Correlation between multifidus fatty atrophy and lumbar disc degeneration in low back pain

An evaluation of the efficacy of a four-grade fat infiltration classification method, presented for the first time in literature

BACKGROUND

The deficiency of the commonly used 3-grade fat infiltration system is discussed by comparing it with the 4-grade fat infiltration system, newly presented to the literature. The aim of this study was to evaluate the efficacy of a semi-quantitative simplified 4-grade fat infiltration measurement system, described for the first time in literature, through comparison with the existing simplified 3-grade fat infiltration system in the prediction of lumbar disc herniation.

METHODS

The study included 51 patients diagnosed with lumbar disc hernia and 50 healthy individuals as the control group. The patients were evaluated in respect of fat infiltration of the right and left lumbar multifidus and erector spina muscles on axial magnetic resonance imaging slices passing through the centre of the disc at L3-S1 level using the 3 and 4-grade fat infiltration measurement systems.

RESULTS

The 3-grade fat infiltration system was found to be insufficient in the prediction of lumbar disc herniation (p > 0.05) and the 4-grade fat infiltration system was determined to be effective in the prediction of lumbar disc herniation (p < 0.001).

CONCLUSION

The 4-grade fat infiltration system was seen to be more effective than the 3-grade fat infiltration system in the determination of the level of fat infiltration in the paraspinal muscles and the prediction of lumbar disc herniation. The 4-grade fat infiltration system is a more effective semi-quantitative grading system which can be used instead of the simplified 3-grade system.

Interleukin-4-induced FABP4 promotes lipogenesis in human skeletal muscle cells by activating the PPAR γ signaling pathway

Chronic low back pain (CLBP) is a common symptom of lumbar degenerative disease. Degeneration of the lumbar paravertebral muscles causes a loss of muscle mass and strength, which is a vital factor causing CLBP and often accompanied by lipid infiltration. Tandem mass spectrometry (TMT) was used to identify differentially expressed proteins in lipid-infiltrated and normal muscles. The results show that fatty acid binding protein 4 (FABP4) participated in the peroxisome proliferator-activated receptor-γ (PPAR γ) signaling pathway as an up-regulated protein, which is related to lipogenesis in diverse cells. In addition, chronic inflammation is believed to be involved in lumbar muscle degeneration and lipogenesis, with interleukin-4 (IL-4) considered as the predominant contributor. In present study, we investigate the effect of FABP4 on lipogenesis in human skeletal muscle cells (HSMCs) stimulated by Interleukin-4 (IL-4) and explore the mechanistic basis. We found expression level of FABP4 in lipid-infiltrated muscles was significantly higher than that in normal muscles. Lipogenesis in HSMCs could be increased by IL-4 treatment, as well as by FABP4 overexpression. FABP4 inhibition suppressed IL-4-mediated lipogenesis in HSMCs, whereas the PPAR γ inhibitor alleviated lipogenesis in both IL-4-treated and FABP4-overexpressed HSMCs. Collectively, the results indicate that FABP4 induces lipogenesis in HSMCs stimulated with IL-4 via activating the PPAR γ signaling pathway. Our study offers a detailed perspective on the pathogenesis of muscle lipid infiltration and provides a potential target for the clinical treatment strategy of muscle lipid infiltration and CLBP.

Risk Factor Analysis for Fat Infiltration in the Lumbar Paraspinal Muscles in Patients With Lumbar Degenerative Diseases

Introduction

This study aimed to investigate factors related to fat infiltration in patients with lumbar degenerative diseases (lumbar disc herniation and/or spinal stenosis), examining a wide range of potential risk variables.

Materials and methods

We studied consecutive adult patients who underwent posterior lumbar spinal surgery for degenerative diseases at our hospital between July 2013 and June 2017. Preoperative magnetic resonance imaging was used to evaluate the presence or absence of fat infiltration at the level of the L4-5 lumbar paraspinal muscles using Kjaer’s evaluation method. Patients without fat infiltration (0%–10%) were rated as grade 0, grade 1 for moderate fat infiltration (10%–50%), and grade 2 for severe fat infiltration (>50%). Patients were then divided into two groups: Group A (without fat infiltration, grade 0) and Group B (with fat infiltration, grade 1 or 2). Detailed patient clinical data were collected and analyzed.

Results

A total of 205 consecutive patients were enrolled; 54 (26.3%) patients were assigned to Group A and 151 (73.7%) to Group B. Logistic regression analysis revealed two independent risk factors for fat infiltration of the lumbar paraspinal muscles: female sex and older age (P < .001).

Discussion

Fat infiltration of the lumbar paraspinal muscles is reported to be associated with the development of pain and dysfunction of the lumbar region and postoperative complications of spinal instrumented fusion surgery. To the best of our knowledge, no previous studies have identified female sex and older age as independent risk factors for fat infiltration in the lumbar paraspinal muscles using multivariate analysis.

Conclusions

Female sex and older age were independent risk factors for fat infiltration in the lumbar paraspinal muscles. The results of the current study may provide useful information for the study of preventive measures for fat infiltration.

Associations of Lumber Disc Degeneration With Paraspinal Muscles Myosteatosis in Discogenic Low Back Pain

Accompanied with intervertebral disc (IVD) degeneration, increasing fat infiltration of paraspinal muscles may be related to discogenic low back pain (DLBP), but their relationship is still unclear and the classical animal models are not completely applicable. The purpose of this study was to assess the paraspinal muscle fat infiltration in patients with DLBP by quantitative MRI, and to develop a novel DLBP rat model to explore the potential relationship between DLBP paraspinal muscle fat infiltration and TNF-α levels. We measured the proton density fat fraction (PDFF) of the multifidus and erector spinae muscles of 70 DLBP patients and 36 healthy volunteers by using quantitative MRI IDEAL-IQ. In addition, we developed a DLBP experimental rat model by puncturing the L4/5 and L5/6 IVDs under the guidance of X-ray fluoroscopy. Then various behavioral experiments, MRI and pathological examination of IVDs were used to evaluate the performance of the DLBP animal model. The gait analysis, hot plate test, acetone test, grasping test and tail suspension test were used to evaluate the pain and muscle dysfunction in rats. Through quantitative MRI and histological examination, the degeneration of IVDs and fat infiltration in the muscles were observed in vivo and ex vivo. Enzyme linked immunosorbent assay detects the level of TNF-α in rat IVDs and paraspinal muscles. In the human study, compared with healthy volunteers, the PDFF of multifidus and erector muscles of DLBP patients increased significantly at L4/5 and L5/S1 levels (p<0.05). In the rat experiment, compared with control group and sham group, DLBP group had reduced gait score, shortened response time to cold and heat stimuli, prolonged bending time, and shortened struggling time. Rat lumbar MRI T2WI showed that the signal intensity of L4/5 and L5/6 IVDs were progressively decreased. Histological examination revealed that IVDs had increased collagen fibers, reduced nucleus pulposus, thickened annulus fibrosus, and distorted shape. The PDFF of multifidus muscle at L4/5 and L5/6 level in the DLBP group were more than that in other groups (p<0.05), and HE staining and oil red O staining of paraspinal muscles showed that the muscle bundle space of the DLBP group muscles increased, and the muscle tissues Increased lipid droplets. Finally, the expression of TNF-α in IVDs and paraspinal muscles in the DLBP group were significantly higher than that in the control group (p<0.05). It is reliable and feasible to establish a DLBP rat model by puncturing the lumbar IVDs under the guidance of X-ray fluoroscopy. The degeneration of lumbar IVDs with DLBP leads to the occurrence of fat infiltration of paraspinal muscles, which is related to the expression of TNF-α.

Advances in research on fat infiltration and lumbar intervertebral disc degeneration

Low back pain (LBP) is a disabling condition with no available cure, severely affecting patients' quality of life. Intervertebral disc degeneration (IVDD) is the leading cause of chronic low back pain (CLBP). IVDD is a common and recurrent condition in spine surgery. Disc degeneration is closely associated with intervertebral disc inflammation. The intervertebral disc is an avascular tissue in the human body. Transitioning from hematopoietic bone marrow to bone marrow fat may initiate an inflammatory response as we age, resulting in bone marrow lesions in vertebrae. In addition, the development of LBP is closely associated with spinal stability imbalance. An excellent functional state of paraspinal muscles (PSMs) plays a vital role in maintaining spinal stability. Studies have shown that the diminished function of PSMs is mainly associated with increased fat content, but whether the fat content of PSMs is related to the degree of disc degeneration is still under study. Given the vital role of PSMs lesions in CLBP, it is crucial to elucidate the interaction between PSMs changes and CLBP. Therefore, this article reviews the advances in the relationship and the underlying mechanisms between IVDD and PSMs fatty infiltration in patients with CLBP.

The effect of posterior lumbar dynamic fixation and intervertebral fusion on paraspinal muscles

BACKGROUND

The aim of this study was to analyze the effect of unilateral K-rod dynamic internal fixation on paraspinal muscles for lumbar degenerative diseases.

METHODS

This study retrospectively collected 52 patients who underwent lumbar surgery with the K-rod group or PLIF. The operation time, intraoperative blood loss, postoperative drainage volume, postoperative exercise time were compared in the two groups. The visual analog scale (VAS) score and the oswestry dysfunction index (ODI) were employed to evaluate the clinical outcomes. The functional cross-sectional area (FCSA) of the paraspinal muscles and paraspinal muscles fat infiltration were measured to assess on the paraspinal muscles.

RESULTS

As compared with the PLIF group, the operation time, the postoperative time in the field, and the average postoperative hospital stay in the K-rod internal fixation group were significantly shortened. At the last follow-up, both the groups showed significant improvement in the VAS score and ODI. The FCSA atrophy of the upper and lower adjacent segments (UAS and LAS) of the K-rod internal group was significantly less than that of the PLIF group. The extent of increase in the fatty infiltration of the paraspinal muscles in the K-rod group was significantly lesser than that in the PLIF group. The postoperative low back pain of the two groups of patients was significantly positively correlated with the FCSA atrophy.

CONCLUSIONS

As compared to PLIF, the posterior lumbar unilateral K-rod dynamic internal fixation showed significantly lesser paraspinal muscle atrophy and fatty infiltration, which were significantly positively correlated with postoperative low back pain.

Analysis of the paraspinal muscle morphology of the lumbar spine using a convolutional neural network (CNN)

PURPOSE

This single-center study aimed to develop a convolutional neural network to segment multiple consecutive axial magnetic resonance imaging (MRI) slices of the lumbar spinal muscles of patients with lower back pain and automatically classify fatty muscle degeneration.

METHODS

We developed a fully connected deep convolutional neural network (CNN) with a pre-trained U-Net model trained on a dataset of 3,650 axial T2-weighted MRI images from 100 patients with lower back pain. We included all qualities of MRI; the exclusion criteria were fractures, tumors, infection, or spine implants. The training was performed using k-fold cross-validation (k = 10), and performance was evaluated using the dice similarity coefficient (DSC) and cross-sectional area error (CSA error). For clinical correlation, we used a simplified Goutallier classification (SGC) system with three classes.

RESULTS

The mean DSC was high for overall muscle (0.91) and muscle tissue segmentation (0.83) but showed deficiencies in fatty tissue segmentation (0.51). The CSA error was small for the overall muscle area of 8.42%, and fatty tissue segmentation showed a high mean CSA error of 40.74%. The SGC classification was correctly predicted in 75% of the patients.

CONCLUSION

Our fully connected CNN segmented overall muscle and muscle tissue with high precision and recall, as well as good DSC values. The mean predicted SGC values of all available patient axial slices showed promising results. With an overall Error of 25%, further development is needed for clinical implementation. Larger datasets and training of other model architectures are required to segment fatty tissue more accurately.

Increased serum CXCL10 levels are associated with clinical severity and radiographic progression in patients with lumbar disc degeneration

BACKGROUND

Lumbar intervertebral degenerative disc disease (IDD) is a multifaceted progressive condition that commonly occurs in conjunction with lumbar disc herniation (LDH). CXCL10 mRNA appears to be increased in both IDD and LHD.

OBJECTIVE

This study was performed to identify the relationship between serum CXCL10 levels and disease severity in patients with IDD.

METHODS

136 IDD patients with low back pain, 127 asymptomatic volunteers and 120 healthy controls were enrolled. Serum CXCL10 protein concentrations were detected using commercial human CXCL10 ELISA Kits. Serum CXCL10 mRNA were examined using qRT-PCR. Clinical severity was assessed using the visual analog scale (VAS) and Oswestry Disability Index(ODI) scores. Radiographic severity was defined using the MRI-based Pfirrmann classification of disc degeneration. Receiver operating characteristic (ROC) curve analysis was used in estimating the correlation between CXCL10 and Pfirrmann grade. The cross-sectional area (CSA) of the lumbar multifidus muscle (LMM) and psoas major (PM) were calculated, and fat infiltration was evaluated by Ropponen-Kjaer criteria.

RESULTS

Serum CXCL10 concentrations were markedly raised in IDD patients with low back pain in contrast to asymptomatic individuals and healthy controls. Serum CXCL10 levels were positively associated with Pfirrmann grade. ROC curve analysis indicated that serum CXCL10 correlated well with Pfirrmann grade. In addition, serum CXCL10 concentrations were significantly higher in IDD patients with LMM and PM degeneration compared with IDD patients without degeneration. Increased CXCL10 levels positively correlated with VAS and ODI scores, as well as decreased CSA and fat filtration of the LMM and PM.

CONCLUSION

Increased serum CXCL10 levels correspond to clinical severity and radiographic progression in IDD patients.

Value of Lumbar MRI Parameters in the Evaluation of Postoperative Curative Effect on Patients with Lumbar Disc Herniation and Analysis of Risk Factors

Objective

For exploring the value of magnetic resonance imaging (MRI) parameters in the evaluation of postoperative curative effect on patients with lumbar disc herniation (LDH) and analyzing risk factors.

Methods

Totally 60 patients confirmed with LDH in our hospital between Jan. 2018 and Jan. 2020 were enrolled into the observation group (Obs group) given transforaminal endoscopic discectomy (TED). In addition, 60 individuals with low back pain but no LDH over the same time span were enrolled into the control group (Con group). The two groups were given lumbar MRI, and the cross-sectional area differences of bilateral psoas major muscle (BPMM) and multifidus muscle of the patients before and after therapy were evaluated. The visual analog scale (VAS) and Japanese Orthopaedic Association (JOA) scores of the two groups before and after therapy were compared, and the associations of the cross-sectional area differences of BPMM and multifidus muscle with efficacy, VAS score, and JOA score were analyzed. According to MacNab criteria, the clinical efficacy on the patients was evaluated, on which the patients were grouped. In addition, logistic regression analysis was performed for analyzing risk factors of clinical efficacy, and receiver operating characteristic (ROC) curves were drawn for analyzing the value of risk factors with differences in clinical efficacy evaluation.

Results

The Obs group presented larger cross-sectional area differences of BPMM and multifidus muscle than the Con group (both P < 0.05). At 6 months after surgery, the Obs group showed a superior rate of 83.33%. In this group, patients with a superior efficacy showed smaller cross-sectional area differences of BPMM and multifidus muscle before surgery and at 6 months after surgery and got lower VAS scores and higher JOA scores than those without a superior efficacy (all P < 0.05). According to Pearson's correlation analysis, the cross-sectional area differences of BPMM and multifidus muscle before surgery and at 6 months after surgery were positively associated with VAS score and negatively associated with JOA score (both P < 0.05). According to logistic regression analysis, the cross-sectional area differences of BPMM and multifidus muscle were risk factors impacting the patients' prognosis. ROC curve-based analysis revealed that the cross-sectional area differences could be adopted as evaluation indexes for clinical efficacy on patients.

Conclusion

The cross-sectional area differences of BPMM and multifidus muscle can serve as reference indexes for evaluating the postoperative efficacy on patients with LDH.

Impact Analysis of 20-Week Multimodal Progressive Functional-Proprioceptive Training among Sedentary Workers Affected by Non-Specific Low-Back Pain: An Interventional Cohort Study

According to the latest data published by the WHO, 1.71 billion people suffer from musculoskeletal disorders and 568 million are affected by back pain, making these the most significant occupational health problems. The aim of this study was to analyze the effects of a newly developed Multimodal Workplace Training Program implemented among young sedentary employees in order to treat and prevent these problems. The 20-week Training Program was conducted at the National Instruments Corporations’ Hungarian subsidiary in Debrecen between January and June, 2019. Pre- and post-intervention questionnaires were used to assess subjective parameters. Baseline and follow-up physical examinations were performed using the SpinalMouse, Y-Balance, Sit and Reach, Prone and Side Plank, Timed Abdominal Curl, and Biering-Sorensen tests. The results for 76 subjects were eligible for statistical analysis. Our Training Program was effective in several aspects, including a reduction in musculoskeletal symptoms and improvements in posture (p < 0.001), in dynamic (p < 0.01) and static-isometric (p < 0.001) core strength, in flexibility (p < 0.001), in spinal inclination in the sagittal (p < 0.001) and frontal (p < 0.01) plane, and in balance and coordination (p < 0.05). The Multimodal Progressive Functional–Proprioceptive Training was highly effective, and the application of such a complex training program can be recommended in workplace settings.

Correlation between Psoas Muscle Index and Degeneration of Spinal Back Muscle in Patients with Back Pain

Sarcopenia is characterized by a decline in systemic muscle mass and physical performance. Disc degeneration also causes back muscle atrophy. Therefore, we aimed to evaluate the influence of systemic muscle mass decline on back muscle atrophy and fatty infiltration compared to disc degeneration. We included 127 patients (65.54 ± 14.93 years) with back pain who underwent lumbar spine magnetic resonance imaging (MRI). Axial T2-weighted MRI data of the L4-5 and L5-S1 levels were used to measure the cross-sectional area (CSA) of the psoas and spinal muscles. The psoas index (cm²/m²) was used as a surrogate for systemic muscle mass. The Pfirrmann grading system was used to evaluate intervertebral disc degeneration. The functional area of the back muscles was calculated by subtracting the fat infiltration area from the CSA; the functional CSA ratio was calculated by dividing the functional CSA by the CSA. Image-processing software (ImageJ; National Institutes of Health, Bethesda, MD, USA) was used for analysis. Psoas index and aging significantly affected CSA and the ratio of functional CSA of the back muscles and multifidi. Disc degeneration did not significantly affect the back muscles beyond aging in patients with back pain. Males showed substantially higher CSA of the back muscles and multifidi than females; however, sex did not affect the functional CSA ratio of these muscles. Systemic muscle mass decline showed a more powerful influence on back muscle atrophy and fatty infiltration than disc degeneration. Therefore, proper evaluation of sarcopenia is needed for patients with chronic back pain and back muscle degeneration.

Lumbar Disc Herniation Automatic Detection in Magnetic Resonance Imaging Based on Deep Learning

Background: Lumbar disc herniation (LDH) is among the most common causes of lower back pain and sciatica. The causes of LDH have not been fully elucidated but most likely involve a complex combination of mechanical and biological processes. Magnetic resonance imaging (MRI) is a tool most frequently used for LDH because it can show abnormal soft tissue areas around the spine. Deep learning models may be trained to recognize images with high speed and accuracy to diagnose LDH. Although the deep learning model requires huge numbers of image datasets to train and establish the best model, this study processed enhanced medical image features for training the small-scale deep learning dataset. Methods: We propose automatic detection to assist the initial LDH exam for lower back pain. The subjects were between 20 and 65 years old with at least 6 months of work experience. The deep learning method employed the YOLOv3 model to train and detect small object changes such as LDH on MRI. The dataset images were processed and combined with labeling and annotation from the radiologist's diagnosis record. Results: Our method proves the possibility of using deep learning with a small-scale dataset with limited medical images. The highest mean average precision (mAP) was 92.4% at 550 images with data augmentation (550-aug), and the YOLOv3 LDH training was 100% with the best average precision at 550-aug among all datasets. This study used data augmentation to prevent under- or overfitting in an object detection model that was trained with the small-scale dataset. Conclusions: The data augmentation technique plays a crucial role in YOLOv3 training and detection results. This method displays a high possibility for rapid initial tests and auto-detection for a limited clinical dataset.

Inter-rater reliability between two examiners with different professional roles in the evaluation of fat infiltration in the lumbar paraspinal muscles using magnetic resonance imaging

[Purpose] To clarify the inter-rater reliability of the evaluation criteria for paraspinal muscle fat infiltration on magnetic resonance images between two examiners with different professional roles in interdisciplinary physical therapy teams. [Participants and Methods] In this retrospective study, we reviewed the clinical data of 225 patients with degenerative lumbar diseases who underwent posterior lumbar surgery at our hospital. A physical therapist and a spinal surgeon visually quantified fat infiltration of the multifidus muscles at the level of L4/5 on the preoperative magnetic resonance images of the patients using Kjaer's criteria (Grade 0: 0-10%, Grade 1: 10-50%, and Grade 2: >50%). We used the kappa coefficient to assess inter-rater reliability. [Results] The participants included 142 males and 83 females (mean age, 64.7 years; range, 21-89 years). The number of patients with grades 0/1/2 were 50/160/15, respectively, for examiner 1; and 59/155/11, respectively, for examiner 2. The kappa coefficient was 0.69, indicating a substantial agreement. [Conclusion] Our study, which is the first to assess the inter-rater reliability of Kjaer's criteria between examiners with different medical occupations, revealed that these criteria could be a reliable tool for evaluating fat infiltration in the multifidus muscles and sharing information between interdisciplinary physical therapy teams.

Correlation between severity of spinal stenosis and multifidus atrophy in degenerative lumbar spinal stenosis

BACKGROUND

Degenerative lumbar spinal stenosis (DLSS) is a common degenerative condition in older adults. Muscle atrophy (MA) is a leading cause of muscle weakness and disability commonly reported in individuals with spinal stenosis. The purpose of this study was to investigate if the MA correlates with the grade of spinal stenosis in patients with DLSS.

METHODS

A retrospective analysis on 48 male and 184 female DLSS patients aged around 54.04 years (54.04 ± 8.93) were involved and divided into 6 groups according to claudication-distance-based grading of spinal stenosis, which confirmed by two independent orthopedic surgeons using T2- weighted images. Using 1.5T MRI scanner, the severity of MA is assessed based on its negative correlation with the ratio of total fat-free multifidus muscle cross-sectional area (TFCSA) to total multifidus muscle cross-sectional area (TCSA). Adobe Photoshop CS6 was used for qualitative image analysis and calculate the TFCSA/TCSA ratio to assess the severity of MA, compare the grade of MA with the spinal stenosis segment, stenosis grade and symptom side.

RESULTS

In DLSS group, The TFCSA/TCSA ratio are 74.33 ± 2.18 in L3/4 stenosis, 75.51 ± 2.79 in L4/5 stenosis, and 75.49 ± 2.69 in L5/S1 stenosis. there were significant decreases in the TFCSA/TCSA ratio of stenotic segments compared with non-stenotic segments of the spinal canal (P < 0.05) while no significant difference between the non-stenotic segments (P > 0.05). TFCSA/TCSA ratios is significant differences in the TFCSA/TCSA ratios of the 6 DLSS groups (F = 67.832; P < 0.05). From Group 1 to Group 6, the TFCSA/TCSA ratio of stenotic segments positively correlated with the absolute claudication distance (ACD). (P < 0.001, r = 0.852). Besides, the TFCSA/TCSA ratios are smaller in the symptomatic sides of the spine than the contralateral sides (t = 4.128, P = 0.001).

CONCLUSIONS

The stenotic segments of the spinal canal are more atrophied than the non-stenotic segment in DLSS patients. It is shows that a strong positive correlation between the severity of multifidus atrophy and the severity of spinal stenosis.

Do Markers of Inflammation and/or Muscle Regeneration in Lumbar Multifidus Muscle and Fat Differ Between Individuals with Good or Poor Outcome Following Microdiscectomy for Lumbar Disc Herniation?

STUDY DESIGN

Observational study.

OBJECTIVE

The aim of this study was to evaluate whether inflammatory and/or muscle regeneration markers in paraspinal tissues (multifidus muscle/fat) during microdiscectomy surgery in patients with lumbar disc herniation (LDH) with radiculopathy, differ between individuals with good or poor outcome.

SUMMARY OF BACKGROUND DATA

Structural back muscle changes, including fat infiltration, muscle atrophy, and fiber changes, are ubiquitous with LBP and are thought to be regulated by inflammatory and regeneration processes. Muscle changes might be relevant for recovery after microdiscectomy, but a link between expression of inflammatory and muscle regeneration genes in paraspinal tissues and clinical outcome has not been tested.

METHOD

Paraspinal tissues from deep multifidus muscles and fat (intramuscular, sub-cutaneous, epidural) were harvested from twenty-one patients with LDH undergoing microdiscectomy surgery. Quantitative polymerase chain reaction (qPCR) measured expression of 10 genes. Outcome was defined as good (visual analogue scale (VAS) low back pain (LBP)+) or poor (VAS LBP-) by an improvement of >33% or ≤33% on the pain VAS, respectively. Good functional improvement was defined as 25% improvement on the physical functioning scale (PFS).

RESULTS

Brain-derived neurotrophic factor expression in deep multifidus was 91% lower (P = 0.014) in the VAS LBP- than VAS LBP+ group. Expression of interleukin-1β in subcutaneous fat was 48% higher (P = 0.026) in the VAS LBP- than VAS LBP+ group. No markers differed based on PFS.

CONCLUSION

Results show a relationship between impaired muscle regeneration profile in multifidus muscle and poor outcome following microdiscectomy for LDH. Inflammatory dysregulation in subcutaneous fat overlying the back region might predict poor surgical outcome.Level of Evidence: 4.

The influence of rotational movement exercise on the abdominal muscle thickness and trunk mobility - Randomized control trial

BACKGROUND

Trunk rotations are important functional movements which form the foundations of human motion pattern, especially in the functions of walking and running. They prevent the functional impairments and structural lesions resulting from axial overloading in static positions such as sitting.

OBJECTIVES

The aim of the study was to assess the influence of rotational movement training exercises on the abdominal muscle thickness and spinal mobility range.

STUDY DESIGN

Randomized controlled trial.

METHODS

The study involved 73 individuals aged 18-45. The subjects were randomly divided into two groups. The study group (TG) comprised 40 people who performed rotational movement exercises over the period of 4 weeks (16 training sessions). In the control group (CG) the training was not applied. Changes in the thickness of selected abdominal muscles on ultrasound imaging were evaluated, as well as trunk mobility, based on the trunk lateral flexion test.

RESULTS

The analysis of the obtained data has demonstrated a statistically significant increase in the thickness of the abdominal internal (IO) (p < 0.05) and external oblique muscles (EO) (p < 0.001) in the study group (TG) between measurements I and II, and measurements I and III. A similar increase in the thickness was found in the summation measurement of TrA + IO + EO. Bilateral increase in the trunk lateral flexion range in the frontal plane has also been noted.

CONCLUSIONS

Rotational movement training of the trunk leads to an increase in the thickness of the abdominal oblique muscles. Rotational movement exercise training increases trunk mobility in the frontal plane.

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

Purpose

Numerous studies have applied a variety of methods to assess paraspinal muscle degeneration. However, the methodological differences in imaging evaluation may lead to imprecise or inconsistent results. This article aimed to provide a pragmatic summary review of the current imaging modalities, measurement protocols, and imaging parameters in the evaluation of paraspinal muscle fat infiltration (FI) in MRI studies.

Methods

Web of Science, EMBASE, and PubMed were searched from January 2005 to March 2020 to identify studies that examined the FI of paraspinal muscles on MRI among patients with lumbar degenerative diseases.

Results

Intramyocellular lipids measured by magnetic resonance spectroscopy and FI measured by chemical‐shift MRI were both correlated to low back pain and several degenerative lumbar diseases, whereas results on the relationship between FI and degenerative lumbar pathologies using conventional MRI were conflicting. Multi‐segment measurement of FI at the lesion segment and adjacent segments could be a prognostic indicator for lumbar surgery. Most studies adopted the center of the intervertebral disc or endplate as the level of slice to evaluate the FI. Compared with visual semiquantitative assessment, quantitative parameters appeared to be precise for eliminating individual or modality differences. It has been demonstrated that fat CSA/total CSA (based on area) and muscle–fat index (based on signal intensity) as quantitative FI parameters are associated with multiple lumbar diseases and clinical outcomes after surgery.

Conclusion

Having a good command of the methodology of paraspinal muscle FI on MRI was effective for diagnosis and prognosis in clinical practice.

Intervertebral disc degeneration and regeneration: a motion segment perspective

Back and neck pain have become primary reasons for disability and healthcare spending globally. While the causes of back pain are multifactorial, intervertebral disc degeneration is frequently cited as a primary source of pain. The annulus fibrosus (AF) and nucleus pulposus (NP) subcomponents of the disc are common targets for regenerative therapeutics. However, disc degeneration is also associated with degenerative changes to adjacent spinal tissues, and successful regenerative therapies will likely need to consider and address the pathology of adjacent spinal structures beyond solely the disc subcomponents. This review summarises the current state of knowledge in the field regarding associations between back pain, disc degeneration, and degeneration of the cartilaginous and bony endplates, the AF-vertebral body interface, the facet joints and spinal muscles, in addition to a discussion of regenerative strategies for treating pain and degeneration from a whole motion segment perspective.

3D analysis of fatty infiltration of the paravertebral lumbar muscles using T2 images-a new approach

PURPOSE

Factors influencing paraspinal muscle degeneration are still not well understood. Fatty infiltration is known to be one main feature of the degeneration cascade. The aim of this cross-sectional study was to illustrate the 3D cluster of paraspinal lumbar muscle degeneration on T2-weighted MRI images using our newly developed software application 'iSix'.

METHODS

Mono- (Mm. rotatores), multi- (Mm. multifidus) and pluri-segmental (M. erector spinae) lumbar muscles groups were segmented on T2-weighted MR sequences using a novel computer-assisted technique for quantitative muscle/fat discrimination. The degree of fatty infiltration of the three predefined muscle groups was compared on a 3-dimensional basis, with regard to segment involvement and age. General linear models were utilized for statistical comparison.

RESULTS

N = 120 segments (age: 52.7; range 16-87 years) could be included. The overall relative fatty infiltration of the mono-segmental muscles was higher (21.1 14.5%) compared to the multi-segmental (16.0 8.8% p = 0.049) and pluri-segmental muscles (8.5 8.0%; p = 0.03). Mono-segmental muscles on the levels L4/5 (22.9 ± 10.2 [CI 17.6-28.2] %) and L5/S1 (27.01 ± 15.1 [CI 21.4-32.7] %) showed a significant higher amount of fat compared to the levels L2/3 (8.2 ± 6.8 [CI 2.2-14.2] %; L4/5 vs. L2/3, p = 0.03; L5/S1 vs. L2/3, p = 0.02) and L3/4 (13.2 ± 5.4 [CI 8.6-17.7]%; L4/5 vs. L3/4, p = 0.02; L5/S1 vs. L3/4, p < 0.01). Multivariate linear regression analyses revealed age and Pfirrmann grade as independent factors for fatty muscle degeneration.

CONCLUSIONS

3D analysis of fatty infiltration is an innovative tool to study lumbar muscle degeneration. Mono-segmental muscles are more severely affected by degeneration compared to multi-/pluri-segmental muscles, especially at the L4/5 and L5/S1 level. Age and disc degeneration independently correlate with muscle degeneration.

Research Progress on the Mechanism of Lumbarmultifidus Injury and Degeneration

This review summarizes recent research progress in the clinical features, image manifestations, and pathological mechanism of multifidus injury. After a brief introduction to the fiber classification, innervation, blood supply, and multifidus function, some factors of multifidus injury, consisting of denervation, intraoperative incision selection and traction, and lumbar degenerative disease are overviewed. In addition, the clinical index of multifidus injury including myoglobin, creatine kinase, IL-6, C-reactive protein, the cross-sectional area of multifidus, the degree of fat infiltration, and intraoperative biopsy are summarized. Furthermore, we recommend that patients with chronic low back pain should take the long-term exercise of lumbodorsal muscles. Finally, some remaining issues, including external fixation and the imaging quantitative evaluation criteria of multifidus, need to be further explored in the future.

Is there a correlation between upper lumbar disc herniation and multifidus muscle degeneration? A retrospective study of MRI morphology

Background

The purpose of the study is to investigate the correlation between upper lumbar disc herniation (ULDH) and multifidus muscle degeneration via the comparison of width, the cross-sectional area and degree of fatty infiltration of the lumbar multifidus muscle.

Methods

Using the axial T2-weighted images of magnetic resonance imaging as an assessment tool, we retrospectively investigated 132 patients with ULDH and 132 healthy individuals. The total muscle cross-sectional area (TMCSA) and the pure muscle cross-sectional area (PMCSA) of the multifidus muscle at the L1/2, L2/3, and L3/4 intervertebral disc levels were measured respectively, and in the meantime, the average multifidus muscle width (AMMW) and degree of fatty infiltration of bilateral multifidus muscle were evaluated. The resulting data were analyzed to determine the presence/absence of statistical significance between the study and control groups. Multivariate logistical regression analyses were used to evaluate the correlation between ULDH and multifidus degeneration.

Results

The results of the analysis of the two groups showed that there were statistically significant differences (p < 0.05) between TMCSA, PMCSA, AMMW and degree of fatty infiltration. The multivariate logistic regression analysis indicated that the TMCSA, PMCSA, AMMW and the degree of fatty infiltration of multifidus muscle were correlated with ULDH, and the differences were statistically significant (P < 0.05).

Conclusions

A correlation could exist between multifidus muscles degeneration and ULDH, that may be a process of mutual influence and interaction. Lumbar muscle strengthening training could prevent and improve muscle atrophy and degeneration.

Reduction of spondylolisthesis and sagittal balance correction by anterior lumbar interbody fusion (ALIF)

PURPOSE

Long time recognized as a cause of lumbar stenosis, degenerative spondylolisthesis has an evolution in interrelation with sagittal balance. This study aimed to assess the role of ALIF in correcting the sagittal balance in patients with degenerative spondylolisthesis.

MATERIAL AND METHODS

Twenty patients aged between 47 and 70 years were operated between July 2011 and September 2014 for degenerative spondylolisthesis by ALIF. The pre-operative and post-operative valid standing full spine radiographs were reviewed retrospectively. Clinical and radiological evaluations were conducted pre-operatively and postoperatively at one year and five years.

RESULTS

Lumbar lordosis (LL) was measured to 41.16 ± 14.25° pre-operatively and 47.27 ± 11.25° post-operatively (p > 0.05). At one year was 49.76 ± 13.31° and at five years 46.93 ± 9.26° (p > 0.05). Mean gain of lordosis after ALIF at index level was calculated to 8 ± 1.6° [4-12°].

CONCLUSIONS

ALIF offers a good reduction of the slipped vertebra providing good conditions for fusion and is an efficient surgical technique to recreate the sagittal spine balance.

The Yield of Lumbosacral Spine MRI in Patients with Isolated Chronic Low Back Pain: A Cross-Sectional Study

Background

The role of routine lumbosacral MRI in patients presented with isolated chronic low back pain (CLBP) is still unclear. Most patients with CLBP will show diverting degenerative changes on MRI. As it is uncertain whether surgical treatment of degenerative MRI changes results in alleviation of back pain or not, the necessity of doing a diagnostic lumbosacral MRI remains questionable. This study aimed to evaluate the yield of lumbosacral MRI among Jordanian patients presented with isolated CLBP.

Methods

We reviewed medical records of all patients who presented to neurosurgery outpatient clinic at Jordan University Hospital from December 2016 to December 2019. Only patients with a chief complaint of isolated CLBP were included. We obtained the relevant data from the computerized medical files and detailed radiological findings from their MRI reports.

Results

One hundred and sixty-seven patients (167) matched the inclusion criteria. We reported positive findings in MRI in 112 patients (67%), but 55 patients (32.93%) had normal MRI findings. Dehydration of intervertebral disc was the most common finding. Positive MRI findings were most evident in the middle-age group (41–60 years old). Disc protrusion finding in middle-aged females was significantly less prevalent than males (P = 0.012).

Conclusion

Jordanian patients presented with CLBP have similar worldwide patterns of lumbar degenerative changes. Providing that near one-third of patients with CLBP have normal MRI findings, we suggest following a streamlined protocol for imaging of patients presented with CLBP to reduce healthcare costs.

Intervertebral disc herniation effects on multifidus muscle composition and resident stem cell populations

BACKGROUND

Paraspinal muscles are crucial for vertebral stabilization and movement. These muscles are prone to develop fatty infiltration (FI), fibrosis, and atrophy in many spine conditions. Fibro-adipogenic progenitors (FAPs), a resident muscle stem cell population, are the main contributors of muscle fibrosis and FI. FAPs are involved in a complex interplay with satellite cells (SCs), the primary myogenic progenitor cells within muscle. Little is known about the stem cell composition of the multifidus. The aim of this study is to examine FAPs and SCs in the multifidus in disc herniation patients. Multifidus muscle samples were collected from 10 patients undergoing decompressive spine surgery for lumbar disc herniation. Hamstring muscle was collected from four patients undergoing hamstring autograft ACL reconstruction as an appendicular control. Multifidus tissue was analyzed for FI and fibrosis using Oil-Red-O and Masson's trichrome staining. FAPs and SCs were visualized using immunostaining and quantified with fluorescence-activated cell sorting (FACS) sorting. Gene expression of these cells from the multifidus were analyzed with reverse transcription-polymerase chain reaction and compared to those from hamstring muscle. FI and fibrosis accounted for 14.2%± 7.4% and 14.8%±4.2% of multifidus muscle, respectively. The multifidus contained more FAPs (11.7%±1.9% vs 1.4%±0.2%; P<.001) and more SCs (3.4%±1.6% vs 0.08%±0.02%; P=.002) than the hamstring. FAPs had greater α Smooth Muscle Actin (αSMA) and adipogenic gene expression than FAPs from the hamstring. SCs from the multifidus displayed upregulated expression of stem, proliferation, and differentiation genes.

CONCLUSION

The multifidus in patients with disc herniation contains large percentages of FAPs and SCs with different gene expression profiles compared to those in the hamstring. These results may help explain the tendency for the multifidus to atrophy and form FI and fibrosis as well as elucidate potential approaches for mitigating these degenerative changes by leveraging these muscle stem cell populations.

The Effect of Paraspinal Muscle Degeneration on Distal Pedicle Screw Loosening Following Corrective Surgery for Degenerative Lumbar Scoliosis

MINI: A total of 137 degenerative lumbar scoliosis patients were divided into two groups. In group A (six or more fused levels), mean rFCSA of erector spinae <0.71 was an independent risk factor of LIV screw loosening. In Group B (four or five fused levels), paraspinal muscle degeneration had no influence on LIV screw loosening.

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to evaluate the effect of degeneration of paraspinal muscles, including psoas muscles, erector spinae muscles, and multifidus muscles on pedicle screw loosening at lower instrumented vertebra (LIV) following corrective surgery for degenerative lumbar scoliosis (DLS).

SUMMARY OF BACKGROUND DATA

The relation between paraspinal muscles and pedicle screw loosening in DLS patients has not been reported.

METHODS

A total of 137 DLS patients underwent corrective surgery with at least 1-year follow-up were included. The patients were divided into two groups: Group A (68 patients) had six or more fused levels and Group B (69 patients) had four or five fused levels. Muscular parameters, including relative cross-sectional area (rCSA) and muscle-fat index (MFI), were measured on preoperative magnetic resonance imaging. rCSA and MFI were measured for both gross muscle (G) and functional muscle (F) as rGCSA, rFCSA, GMFI, and FMFI. Muscle ratio was calculated as rFCSA/rGCSA. Pedicle screw loosening was assessed on spine radiographs or CT at final follow-up. Clinical and radiological screw loosening were classified according to clinical significance.

RESULTS

LIV screw loosening occurred in 77 patients at final follow-up. In Group A, patients with LIV screw loosening had significantly higher FMFI of psoas muscles and lower rFCSA and rGCSA of erector spinae. Logistic regression revealed that mean rFCSA of erector spinae <0.71 (odds ratio = 5.0, 95% confidence interval = 1.5-16.4) was an independent risk factor of LIV screw loosening. Mean muscle ratio of erector spinae was significantly lower in patients with clinical screw loosening compared with radiological screw loosening in univariate analysis. In Group B, all muscular parameters showed no significant difference.

CONCLUSION

Degeneration of paraspinal muscles, especially psoas muscles and erector spinae, affected LIV screw loosening in six or more level fusion in corrective surgery for DLS, whereas the four- or five-level fusion had no this influence.

LEVEL OF EVIDENCE

3.