Infiltration In Paraspinal Muscles Research Articles

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.

Identification and impact of failure of pelvic compensation in patients with adult spinal deformity

BACKGROUND CONTEXTPrevious research has identified a specific subtype known as failure of pelvic compensation (FPC) in patients with adult spinal deformity (ASD). However, the criteria for assessing FPC remain inconsistent, and its impacts on spinal sagittal alignment and health-related quality-of-life (HRQoL) scores remain unclear. PURPOSETo propose a novel criterion for identifying FPC based on variations in spinopelvic alignment during the transition from the supine to upright position and to evaluate the effects of FPC on patients' spinal sagittal alignment and HRQoL scores. STUDY DESIGN/SETTINGRetrospective cross-sectional study. PATIENT SAMPLEPatients with ASD from a monocenter database. OUTCOME MEASURESRadiographic measures, including thoracic kyphosis (TK), lumbar lordosis (LL), sacral slope (SS), pelvic tilt, pelvic incidence (PI), and sagittal vertical axis (SVA), were measured on lateral whole-spine radiographs. LL and SS were also measured on reconstructed lumbar computed tomography images in the sagittal view taken in the supine position. The relative functional cross-sectional area (rFCSA) of paraspinal muscles was evaluated via lumbar magnetic resonance imaging. HRQoL measures, encompassing visual analog scale for back pain (VAS-BP), Oswestry Disability Index (ODI), and Scoliosis Research Society-22R (SRS-22R), were collected. METHODSA total of 154 patients were enrolled. Based on the calculated minimum detectable change of SS, FPC was defined as the change in SS of less than 3.4° between supine and upright positions. Patients were divided into 3 groups: sagittal balance with pelvic compensation (SI-PC), sagittal imbalance with pelvic compensation (SI-PC), and sagittal imbalance with failure of pelvic compensation (SI-FPC). Radiographic parameters and HRQoL scores were compared among the groups. RESULTSThirty-six patients were categorized into the SB-PC group, 87 into the SI-PC group, and 31 into the SI-FPC group. Patients with low PI and small paraspinal muscles rFCSA were more prone to experiencing FPC accompanied by severe sagittal imbalance. The SI-FPC group exhibited less TK and a larger SS than the SI-PC group exhibited and had a similar SVA as that of the SI-PC group. Additionally, they displayed worse VAS-BP, ODI, SRS-function, and SRS-22 total scores than the SB-PC group displayed. CONCLUSIONSIn patients with ASD, an inherently low pelvic compensatory reserve and a high fatty infiltration in paraspinal muscles are pivotal factors contributing to FPC. Compared with SI-PC patients, SI-FPC patients demonstrate a thoracic-dominant compensatory pattern for sagittal malalignment. In addition, these patients experienced more severe pain and functional decline than the SB-PC patients experienced.

Relation of bone mineral density with fat infiltration of paraspinal muscles: The Goutallier classification

ObjectivesMuscle and bone tissue are interrelated throughout their developmental processes via paracrine and endocrine pathways. Osteosarcopenia has emerged with the growing data proving the high rate of simultaneous occurrence of sarcopenia and osteoporosis. We aimed to evaluate the relationship between osteoporosis, and muscle quality by grading the fatty infiltration in paraspinal muscles according to the Goutallier classification in magnetic resonance imaging (MRI). MethodsData of postmenopausal patients who underwent MRI for low back pain were analyzed retrospectively. Lumbar spine and femoral neck bone mineral density (BMD) were measured by using dual energy X-ray absorptiometry (DXA). Grade of paraspinal muscle fatty infiltration for each level of lumbar vertebrae including L1-L2, L2-L3, L3-L4, was evaluated separately according to Goutallier classification system. ResultsA total of 91 postmenopausal women were included in the study. The mean age of the study population was 60.5 ± 11. Lumbar vertebrae L1-L4 total T-scores and BMD g/cm2 were lower in patients with higher grades of Goutallier classification (P = 0.031 and P = 0.023, respectively). The distribution of the severity of fatty degeneration was significantly higher in the osteoporosis/osteopenia group at all 3 disc levels. No significant correlation was observed between femoral neck BMD and paraspinal muscle fat infiltration. ConclusionsThere is a strong relationship between osteoporosis of the lumbar spine and paraspinal muscle quality, which can be considered as a reflection of osteosarcopenia. The Goutailler classification can be an effective and easy method in the evaluation of muscle quality with MRI.

Evidence of MRI image features and inflammatory biomarkers association with low back pain in patients with lumbar disc herniation

BACKGROUND CONTEXTWhile MRI image features and inflammatory biomarkers are frequently used for guiding treatment decisions in patients with lumbar disc herniation (LDH) and low back pain (LBP), our understanding of the connections between these features and LBP remains incomplete. There is a growing interest in the potential significance of MRI image features and inflammatory biomarkers, both for quantification and as emerging therapeutic tools for LBP. PURPOSETo investigate the evidence supporting MRI image features and inflammatory biomarkers as predictors of LBP and to determine their relationship with pain intensity. STUDY DESIGNProspective cohort study. PATIENT SAMPLEAll consecutive patients with LDH who underwent discectomy surgery at our institution from February 2020 to June 2023 at the author's institution were included. OUTCOME MEASURESMRI image features in discogenic, osseous, facetogenic, and paraspinal muscles, as well as inflammatory biomarkers in serum (including CRP (C-reactive protein), ESR (erythrocyte sedimentation rate), PCT (procalcitonin), TNF (tumor necrosis factor), interleukin-1 beta (IL-1β), and IL-6), and paraspinal muscles (including TNF, IL-1β, IL-6, IL-10, and transforming growth factor beta 1 (TGF-β1)). METHODSA series of continuous patients diagnosed with LDH were categorized into acute LBP (<12 weeks), chronic LBP (≥12 weeks), and nonLBP groups. MRI image features and inflammatory biomarkers relation to pain intensity was assessed using the independent t-test, Chi-squared tests, Spearman rank correlation coefficient, and logistic regression test. RESULTSCompared to the nonLBP group, the chronic LBP group exhibited a higher incidence of intervertebral disc (IVD) degeneration (≥ grade 3) and high-fat infiltration in paraspinal muscles, alongside a significant reduction in the cross-sectional area (CSA) and fatty degeneration of the multifidus muscle. Furthermore, there was a greater expression of IL-6 in serum and TNF in paraspinal muscles in the chronic LBP group and a greater expression of CRP and IL-6 in serum and TNF in paraspinal muscles in the acute LBP group. CSA and fatty degeneration of multifidus muscle were moderately negatively correlated with chronic LBP scores. The expression of TNF and IL-6 in serum and the expression of TNF in the multifidus muscle were moderately correlated with preoperative LBP. IVD degeneration and high-fat infiltration were identified as risk factors for chronic LBP. CONCLUSIONThe results provide evidence that IVD degeneration, high-fat infiltration, and the reduction of CSA in paraspinal muscles were associated with the development of chronic LBP in patients with LDH, and these associations are linked to inflammatory regulation. This deepens our understanding of the etiology and pathophysiology of LBP, potentially leading to improved patient stratification and more targeted interventions.

Effects of high-intensity training on fatty infiltration in paraspinal muscles in elderly males with osteosarcopenia – the randomized controlled FrOST study

BackgroundOsteosarcopenia is a common geriatric syndrome with an increasing prevalence with age, leading to secondary diseases and complex consequences such as falls and fractures, as well as higher mortality and frailty rates. There is a great need for prevention and treatment strategies.MethodsIn this analysis, we used magnetic resonance imaging (MRI) data from the randomised controlled FrOST trial, which enrolled community-dwelling osteosarcopenic men aged > 72 years randomly allocated to 16 months of twice-weekly high-intensity resistance training (HIRT) or a non-training control group. MR Dixon imaging was used to quantify the effects of HIRT on muscle fat infiltration in the paraspinal muscles, determined as changes in muscle tissue, fat faction and intermuscular adipose tissue (IMAT) in the erector spinae and psoas major muscles. Intention-to-treat analysis with multiple imputation was used to analyse the data set.ResultsAfter 16 months of intervention, 15 men from the HIRT and 16 men from the CG were included in the MRI analysis. In summary, no positive effects on the fat infiltration of the erector spinae and psoas major muscles were observed.ConclusionsThe previously reported positive effects on lumbar spine bone mineral density (BMD) suggest that mechanotransduction induces tropic effects on bone, but that fat infiltration of the erector spinae and psoas major muscles are either irreversible or, for some unknown reason, resistant to exercise. Because of the beneficial effects on spinal BMD, HIRT is still recommended in osteosarcopenic older men, but further research is needed to confirm appropriate age-specific training exercises for the paraspinal muscles. The potential of different MRI sequences to quantify degenerative and metabolic changes in various muscle groups must be better characterized.Trial registrationsFrOST was approved by the University Ethics Committee of the Friedrich-Alexander University of Erlangen-Nürnberg (number 67_15b and 4464b) and the Federal Office for Radiation Projection (BfS, number Z 5–2,246,212 – 2017–002). Furthermore, it fully complies with the Declaration of Helsinki and is registered at ClinicalTrials.gov: NCT03453463 (05/03/2018). JAMA 310:2191–2194, 2013.

A Retrospective Study of the Effect of Spinopelvic Parameters on Fatty Infiltration in Paraspinal Muscles in Patients With Lumbar Spondylolisthesis.

The effect on fat infiltration (FI) of paraspinal muscles in degenerative lumbar spinal diseases has been demonstrated except for spinopelvic parameters. The present study is to identify the effect of spinopelvic parameters on FI of paraspinal muscle (PSM) and psoas major muscle (PMM) in patients with degenerative lumbar spondylolisthesis. A single-center, retrospective cross-sectional study of 160 patients with degenerative lumbar spondylolisthesis (DLS) and lumbar stenosis (LSS) who had lateral full-spine x-ray and lumbar spine magnetic resonance imaging was conducted. PSM and PMM FIs were defined as the ratio of fat to its muscle cross-sectional area. The FIs were compared among patients with different pelvic tilt (PT) and pelvic incidence (PI), respectively. The PSM FI correlated significantly with pelvic parameters in DLS patients, but not in LSS patients. The PSM FI in pelvic retroversion (PT > 25°) was 0.54 ± 0.13, which was significantly higher in DLS patients than in normal pelvis (0.41 ± 0.14) and pelvic anteversion (PT < 5°) (0.34 ± 0.12). The PSM FI of DLS patients with large PI ( > 60°) was 0.50 ± 0.13, which was higher than those with small ( < 45°) and normal PI (0.37 ± 0.11 and 0.36 ± 0.13). However, the PSM FI of LSS patients didn't change significantly with PT or PI. Moreover, the PMM FI was about 0.10-0.15, which was significantly lower than the PSM FI, and changed with PT and PI in a similar way of PSM FI with much less in magnitude. FI of the PSMs increased with greater pelvic retroversion or larger pelvic incidence in DLS patients, but not in LSS patients.

Facet Joint Orientation/Tropism Could Be Associated with Fatty Infiltration in the Lumbar Paraspinal Muscles

Facet joint orientation (FJO) and facet joint tropism (FJT) are associated with intervertebral disc degeneration and paraspinal muscle atrophy. However, none of the previous studies has evaluated the association of FJO/FJT with fatty infiltration in the multifidus, erector spinae, and psoas muscles at all lumbar levels. In the present study, we aimed to analyze whether FJO and FJT were associated with fatty infiltration in the paraspinal muscles at any lumbar level. Paraspinal muscles and FJO/FJT were evaluated from L1-L2 to L5-S1 intervertebral disc levels on T2-weighted axial lumbar spine magnetic resonance imaging. Facet joints were more sagittally and coronally oriented at the upper and lower lumbar levels, respectively. FJT was more obvious at lower lumbar levels. The FJT/FJO ratio was higher at upper lumbar levels. Patients with sagittally oriented facet joints at the L3-L4 and L4-L5 levels had fattier erector spinae and psoas muscles at the L4-L5 level. Patients with increased FJT at upper lumbar levels had fattier erector spinae and multifidus at lower lumbar levels. Patients with increased FJT at the L4-L5 level had less fatty infiltration in the erector spinae and psoas at the L2-L3 and L5-S1 levels, respectively. Sagittally oriented facet joints at lower lumbar levels could be associated with fattier erector spinae and psoas muscles at lower lumbar levels. The erector spinae at upper lumbar levels and psoas at lower lumbar levels might have become more active to compensate the FJT-induced instability at lower lumbar levels.

Is fatty infiltration in paraspinal muscles reversible with exercise in people with low back pain? A systematic review.

Increased fatty infiltration in paraspinal muscles has been recognized as a feature of muscle quality loss in people with Low Back Pain (LBP) and is highly associated with the severity of LBP and dysfunction. Reducing fatty infiltration has been recognized as a rehabilitation aim. An earlier systematic review published in 2014 revealed conflicting evidence for the reversibility of paraspinal muscle quality by means of exercise and no updates have been published since. A new systematic literature search is warranted. Pubmed, CINAHL and Embase were searched from inception to July 2022. Randomized, non-randomized controlled trials (RCT and non-RCT) and single-arm trials were included if they reported the effect of exercise on paraspinal fatty infiltration in people with LBP. Effect sizes and statistical power were calculated for (1) exercise versus control, and (2) pre-post exercise changes. Available data from the RCTs were pooled via meta-analysis when appropriate. Otherwise, data were synthesized qualitatively. Two RCTs, one non-RCT and three single-arm trials met the selection criteria. Data were not pooled due to substantial clinical heterogeneity. Effect sizes from the RCTs revealed no significant difference for exercise versus control. One single-arm trial with high risk of bias demonstrated a significant pre-post difference with moderate effect size, but only at one (T12-L1) of the investigated levels. Moderate quality evidence is available that paraspinal fatty infiltration is not reversible with exercise in people with LBP. More larger RCT's are needed to draw firmer conclusions.

Correlation between the fatty infiltration of paraspinal muscles and disc degeneration and the underlying mechanism

BackgroundLow back pain (LBP) is associated with lumbar disc degeneration (LDD) and fatty infiltration of paraspinal muscles. However, there are some controversies about the relationship between LDD and fatty infiltration of paraspinal muscles, and the causation of them is also not clear. Thus, we investigated whether the degree of LDD was associated with fatty infiltration of paraspinal muscles and preliminarily explored the underlying mechanism.MethodsA retrospective study was conducted on 109 patients with chronic LBP. The degree of LDD was assessed by the Pfirrmann classification. Total muscle cross-sectional area, L4 vertebral body endplate area, and fat cross-sectional area at axial T2-weighted MRI were measured. Multifidus and lumbar disc specimens were taken from eight individuals undergoing discectomy for disc herniation. Gene and protein expression levels of TNF were quantified through qPCR assays and ELISA, respectively.ResultsThe relative cross-sectional area, total muscle cross-sectional area, and muscle cross-sectional area asymmetry were not related to LDD. Pfirrmann grades correlated strongly with fatty infiltration of the multifidus and moderately with fatty infiltration of the erector spinae and the psoas muscles. Linear regression analysis suggested that Pfirrmann grades were most associated with fatty infiltration of the multifidus. Compared with II-degree degeneration discs (mild-degeneration group), fatty infiltration of the multifidus in IV-degree degeneration discs (severe-degeneration group) significantly increased, accompanied by increased mRNA expression of TNF. Meanwhile, the protein expression levels of TNF (pg/g protein) in discs (16.62 ± 4.33) and multifidus (13.10 ± 2.76) of the severe-degeneration group were higher than those in the mild-degeneration group (disc: 9.75 ± 2.18; multifidus: 7.84 ± 2.43). However, the mRNA expression of TNF in the multifidus was not significantly different between the two groups.ConclusionsThe results suggest that LDD is associated with fatty infiltration of the multifidus. The possible underlying mechanism is that LDD induces fatty infiltration by inflammation. Furthermore, compared with the erector spinae and the psoas muscles, fatty infiltration of the multifidus shows an optimal correlation with LDD, which may contribute to further understanding of LDD pathology.

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

PurposeNumerous studies have applied a variety of methods to assess paraspinal muscle degeneration. However, the methodological differences in imaging evaluation may lead to imprecise or inconsistent results. This article aimed to provide a pragmatic summary review of the current imaging modalities, measurement protocols, and imaging parameters in the evaluation of paraspinal muscle fat infiltration (FI) in MRI studies.MethodsWeb of Science, EMBASE, and PubMed were searched from January 2005 to March 2020 to identify studies that examined the FI of paraspinal muscles on MRI among patients with lumbar degenerative diseases.ResultsIntramyocellular lipids measured by magnetic resonance spectroscopy and FI measured by chemical‐shift MRI were both correlated to low back pain and several degenerative lumbar diseases, whereas results on the relationship between FI and degenerative lumbar pathologies using conventional MRI were conflicting. Multi‐segment measurement of FI at the lesion segment and adjacent segments could be a prognostic indicator for lumbar surgery. Most studies adopted the center of the intervertebral disc or endplate as the level of slice to evaluate the FI. Compared with visual semiquantitative assessment, quantitative parameters appeared to be precise for eliminating individual or modality differences. It has been demonstrated that fat CSA/total CSA (based on area) and muscle–fat index (based on signal intensity) as quantitative FI parameters are associated with multiple lumbar diseases and clinical outcomes after surgery.ConclusionHaving a good command of the methodology of paraspinal muscle FI on MRI was effective for diagnosis and prognosis in clinical practice.

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

Fatty infiltration, as a result of aging, is an essential biomarker of muscle degeneration. This research aimed to investigate the age-dependent change of fatty degeneration in the paraspinal muscles of healthy Chinese women. This study also explores the effect of body size on fatty infiltration of paraspinal muscles. Cross-sectional area of paraspinal muscles (CSAmuscle) and intermuscular adipose tissue (CSAIMAT) were measured at the L3 mid-vertebral level of 516 healthy females, who underwent abdomen quantitative computed tomography (QCT) scans. Subsequently, IMAT% [CSAIMAT / (CSAIMAT + CSAmuscle)] were calculated. The relationship between basic information and measurements was evaluated using Spearman correlations. Comparisons of QCT results among different BMI subgroups in different age groups were analyzed with the Kruskal-Wallis H test and LSD, post-hoc correction. Age-related changes were calculated after the adjustment of height and weight. The mean CSAIMAT of 20-29 years group (n=69) and 70-79 years group (n=25) were 3.00 cm2 and 11.06 cm2, respectively. While the mean CSAmuscle of 20-29 years group was 38.46 cm2 and 70-79 years group was 30.86 cm2. The mean IMAT% difference between 20-29 years group and 70-79 years group was -18.55%. Strong, positive non-linear associations were observed between ageing and CSAIMAT, along with IMAT% (r=0.656, P<0.01; r=0.714, P<0.01). However, CSAmuscle was shown to decrease with age in a weak, negative linear fashion (r=-0.265, P<0.01). Positive relationships between BMI and CSAIMAT, CSAmuscle, along with IMAT%, were found. Significant differences were observed between obesity and normal BMI subgroup for all variables in three age groups. CSAIMAT showed a larger age-related difference compared to CSAmuscle. Fatty infiltration in paraspinal muscles increased with age and BMI, while muscle loss may be associated with aging. The present study provided standardized reference data for the fatty degeneration of paraspinal muscles across the adult lifespan of Chinese females, which will play a critical role in future studies.

Automatic quantification of fat infiltration in paraspinal muscles using T2-weighted images: An OsiriX application

Fat infiltration of paraspinal muscles has been related with low back pain and quantified using T2w MR images and manual segmentation techniques. This methodology is time consuming and has low reproducibility. Moreover, the accuracy of T2w images to quantify fat has not been validated. This paper presents the development and validation of an OsiriX application to semi-automatically segment infiltrated fat on T2w images. This software was also utilized to validate the quantification of muscle fat infiltration with T2w images, considering Dixon fat images assessments as a gold standard.Two databases have been considered: 1)T2w images of 37 patients for comparison between manual and semi-automatic segmentations; 2)T2w and Dixon fat images of 10 healthy volunteers and 10 patients to validate the use of T2w images. The OsiriX application was based on automatic thresholding techniques. The fat infiltration fraction was measured in 4 muscle groups (erector spinae and multifidus) and in 5 cross-sectional areas (from L1-L2 to L5-S1) for both databases. From the 37 patients, we randomly selected 15 patients to assess reproducibility of the measurements.Manual and automatic fat quantifications using T2w images showed a correlation of 0.86, no statistical differences, bias of 0.05 % of the muscle area, and limits of agreement of [-12.52, 12.63]% of muscle area. Fat quantifications using Dixon and T2w images showed correlation of 0.94, no statistical differences, bias of 0.38 % of the muscle area, and limits of agreement of [-8.64, 9.41]% of the muscle area.T2w images segmented with this new OsiriX application are reliable and accurate for quantifying fat infiltration in paraspinal muscles.

P33. Degenerative paraspinal muscles impact thoracic spine compensation in ASD patients

BACKGROUND CONTEXT Flattening of the thoracic spine is a common biomechanical compensatory mechanism for adult spinal deformity (ASD). The literature shows that younger ASD patients recruit more thoracic flattening than older patients. It is hypothesized that differences in muscle quality between younger and older ASD patients explains this difference in the recruitment of thoracic compensation. PURPOSE Investigate the relationship between paraspinal muscle degeneration and recruitment of thoracic compensation. STUDY DESIGN/SETTING Retrospective review of a prospective database. PATIENT SAMPLE ASD patients from a prospective database. OUTCOME MEASURES Posterior paraspinal muscle fat infiltration, thoracic kyphosis between T4 and T12 (TK) and pelvic retroversion (PT). METHODS ASD patients with spino-pelvic deformity (defined as SRS-Schwab PI-LL modifier of + or ++) and available pre-op CT imaging were identified from a retrospective database. Patients with previous fusion of the thoracic spine were excluded. Erector spinae and multifidus measurements were manually contoured on CT imagesat three vertebral levels (T2, T10, and L3), at three locations per level: immediately inferior to the superior end plate, in the middle of the vertebral body, and superior to the inferior end plate. Fat infiltration (Fat) within each muscle was defined as the number of voxels with a Hounsfield unit (HU) corresponding to fat (-190 to 0) divided by the total number of voxels. The maximum fat infiltration (MaxFat) was determined by taking the muscle with the highest percentage of Fat. After a Pearson correlation analysis, the cohort was separated into 2 groups: high Fat (HFat) and Low Fat (LFat) based on MaxFat threshold of 35%. Demographics and radiographic parameters including TK and PT were compared between groups. RESULTS Of the 57 patients (mean age 61 yrs, 75% F, BMI 28) that met inclusion, 26% had a fused lumbar spine. Assessed by +/++ SRS-Schwab modifiers, 90% of patients had severe PT malalignment and 75% a severe SVA malalignment. Breakdown of Fat and area by vertebral level was: T2 (35% and 1332mm²), T10 (30% and 1910mm²), L3 (38% and 3915mm²). TK correlated significantly with Fat at all levels from T2 to L3 (r=-0.498, r=-0.519, r=-0.472), FatMax (r=-0.470) and area at T10 (r=-0.341). PT correlated significantly with FatMax (r=0.333) and T10 Fat(r=0.548). After grouping, 31 pts were HFat, and 25 pts were LFat. HFat pts were older (64.2 vs 56.3, p=0.047) and had a greater BMI (30.1 vs 25, p=0.002). The groups did not differ in sex or rates of lumbar fusion. In terms of spinal alignment, HFat pts had a higher T1 pelvic angle (30.7° vs 23.7°), a higher TK (-34.6° vs -22.9°), and a higher PT (30.1° vs 25.2°), without difference in lumbar deformity or other sagittal parameters. CONCLUSIONS Patients with higher fat infiltration in paraspinal muscles show less compensation with the thoracic spine than patients with leaner musculature, despite having similar lumbar deformities. Consequently, patients with degenerative paraspinal musculature have more pelvic retroversion, causing greater gait disruption due to limitation in hip extension. The assessment of fatty infiltration in posterior paraspinal muscles could help identify patient compensatory profile and aid in surgical planning. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Relationships between paraspinal muscle morphology and neurocompressive conditions of the lumbar spine: a systematic review with meta-analysis

BackgroundIndividual study results have demonstrated unclear relationships between neurocompressive disorders and paraspinal muscle morphology. This systematic review aimed to synthesize current evidence regarding the relationship lumbar neurocompressive disorders may have with lumbar paraspinal muscle morphology.MethodsSearches were conducted in seven databases from inception through October 2017. Observational studies with control or comparison groups comparing herniations, facet degeneration, or canal stenosis to changes in imaging or biopsy-identified lumbar paraspinal muscle morphology were included. Data extraction and risk of bias assessment were performed by review author pairs independent of one another. Morphological differences between individuals with and without neurocompressive disorders were compared qualitatively, and where possible, standardised mean differences were obtained.ResultsTwenty-eight studies were included. Lumbar multifidus fiber diameter was smaller on the side of and below herniation for type I [SMD: −0.40 (95% CI = −0.70, −0.09) and type II fibers [SMD: −0.38 (95% CI = −0.69, −0.06)] compared to the unaffected side. The distribution of type I fibers was greater on the herniation side [SMD: 0.43 (95% CI = 0.03, 0.82)]. Qualitatively, two studies assessing small angular fiber frequency and fiber type groupings demonstrated increases in these parameters below the herniation level. For diagnostic imaging meta-analyses, there were no consistent differences across the various assessment types for any paraspinal muscle groups when patients with herniation served as their own control. However, qualitative synthesis of between-group comparisons reported greater multifidus and erector spinae muscle atrophy or fat infiltration among patients with disc herniation and radiculopathy in four of six studies, and increased fatty infiltration in paraspinal muscles with higher grades of facet joint degeneration in four of five studies. Conflicting outcomes and variations in study methodology precluded a clear conclusion for canal stenosis.ConclusionsBased on mixed levels of risk of bias data, in patients with chronic radiculopathy, disc herniation and severe facet degeneration were associated with altered paraspinal muscle morphology at or below the pathology level. As the variability of study quality and heterogeneous approaches utilized to assess muscle morphology challenged comparison across studies, we provide recommendations to promote uniform measurement techniques for future studies.Trial registrationPROSPERO 2015: CRD42015012985

Correlation between paravertebral muscle fat infiltration in magnetic resonance imaging and lumbar canal stenosis

Lumbar central canal stenosis (CCS) is one of the common diseases, which increases by aging. We used quantitative image processing program to assess fat infiltration in paraspinal muscles especially multifidus as a diagnostic tool and its correlation with severity of CCS. About 59 women with focal L4-L5 CCS as case group and 64 women as control group were enrolled. The bilateral multifidus innervated by L5 was assessed by image processing program. Moreover, Oswestry disability index (ODI) questionnaire was filled out by individuals. The mean ± standard deviation (SD) of fat tissue deposition percentile in multifidus muscle of case and control group were 45.87 ± 23.42% and 36.48 ± 13.05%, respectively ( P -value < 0.05). Besides, it correlated with severity of canal stenosis. A cut-off value of 46.7% fat percentile were measured for clinical diagnosis of canal stenosis severity. The fat infiltration did not correlated with weight of the participants in both case and control groups. We showed that age had effect on the fat degeneration totally, however it did not correlate with fat deposition in case and control group separately (Pearson correlation coefficient r = 0.19 for case and r = 0.18 for control group and P -value > 0.05). It has been suggested that percentile of fat infiltration by our image processing program is a good diagnostic tool of CCS besides clinical symptoms of the patients. 46.7% cut-off value can be used in clinical setting for diagnosis critical stage of CCS.

Indices of Paraspinal Muscles Degeneration: Reliability and Association With Facet Joint Osteoarthritis: Feasibility Study.

A reliability and cross-sectional observational study. To introduce a scoring system for visible fat infiltration in paraspinal muscles; to evaluate intertester and intratester reliability of this system and its relationship with indices of muscle density; to evaluate the association between indices of paraspinal muscle degeneration and facet joint osteoarthritis. Current evidence suggests that the paraspinal muscles degeneration is associated with low back pain, facet joint osteoarthritis, spondylolisthesis, and degenerative disc disease. However, the evaluation of paraspinal muscles on computed tomography is not radiological routine, probably because of absence of simple and reliable indices of paraspinal degeneration. One hundred fifty consecutive computed tomography scans of the lower back (N=75) or abdomen (N=75) were evaluated. Mean radiographic density (in Hounsfield units) and SD of the density of multifidus and erector spinae were evaluated at the L4-L5 spinal level. A new index of muscle degeneration, radiographic density ratio=muscle density/SD of density, was calculated. To evaluate the visible fat infiltration in paraspinal muscles, we proposed a 3-graded scoring system. The prevalence of facet joint osteoarthritis was also evaluated. Intraclass correlation and κ statistics were used to evaluate inter-rater and intra-rater reliability. Logistic regression examined the association between paraspinal muscle indices and facet joint osteoarthritis. Intra-rater reliability for fat infiltration score (κ) ranged between 0.87 and 0.92; inter-rater reliability between 0.70 and 0.81. Intra-rater reliability (intraclass correlation) for mean density of paraspinal muscles ranged between 0.96 and 0.99, inter-rater reliability between 0.95 and 0.99; SD intra-rater reliability ranged between 0.82 and 0.91, inter-rater reliability between 0.80 and 0.89. Significant associations (P<0.01) were found between facet joint osteoarthritis, fat infiltration score, and radiographic density ratio. Two suggested indices of paraspinal muscle degeneration showed excellent reliability and were significantly associated with facet joint osteoarthritis. Additional studies are needed to evaluate the associations with other spinal degeneration features and low back pain.

No. 42 What Impairs Balance in Ankylosing Spondylitis? Posture or Disease Activity?

Disclosure: None. Objective: To compare the lumbar paraspinal muscles in subjects with degenerative spondylolisthesis (DS) who chose to have surgery with those who did not. Design: Retrospective study on prospectively collected data. Setting: University based spine center. Participants: Seventy subjects with DS (mean age 69.20 11.09 years, female:48 male:22). Main Outcome Measures: We measured atrophy and fatty infiltration in lumbar multifidus and erector spinae muscles on T1-weighted axial MR images. The expected cross-sectional area and functional CSA (FCSA) of the muscles were measured by using free hand technique on OsiriX . Then the percentage of muscle atrophy was calculated. Fatty infiltration was graded by using Goutallier and quartile classifications. Facet joint widening was determined as the largest distance between the apparent articular surfaces. Results: The groups were the same in age (p>0.05). The surgery group had significantly less multifidus atrophy at all disc levels and also had significantly less erector spinae atrophy at all disc levels except L5-S1 (p<0.035). The surgery group had higher fatty infiltration scores for the erector spinae at L5-S1 (p<0.002) and significantly more facet joint widening than the non-surgical group (p1⁄40.036). The facet joint widening was seen in 26.31% and 60.71% of non-surgical and nonsurgical subjects respectively. Conclusions: The subjects with DS who chose to have surgery had significant instability and more fatty infiltration in erector spinae at L5-S1. We think the surgical group had significantly less atrophy in multifidus and erector spinae muscles as a result of instability which led muscles to work more to stabilize the spondylolisthesis. More studies are needed to identify whether the patients with unstable DS with fatty infiltration in paraspinal muscles are the patients who would benefit the most from the surgical treatments.