Is there an interdependence between paraspinal muscle mass and lumbar disc degeneration? A MRI based study at 2520 levels in 504 patients

A Comprehensive Analysis Between Disk Geometry and Posterior Muscle Characteristics Among Degenerative Spine Patients: An Internal Retrospective Review

STUDY DESIGN

A retrospective Cohort Study.

OBJECTIVE

The aim of this study is to investigate the associations between posterior muscle health characteristics and disk geometry parameters between L1 and S1.

SUMMARY OF BACKGROUND DATA

Paralumbar muscle changes have been associated with clinical outcomes. However, the relationship between disk geometry and paralumbar muscle changes has not been defined.

METHODS

Axial T2 MRI was analyzed for paralumbar muscle measurements, and lateral radiographs were analyzed for disk geometry parameters in patients with disk degeneration. Associations between disk shape and muscle health at each individual lumbar level were evaluated using a partial correlation controlling for age and sex. Demographic data were compared between the listhesis groups, and an ANCOVA analysis controlling for significant demographic parameters was conducted to evaluate differences in muscle characteristics.

RESULTS

In all, 435 patients were included (age: 55.6±15, BMI: 29.5±6, 60.9% female, 41.3% White). Muscle health median characteristics were CSA/BMI=140, LIV=13, and Goutallier Classification of 1. Partial correlations between focal disk parameters and muscle health controlling for age and sex showed moderate significant positive associations between focal lordosis and lumbar indentation value (LIV) at every level L1-S1 (mean r=0.264 between L1 and L5, P<0.001), weak positive association between focal lordosis and CSA/BMI (mean r=0.113 at L2-L5, P <0.03), and weak negative associations between disk height and Goutallier Classification (mean r=0.158 at L1-L5, P<0.03). Listhesis at L4-S1 was stratified, and ANCOVA controlling for sex and age demonstrated no significant association between S and R groups and CSA/BMI, LIV, or Goutallier classification (P>0.1).

CONCLUSIONS

Posterior muscle health was significantly associated with disk shape, especially disk height and disk lordosis, with larger and more lordotic disks being associated with better muscle health. Disk listhesis was not significantly associated with muscle quality when controlling for demographic characteristics, and no differences in muscle health parameters were observed in patients with spondylolisthesis versus retrolisthesis. Overall, the results highlight important associations between lumbar compensation, disk geometry, and posterior muscle health.

The influence of workload on muscle fatigue, tissue properties, and postural stability in older and younger workers

Demographic aging and extended working lives have prompted interest in the physiological changes that occur with age, particularly in the lumbar spine. Age-related declines in muscle quality and intervertebral disc alterations may reduce muscular endurance, strength, and postural stability, potentially increasing the risk of musculoskeletal injuries in older workers. As experienced workers play an important role in addressing labor shortages, understanding the impact of age-related physiological changes on the biomechanical properties of the lumbar spine is key to ensure safe and sustainable employment for aging individuals. This study aimed to compare the impact of daily work-related physical efforts on lumbar muscular endurance and fatigue, spine tissue properties, and postural stability between older and younger workers. A total of 40 participants, 20 in Group 1 (young workers: ≤50 years; mean age: 28.89 ± 7.23) and 20 in Group 2 (older workers: >50 years; mean age: 59.40 ± 5.29) were recruited. Measurements taken at the beginning and end of the workday included lumbar muscle endurance, maximal voluntary contraction, disc height and postural stability. Age groups were compared using repeated measures ANOVA across the two measurement times. No significant interaction between age and time of day was observed, indicating that, for similar workload, both age groups experienced similar changes. Despite age-related effects on maximal force production and postural stability, incorporating weight as a covariate revealed that these differences were partially explained by the weight discrepancy between older and younger workers. The study suggests that age may not be the primary determinant of the impact of a workday on older workers.

The Differences on the Fatty Infiltration of Paraspinal Muscles between Single- and Multiple-level Intervertebral Disc Degeneration in Patients with Lumbar Disc Herniation

OBJECTIVE

Multiple-level Intervertebral disc degeneration (IDD) in patients with lumbar disc herniation (LDH) is related to postoperative re-herniation and low back pain. Although many investigators believed that there is an interdependence between paraspinal muscles degeneration and IDD, few studies focused on the fatty infiltration of paraspinal muscles on single- and multiple-level IDD in patients with LDH. This study aims to investigate the difference on the fatty infiltration of paraspinal muscles between single- and multiple-levels IDD in patients with LDH. and to explore in patients with LDH whether fatty infiltration is a potential risk factor for multiple-level IDD.

METHODS

This study was conducted as a retrospective observational analysis of 82 patients with LDH from January 1, 2020 to December 30, 2020 in our hospital were enrolled. Twenty-seven cases had single-level IDD (Group A), and 55 cases had multiple-level IDD (Group B). We measured the mean computed tomography (CT) density value of the paraspinal muscles, including multifidus (MF), erector spinae (ES) and psoas muscle (PM) at each disc from L1 to S1. Subgroups were set to further analyze the odds ratio (OR) of fatty infiltration of paraspinal muscles in different sex and BMI groups. We measured sagittal angles and analyzed the relationships between these angles and IDD. Finally, we use logistic regression, adjusted for other confounding factors, to investigate whether fatty infiltration is an independent risk factor for multi-level IDD.

RESULTS

The average age in multi-level IDD (51.40 ± 15.47 years) was significantly higher than single-level IDD (33.37 ± 7.10 years). The mean CT density value of MF, ES and PM in single-level IDD was significantly higher than multi-level IDD (all ps < 0.001). There was no significant difference of the mean value of angles between the two groups. No matter being fat (body mass index [BMI] > 24.0 kg/m2) or normal, patients with low mean muscle CT density value of MF and ES are significantly easier to suffer from multiple-level IDD. In the pure model, the average CT density value of the MF, ES and PM is all significantly associated with the occurrence of multi-IDD. However, after adjusting for various confounding factors, only the OR of the average CT density value for MF and ES remains statistically significant (OR = 0.810, 0.834, respectively).

CONCLUSIONS

In patients with LDH, patients with multiple-level IDD have more severe fatty infiltration of MF and ES than those with single-level IDD. Fatty infiltration of MF and ES are independent risk factors for multiple-level IDD in LDH patients.

Spine-specific sarcopenia: distinguishing paraspinal muscle atrophy from generalized sarcopenia

BACKGROUND CONTEXT

Atrophy of the paraspinal musculature (PM) as well as generalized sarcopenia are increasingly reported as important parameters for clinical outcomes in the field of spine surgery. Despite growing awareness and potential similarities between both conditions, the relationship between "generalized" and "spine-specific" sarcopenia is unclear.

PURPOSE

To investigate the association between generalized and spine-specific sarcopenia.

STUDY DESIGN

Retrospective cross-sectional study.

PATIENT SAMPLE

Patients undergoing lumbar spinal fusion surgery for degenerative spinal pathologies.

OUTCOME MEASURES

Generalized sarcopenia was evaluated with the short physical performance battery (SPPB), grip strength, and the psoas index, while spine-specific sarcopenia was evaluated by measuring fatty infiltration (FI) of the PM.

METHODS

We used custom software written in MATLAB® to calculate the FI of the PM. The correlation between FI of the PM and assessments of generalized sarcopenia was calculated using Spearman's rank correlation coefficient (rho). The strength of the correlation was evaluated according to established cut-offs: negligible: 0-0.3, low: 0.3-0.5, moderate: 0.5-0.7, high: 0.7-0.9, and very high≥0.9. In a Receiver Operating Characteristics (ROC) analysis, the Area Under the Curve (AUC) of sarcopenia assessments to predict severe multifidus atrophy (FI≥50%) was calculated. In a secondary analysis, factors associated with severe multifidus atrophy in nonsarcopenic patients were analyzed.

RESULTS

A total of 125 (43% female) patients, with a median age of 63 (IQR 55-73) were included. The most common surgical indication was lumbar spinal stenosis (79.5%). The median FI of the multifidus was 45.5% (IQR 35.6-55.2). Grip strength demonstrated the highest correlation with FI of the multifidus and erector spinae (rho=-0.43 and -0.32, p<.001); the other correlations were significant (p<.05) but lower in strength. In the AUC analysis, the AUC was 0.61 for the SPPB, 0.71 for grip strength, and 0.72 for the psoas index. The latter two were worse in female patients, with an AUC of 0.48 and 0.49. Facet joint arthropathy (OR: 1.26, 95% CI: 1.11-1.47, p=.001) and foraminal stenosis (OR: 1.54, 95% CI: 1.10-2.23, p=.015) were independently associated with severe multifidus atrophy in our secondary analysis.

CONCLUSION

Our study demonstrates a low correlation between generalized and spine-specific sarcopenia. These findings highlight the risk of misdiagnosis when relying on screening tools for general sarcopenia and suggest that general and spine-specific sarcopenia may have distinct etiologies.

Advances in the interaction between lumbar intervertebral disc degeneration and fat infiltration of paraspinal muscles: critical summarization, classification, and perspectives

More than 619 million people in the world suffer from low back pain (LBP). As two potential inducers of LBP, intervertebral disc degeneration (IVDD) and fat infiltration of paraspinal muscles (PSMs) have attracted extensive attention in recent years. So far, only one review has been presented to summarize their relationship and relevant mechanisms. Nevertheless, it has several noticeable drawbacks, such as incomplete categorization and discussion, lack of practical proposals, etc. Consequently, this paper aims to systematically summarize and classify the interaction between IVDD and fat infiltration of PSMs, thus providing a one-stop search handbook for future studies. As a result, four mechanisms of IVDD leading to fat infiltration of PSMs and three mechanisms of fat infiltration in PSMs causing IVDD are thoroughly analyzed and summarized. The typical reseaches are tabulated and evaluated from four aspects, i.e., methods, conclusions, benefits, and drawbacks. We find that IVDD and fat infiltration of PSMs is a vicious cycle that can promote the occurrence and development of each other, ultimately leading to LBP and disability. Finally, eight perspectives are proposed for future in-depth research.

Effect of Tuina along "bladder meridian" alleviating intervertebral disc degeneration by regulating the transforming growth factor-β1/Smad signaling pathway in a rabbit model

OBJECTIVE

The aim of this study was to investigate the protective effects of Tuina (a traditional Chinese massage therapy) on intervertebral disc (IVD) degeneration and the regulatory mechanisms of the transforming growth factor-β1 (TGF-β1)/small mothers against decapentaplegic (Smad) signaling pathway.

METHODS

Thirty New Zealand white rabbits were randomized into five groups: the control group, model group, model + Tuina group (Tuina group), model + TGF-β1 group (TGF-β1 group), and model + TGF-β1 inhibitor SB431542 group (SB431542 group). The model was established by posterolateral annulus fibrosus puncturing (AFP). Recombinant TGF-β1 and inhibitor SB431542 was injected into the TGF-β1 group and SB431542 group with a microsyringe, respectively. The rabbits in the Tuina group received Tuina treatment along the bladder meridian for 4 weeks. Magnetic resonance imaging (MRI) was performed on rabbits before AFP and after 4 weeks of intervention. Lumbar IVDs (L2-L3 to L4-L5) were harvested after intervention. Histopathological changes in the IVDs were measured by hematoxylin and eosin (HE) staining. Type I collagen was analyzed by immunohistochemistry detection. The expression level of matrix metalloproteinase-3 (MMP3) was determined by enzyme-linked immunosorbent assay. Cell apoptosis was evaluated by terminal deoxynucleotidyl transferase-mediated nick end labeling and Western blotting. Real-time polymerase chain reaction and Western blotting were used to analyze the expression of TGF-β1 and Smad2/3/4 and a disintegrin and metalloproteinase with thrombospondin motifs 5.

RESULTS

Posterolateral AFP induced IVD degeneration in rabbits with histopathological damage and noticeable changes in MRI images. Tuina alleviated histo-pathological changes and reversed the expression of extracellular matrix degeneration-related molecules and apoptosis-related proteins. Furthermore, AFP induced the activation of TGF-β1 and Smad2/3/4, whereas Tuina therapy markedly reduced the protein expression of Smad2/3 and the gene expression of TGF-β1 and Smad2/3/4. Additionally, the TGF-β1/Smad signaling pathway was activated in the TGF-β1 group, while the TGF-β1/Smad signaling pathway was inhibited in the SB431542 group.

CONCLUSION

Posterolateral AFP induced disc degeneration as determined by MRI assessment and histological analysis. Tuina alleviated disc degeneration, possibly by inhibiting the fibrotic response mediated by the TGF-β1/Smad pathway, thus alleviating extracellular matrix degeneration and reducing cell apoptosis.

Association of lumbar vertebral bone marrow and paraspinal muscle fat composition with intervertebral disc degeneration: 3T quantitative MRI findings from the population-based KORA study

OBJECTIVE

To assess the association of lumbar bone marrow adipose tissue fat fraction (BMAT-FF) and paraspinal muscle proton density fat fraction (PDFF) and their interplay with intervertebral disc degeneration (IVDD).

METHODS

In this retrospective cross-sectional study based on a prospective population-based cohort, BMAT-FF and PDFF of asymptomatic individuals were calculated based on 3T-MRI dual-echo and multi-echo Dixon VIBE sequences. IVDD was assessed at motion segments L1 to L5 and dichotomized based on Pfirrmann grade ≥ 4 and/or presence of other severe degenerative changes or spinal abnormalities at least at one segment. Pearson's correlation coefficients were calculated for BMAT-FF and PDFF. Univariable and multivariable logistic regression models for IVDD were calculated.

RESULTS

Among 335 participants (mean age: 56.2 ± 9.0 years, 43.3% female), the average BMI was 27.7 ± 4.5 kg/m2 and the prevalence of IVDD was high (69.9%). BMAT-FF and PDFF were significantly correlated (r = 0.31-0.34; p < 0.001). The risk for IVDD increased with higher PDFF (OR = 1.45; CI 1.03, 2.04) and BMAT-FF (OR = 1.56; CI 1.16, 2.11). Pairwise combinations of PDFF and BMAT-FF quartiles revealed a lower risk for IVDD in individuals in the lowest BMAT-FF and PDFF quartile (OR = 0.21; CI 0.1, 0.48). Individuals in the highest BMAT-FF and PDFF quartile showed an increased risk for IVDD (OR = 5.12; CI 1.17, 22.34) CONCLUSION: Lumbar BMAT-FF and paraspinal muscle PDFF are correlated and represent both independent and additive risk factors for IVDD. Quantitative MRI measurements of paraspinal myosteatosis and vertebral bone marrow fatty infiltration may serve as imaging biomarkers to assess the individual risk for IVDD.

KEY POINTS

• Fat composition of the lumbar vertebral bone marrow is positively correlated with paraspinal skeletal muscle fat. • Higher fat-fractions of lumbar vertebral bone marrow and paraspinal muscle are both independent as well as additive risk factors for intervertebral disc degeneration. • Quantitative magnetic resonance imaging measurements of bone marrow and paraspinal muscle may serve as imaging biomarkers for intervertebral disc degeneration.

Paraspinal muscles atrophy on both sides and at multiple levels after unilateral lumbar partial discectomy

To identify the changes in cross-sectional areas (CSAs) and fatty infiltration of both sides of the paravertebral muscles and their associations with prognostic factors in patients who underwent unilateral lumbar discectomy. We retrospectively reviewed 27 patients who underwent magnetic resonance imaging before and after 1- or 2-level lumbar discectomy. The CSAs and functional cross-sectional areas of the paraspinal muscles were bilaterally measured from L1 to L2 to L5 to S1 based on T2-weighted axial images. These parameters were compared pre-and postoperatively. CSAs and functional cross-sectional areas decreased also in non-operative, non-surgical levels, not only in operated levels after discectomy. In the correlation analysis, the CSA of psoas major muscle at L1 to L2 was significantly decreased in patients with lower preoperative lordosis (r = 0.598, P = .040). The postoperative CSA of psoas major muscle at L4 to L5 was lower in those with the higher Pfirrmann grade (r = -0.590, P = .002); however, the CSA of quadratus lumborum muscle at L1 to L2 showed the opposite result (r = 0.526, P = .036). Similar results were also observed in the partial correlation adjusted for age and postoperative duration. Patients who underwent discectomy experienced overall paraspinal muscle atrophy in the lumbar region, including surgical and non-surgical sites. Such atrophic changes emphasized the need for core strengthening and lumbar rehabilitation from the early period after partial discectomy.