymmetry caused by LSS was observed only in erector spinae. Disc degeneration, endplate abnormalities, and lumbar spinopelvic alignment, rather than spinal stenosis and LSS symptoms, were more associated with paraspinal muscle atrophy or fat infiltration.

The role of muscle degeneration and spinal balance in the pathophysiology of lumbar spinal stenosis: Study protocol of a translational approach combining in vivo biomechanical experiments with clinical and radiological parameters

OBJECTIVE

To describe a study protocol for investigating the functional association between posture, spinal balance, ambulatory biomechanics, paraspinal muscle fatigue, paraspinal muscle quality and symptoms in patients with symptomatic lumbar spinal stenosis (sLSS) before and 1-year after elective surgical intervention.

DESIGN

Single-centre prospective, experimental, multimodal (clinical, biomechanical, radiological) study with three instances of data collection: baseline (study visit 1), 6-month follow-up (remote) and 1-year follow-up (study visit 2). Both study visits include an in vivo experiment aiming to elicit paraspinal muscle fatigue for postural assessment in a non-fatigued and fatigued state.

EXPERIMENTAL PROTOCOL

At baseline and 1-year follow-up, 122 patients with sLSS will be assessed clinically, perform the back-performance scale assessment and complete several patient-reported outcome measure (PROMs) questionnaires regarding overall health, disease-related symptoms and kinesiophobia. Posture and biomechanical parameters (joint kinematics, kinetics, surface electromyography, back curvature) will be recorded using an optoelectronic system and retroreflective markers during different tasks including overground walking and movement assessments before and after a modified Biering-Sørensen test, used to elicit paraspinal muscle fatigue. Measurements of muscle size and quality and the severity of spinal stenosis will be obtained using magnetic resonance imaging (MRI) and sagittal postural alignment data from EOS radiographies. After each study visit, physical activity level will be assessed during 9 days using a wrist-worn activity monitor. In addition, physical activity level and PROMs will be assessed remotely at 6-month follow-up.

CONCLUSION

The multimodal set of data obtained using the study protocol described in this paper will help to expand our current knowledge on the pathophysiology, biomechanics, and treatment outcome of degenerative sLSS. The results of this study may contribute to defining and/or altering patient treatment norms, surgery indication criteria and post-surgery rehabilitation schedules.

TRIAL REGISTRATION

The protocol was approved by the regional ethics committee and has been registered at clinicaltrials.gov (NCT05523388).

Risk Factors of Low Back Pain Aggravation After Tubular Microdiscectomy of Lumbar Disc Herniation

BACKGROUND

Although lumbar disc herniation (LDH) patients' sciatic symptoms such as leg pain can be improved by decompressive surgery, some patients report postoperative aggravated low back pain (LBP). However, the exact reason for this phenomenon remained unknown.

METHODS

We retrospectively analyzed the prospectively collected LDH data of patients who underwent tubular microdiscectomy between December 2015 and December 2020. The patients were divided into aggravated and non-aggravated group according to whether the postoperative LBP visual analogue scale (VAS) score was higher than the preoperative score. We analyzed the relationship of the clinical and radiologic parameters with aggravated LBP.

RESULTS

Postoperative aggravated LBP cases accounted for 14.1% (57 of 404) of this series. Of the 57 patients, 88% (50 of 57) had mild postoperative LBP aggravation (1-2), and 12% (7 of 57) had severe LBP aggravation (>2). The preoperative LBP VAS score of the aggravated group was significantly lower than that of the non-aggravated group (P < 0.001), while the LBP VAS score and Oswestry Disability Index at final follow-up was significantly higher in the aggravated group (P < 0.05). Additionally, the proportion of preoperative moderate-to-severe multifidus fatty atrophy (MFA) and lumbar facet joint degeneration (LFJD) was significantly higher in the aggravated group. A multiple stepwise logistic regression analysis indicated that the preoperative LBP VAS score (P < 0.001, odds ratio 0.266, 95% CI 0.161-0.439) and MFA (P < 0.001, odds ratio 4.491, 95% CI 2.092-9.640) were the risk factors for postoperative aggravated LBP.

CONCLUSIONS

A preoperative lower LBP VAS score and moderate-to-severe MFA were associated with postoperative aggravated LBP. This will provide important guidance for patient's preoperative assessment and education.

The Difference in Paraspinal Muscle Parameters and the Correlation with Health-Related Quality of Life among Healthy Individuals, Patients with Degenerative Lumbar Scoliosis and Lumbar Spinal Stenosis

(1) Background: Paraspinal muscle degeneration affects the quality of life in patients with degenerative lumbar scoliosis (DLS) and lumbar spinal stenosis (LSS). We aimed to describe the characteristics and differences in the paraspinal muscle parameters between patients with DLS and LSS and investigate their correlation with health-related quality of life (HRQOL). (2) Methods: There were forty-four participants in each group, namely the DLS, LSS, and healthy groups, who were matched at a ratio of 1:1 according to age, sex, and BMI. Differences in paraspinal muscle parameters among the three groups were compared using analysis of variance or the Mann-Whitney U test, and paraspinal muscle degeneration and HRQOL were analyzed using Spearman's correlation analysis. (3) Results: In the upper lumbar, the psoas (PS), quadratus lumborum (QL), and multifidus (MF) cross-sectional area (CSA) in the DLS group were smaller than those in the other groups. In the lower lumbar region, the CSA of the PS, QL, erector spinae (ES), and gross CSA (GCSA) of the MF in the DLS group were not significantly different from those in the LSS group. These values were lower than those observed in the healthy group. The lean muscle fat index (LMFI) of the MF and ES groups was higher than those of the other groups. Regarding HRQOL, we found that PS and MF CSA were strongly associated with HRQOL in healthy individuals; however, only MF was associated with HRQOL in the LSS group. (4): Conclusion: PS in the upper lumbar region and MF degeneration were more severe in patients with DLS than in those with LSS. ES degeneration was similar between the LSS and DLS groups. MF muscle atrophy in patients with LSS and asymmetric changes in the MF in DLS are associated with quality of life.

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.

Preoperative cross-sectional area of psoas muscle correlates with short-term functional outcomes after posterior lumbar surgery

PURPOSE

To determine the optimal level for the measurement of psoas cross-sectional area and examine the correlation with short-term functional outcomes of posterior lumbar surgery.

METHODS

Patients who underwent minimally invasive posterior lumbar surgery were included in this study. The cross-sectional area of psoas muscle was measured at each intervertebral level on T2-weighted axial images of preoperative MRI. Normalized total psoas area (NTPA) (mm2/m2) was calculated as total psoas area normalized to patient height. Intraclass Correlation Coefficient (ICC) was calculated for the analysis of inter-rater reliability. Patient reported outcome measures including Oswestry disability index (ODI), visual analog scale (VAS), short form health survey (SF-12) and patient-reported outcomes measurement information system were collected. A multivariate analysis was performed to elucidate independent predictors associated with failure to reach minimal clinically important difference (MCID) in each functional outcome at 6 months.

RESULTS

The total of 212 patients were included in this study. ICC was highest at L3/4 [0.992 (95% CI: 0.987-0.994)] compared to the other levels [L1/2 0.983 (0.973-0.989), L2/3 0.991 (0.986-0.994), L4/5 0.928 (0.893-0.952)]. Postoperative PROMs were significantly worse in patients with low NTPA. Low NTPA was an independent predictor of failure to reach MCID in ODI (OR = 2.68; 95% CI: 1.26-5.67; p = 0.010) and VAS leg (OR = 2.43; 95% CI: 1.13-5.20; p = 0.022).

CONCLUSION

Decreased psoas cross-sectional area on preoperative MRI correlated with functional outcomes after posterior lumbar surgery. NTPA was highly reliable, especially at L3/4.

Effect of Muscularity and Fatty Infiltration of Paraspinal Muscles on Outcome of Lumbar Interbody Fusion

BACKGROUND

Lumbar paraspinal muscles play an important role in maintaining global spinal alignment and are associated with lower back pain; however, only a few studies on the effect of the paraspinal muscles on the surgical outcome exist. Therefore, this study aimed to analyze the association of preoperative muscularity and fatty infiltration (FI) of paraspinal muscles with the outcome of lumbar interbody fusion.

METHODS

Postoperative clinical and radiographic outcomes were analyzed in 206 patients who underwent surgery for a degenerative lumbar disease. The preoperative diagnosis was spinal stenosis or low-grade spondylolisthesis, and the surgery performed was posterior lumbar interbody fusion or minimally invasive transforaminal lumbar interbody fusion. Indications for surgery were a complaint of severe radiating pain that did not improve with conservative treatment and neurological symptoms accompanied by lower extremity motor weakness. Patients with fractures, infections, tumors, or a history of lumbar surgery were excluded from this study. Clinical outcome measures included functional status, measured using the Oswestry disability index (ODI) and visual analog scale (VAS) score for lower back and leg pain. Other radiographic parameters included measures of spinal alignment, including lumbar lordosis, pelvic tilt, sacral slope, pelvic incidence, C7 sagittal vertical axis, and pelvic incidence-lumbar lordosis mismatch. Lumbar muscularity (LM) and FI were measured preoperatively using a lumbar magnetic resonance image (MRI).

RESULTS

The high LM group showed more significant improvement in VAS score for lower back pain than the low LM group. In contrast, the VAS score for leg pain demonstrated no statistical significance. The high LM group showed more significant improvement in ODI postoperatively than the medium group. The severe FI group showed more significant improvement in ODI postoperatively, whereas the less severe FI group showed more significant improvement in the sagittal balance postoperatively.

CONCLUSION

Patients with high LM and mild FI ratio observed on preoperative MRI demonstrated more favorable clinical and radiographic outcomes after lumbar interbody fusion. Therefore, preoperative paraspinal muscle condition should be considered when planning lumbar interbody fusion.

Effectiveness of X-stop Interspinous Distractor Device Versus Laminectomy for Treatment of Lumbar Stenosis: A Systematic Review and Meta-Analysis

Lumbar spinal stenosis refers to the narrowing of the spinal canal in the lumbar region. There is an increasing need to determine the treatment modality for lumbar spinal stenosis by comparing the outcomes of X-stop interspinous distractors and laminectomy. The objective of this study is to determine the effectiveness of the X-stop interspinous distractor compared to laminectomy. This systematic review fundamentally abides by the procedures delineated in the Cochrane methodology while the reporting is done according to the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines. Three databases searched generated a total of 943 studies, with PubMed being the source for the bulk of the articles. Six studies were selected for inclusion in this study. The effectiveness of the interspinous distractor devices and laminectomy can be determined through their impact on the quality of life, rates of complications, and the amount of money utilized. This meta-analysis fundamentally emphasizes that laminectomy is a more effective intervention for the treatment of lumbar spinal stenosis as it is more cost-effective and results in fewer complications in the long term.

Influence of Handgrip Strength and Paraspinal Muscles' Volume on Clinical Outcomes in the Patients With Each Sagittal Imbalance and Lumbar Spinal Stenosis

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To compare handgrip strength (HGS), paraspinal muscles' (PSM) volume, and their effects on clinical symptom severity between the patients with sagittal imbalance (SI) and symptomatic lumbar spinal stenosis (LSS).

METHODS

A total of 54 paired consecutive patients with SI and LSS were enrolled after propensity score matching. Preoperative HGS, cross-sectional area (CSA) of psoas (PS) and multifidus (MF) muscles, and patient-reported measures, including visual analog scale (VAS) for back/ leg pain, Oswestry Disability Index (ODI), and EuroQOL (EQ-5D) were compared between both groups. Within each SI and LSS group, patient-reported measures were compared between high and low HGS subgroups. The correlation of HGS and CSA of PSMs to patient-reported measures was evaluated.

RESULTS

There was no difference in HGS between 2 groups, however, the CSA of PS and MF muscles in SI group was significantly lower than those in LSS group. Patients with low HGS showed inferior results for ODI and EQ-5D, compared to those with high HGS subgroup in both SI and LSS groups. HGS and CSA of MF muscle were correlated with ODI in both groups.

CONCLUSIONS

There was no significant difference between the SI and LSS groups in HGS, however, PSMs' volume in SI group were significantly lower than those in LSS group. Therefore SI would be associated with loss of localized muscle mass in back area, rather than global skeletal muscle weakness. HGS and PSMs' volume were adversely associated with functional status in SI and LSS patients.

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.

Does type 2 diabetes affect the efficacy of therapeutic exercises for degenerative lumbar spinal stenosis?

DESIGN

Propensity-matched retrospective study.

OBJECTIVES

To determine whether type 2 diabetes mellitus (T2D) would affect prognosis in patients with degenerative lumbar spinal stenosis (DLSS) who underwent therapeutic exercises.

METHODS

This study included consecutive patients with or without T2D who underwent therapeutic exercises for symptomatic DLSS from December 2018 to January 2020. Baseline demographics and clinical and radiological data were collected. The 2 groups of patients were further matched in a 1:1 fashion based on the propensity score, balancing the groups on pre-treatment factors including age, sex, leg and back pain, and low back disability. The primary outcomes included self-reported leg pain intensity (Numerical Rating Scale, NRS) and low back disability (Oswestry Disability Index, ODI) and the secondary outcomes included low back pain intensity and walking capacity (self-paced walking test, SPWT) were compared at baseline, 6 weeks, and 12 weeks.

RESULTS

Forty-one pairs of patients were selected by propensity matching. After 6-week therapeutic exercises, patients with T2D achieved a lower improvement in leg pain at 6 weeks (NRS leg change, 1.21 ± 0.40 vs. 1.78 ± 0.52, P = 0.021) and 12 weeks (NRS leg change, 1.52 ± 0.92 vs. 2.18 ± 0.96, P = 0.007) above minimal clinically important difference (MCID), with a significant Group × Time interactions (F_1,80 = 16.32, p < 0.001, ηp2 = 0.053). However, the two groups showed no difference in the improvement of ODI, although the sample had significant improvements at 6 weeks (ODI change 3.02 [95% CI, 2.08 to 2.77], P < 0.001) and 12 weeks ([ODI change 3.82 [95% CI, 4.03 to 4.90], P < 0.001), 46% of the patients achieved an MCID.

CONCLUSION

Six-week therapeutic exercises have an inferior effect on DLSS patients with T2D. Findings from this study will provide an increased understanding of exercise treatment in patients with DLSS.

Correlation Between Postoperative Imaging Parameters and Clinical Outcomes of Percutaneous Endoscopic Transforaminal Decompression for Lumbar Spinal Foraminal and Lateral Recess Stenosis

Objective

To investigate the correlation between postoperative imaging parameters and clinical outcomes in patients with foraminal stenosis (FS) and lateral recess stenosis (LRS) who underwent percutaneous endoscopic transforaminal decompression (PETD).

Methods

The study included 104 eligible patients who underwent PETD, and the mean follow-up time was 2.4 years (range 2.2-3.6 years). Visual Analog Scale (VAS) scores, Oswestry Disability Index (ODI) scores, and the modified MacNab criteria were used to evaluate the clinical outcomes. The related parameters of the FS and LRS based on computed tomography and magnetic resonance imaging were measured before and after surgery. Correlations between the imaging parameters and clinical outcomes were investigated.

Results

The proportion of excellent and good results following MacNab evaluation was 82.6%. In the treatment of LRS, VAS-back, VAS-leg, and ODI at the 2-year follow-up were negatively correlated with postoperative facet joint length based on computed tomography. In the treatment of FS, the above clinical results were positively correlated with the variation of foraminal width and nerve root-facet distance before and after surgery based on magnetic resonance imaging.

Conclusion

PETD can achieve good clinical outcomes in the treatment of patients with LRS or FS. Postoperative facet joint length was negatively correlated with clinical outcomes of LRS patients. In FS patients, the variation in foraminal width and nerve root-facet distance before and after surgery were positively correlated with their clinical outcomes. These findings may help surgeons optimize treatment strategies and selection of surgical candidates.

Correlation of psoas major muscle morphology with function and clinical symptoms in patients with symptomatic multilevel lumbar spinal stenosis

OBJECTIVE

This study was performed to quantify the morphological characteristics of the psoas major muscle in patients with symptomatic multilevel degenerative lumbar spinal stenosis (SMLSS) and assess the correlations of these morphological characteristics with function and clinical symptoms.

METHODS

One hundred fourteen patients diagnosed with SMLSS (≥ 3 segments) were included. The patients' presenting symptoms were assessed with the Oswestry Disability Index (ODI), and visual analogue scale (VAS) scores were recorded. The morphology of the psoas major was evaluated at the L3/4 intervertebral disc level in three ways: by measuring (i) the psoas muscle mass index (PMI); (ii) the mean muscle attenuation (Hounsfield units, HU); and (iii) the morphologic change of the psoas major (mean ratios of the short axis to the long axis of the bilateral psoas major).

RESULTS

Men had a higher PMI than women (p = 0.001). Patients with severe disability had a significantly lower PMI (p = 0.002) and muscle attenuation (p = 0.001). The PMI and muscle attenuation were significantly higher in the patients with no or mild back pain (both p < 0.001). In the univariable and multivariable analyses, a greater HU value was associated with a higher functional status as assessed by the ODI (p = 0.002), and a higher PMI was associated with less severe back pain as measured by the VAS score (p < 0.001).

CONCLUSION

This study showed that muscle attenuation of psoas major positively correlated with the functional status and PMI negatively correlated with low back pain severity in patients diagnosed with SMLSS. Future prospective studies are needed to evaluate whether improvement in such muscle parameters through physiotherapy programs can alleviate the clinical symptoms and improve the functional status of patients with SMLSS.

Morphology of paraspinal muscles in frail and non-frail older adults evaluated through FRAIL scale

BACKGROUND

Frailty is a condition characterized by the progressive deterioration of physiological functioning, which is closely related to adverse events. Multiple previous investigations applied frailty scales for spine research, and the purpose of this study is to investigate the differences in the morphology of the paraspinal muscles in frail and non-frail older adults evaluated through FRAIL scale.

METHODS

The sample of this retrospectively cross-sectional study consisted of individuals who were ≥ 60 years of age and with lumbar degenerative disease. We divided patients into two groups (0-2 = non-Frail, 3-5 = Frail) according to the FRAIL scale. The cross-sectional area (CSA) and percentage of the fatty infiltration (FI%) of the paraspinal muscles were compared between the two groups.

RESULTS

The fCSA (functional cross-sectional area) of the non-Frail group (32.78 [28.52, 38.28]) (cm²) was significantly greater than that of the Frail group (28.50 [24.11, 34.77]) (p < 0.001). The ES FI% (erector spinae fatty infiltration rate) (24.83 ± 6.61 vs. 29.60 ± 7.92, p < 0.001) and MF FI% (multifidus fatty infiltration rate) (31.68 ± 5.63 vs. 41.12 ± 7.04, p < 0.001) of the non-Frail group were significantly lower than that of Frail group.

CONCLUSIONS

The paraspinal muscles of elderly Frail patients screened by the FRAIL scale are worse than those of the non-Frail patients, and the ability of the FRAIL scale to distinguish paraspinal muscle morphology has important clinical significance.

The Effect of Paraspinal Fatty Muscle Infiltration and Cumulative Lumbar Spine Degeneration on the Outcome of Patients With Lumbar Spinal Canal Stenosis: Analysis of the Lumbar Stenosis Outcome Study (LSOS) Data

STUDY DESIGN

Prospective.

OBJECTIVE

To investigate the influence of paraspinal fatty muscle infiltration (FMI) and cumulative lumbar spine degeneration as assessed by magnetic resonance imaging on long-term clinical outcome measures in patients with lumbar spinal canal stenosis (LSCS) of the Lumbar Stenosis Outcome Study (LSOS) cohort.

SUMMARY OF BACKGROUND DATA

Past studies have tried to establish correlations of morphologic imaging findings in LSCS with clinical endpoints. However, the impact of FMI and overall lumbar spinal degeneration load has not been examined yet.

MATERIALS AND METHODS

Patients from the LSOS cohort with moderate to severe LSCS were included. Two radiologists assessed the degree of LSCS as well as cumulative degeneration of the lumbar spine. FMI was graded using the Goutallier scoring system. Spinal Stenosis Measure (SSM) was used to measure the severity level of symptoms and disability. European Quality of Life 5 Dimensions 3 Level Version (EQ-5D-3L) was used to measure health-related quality of life.

RESULTS

The nonsurgically treated group consisted of 116 patients (age 74.8±8.5 yr), whereas the surgically treated group included 300 patients (age 72.3±8.2 yr). Paraspinal FMI was significantly different between the groups (54.3% vs. 32.0% for Goutallier grade ≥2; P <0.001). Total degeneration score was comparable in both groups (9.5±2.0 vs. 9.3±2.0; P =0.418). FMI was associated with lower SSM function and lower EQ-5D-3L (all P <0.05), but not with SSM symptoms. Total degeneration of the lumbar spine was associated neither with SSM symptoms, nor with SSM function, nor with EQ-5D-3L (all P >0.05).

CONCLUSIONS

FMI is associated with higher disability and worse health-related quality of life of LSCS patients in the LSOS cohort. There was no significant association between total cumulative lumbar spine degeneration and the outcome of either surgically or nonsurgically treated patients.

LEVEL OF EVIDENCE

3.

Correlation between surgical segment mobility and paravertebral muscle fatty infiltration of upper adjacent segment in single-segment LDD patients: retrospective study at a minimum 2 years' follow-up

OBJECTIVE

The purpose of this study was to investigate the relationship between surgical segment mobility and fatty infiltration of the adjacent segment paravertebral muscles in patients with single-segment lumbar degenerative disease (LDD) who underwent decompression with fusion or dynamic stabilization.

METHODS

Retrospective analysis of patients who underwent lumbar decompression combined with titanium rod fixation intertransverse fusion (PITF group), Isobar TTL dynamic stabilization (TTL group) or Isobar EVO dynamic stabilization (EVO group) for single-segment lumbar degenerative disease, from March 2012 to July 2018. The preoperative and final follow-up clinical indexes C-LDSI and the measured imaging indexes (range of motion of the surgical segment and the upper adjacent segment, and Goutallier grade of the upper adjacent segment) were counted, and the differences between the preoperative and final follow-up indexes were compared.

RESULTS

According to the inclusion and exclusion criteria, 68 patients were included in this study, 21 in the PITF group, 24 in the TTL group, and 23 in the EVO group. At the final follow-up, the C-LSDI score had significantly higher in the PITF group than the TTL and EVO groups, and the C-LSDI score was a very strongly negatively correlated with ROM of surgical segment (r=-0.7968, p < 0.001). There was a strong negative correlation between surgical segment and upper adjacent segment mobility (r = -0.6959, p < 0.001). And there was a very strong negative correlation between ROM of surgical segment and upper adjacent segment paravertebral muscle Goutallier classification (r = -0.8092, p < 0.001), whereas the ROM of the upper adjacent segment was strong positive correlated with the Goutallier classification (r = 0.6703, P < 0.001).

CONCLUSION

Compared with decompression combined with rigid fusion, decompression combined with dynamic fixation for single-segment lumbar degenerative disease can significantly reduce postoperative low back stiffness. And a certain range of increased mobility of the dynamic stabilization device can effectively reduce the compensatory mobility of the upper adjacent segment and slow down the fatty infiltration of the paravertebral muscle in the adjacent segment.

Identification of preoperative radiological risk factors for reoperation following percutaneous endoscopic lumbar decompression to treat degenerative lumbar spinal stenosis

Background

This study aimed to identify radiological risk factors associated with reoperation after percutaneous transforaminal endoscopic decompression (PTED) for degenerative lumbar spinal stenosis (DLSS).

Methods

The preoperative clinical data of 527 consecutive patients with DLSS who underwent PTED were retrospectively reviewed. Overall, 44 patients who underwent reoperation were matched for age, sex, body mass index, and surgical segment to 132 control patients with excellent or good clinical outcomes. Radiological characteristics were compared between the groups using independent sample t-tests and Pearson's chi-square tests. A predictive model was established based on multivariate logistic regression analysis.

Results

The analyses revealed significant differences in the presence of lumbosacral transitional vertebra (LSTV, 43.2% vs. 17.4%, p = 0.001), the number of levels with senior-grade disc degeneration (2.57 vs. 1.96, p = 0.018) and facet degeneration (1.91 vs. 1.25 p = 0.002), and the skeletal muscle index (SMI, 849.7 mm²/m² vs. 1008.7 mm²/m², p < 0.001) between patients in the reoperation and control groups. The results of the logistic analysis demonstrated that LSTV (odds ratio [OR] = 2.734, 95% confidence interval [CI]:1.222-6.117, p < 0.014), number of levels with senior-grade facet degeneration (OR = 1.622, 95% CI:1.137-2.315, p = 0.008), and SMI (OR = 0.997, 95% CI:0.995-0.999, p = 0.001) were associated with reoperation after PTED. The application of the nomogram based on these three factors showed good discrimination (area under the receiver operating characteristic curve 0.754, 95% CI 0.670-0.837) and good calibration.

Conclusion

LSTV, more levels with senior-grade facet degeneration, and severe paraspinal muscle atrophy are independent risk factors for reoperation after PTED. These factors can thus be used to predict reoperation risk and to help tailor treatment plans for patients with DLSS.

Evaluating the causal relationship between five modifiable factors and the risk of spinal stenosis: a multivariable Mendelian randomization analysis

Background

Spinal stenosis is a neurological disorder related to the compression of the spinal cord or nerve roots, and its incidence increases yearly. We aimed to use Mendelian randomization (MR) to investigate the causal relationship between several modifiable risk factors and the risk of spinal stenosis.

Methods

We obtained genome-wide association study summary data of large-sample projects (more than 100,000 individuals) from public databases. The data were associated with traits, including years of schooling (educational attainment) from the IEU OpenGWAS Project, smoking behavior (never vs. initiation) from the IEU OpenGWAS Project, body mass index (BMI) from the UK Biobank, length of mobile phone use from the UK Biobank, time spent watching television (TV) from the UK Biobank, and spinal stenosis from FinnGen biobank. Spinal stenosis was used as the outcome, whereas the other four traits were used as exposures. Inverse variance weighted (IVW) regressions were used as a primary to estimate the causal-effect size. Several sensitive analyses (including consistency, heterogenicity, and pleiotropy analyses) were conducted to test the stability and reliability of causal estimates.

Results

Univariable MR analyses showed that genetically predicted higher educational attainment (IVW; odds ratio (OR) = 0.606; 95% confidence interval (CI): 0.507-0.724; P = 3.37 × 10^-8) and never smoking (IVW; OR = 1.388; 95% CI [1.135-1.697]; P = 0.001) were negatively correlated with the risk of spinal stenosis. Meanwhile, a higher BMI (IVW; OR = 1.569; 95% CI [1.403-1.754]; P = 2.35 × 10^-8), longer time spent using a mobile phone (IVW; OR = 1.895; 95% CI [1.306-2.750]; P = 0.001), and watching TV (IVW; OR = 1.776; 95% CI [1.245-2.532]; P = 0.002) were positively associated with the risk of spinal stenosis. Multivariable MR analysis indicated that educational attainment (IVW; OR = 0.670; 95% CI [0.465-0.967]; P = 0.032) and BMI (IVW; OR = 1.365; 95% CI [1.179-1.580]; P = 3.12 × 10^-5) were independently causally related to the risk of spinal stenosis.

Conclusion

Our findings supported the potential causal associations of the five factors (educational attainment, smoking behavior, BMI, length of mobile phone use, and watching TV) with the risk for spinal stenosis. While replication studies are essential, these findings may provide a new perspective on prevention and intervention strategies directed toward spinal stenosis.

Imaging of muscle and adipose tissue in the spine: A narrative review

Interpretation of the morphology and characteristics of soft tissues, such as paravertebral muscles and fat, has always been a "relative blind spot" in the spine. The imaging features of the non-bony structures of the spine have been studied and reinterpreted, and changes in the non-bony structure are associated with spinal disease. Soft tissue parameters such as, the "paraspinal muscle cross-sectional area," "subcutaneous fat thickness," and the "paraspinal muscle fat infiltration rate" on computed tomography, magnetic resonance imaging and other imaging techniques are reproducible in the diagnosis, treatment and prognosis of spinal disorders and have the potential for clinical application. In addition, focus on the association between sarcopenia and spinal epidural lipomatosis with spinal disorders is increasing. Currently, there is no summary of studies on fat and muscle in the spinal region. Given this, within the context of recent research trends, this article provides a synthesis of research on adipose and muscle tissue in the spine, discusses advances in the study of the imaging manifestations of these structures in spinal disorders, and expands the perspectives.

Alteration in the Cross-sectional Area (CSA) Ratio of the Paraspinal Muscles following Vertebral Insufficiency Fractures

Background  Vertebral insufficiency fractures in the elderly are associated with increased morbidity and mortality. Early diagnosis is essential to direct patient-specific rehabilitation. Aims  We hypothesize that in patients with vertebral insufficiency fractures, there is atrophy of the psoas and paraspinal muscles with alteration in the cross-sectional area (CSA) of the muscles. Materials and Methods  Magnetic resonance imaging (MRI) studies for 100 consecutive patients, older than 60 years presenting with lower back pain, were included in the study. For each MRI study, the CSA of the psoas and paraspinal muscles (multifidus) at the level of L4/5-disc space was measured to calculate the cross-sectional area ratio (CSAR) by two readers. One reader repeated the measurements after an interval of 2 weeks. We divided the patients ( n  = 100) into various groups based on the number of vertebral fractures. Results  In total, 77 patients with vertebral body fractures (48 with one, 16 with two and 13 with more than two fractures) were identified with a mean age of 73 (range 60-92) years. The ratio of multifidus CSA to psoas CSA was calculated with mean values of each group (1-4) as 2.56, 1.89, 2.09 and 2.16, respectively. There was statistically significance difference of the CSAR between the cohorts ( p -value = 0.0115). Conclusion  Vertebral insufficiency fractures in the elderly are associated not only with atrophy of psoas and the multifidus group of muscles as evident by the CSA values, but they also affect the CSAR depending on the number of fractures. This finding may help to direct targeted patient-specific physiotherapy rehabilitation and interventions to prevent further such fractures.

Facet overhang: A novel parameter in the pathophysiology of multifidus muscle atrophy

The relationship between degenerative zygapophysial joint (facet) arthropathy and multifidus muscle atrophy has not been rigorously evaluated. The purpose of this study was to determine if specific morphological features of degenerative facet arthropathy are correlated with multifidus muscle atrophy. We retrospectively reviewed medical records and imaging studies of patients with lumbar spinal stenosis. Facet overhang, bridging osteophyte formation, facet effusion, and facet angles were evaluated by univariable and multivariable regression to identify independent associations with deep and superficial parts of the multifidus total cross-sectional area (tCSA), functional cross-sectional area (fnCSA), and fatty infiltration (FI). Facet overhang was classified as severe in 50 females (53.2%) versus 56 males (36.9%) (p = 0.030). Severity of facet overhang and female sex were independently associated with smaller deep part of the multifidus tCSA and fnCSA as well as higher FI, reflecting greater atrophy of the deep region compared to total muscle mass. In comparison, severe facet overhang (p < 0.001; OR = 3.47, 95% CI = 2.13-5.66) and female sex (p < 0.001; OR = 4.19, 95% CI = 2.58-6.79) were independently associated only with higher superficial part of the multifidus FI, reflecting muscle steatosis without significant lean muscle atrophy. In patients with degenerative lumbar spinal stenosis, facet overhang is an independent risk factor for deep part of the multifidus atrophy. Bridging osteophyte formation, facet effusion, and facet angles were not independently associated with deep part of the multifidus atrophy.

Association between muscle health and patient-reported outcomes after lumbar microdiscectomy: early results

BACKGROUND CONTEXT

Poor muscle health has been implicated as a source of back pain among patients with lumbar spine pathology. Recently, a novel magnetic resonance imaging (MRI)-based lumbar muscle health grade was shown to correlate with health-related quality of life scores. However, the impact of muscle health on postoperative functional outcomes following spine surgery remains to be investigated.

PURPOSE

To determine whether muscle health grade measured by preoperative psoas and paralumbar muscle cross-sectional areas impact the achievement of minimal clinically important difference (MCID) following lumbar microdiscectomy.

STUDY DESIGN/SETTING

Retrospective cohort study.

PATIENT SAMPLE

Consecutive patients who underwent 1-level lumbar microdiscectomy in a single institution between 2017 and 2021.

OUTCOME MEASURES

Rate of MCID achievement, time to MCID achievement, PROMs including Oswestry Disability Index (ODI), visual analog scale for back pain (VAS back), VAS leg, Short Form 12 Physical Component Summary (SF-12 PCS), SF-12 Mental Component Summary (SF-12 MCS), and Patient Reported Outcomes Measurement Information System Physical Function (PROMIS PF).

METHODS

Two previously validated methods for muscle health grading were applied. Axial T2 MRI were analyzed for muscle measurements. The psoas-based method utilized the normalized total psoas area (NTPA), which is the psoas cross-sectional area divided by the square of patient height (mm2/m2). Patients were divided into low and high NTPA groups based on sex-specific lowest quartile NTPA thresholds. The paralumbar-based method incorporated the paralumbar cross-sectional area normalized by body mass index (PL-CSA/BMI) and Goutallier classification. Score of 1 was added for either PL-CSA/BMI >130 or Goutallier class of ≤2. "Good" muscle health was defined as score of 2, and "poor" muscle health was defined as score of 0 to 1. Prospectively collected PROMs were analyzed at 2-week, 6-week, 3-month, 6-month, 1-year, and 2-year postoperative timepoints. The rate of and time to MCID achievement were compared among the cohorts. Bivariate analyses were performed to assess for correlations between psoas/paralumbar cross-sectional areas and change in PROM scores from baseline.

RESULTS

The total cohort included 163 patients with minimum follow-up of 6 months and mean follow-up of 16.5 months. 40 patients (24.5%) were categorized into the low NTPA group, and 55 patients (33.7%) were categorized into the poor paralumbar muscle group. Low NTPA was associated with older age, lower BMI, and greater frequencies of Charlson Comorbidity Index (CCI) ≥1. Poor paralumbar muscle health was associated with older age, female sex, higher BMI, and CCI ≥1. There were no differences in rates of MCID achievement for any PROMs between low versus high NTPA groups or between poor versus good paralumbar groups. Low NTPA was associated with longer time to MCID achievement for ODI, VAS back, VAS leg, and SF-12 MCS. Poor paralumbar muscle health was associated with longer time to MCID achievement for VAS back, VAS leg, and SF-12 PCS. NTPA negatively correlated with change in VAS back (6-week, 12-week) and VAS leg (6-month). PL-CSA/BMI positively correlated with change in PROMIS-PF at 3 months follow-up.

CONCLUSIONS

Among patients undergoing lumbar microdiscectomy, patients with worse muscle health grades achieved MCID at similar rates but required longer time to achieve MCID. Lower NTPA was weakly correlated with larger improvements in pain scores. PL-CSA/BMI positively correlated with change in PROMIS-PF. Our findings suggest that with regards to functional outcomes, patients with worse muscle health may take longer to recuperate postoperatively compared to those with better muscle health.

MRI grading of spinal stenosis is not associated with the severity of low back pain in patients with lumbar spinal stenosis

Background

Although lumbar spinal stenosis (LSS) often coexists with other degenerative conditions, few studies have fully assessed possible contributing factors for low back pain (LBP) in patients with LSS. The purpose of this study was to identify factors associated with the severity of LBP in patients with LSS.

Methods

The patients with neurogenic claudication caused by LSS, which was confirmed by magnetic resonance imaging (MRI) were included in this cross-sectional study. Data included ratings of LBP, buttock and leg pain, and numbness on a numerical rating scale (NRS), 36-item Short-Form Survey (SF-36) scores, muscle mass measured by bioelectrical impedance analysis, and radiographic measurements including lumbopelvic alignment and slippage. The severity of LSS, endplate defects, Modic endplate changes, intervertebral disc degeneration, and facet joint osteoarthritis were evaluated on MRI. Spearman correlation and multivariate linear regression analyses were used to examine the factors associated with the severity of LBP (NRS score).

Results

A total of 293 patients (135 male and 158 female, average age 72.6 years) were analyzed. LBP was moderately correlated with buttock and leg pain, and buttock and leg numbness. Significant but weak correlations were observed between LBP and body mass index, appendicular and trunk muscle mass, all domains of SF-36, pelvic tilt, total number of endplate defects and Modic endplate changes, and summary score of disc degeneration grading, but not severity or number of spinal stenoses. In the multivariate regression analysis, age, female sex, trunk muscle mass, diabetes, NRS buttock and leg pain, NRS buttock and leg numbness, SF-36 vitality, pelvic tilt, and total number of endplate defects were associated with the severity of LBP.

Conclusions

Trunk muscle mass, lumbopelvic alignment, and endplate defects, but not severity of stenosis are partly associated with severity of LBP, but buttock and leg pain and buttock and leg numbness have strongest relationships with LBP in patients with LSS.

Age- and sex-dependent differences in the morphology and composition of paraspinal muscles between subjects with and without lumbar degenerative diseases

BACKGROUND

The quality of the paraspinal muscles has been recommended as a surrogate marker for the evaluation of the severity of the lumbar degenerative diseases (LDD). The purpose of this study is to determine the age- and sex-dependent differences in the morphology and composition of the paraspinal muscles between LDD and asymptomatic subjects.

METHODS

We analyzed data from 370 patients and 327 asymptomatic volunteers aged between 18-85 years. The measurement of the cross-sectional area (CSA) of the erector spinae, multifidus, and psoas at the L4/5-disc level was performed by the magnetic resonance imaging (MRI). The fatty infiltration ratio (FI %) of the multifidus and erector spinae was calculated.

RESULTS

FI % of the lumbar paraspinal muscles were significantly and positively correlated with the severity of LDD instead of the CSA. Males had greater CSA than females, and females showed higher FI % than males in the paraspinal muscles. With the increase of age, the CSA of the lumbar paraspinal muscles gradually decreased, and the psoas showed the most significant decreasing trend. However, the FI % gradually increased in both LDD and asymptomatic groups with aging.

CONCLUSION

Age- and sex-dependent differences were found in the morphology and composition of the paraspinal muscles between subjects with and without LDD. Further long-term follow up investigations and basic studies will continue to confirm the natural history of the paraspinal muscles with aging and their association with LDD.

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.

Correlations between paraspinal extensor muscle endurance and clinical outcomes in preoperative LSS patients and clinical value of an endurance classification

Background

Few study has investigated how paraspinal muscle endurance deteriorates in lumbar spinal stenosis (LSS) patients. In addition, little information is available on the relationship between clinical outcomes and the endurance of paraspinal muscles.

Objective

To explore the correlation between paraspinal extensor muscle endurance, quality of life (QOL) and sagittal spinopelvic alignment. Besides, we attempted to propose a paraspinal extensor muscle endurance test (PEMET) classification for identifying the severity of clinical symptoms and sagittal imbalance in LSS patients.

Methods

171 hospitalized LSS patients and 100 healthy controls from the community were prospectively enrolled in this study. The paraspinal extensor endurance test was performed at baseline according to Ito test. The LSS patients were stratified into three groups based on the performance time of endurance test: grade I (<10s); grade II (10–60s); and grade III (>60s). Clinical measures of QOL included the visual analog scale scores (VAS) for back pain and leg pain and the Oswestry Disability Index (ODI). Sagittal alignment was analysed by standing posteroanterior and lateral whole spine X-ray in LSS patients.

Results

The LSS group had a significantly shorter performance time of the endurance test than the control group. The paraspinal muscle endurance significantly correlated with VAS-back, VAS-leg, ODI, pelvic tilt, lumbar lordosis and sagittal vertical axis (SVA; all p < 0.05). In binary logistic regression, the performance time of the endurance test was an independent factor of both poor functional status (ODI >40; p = 0.005, OR = 0.985) and global sagittal imbalance (SVA >50 mm; p = 0.019, OR = 0.985). Based on PEMET classification, moving from the grade III group to the grade I group, there was progressive worsening in VAS-back and ODI (all adjusted p < 0.05). Moreover, the grade I group had significantly greater VAS- leg, less LL and greater SVA than the other two groups (all adjusted p < 0.05).

Conclusion

Paraspinal muscle endurance was associated with QOL and sagittal spinopelvic alignment in LSS patients. A PEMET classification system has been constructed and has shown a correlation with QOL and sagittal imbalance.

Translational potential statement

The PEMET classification system proposed in this study could be available for identifying the severity of clinical symptoms and sagittal imbalance during preoperative evaluation in LSS patients.