Lumbar paraspinal muscle morphometry and its correlations with demographic and radiological factors in adult isthmic spondylolisthesis: a retrospective review of 120 surgically managed cases

Diverse and multifunctional roles for perlecan (HSPG2) in repair of the intervertebral disc

Perlecan is a widely distributed, modular, and multifunctional heparan sulfate proteoglycan, which facilitates cellular communication with the extracellular environment to promote tissue development, tissue homeostasis, and optimization of biomechanical tissue functions. Perlecan-mediated osmotic mechanotransduction serves to regulate the metabolic activity of cells in tissues subjected to tension, compression, or shear. Perlecan interacts with a vast array of extracellular matrix (ECM) proteins through which it stabilizes tissues and regulates the proliferation or differentiation of resident cell populations. Here we examine the roles of the HS-proteoglycan perlecan in the normal and destabilized intervertebral disc. The intervertebral disc cell has evolved to survive in a hostile weight bearing, acidic, low oxygen tension, and low nutrition environment, and perlecan provides cytoprotection, shields disc cells from excessive compressive forces, and sequesters a range of growth factors in the disc cell environment where they aid in cellular survival, proliferation, and differentiation. The cells in mechanically destabilized connective tissues attempt to re-establish optimal tissue composition and tissue functional properties by changing the properties of their ECM, in the process of chondroid metaplasia. We explore the possibility that perlecan assists in these cell-mediated tissue remodeling responses by regulating disc cell anabolism. Perlecan's mechano-osmotic transductive property may be of potential therapeutic application.

Erector spinae could be the game changer in surgical decision-making in patients with lumbar spondylolisthesis: a cross-sectional analysis of an age-, sex-, subtype-, level-matched patients with similar spinopelvic parameters received surgical or conservative management

PURPOSE

In this study we aimed to identify whether paraspinal muscle morphology could play a role in surgical decision-making in patients with lumbar spondylolisthesis.

METHODS

We conducted a cross-sectional analysis of a prospectively collected database between January 2013 and May 2023. Consecutive women and men, who visited our outpatient clinics with chronic LBP, neurogenic claudication, and had lumbar spine magnetic resonance imaging (MRI) for their complaints were included into the preliminary dataset. We compared the patients who had conservative management (conservative group) or underwent surgery for lumbar spondylolisthesis (surgical group) in terms of intervertebral disc degeneration, end-plate changes, fatty infiltration in the paraspinal muscles and spinopelvic parameters.

RESULTS

Conservative and surgical groups were similar in terms of severe IVDD and Modic changes at any lumbar level. Surgical group had significantly fattier erector spinae compared to the conservative group. Regression analysis and ROC analysis revealed an OR of 1.088 and a cut-off value of 17 points for fatty infiltration in the erector spinae to predict which patient could undergo surgery for lumbar spondylolisthesis.

CONCLUSION

Each 1-point increment in fatty infiltration in the erector spinae at any lumbar level increased the likelihood of surgery by 8%. Lumbar spondylolisthesis patients with fatty infiltration score for erector spinae at or above 17 were more likely to have surgery. We recommend clinicians to focus on improving erector spinae muscles in patients with lumbar spondylolisthesis.

What are the differences in paraspinal muscle morphometry among degenerative spondylolisthesis patients, isthmic spondylolisthesis patients, and healthy individuals? A propensity score matching analysis

PURPOSE

To compare the morphometry of paraspinal muscles in patients with degenerative spondylolisthesis (DS), isthmic spondylolisthesis (IS), and healthy individuals.

METHODS

Thirty-seven pairs of DS patients were selected using propensity score matching with IS patients, while 37 healthy individuals matched for age, sex, and BMI were selected as controls. The relative cross-sectional area (rCSA), and relative functional cross-sectional area (rfCSA) of paraspinal muscles were measured, and the degree of fatty infiltration (FI) was calculated. Based on occupational differences, the patients were also divided into worker and farmer groups, and the same measurements were taken on them.

RESULTS

At the L3/L4 level, the multifidus (MF) FI was greater in the DS and IS groups than in the control group, the erector spinae (ES) rfCSA was higher in the IS group than in the DS and control groups. At the L4/L5 level, MF rfCSA was smaller in the DS and IS groups than in the control group; ES rfCSA was higher in the IS group than in the DS and control groups. At the L5/S1 level, MF rfCSA was smaller in the DS and IS groups than in the control group; ES rfCSA was higher in the IS group than in the DS group. At the L3/L4, L4/L5 level, MF rfCSA were higher in the worker group than in the farmer group (p < 0.05).

CONCLUSION

The morphological changes in paraspinal muscles in patients with DS were dominated by selective atrophy of the MF, while in patients with IS, the morphological changes in paraspinal muscle showed selective atrophy of the MF accompanied by compensatory hypertrophy of the ES. The surgeon should consider the morphological differences in paraspinal muscle between different types of lumbar spondylolisthesis when establishing the appropriate surgical program.

Role of End Plate Changes and Paraspinal Muscle Pathology in Lower Back Pain: A Narrative Review

Degenerative changes of the lumbar intervertebral disc are the most significant causes of enduring lower back pain. The possibility of the diagnosis is limited in people with this low back pain. Therefore, it is essential to identify the relevant back pain subgroups. The paraspinal muscles, that is, the muscles that attach to the spine, are necessary for the proper functioning of the spine and the body; insufficiency can result in back pain. Lower back pain disorders are strongly associated with altered function or structure of these paraspinal muscles, especially fibrosis and fatty infiltration. Modic changes are the bone marrow changes of the end plate in the vertebral body seen on MRI. These are strongly related to degeneration of the disc and are common in individuals with back pain symptoms. Articles were selected from Google Scholar using the terms 'Modic changes,' 'end plate changes,' 'paraspinal muscles,' and 'lower back pain. ' This article compiled different studies aiming to enhance the comprehension of biochemical processes resulting in the development of lumbar pain. Search using the keywords 'Modic changes,'' end plate changes lower back pain,' 'paraspinal muscles lower back pain,' and 'Modic changes lower back pain' on Google Scholar yielded 33000, 41000, 49400, and 17,800 results, and 958, 118, 890 and 560 results on Pubmed respectively.

Comparison of lumbar muscle morphology in patients with chronic nonspecific low back pain with and without clinical lumbar segmental instability

OBJECTIVES

Evaluation of spinal muscle morphology may be critical because of its impact on segmental stability and control of the lumbar spine in the subset of patients with clinical lumbar segmental instability (LSI). The purpose of this study was to compare lumbar muscle morphology in CNLBP patients with clinical LSI, CNLBP patients without clinical LSI.

METHODS

This case-control study included 30 patients with CNLBP (15 with clinical LSI and 15 without clinical LSI) and 15 subjects without LBP. Axial magnetic resonance images from the L2 to S1 lumbar levels were used to evaluate the morphology of the lumbar muscles.

RESULTS

A significant increase in the muscle-to-fat infiltration index and a significant decrease in the relative muscle cross-sectional area (rmCSA) of the multifidus muscle at the L3-L4 to L5-S1 levels were observed in both CNLBP groups compared to the control group (p<0.05). The mean erector spinae mean rmCSA was significantly greater in the clinical LSI group compared to the control group (SMD = 0.853, 95% CI = 0.105 to -1.6, P = 0.044) and also compared to the CNLBP without clinical LSI (SMD = 0.894, 95% CI = -1.645 to -0.144, P = 0.030) at the L4-L5 level.

CONCLUSIONS

The atrophic changes of the multifidus muscle, in CNLBP patients with or without clinical LSI was observed. However, hypertrophic changes of the erector spinae muscle at the L4-L5 lumbar level were observed only in the clinical LSI group. Psaos major did not show significant atrophic or hypertrophic changes.

Fat infiltration of the posterior paraspinal muscles is inversely associated with the fat infiltration of the psoas muscle: a potential compensatory mechanism in the lumbar spine

BACKGROUND

The function of the paraspinal muscles and especially the psoas muscle in maintaining an upright posture is not fully understood. While usually considered solely as a hip flexor, the psoas muscle and its complex anatomy suggest that the muscle has other functions involved in stabilizing the lumbar spine. The aim of this study is to determine how the psoas muscle and the posterior paraspinal muscles (PPM; erector spinae and multifidus) interact with each other.

METHODS

A retrospective review including patients undergoing posterior lumbar fusion surgery between 2014 and 2021 at a tertiary care center was conducted. Patients with a preoperative lumbar magnetic resonance imaging (MRI) scan performed within 12 months prior to surgery were considered eligible. Exclusion criteria included previous spinal surgery at any level, lumbar scoliosis with a Cobb Angle > 20° and patients with incompatible MRIs. MRI-based quantitative assessments of the cross-sectional area (CSA), the functional cross-sectional area (fCSA) and the fat area (FAT) at L4 was conducted. The degree of fat infiltration (FI) was further calculated. FI thresholds for FIPPM were defined according to literature and patients were divided into two groups (< or ≥ 50% FIPPM).

RESULTS

One hundred ninetypatients (57.9% female) with a median age of 64.7 years and median BMI of 28.3 kg/m2 met the inclusion criteria and were analyzed. Patients with a FIPPM ≥ 50% had a significantly lower FI in the psoas muscle in both sexes. Furthermore, a significant inverse correlation was evident between FIPPM and FIPsoas for both sexes. A significant positive correlation between FATPPM and fCSAPsoas was also found for both sexes. No significant differences were found for both sexes in both FIPPM groups.

CONCLUSION

As the FIPPM increases, the FIPsoas decreases. Increased FI is a surrogate marker for a decrease in muscular strength. Since the psoas and the PPM both segmentally stabilize the lumbar spine, these results may be indicative of a potential compensatory mechanism. Due to the weakened PPM, the psoas may compensate for a loss in strength in order to stabilize the spine segmentally.

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

Purpose

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

Methods

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

Results

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

Conclusion

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

Intrinsic variables associated with low back pain and lumbar spine injury in fast bowlers in cricket: a systematic review

BACKGROUND

Lumbar spine injuries in fast bowlers account for the greatest missed playing time in cricket. A range of extrinsic and intrinsic variables are hypothesised to be associated with low back pain and lumbar spine injury in fast bowlers, and an improved understanding of intrinsic variables is necessary as these may alter load tolerance and injury risk associated with fast bowling. This review critically evaluated studies reporting intrinsic variables associated with low back pain and lumbar spine injury in fast bowlers and identified areas for future investigation.

METHODS

OVID Medline, EMBASE, SPORTDiscus, CINAHL, Web of Science and SCOPUS databases were last searched on 3 June 2022 to identify studies investigating intrinsic variables associated with low back pain and lumbar spine injury in cricket fast bowlers. Terms relevant to cricket fast bowling, and intrinsic variables associated with lumbar spine injury and low back pain in fast bowlers were searched. 1,503 abstracts were screened, and 118 full-text articles were appraised to determine whether they met inclusion criteria. Two authors independently screened search results and assessed risk of bias using a modified version of the Quality in Prognostic Studies tool.

RESULTS

Twenty-five studies met the inclusion criteria. Overall, no included studies demonstrated a low risk of bias, two studies were identified as moderate risk, and twenty-three studies were identified as high risk. Conflicting results were reported amongst studies investigating associations of fast bowling kinematics and kinetics, trunk and lumbar anatomical features, anthropometric traits, age, and neuromuscular characteristics with low back pain and lumbar spine injury.

CONCLUSION

Inconsistencies in results may be related to differences in study design, injury definitions, participant characteristics, measurement parameters, and statistical analyses. Low back pain and lumbar spine injury occurrence in fast bowlers remain high, and this may be due to an absence of low bias studies that have informed recommendations for their prevention. Future research should employ clearly defined injury outcomes, analyse continuous datasets, utilise models that better represent lumbar kinematics and kinetics during fast bowling, and better quantify previous injury, lumbar anatomical features and lumbar maturation.

TRIAL REGISTRATION

Open Science Framework https://doi.org/10.17605/OSF.IO/ERKZ2 .

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Muscle group-specific skeletal muscle aging: a 5-yr longitudinal study in septuagenarians

There is some evidence that the age-associated change in skeletal muscle mass is muscle specific, yet the number of specific muscles that have been studied to form our understanding in this area is limited. In addition, few aging investigations have examined multiple muscles in the same individuals. This longitudinal investigation compared changes in skeletal muscle size via computed tomography of the quadriceps (rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius), hamstrings (biceps femoris short and long heads, semitendinosus, and semimembranosus), psoas, rectus abdominis, lateral abdominals (obliques and transversus abdominis), and paraspinal muscles (erector spinae and multifidi) of older individuals from the Health, Aging, and Body Composition (Health ABC) study at baseline and 5.0 ± 0.1 years later (n = 469, 73 ± 3 yr and 78 ± 3 yr, 49% women, 33% black). Skeletal muscle size decreased (P < 0.05) in quadriceps (-3.3%), hamstrings (-5.9%), psoas (-0.4%), and rectus abdominis (-7.0%). The hamstrings and rectus abdominis atrophied approximately twice as much as the quadriceps (P < 0.05), whereas the quadriceps atrophied substantially more than the psoas (P < 0.05). The lateral abdominals (+5.9%) and paraspinals (+4.3%) hypertrophied (P < 0.05) to a similar degree (P > 0.05) over the 5 years. These data suggest that older individuals experience skeletal muscle atrophy and hypertrophy in a muscle group-specific fashion in the eighth decade, a critical time period in the aging process. A broader understanding of muscle group-specific skeletal muscle aging is needed to better guide exercise programs and other interventions that mitigate decrements in physical function with aging.NEW & NOTEWORTHY These longitudinal analyses of six muscle groups in septuagenarians provide novel information on the muscle group-specific aging process. Although the quadriceps, hamstrings, psoas, and rectus abdominis atrophied with different magnitudes, the lateral abdominals and paraspinals hypertrophied over the 5 years. These findings contribute to a better understanding of the skeletal muscle aging process and highlight the need to complete studies in this area with a muscle-specific focus.

Factors associated with an increased risk of developing postoperative symptomatic lumbar spondylolisthesis after decompression surgery: an explorative two-centre international cohort study

PURPOSE

Symptomatic lumbar spinal stenosis can be treated with decompression surgery. A recent review reported that, after decompression surgery, 1.6-32.0% of patients develop postoperative symptomatic spondylolisthesis and may therefore be indicated for lumbar fusion surgery. The latter can be more challenging due to the altered anatomy and scar tissue. It remains unclear why some patients get recurrent neurological complaints due to postoperative symptomatic spondylolisthesis, though some associations have been suggested. This study explores the association between key demographic, biological and radiological factors and postoperative symptomatic spondylolisthesis after lumbar decompression.

METHODS

This retrospective cohort study included patients who had undergone lumbar spinal decompression surgery between January 2014 and December 2016 at one of two Spine Centres in the Netherlands or Switzerland and had a follow-up of two years. Patient characteristics, details of the surgical procedure and recurrent neurological complaints were retrieved from patient files. Preoperative MRI scans and conventional radiograms (CRs) of the lumbar spine were evaluated for multiple morphological characteristics. Postoperative spondylolisthesis was evaluated on postoperative MRI scans. For variables assessed on a whole patient basis, patients with and without postoperative symptomatic spondylolisthesis were compared. For variables assessed on the basis of the operated segment(s), surgical levels that did or did not develop postoperative spondylolisthesis were compared. Univariable and multivariable logistic regression analyses were used to identify associations with postoperative symptomatic spondylolisthesis.

RESULTS

Seven hundred and sixteen patients with 1094 surgical levels were included in the analyses. (In total, 300 patients had undergone multilevel surgery.) ICCs for intraobserver and interobserver reliability of CR and MRI variables ranged between 0.81 and 0.99 and 0.67 and 0.97, respectively. In total, 66 of 716 included patients suffered from postoperative symptomatic spondylolisthesis (9.2%). Multivariable regression analyses of patient-basis variables showed that being female [odds ratio (OR) 1.2, 95%CI 1.07-3.09] was associated with postoperative symptomatic spondylolisthesis. Higher BMI (OR 0.93, 95%CI 0.88-0.99) was associated with a lower probability of having postoperative symptomatic spondylolisthesis. Multivariable regression analyses of surgical level-basis variables showed that levels with preoperative spondylolisthesis (OR 17.30, 95%CI 10.27-29.07) and the level of surgery, most importantly level L4L5 compared with levels L1L3 (OR 2.80, 95%CI 0.78-10.08), were associated with postoperative symptomatic spondylolisthesis; greater facet joint angles (i.e. less sagittal-oriented facets) were associated with a lower probability of postoperative symptomatic spondylolisthesis (OR 0.97, 95%CI 0.95-0.99).

CONCLUSION

Being female was associated with a higher probability of having postoperative symptomatic spondylolisthesis, while having a higher BMI was associated with a lower probability. When looking at factors related to postoperative symptomatic spondylolisthesis at the surgical level, preoperative spondylolisthesis, more sagittal orientated facet angles and surgical level (most significantly level L4L5 compared to levels L1L3) showed significant associations. These associations could be used as a basis for devising patient selection criteria, stratifying patients or performing subgroup analyses in future studies regarding decompression surgery with or without fusion.

Radiological Changes of Paraspinal Muscles: A Comparative Study of Patients with Isthmic Spondylolisthesis, Patients with Degenerative Lumbar Spondylolisthesis, and Healthy Subjects

Objective

To investigate the differences, correlations, and clinical significance of the paraspinal muscles among patients with isthmic spondylolisthesis (IS), degenerative lumbar spondylolisthesis (DLS), and age-matched healthy subjects.

Methods

This study involved 159 age-matched patients with L4 anterior spondylolisthesis. The patients were divided into the IS group (n = 81) and DLS group (n = 78). Eighty-four age-matched healthy adults were enrolled as the control group. The cross-sectional area (CSA) of paraspinal muscles (multifidus [MF], erector spinae [ES], and psoas [PS]) and the relative CSA of the paraspinal muscles (paraspinal muscle CSA/vertebral CSA) were measured in the IS group, DLS group, and control group. The degree of fat infiltration was simultaneously observed.

Results

There was no significant difference in age or sex among the three groups. The relative CSA of the MF and PS was higher in control group than in IS and DLS groups (p < 0.05). The relative CSA of ES was higher in IS and control groups than in DLS group (p < 0.05). The relative CSA of total paraspinal muscles decreased in the order of control group > IS group > DLS group (p < 0.05). Logistic regression analysis showed that the relative CSA of MF, and the degree of fat infiltration of ES were independent protective factors for IS (odds ratio < 1, p < 0.05). The relative CSA of MF was an independent protective factor for DLS (odds ratio < 1, p < 0.05), whereas BMI and the degree of fat infiltration of MF were independent risk factor for DLS (odds ratio > 1, p < 0.05).

Conclusion

Compared with the control group, patients with IS and DLS showed varying degrees of degeneration, and the degree of degeneration in patients with DLS was more severe at the same age. Lower fat infiltration and higher paraspinal muscle CSA are protective factors for IS and DLS, whereas the higher BMI is risk factor for DLS.

Different degeneration patterns of paraspinal muscles in degenerative lumbar diseases: a MRI analysis of 154 patients

STUDY DESIGN

A retrospective study.

OBJECTIVE

To evaluate the different degeneration patterns of paraspinal muscles in degenerative lumbar diseases and their correlation with lumbar spine degeneration severity. The degeneration characteristics of different paraspinal muscles in degenerative lumbar diseases remain unclear.

METHODS

78 patients diagnosed with single-level degenerative lumbar spondylolisthesis (DLS) and 76 patients with degenerative lumbar kyphosis (DLK) were included as DLS and DLK groups. Paraspinal muscle parameters of psoas major (PS), erector spinae (ES) and multifidus muscle (MF) were measured, including fatty infiltration (FI) and relative cross-sectional area (rCSA), namely the ratio of the paraspinal muscle CSA to the CSA of the vertebrae of the same segment. Sagittal parameters including lumbar lordosis (LL) and sagittal vertical axis (SVA) were measured. The paraspinal muscle parameters and ES/MF rCSA ratio were compared between the two groups. Paraspinal muscles parameters including rCSA and FI were also compared between each segments from L1 to L5 in both DLS and DLK groups. In order to determine the influence of sagittal spinal alignment on paraspinal muscle parameters, correlation analysis was conducted between the MF, ES, PS rCSA and FI and the LL in DLS and DLK group.

RESULT

MF atrophy is more significant in DLS patients compared with DLK. Also, MF fatty infiltration in the lower lumbar spine of DLS patients was greater compared to DLK patients. DLK patients showed more significant atrophy of ES and heavier ES fatty infiltration. MF FI was significantly different between all adjacent segments in both DLS and DLK groups. In DLS group, ES FI was significantly different between L2/L3 to L3/L4 and L4/L5 to L5/S1, while in DLK group, the difference of ES FI between all adjacent segments was not significant, and ES FI was found negatively correlated with LL.

CONCLUSIONS

Paraspinal muscles show different degeneration patterns in degenerative lumbar diseases. MF degeneration is segmental in both DLS and DLK patients, while ES degenerated diffusely in DLK patients and correlated with the severity of kyphosis. MF degeneration is more significant in the DLS group, while ES degeneration is more significant in DLK patients. MF is the stabilizer of the lumbar spine segments, while the ES tends to maintain the spinal sagittal balance.

Factors associated with paravertebral muscle cross-sectional area in patients with chronic low back pain

Background

This study was performed to reveal the relationships between the cross-sectional areas (CSAs) of the paraspinal muscles and the severity of low back pain (LBP), including the level of disability.

Methods

This single-center cross-sectional study was conducted on 164 patients with chronic LBP. The effects of demographic characteristics, posture, level of physical activity, disc herniation type, and sarcopenia risk on the CSAs of paraspinal muscles were evaluated along with the relationship between the CSAs and severity of pain and disability in all patients. The CSAs of paraspinal muscles were evaluated using the software program Image J 1.53.

Results

A negative significant correlation was found between age and the paraspinal muscle’s CSA (P < 0.05), whereas a positive correlation was present between the level of physical activity and the CSA of the paraspinal muscle at the L2-3 and L3-4 levels. The CSAs of paraspinal muscles in patients with sarcopenia risk was significantly lower than those in patients without sarcopenia risk (P < 0.05). The CSAs of paraspinal muscles at the L2-3 and L3-4 levels in obese patients were significantly higher than those in overweight patients (P = 0.028, P = 0.026, respectively). There was no relationship between the CSAs of paraspinal muscles and pain intensity or disability.

Conclusions

Although this study did not find a relationship between paraspinal CSAs and pain or disability, treatment regimens for preventing paraspinal muscles from atrophy may aid pain physicians in relieving pain, restoring function, and preventing recurrence in patients with chronic LBP.

The association between spondylolisthesis and decreased muscle health throughout the lumbar spine for patients with operative lumbar spinal stenosis

PURPOSE

There are data underlining the relationship between muscle health and spine related pathology, but little data regarding changes in paralumbar muscle associated with lumbar spondylolisthesis. We aimed to define changes in paralumbar muscle health associated with spondylolisthesis.

METHODS

A retrospective review was performed on consecutive patients with lumbar spine pathology requiring an operation. A pre-operative lumbar MRI was analysed for muscle health measurements including lumbar indentation value (LIV), paralumbar cross-sectional area divided by body mass index (PL-CSA/BMI), and Goutallier classification of fatty atrophy. All measurements were taken from an axial slice of a T2-weighted image at lumbar disc spaces. Baseline health-related quality of life scores (HRQOLs), narcotic use and areas of stenosis were tracked. We performed Chi-square analyses and student's t test to determine statistically significant differences between cohorts.

RESULTS

There were 307 patients (average age 56.1 ± 16.7 years, 141 females) included within our analysis. 112 patients had spondylolisthesis. There were no differences in baseline HRQOLs between the spondylolisthesis cohort (SC) and non-spondylolisthesis cohort (non-SC). There were significantly worse PL-CSA/BMI at L2-L3 (p = 0.03), L3-L4 (p = 0.04) and L4-L5 (p = 0.02) for the SC. Goutallier classification of paralumbar muscle was worse for SC at L1-L2 (p = 0.04) and at L4-L5 (p < 0.001). Increased grade of spondylolisthesis was associated with worse PL-CSA at L1-L2 (p = 0.02), L2-L3 (p = 0.03) and L3-L4 (p = 0.05). Similarly, there were worse Goutallier classification scores associated with higher-grade spondylolisthesis at all levels (p < 0.05).

CONCLUSION

There are significant detrimental changes to paralumbar muscle health throughout the lumbar spine associated with spondylolisthesis.

Lumbar spondylolisthesis: STATE of the art on assessment and conservative treatment

INTRODUCTION

There is weak relationship between the presence of lumbar spondylolisthesis [SPL] and low back pain that is not always associated with instability, either at the involved lumbar segment or at different spinal levels. Therefore patients with lumbar symptomatic SPL can be divided into stable and unstable, based on the level of mobility during flexion and extension movements as general classifications for diagnostic and therapeutic purposes. Different opinions persist about best treatment (conservative vs. surgical) and among conservative treatments, on the type, dosage, and progression of physical therapy procedures.

PURPOSE AND IMPORTANCE TO PRACTICE

The aim of this Masterclass is to provide clinicians evidence-based indications for assessment and conservative treatment of SPL, taking into consideration some subgroups related to specific clinical presentations.

CLINICAL IMPLICATIONS

This Masterclass addresses the different phases of the assessment of a patient with SPL, including history, imaging, physical exam, and questionnaires on disability and cognitive-behavioral components. Regarding conservative treatment, self- management approaches and graded supervised training, including therapeutic relationships, information and education, are explained. Primary therapeutic procedures for pain control, recovery of the function and the mobility through therapeutic exercise, passive mobilization and antalgic techniques are suggested. Moreover, some guidance is provided on conservative treatment in specific clinical presentations (lumbar SPL with radiating pain and/or lumbar stenosis, SPL complicated by other factors, and SPL in adolescents) and the number/duration of sessions.

FUTURE RESEARCH PRIORITIES

Some steps to improve the diagnostic-therapeutic approach in SPL are to identify the best cluster of clinical tests, define different lumbar SPL subgroups, and investigate the effects of treatments based on that classification, similarly to the approach already proposed for non-specific LBP.

Association of Lumbar Paraspinal Muscle Morphometry with Degenerative Spondylolisthesis

The objective of this study was to assess the cross-sectional areas (CSA) of lumbar paraspinal muscles and their fatty degeneration in adults with degenerative lumbar spondylolisthesis (DLS) diagnosed with chronic radiculopathy, compare them with those of the same age- and sex-related groups with radiculopathy, and evaluate their correlations and the changes observed on magnetic resonance imaging (MRI). This retrospective study included 62 female patients aged 65–85 years, who were diagnosed with lumbar polyradiculopathy. The patients were divided into two groups: 30 patients with spondylolisthesis and 32 patients without spondylolisthesis. We calculated the CSA and fatty degeneration of the erector spinae (ES) and multifidus (MF) on axial T2-weighted magnetic resonance (MR) images from the inferior end plate of the L4 vertebral body levels. The functional CSA (FCSA): CSA ratio, skeletal muscle index (SMI), and MF CSA: ES CSA ratio were calculated and compared between the two groups using an independent t-test. We performed logistic regression analysis using spondylolisthesis as the dependent variable and SMI, FCSA, rFCSA, fat infiltration rate as independent variables. The result showed more fat infiltration of MF in patients with DLS (56.33 vs. 44.66%; p = 0.001). The mean FCSA (783.33 vs. 666.22 mm²; p = 0.028) of ES muscle was a statistically larger in the patients with DLS. The ES FCSA / total CSA was an independent predictor of lumbar spondylolisthesis (odd ratio =1.092, p = 0.016), while the MF FCSA / total CSA was an independent protective factor (odd ratio =0.898, p = 0.002)

Effect of race, age, and gender on lumbar muscle volume and fat infiltration in the degenerative spine

BACKGROUND

The quantity and quality of spinal muscles in patients with degenerative spinal diseases and various backgrounds such as age, gender, or race is unclear. We quantitatively evaluated the cross-sectional area (CSA) and fatty degeneration of the muscles around the spine, using magnetic resonance imaging (MRI) in patients with degenerative spinal disease, and studied the effects of age, gender, and race in multicenter retrospective study.

METHODS

The subjects were Caucasian and Asian patients with degenerative lumbar disease who underwent L4-5 single level spinal fusion surgery at centers in the United States and Japan. Using preoperative axial T2 MRI at the L4-5 disc level, the cross-sectional areas of the psoas and paraspinal muscles were measured. Fat infiltration was measured using the threshold method, and percent fat area (%FA) was calculated for each muscle. The muscle/disc area ratio (MDAR) was used to control for size differences per patient. T-test, Pearson's correlation coefficient, partial correlation, and multiple linear regression were used for statistical analysis.

RESULTS

In total, 140 patients (53 men; 87 women; mean age, 69.2 years) were analyzed. Age was similar in Caucasians (n = 64) and Asians (n = 76). MDARs were larger in Caucasians for paraspinal and psoas muscles (p < 0.005). Percent FA of psoas was similar in Caucasians and Asians, but greater in the paraspinal muscles of Asians (p < 0.05). After controlling for race and gender, age was correlated negatively with MDAR (p < 0.001) and positively with %FA (p < 0.001). In the multiple linear regression analysis, age, gender, and race were independently affected by MDAR and %FA.

CONCLUSIONS

Lumbar muscle mass and quality were affected by age, gender, and race, independently, in patients with degenerative lumbar disease.

Clinical Significance of Paraspinal Muscle Parameters as a prognostic factor for survival in Gastric Cancer Patients who underwent Curative Surgical Resection

Background: The quantitative and qualitative skeletal muscle parameters have been proposed to predict the outcome of patients with gastric cancer. However, the evidence for their association with long-term survival is still conflicting. This study aimed to investigate the effect of paraspinal muscle parameters on overall survival (OS) and disease-free survival (DFS) in patients with gastric cancer who underwent curative resection.

Methods: Patients with stages I or II gastric cancer who underwent curative resection between October 2006 and June 2016 were identified from electrical medical records. Paraspinal muscle area and attenuation were measured at the level of the third lumbar vertebra using computerized tomography images. For the analysis of OS and DFS, proportional hazards model was used, incorporating demographic, pathologic, laboratory, and radiologic variables.

Results: This study enrolled 296 patients (192 men and 104 women). In the multivariate proportional hazards model, total gastrectomy (hazard ratio [HR], 2.65; 95% Confidence interval [CI], 1.36-5.19; p = 0.0044), neutrophil-lymphocyte ratio (NLR) (HR, 1.27; 95% CI, 1.06-1.51; p = 0.0081), serum albumin level (HR, 0.16; 95% CI, 0.07-0.39; p < 0.0001), paraspinal muscle area adjusted for body surface area (PMA_BSA) (HR, 3.06; 95% CI, 1.65-5.67; p = 0.0004), and mean attenuation in paraspinal muscle (PMMA) (HR, 3.38; 95% CI, 1.75-6.53; p = 0.0003) were prognostic factors for OS. Similarly, total gastrectomy (HR, 2.11; 95% CI, 1.10-4.06; p = 0.0243), NLR (HR, 1.25; 95% CI, 1.06-1.48; p = 0.0071), serum albumin level (HR, 0.22; 95% CI, 0.10-0.51; p = 0.0035), PMA_BSA (HR, 2.42; 95% CI, 1.34-4.37; p = 0.0035), and PMMA (HR, 3.19; 95% CI, 1.71-5.93; p = 0.0003) were prognostic factors for DFS.

Conclusions: The pretreatment paraspinal muscle parameters such as PMA_BSA and PMMA along with total gastrectomy, NLR, and serum albumin level could predict OS and DFS in patients with stages I or II gastric cancer who underwent curative surgical resection. Because PMA_BSA and PMMA are newly characterized parameters in gastric cancer, the relationship with the survival of these parameters requires further validation in further studies before they are subjected to clinical applications.

The Implications of Paraspinal Muscle Atrophy in Low Back Pain, Thoracolumbar Pathology, and Clinical Outcomes After Spine Surgery: A Review of the Literature

STUDY DESIGN

Literature review.

OBJECTIVES

Paraspinal muscle integrity is believed to play a critical role in low back pain (LBP) and numerous spinal deformity diseases and other pain pathologies. The influence of paraspinal muscle atrophy (PMA) on the clinical and radiographic success of spinal surgery has not been established. We aim to survey the literature in order to evaluate the impact of paraspinal muscle atrophy on low back pain, spine pathologies, and postoperative outcomes of spinal surgery.

METHODS

A review of the literature was conducted using a total of 267 articles identified from a search of the PubMed database and additional resources. A full-text review was conducted of 180 articles, which were assessed based on criteria that included an objective assessment of PMA in addition to measuring its relationship to LBP, thoracolumbar pathology, or surgical outcomes.

RESULTS

A total of 34 studies were included in this review. The literature on PMA illustrates an association between LBP and both decreased cross-sectional area and increased fatty infiltration of paraspinal musculature. Atrophy of the erector spinae and psoas muscles have been associated with spinal stenosis, isthmic spondylolisthesis, facet arthropathy, degenerative lumbar kyphosis. A number of studies have also demonstrated an association between PMA and worse postoperative outcomes.

CONCLUSIONS

PMA is linked to several spinal pathologies and some studies demonstrate an association with worse postoperative outcomes following spinal surgery. There is a need for further research to establish a relationship between preoperative paraspinal muscle integrity and postoperative success, with the potential for guiding surgical decision making.

Reciprocal relationship between multifidus and psoas at L4-L5 level in women with low back pain

Background Low back pain (LBP) may originate from different sources such as intervertebral disc degeneration (IVDD), end-plate and paraspinal muscle changes. Our aim is to explore the relevance of paraspinal muscles' fat-infiltration in women with LBP and its association with IVDD and Modic changes.Methods Consecutive female patients presenting with chronic LBP to the outpatient clinics were included. Patients were evaluated in terms of IVDD, vertebral end-plate changes, and fatty infiltration in the paraspinal muscles at all lumbar levels on lumbar spine magnetic resonance imaging (MRI). Visual Analogue Scale (VAS) scores were recorded using our prospectively collected database.Results Patients with higher VAS scores were significantly more likely to have more fatty infiltration in the multifidus and less fatty infiltration in the psoas at L4-L5 level when compared to those with lower VAS scores (69.1 vs. 31.8%, p = 0.003). To predict LBP, fatty infiltration in the multifidus and psoas had odds ratio (OR) of 4 (p = 0.010), and 0.3 (p = 0.013), respectively; whereas disc degeneration had an OR of 0.5 (p = 0.028).Conclusion This is the first clinical cross-sectional study suggested that women with chronic low back pain could have less fat-infiltrated psoas to compensate more fat-infiltrated multifidus at L4-L5 disc level.

Effects of the Russian current in the treatment of low back pain in women: A randomized clinical trial

BACKGROUND

Low back pain (LBP) is a high impact condition that affects the working population, generating social and economic repercussions, the most relevant symptoms being pain and functional disability. Conservative treatment is often based on stabilizing spinal muscles with exercises: the Russian current (RC) is reported as an alternative, because it promotes muscle contraction, providing muscle strengthening and hypertrophy.

OBJECTIVE

To assess the effectiveness of the RC in aiding the treatment of low back pain.

METHODS

This randomized study included 23 women aged 18-30 years, divided into two groups: the control group (CG) and the Russian current group (RCG), for four weeks. Pain (visual analogue scale, VAS; pressure algometer, PA), function (Oswestry Low Back Disability Index), resistance (trunk resistance [TR] test) and thickness changes in the muscle (ultrasound image) were evaluated before and after the RC protocol and at one-month follow-up.

RESULTS

There were significant VAS reductions in both groups, but at follow-up these had only been maintained in the RCG, which presented lower values than the CG in the second evaluation. For PA, Oswestry and TR, there were differences only in the RCG. In a comparison of LBP between the groups, the initial difference disappeared in subsequent evaluations; TR presented higher values in evaluation 2 and 3 in the RCG group. In terms of thickness changes, differences between the groups were reduced after treatment.

CONCLUSION

The proposed treatment was effective in the reduction of LBP, with short-term improvement in resistance and thickness changes of the multifidus.

Age-related degeneration of the lumbar paravertebral muscles: Systematic review and three-level meta-regression

BACKGROUND

Morphological changes of the lumbar spine muscles are not well characterised with ageing. To further the understanding of age-related degeneration of the lumbar spine musculature, normative morphological changes that occur within the paravertebral muscles must first be established.

METHODS

A systematic review and meta-regressions were conducted adhering to PRISMA guidelines. Searches for published and unpublished data were completed in June 2019.

RESULTS

Searches returned 4781 articles. 34 articles were included in the quantitative analysis. Three-level meta-analyses showed age-related atrophy (r = -0.26; 95% CI: -0.33, -0.17) and fat infiltration (r = 0.39; 95% CI: 0.28, 0.50) in the lumbar paravertebral muscles. Degenerative changes were muscle-specific and men (r = -0.32; 95% CI: -0.61, 0.01) exhibited significantly greater muscle atrophy than women (r = -0.24; 95% CI: -0.47, 0.03). Imaging modality, specifically ultrasound, also influenced age-related muscle atrophy. Measurements taken across all lumbar levels revealed the greatest fat infiltration with ageing (r = 0.58, 95% CI: 0.35, 0.74). Moderators explained a large proportion of between-study variance in true effects for muscle atrophy (72.6%) and fat infiltration (79.8%) models.

CONCLUSIONS

Lumbar paravertebral muscles undergo age-related degeneration in healthy adults with muscle, lumbar level and sex-specific responses. Future studies should use high-resolution imaging modalities to quantify muscle atrophy and fat infiltration.

Association of MRI-defined lumbar paraspinal muscle mass and slip percentage in degenerative and isthmic spondylolisthesis: A multicenter, retrospective, observational study

The objective of this study is to investigate the role of paraspinal muscles in the progression of different types of spondylolisthesis by examining the correlation between cross-sectional area (CSA) of lumbar paraspinal muscle and slip percentage (SP) in degenerative spondylolisthesis and isthmic spondylolisthesis.A multicenter retrospective analysis was carried out including 219 subjects diagnosed with lumbar spondylolisthesis. Using T2-weighted axial magnetic resonance imgaging, CSAs of the psoas major (PM), multifidus (MU), and erector spinae were measured and divided by L5 vertebral body (VB) CSA. SP was measured using sagittal T2-weighted images. Correlations between muscle CSA ratio and SP were calculated in each group. Regression analysis was performed to predict the influence of each muscle CSA/VB CSA ratio on SP.No significant correlation was found in the degenerative spondylolisthesis group between any of the muscle CSA ratios and SP. Both PM/VB ratio (r = -0.24, P = .021) and MU/VB ratio (r = -0.26, P = .012) were negatively correlated with SP in the isthmic spondylolisthesis group. MU had more influence on SP than PM in the isthmic spondylolisthesis group (regression coefficient MU/VB: -8.08, PM/VB: -4.34).Both PM and MU muscle CSA ratios were negatively correlated with SP in the isthmic group. MU had more influence on SP than PM. No muscles had any correlations with SP in the degenerative group. This discrepancy between the two groups suggests that exercise programs or interventions regarding the segmental stability of isthmic spondylolisthesis and degenerative spondylolisthesis should be distinguished in clinical practice.Clinical Research Information Service of Korea Centers for Disease control and Prevention, KCT0002588. Registered on 12 December 2017, https://cris.nih.go.kr/cris/search/search_result_st01.jsp?seq=10702.

Chondroid metaplasia of paraspinal connective tissue in the degenerative spine

A 51-year-old male was routinely biopsied during a paraspinal muscle study. The biopsy sample was taken from the right erector spinae muscle at the fourth lumbar vertebra. The patient had no history of (diagnosed) major back trauma. The obtained sample was histologically analyzed (hematoxylin and eosin, safranin O), and complementary magnetic resonance imaging was performed. The biopsied sample contained chondroid tissue. Based on its location, the biopsy sample was appointed as chondroid metaplasia. Although chondroid metaplasia is not uncommon in humans, this is the first report of chondroid metaplasia within the paraspinal connective tissue. We propose a novel mechanism to explain the paraspinal chrondrogenic changes, related to spinal degeneration.

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

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Muscle Atrophy Measurement as Assessment Method for Low Back Pain Patients

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

Atrophy of gluteus maximus among women with a history of chronic low back pain

BACKGROUND

Although the relationship between low back pain (LBP) and the size of certain trunk muscles has been extensively studied, the relationship between gluteus maximus (GM) size and LBP has been only minimally examined. Determining whether such a relationship exists would help improve our understanding of the etiology of LBP, and possibly provide a rationale for the use of therapeutic exercise interventions targeting GM with LBP patients. The objective of this study was to compare gluteus maximus cross-sectional area in individuals with chronic LBP, and in a group of individuals without LBP. Our hypothesis was that individuals with LBP would have greater atrophy in their gluteus maximus muscles than our control group.

MATERIALS AND METHODS

For this case-control study, we analyzed medical history and pelvic computed tomography (CT) scans for 36 female patients with a history of chronic LBP, and 32 female patients without a history of LBP. Muscle cross-sectional area of gluteus maximus was measured from axial CT scans using OsiriX MD software, then was normalized to patient height, and used to compare the two groups. The number of back pain-related medical visits was also correlated with gluteus maximus cross-sectional area.

RESULTS

Mean normalized cross-sectional area was significantly smaller in the LBP group than in the control group, with t = 2.439 and P<0.05. The number of back pain-related visits was found to be significantly correlated with normalized cross-sectional area, with r = -0.270 and P<0.05. The atrophy seen in the present research may reflect incidental disuse atrophy seen with LBP, which is present in many muscle groups after prolonged immobilization or with a sedentary lifestyle.

CONCLUSIONS

This research demonstrated a previously only minimally explored relationship between gluteus maximus cross-sectional area and LBP in women. Further research is indicated in individuals with varying age, sex, and LBP diagnoses.

Back Muscle Morphometry: Effects on Outcomes of Spine Surgery

BACKGROUND

This review seeks to synthesize emerging literature on the effects of back muscle size on outcomes in spine surgery. Risk factors that contribute to poor surgical outcomes continue to be an area of interest in spine surgery because proper risk stratification can result in reduction in morbidity and enhanced patient care. However, the impact of muscle size on spine surgical outcomes is an understudied avenue with paucity of data evaluating the relationship among back muscles and surgical outcomes, patient's quality of life, and functional improvement postoperatively.

METHODS

This review was centered around identifying studies that assessed the impact of back muscle size on spine surgery outcomes.

RESULTS

Five retrospective studies were selected for review. All studies set out to see if differences in muscle size existed in patients with disparate post-operative outcomes as a primary objective. The studies support the association between larger back muscles and improved outcomes. The size and relative cross sectional area of paraspinal muscles and the size of the psoas muscle were associated with functional outcomes, incidence of complications and also fusion rates.

CONCLUSION

With reduction in surgical complications and improvement in postoperative functional outcomes, back muscle morphometry ought to be included in the preoperative surgical planning as a predictor of outcomes.

The Association between Imaging Parameters of the Paraspinal Muscles, Spinal Degeneration, and Low Back Pain

This narrative review investigated imaging parameters of the paraspinal muscles and their association with spinal degenerative features and low back pain (LBP) found in the literature. Three principal signs of muscle degeneration were detected on imaging: decreased muscle size, decreased radiographic density, and increased fat deposits. Men have a higher density of paraspinal muscles than women, younger individuals have a higher density than older ones, and lean individuals have a higher density than those with an increased body mass index. Fatty infiltration appears to be a late stage of muscular degeneration and can be measured noninvasively by an MRI scan. Fatty infiltration in the lumbar multifidus is common in adults and is strongly associated with LBP, especially in women, independent of body composition. Fatty infiltration develops in areas where most degenerative changes are found. MR spectroscopy studies have corroborated that the lumbar multifidus in LBP subjects has a significantly higher fat content than asymptomatic controls. There is a strong need for establishing uniform methods of evaluating normal parameters and degenerative changes of the paraspinal muscles. Additional imaging studies are needed to improve the understanding of the association and causal relationships between LBP, spinal degeneration, and changes in the paraspinal muscles.