Correlation between lumbar dysfunction and fat infiltration in lumbar multifidus muscles in patients with low back pain

Background

Lumbar multifidus muscles (LMM) are important for spinal motion and stability. Low back pain (LBP) is often associated with fat infiltration in LMM. An increasing fat infiltration of LMM may lead to lumbar dysfunction. The purpose of this study was to investigate whether there is a correlation between the severity of lumbar dysfunction and the severity of fat infiltration of LMM.

Methods

In a cross-sectional study, 42 patients with acute or chronic LBP were recruited. Their MRI findings were visually rated and graded using three criteria for fat accumulation in LMM: Grade 0 (0–10%), Grade 1 (10–50%) and Grade 2 (>50%). Lumbar sagittal range of motion, dynamic upright and seated posture control, sagittal movement control, body awareness and self-assessed functional disability were measured to determine the patients’ low back dysfunction.

Results

The main result of this study was that increased severity of fat infiltration in the lumbar multifidus muscles correlated significantly with decreased range of motion of lumbar flexion (p = 0.032). No significant correlation was found between the severity of fat infiltration in LMM and impaired movement control, posture control, body awareness or self-assessed functional disability.

Conclusion

This is the first study investigating the relationship between the severity of fat infiltration in LMM and the severity of lumbar dysfunction. The results of this study will contribute to the understanding of the mechanisms leading to fat infiltration of LMM and its relation to spinal function. Further studies should investigate whether specific treatment strategies are effective in reducing or preventing fat infiltration of LMM.

Macrophage polarization contributes to local inflammation and structural change in the multifidus muscle after intervertebral disc injury

PURPOSE

Intervertebral disk (IVD) lesion and its subsequent degeneration have a profound effect on the multifidus muscle. The subacute/early chronic phase of multifidus remodeling after IVD lesion has been proposed to be regulated by inflammatory processes. The balance between pro-inflammatory (M1) and anti-inflammatory (M2) macrophages plays an important role in maintaining tissue integrity after injury. The localization, polarization of macrophage subtypes and their mediation of the pro-inflammatory cytokine tumor necrosis factor (TNF) are unknown in paraspinal muscles during IVD degeneration. A sheep model of IVD degeneration was used to investigate the role of macrophages and TNF in the structural alterations that occur within the multifidus muscle.

METHODS

Anterolateral lesions were induced at L3-4 IVD in sheep. Multifidus muscle tissue at L4 was harvested 3 and 6 months after lesion and used for immunofluorescence assays to examine total macrophage number, macrophage polarization between M1 and M2, and to assess the localization of TNF expression in muscle, adipose and connective tissues from injured and naïve control animals.

RESULTS

A greater proportion of M1 macrophages is present in muscle at both 3 and 6 months after IVD lesion, and adipose tissue at 6 months. Total number of macrophages is unchanged. At 6 months, expression of TNF is increased in adipose and connective tissue and the proportion of TNF expressed by M1 macrophages is increased.

CONCLUSIONS

These data support the proposal that macrophages and TNF (pro-inflammatory cytokine) play an active role in the subacute/early chronic phase of remodeling in muscle, adipose and connective tissues of the multifidus during IVD degeneration. This presents a novel target for treatment. These slides can be retrieved under Electronic Supplementary Material.

ISSLS Prize in Basic science 2019: Physical activity attenuates fibrotic alterations to the multifidus muscle associated with intervertebral disc degeneration

PURPOSE

Chronic low back pain causes structural remodelling and inflammation in the multifidus muscle. Collagen expression is increased in the multifidus of humans with lumbar disc degeneration. However, the extent and mechanisms underlying the increased fibrotic activity in the multifidus are unknown. Physical activity reduces local inflammation that precedes multifidus fibrosis during intervertebral disc degeneration (IDD), but its effect on amelioration of fibrosis is unknown. This study aimed to assess the development of fibrosis and its underlying genetic network during IDD and the impact of physical activity.

METHODS

Wild-type and SPARC-null mice were either sedentary or housed with a running wheel, to allow voluntary physical activity. At 12 months of age, IDD was assessed with MRI, and multifidus muscle samples were harvested from L2 to L6. In SPARC-null mice, the L1/2 and L3/4 discs had low and high levels of IDD, respectively. Thus, multifidus samples from L2 and L4 were allocated to low- and high-IDD groups compared to assess the effects of IDD and physical activity on connective tissue and fibrotic genes.

RESULTS

High IDD was associated with greater connective tissue thickness and dysregulation of collagen-III, fibronectin, CTGF, substance P, TIMP1 and TIMP2 in the multifidus muscle. Physical activity attenuated the IDD-dependent increased connective tissue thickness and reduced the expression of collagen-I, fibronectin, CTGF, substance P, MMP2 and TIMP2 in SPARC-null animals and wild-type mice. Collagen-III and TIMP1 were only reduced in wild-type animals.

CONCLUSIONS

These data reveal the fibrotic networks that promote fibrosis in the multifidus muscle during chronic IDD. Furthermore, physical activity is shown to reduce fibrosis and regulate the fibrotic gene network. These slides can be retrieved under Electronic Supplementary Material.

Effect of different exercise programs on non-specific chronic low back pain and disability in people who perform sedentary work

BACKGROUND

This study compared the short- and long-term effects of different exercise programs on lumbar muscle function, cross-sectional area of the multifidus muscle, functional disability and low back pain in people who perform sedentary work.

METHODS

A total of 70 volunteer women with sedentary occupations suffering from low back pain were randomized to either the lumbar stabilization exercise program group or the lumbar muscle strengthening exercise program group. All subjects entered the 20-week exercise programs. The measurement of the cross-sectional area of the multifidus muscle was executed by using an ultrasound system, isokinetic peak torque was measured applying an isokinetic dynamometer.

FINDINGS

The results indicated that the 20-week exercise programs reduced low back pain and functional disability. Positive effects for the cross-sectional area of the multifidus muscle, functional disability and low back pain lasted for 4 weeks after the application of lumbar muscle strengthening exercise program and for 12 weeks after the application of lumbar stabilization exercise program. The lumbar muscle strength increased and lasted for 8 weeks after both exercise programs.

INTERPRETATION

The 20-week lumbar stabilization exercise and muscle strengthening exercise programs were efficacious in decreasing LBP and functional disability in people performing sedentary work, however the lumbar stabilization exercise program was more effective, and this effect lasted for 12 weeks after completion of the program.

Exercise and tropism of the multifidus muscle in low back pain: a short review

[Purpose] The purpose of this review was to investigate the types of exercises that can improve the tropism of the multifidus muscles, based on clinical evidence. [Methods] Following to the PICO (Problem, Intervention, Comparison, Outcome) model, we considered studies of subjects with specific or non-specific LBP that used exercises aimed at activating the lumbar multifidus muscle and measured its cross-sectional area or thickness with ultrasound, computed tomography or magnetic resonance imaging. [Results] This review found that most studies compared different types of exercises for lumbar muscles, but without specifically investigating the multifidus muscle. However, a few studies showed that the cross-sectional area and thickness of the multifidus muscle can be increased by activating this muscle, and they progressed from motor control to increased static and dynamic loads. [Conclusion] A review of the literature revealed that specific supervised and home exercises may improve the symmetry of the multifidus muscle.

Fat Infiltration in the Multifidus Muscle as a Predictor of Prognosis After Decompression and Fusion in Patients with Single-Segment Degenerative Lumbar Spinal Stenosis: An Ambispective Cohort Study Based on Propensity Score Matching

OBJECTIVE

To determine whether fat infiltration in the multifidus muscle would predict surgical prognosis in patients with degenerative lumbar spinal stenosis (DLSS).

METHODS

This ambispective cohort study enrolled 118 consecutive patients undergoing surgery for L4-5 single-segment DLSS. Fat infiltration rate (FIR) on magnetic resonance images of the multifidus muscle at L5-S1 were measured using ImageJ software. The enrolled patients were divided into FIR <25% and FIR ≥25% groups according to their FIR of the multifidus muscle at L5-S1. The 2 groups of patients who finished follow-up were further matched for the baseline covariates based on propensity scores. Patients' reported outcomes including the visual analog scale score for back pain and leg pain, and the Oswestry Disability Index (ODI) score were compared between groups at follow-up and further adjusted using generalized linear models.

RESULTS

Patients in the FIR <25% group showed statistically significantly greater reduction in ODI at 6 and 18 months after surgery than did patients in the FIR ≥25% group in either cohort regardless of adjustment; however, the 2-point between-group difference was smaller than the predefined minimum clinically important difference. In addition, more patients in the FIR <25% group achieved clinically significant improvement in ODI than those in the FIR ≥25% group in either complete cohort or matching cohort (63.8% vs. 21.1%, P < 0.001; 70.3% vs. 24.1%, P < 0.001, respectively) before and after adjustment (63.3% vs. 27.8%, P < 0.001; 69.1% vs. 31.0%, P < 0.001, respectively).

CONCLUSIONS

Fat infiltration in multifidus muscle at L5-S1 could be a potential predictor of functional improvement after surgery in patients with L4-5 single-segment DLSS.

Comparison of pedicle fixation by the Wiltse approach and the conventional posterior open approach for thoracolumbar fractures, using MRI, histological and electrophysiological analyses of the multifidus muscle

PURPOSE

To use imaging, histology and electrophysiological assessment to compare the Wiltse approach to pedicle fixation with the conventional posterior open approach for thoracolumbar fractures.

METHODS

We analyzed clinical and histopathological information of consecutive patients with thoracolumbar fractures who underwent short-segment pedicle fixation using either the Wiltse approach or the posterior open approach. Seventy-five patients were enrolled between June 2010 and August 2014 (Wiltse group 35 cases; posterior open group 40 cases). The two groups were compared for MRI appearance, histological and electrophysiological changes in multifidus muscle.

RESULTS

On MRI, multifidus cross-sectional area (CSA) in the Wiltse group decreased by only 7.6% between pre-op and the last follow-up, compared to 35.4% in the posterior open group, and less fatty infiltration was found in the Wiltse group. Histologically, post-op (removal of internal fixation) tissue from the posterior open group showed disordered myofibrils, with diameter and CSA decreased by 11.6 and 24.3%, respectively; also, the myofibril gap became larger with fat deposition and scar formation. The Wiltse group had no such significant changes. Electrophysiologically, in the posterior open group, median frequency slope (MFs) significantly increased by 67.6% with average amplitude (AA) significantly decreased by 17.5% between pre-op and 12 months post-op. No significant changes were found in the Wiltse group. At 12 months post-op, AA was significantly lower and MFs was higher in the posterior open group than the Wiltse group.

CONCLUSION

The Wiltse approach showed a lower incidence of multifidus atrophy and denervation, and less fatty infiltration. It is an effective and minimally invasive approach for thoracolumbar fractures.

Three-Year Durability of Restorative Neurostimulation Effectiveness in Patients With Chronic Low Back Pain and Multifidus Muscle Dysfunction

BACKGROUND

Restorative neurostimulation is a rehabilitative treatment for patients with refractory chronic low back pain (CLBP) associated with dysfunction of the lumbar multifidus muscle resulting in impaired neuromuscular control. The ReActiv8-B randomized, sham-controlled trial provided evidence of the effectiveness and safety of an implanted, restorative neurostimulator. The two-year analysis previously published in this journal demonstrated accrual of clinical benefits and long-term durability.

OBJECTIVE

Evaluation of three-year effectiveness and safety in patients with refractory, disabling CLBP secondary to multifidus muscle dysfunction and no indications for spine surgery.

MATERIALS AND METHODS

Prospective, observational follow-up of the 204 implanted trial participants. Low back pain visual analog scale (VAS), Oswestry Disability Index (ODI), EuroQol quality of life survey, and opioid intake were assessed at baseline, six months, and one, two, and three years after activation. The mixed-effects model repeated measures approach was used to provide implicit imputations of missing data for continuous outcomes and multiple imputation for proportion estimates.

RESULTS

Data were collected from 133 participants, and 16 patients missed their three-year follow-up because of coronavirus disease restrictions but remain available for future follow-up. A total of 62% of participants had a ≥ 70% VAS reduction, and 67% reported CLBP resolution (VAS ≤ 2.5cm); 63% had a reduction in ODI of ≥ 20 points; 83% had improvements of ≥ 50% in VAS and/or ≥ 20 points in ODI, and 56% had these substantial improvements in both VAS and ODI. A total of 71% (36/51) participants on opioids at baseline had voluntarily discontinued (49%) or reduced (22%) opioid intake. The attenuation of effectiveness in the imputed (N = 204) analyses was relatively small and did not affect the statistical significance and clinical relevance of these results. The safety profile remains favorable, and no lead migrations have been observed to date.

CONCLUSION

At three years, 83% of participants experienced clinically substantial improvements in pain, disability, or both. The results confirm the long-term effectiveness, durability, and safety of restorative neurostimulation in patients with disabling CLBP associated with multifidus muscle dysfunction.

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT02577354.

Assessment of pain quality reveals distinct differences between nociceptive innervation of low back fascia and muscle in humans

Introduction/Objectives

Verbal descriptors are an important pain assessment parameter. The purpose of this study was to explore the ability to discriminate deep muscle pain and overlying fascia pain according to verbal descriptors and compare the pattern with skin stimulation (from previously published data).

Methods

In 16 healthy human subjects, electrical stimulation was chosen to excite a broad spectrum of nociceptive primary afferents innervating the respective tissues. The 24-item Pain Perception Scale (Schmerzempfindungsskala [SES]) was used to determine the induced pain quality.

Results

Overall, affective (P = 0.69) and sensory scores (P = 0.07) were not significantly different between muscle and fascia. Factor analysis of the sensory descriptors revealed a stable 3-factor solution distinguishing superficial thermal ("heat pain" identified by the items "burning," "scalding," and "hot") from superficial mechanical ("sharp pain" identified by the items "cutting," "tearing," and "stinging") and "deep pain" (identified by the items "beating," "throbbing," and "pounding"). The "deep pain" factor was more pronounced for muscle than fascia (P < 0.01), whereas the other 2 factors were more pronounced for fascia (both P < 0.01). The patterns of skin and fascia matched precisely in sensory factors and on single-item level.

Conclusion

The differences in sensory descriptor patterns between muscle and fascia may potentially guide treatment towards muscle or fascia in low back pain physiotherapeutic regimes. The similarity of descriptor patterns between fascia and skin, both including the terms "burning" and "stinging," opens the possibility that neuropathic back pain (when the dorsal ramus of the spinal nerve is affected) may be confused with low back pain of fascia origin.

Volumetric Muscle Measurements Indicate Significant Muscle Degeneration in Single-Level Disc Herniation Patients

BACKGROUND

There is a strong relationship between lower back pain and paraspinal muscle atrophy. In this study, we aimed to investigate the prevalence of lumbar paravertebral muscle atrophy in patients with and without single-level disc herniation.

METHODS

The 110 retrospectively analyzed patients in this study were divided into 2 groups. Group A included 55 patients with radiologically confirmed single-level disc herniation with back pain and radiculopathy. Group B included 55 patients with back pain without radiologic lumbar disc herniation. The paravertebral muscle cross-sectional areas were measured in both groups by 2 independent observers.

RESULTS

In total, 68 women and 42 men were examined. Their mean age was 40.85 years old. The mean ages of groups A and B were 42.49 and 39.22 years, respectively. The cross-sectional areas of the multifidus muscles (MM) and erector spinae muscles were significantly greater in group B than in group A (P < 0.0001). However, there were no statistically significant differences in the psoas major cross-sectional areas, disc heights, and perpendicular distances between the MM and the laminae.

CONCLUSIONS

The MM and erector spinae muscle groups are innervated by the dorsal root of the spinal nerve arising from the same level; therefore, long-term pressure on the root caused by disc herniation can cause atrophy and degeneration of that muscle group.

The Intervention Effects of Different Treatment for Chronic Low Back Pain as Assessed by the Cross-sectional Area of the Multifidus Muscle

[Purpose] The purpose of this this study was to examine the immediate effects of intervention of proprioceptive neuromuscular facilitation (PNF), neuromuscular joint facilitation (NJF) and NJF+pelvic floor muscle (PFM) exercise. [Subjects] Thirteen young people (5 males, 8 females) who had chronic low back pain on one side for more than 6 months. [Methods] Subjects were asked to lie on their sides with the painful side uppremost. The subjects received PNF, and NJF, NJF+PFM exercise treatments. The changes in the cross-sectional area of the multifidusmuscle were measured using ultrasonography. [Results] The cross-sectional area of the multifidus muscle of NJF+PFM group showed the largest increases on both the sides with and without pain. [Conclusion] Our results show that chronic low back pain can be improved by a combination of PFM exercise and the NJF pattern.

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.

Ultrasonography of multifidus muscle morphology and function in ice hockey players with and without low back pain

OBJECTIVES

To examine the relationship between lumbar multifidus (LM) morphology, function, echo-intensity (EI) and body composition among a group of university level ice hockey players with and without low back pain (LBP).

DESIGN

Cross-sectional study.

SETTING

University Research Centre.

PARTICIPANTS

Thirty-two hockey players (18 females, 14 males) participated in this study.

MAIN OUTCOME MEASURES

Resting LM cross-sectional area (CSA) was assessed bilaterally at the L5 level in prone and standing using ultrasound imaging. The LM thickness at rest and during contraction was evaluated in addition to LM EI. Body composition measures were acquired using dual-energy X-ray absorptiometry (DEXA) and LBP history was acquired using a self-reported questionnaire.

RESULTS

LM muscle CSA was significantly associated with body composition measurements. LM EI was strongly associated with total % body fat and significantly greater in females. Resting LM muscle CSA and thickness (prone) was significantly smaller in players with LBP 4-weeks prior. LM side-to-side asymmetry (standing) was also significantly greater in players with LBP 3-months prior.

CONCLUSION

The results provide new insights with regards to LM morphology and activation in ice hockey players and revealed specific deficits in LM morphology in athletes with LBP. LM morphology was strongly associated with body composition measurements.

Fatty infiltration of the multifidus muscle independently increases osteoporotic vertebral compression fracture risk

BACKGROUND

Vertebral compression fractures decrease daily life activities and increase economic and social burdens. Aging decreases bone mineral density (BMD), which increases the incidence of osteoporotic vertebral compression fractures (OVCFs). However, factors other than BMD can affect OVCFs. Sarcopenia has been a noticeable factor in the aging health problem. Sarcopenia, which involves a decrease in the quality of the back muscles, influences OVCFs. Therefore, this study aimed to evaluate the influence of the quality of the multifidus muscle on OVCFs.

METHODS

We retrospectively studied patients aged 60 years and older who underwent concomitant lumbar MRI and BMD in the university hospital database, with no history of structurally affecting the lumbar spine. We first divided the recruited people into a control group and a fracture group according to the presence or absence of OVCFs, and further divided the fracture group into an osteoporosis BMD group and an osteopenia BMD group based on the BMD T-score of -2.5. Using images of lumbar spine MRI, the cross-sectional area and percentage of muscle fiber (PMF) of the multifidus muscle were obtained.

RESULTS

We included 120 patients who had visited the university hospital, with 45 participants in the control group and 75 in the fracture group (osteopenia BMD: 41, osteoporosis BMD: 34). Age, BMD, and the psoas index significantly differed between the control and fracture groups. The mean cross-sectional area (CSA) of multifidus muscles measured at L4-5 and L5-S1, respectively, did not differ among the control, P-BMD, and O-BMD groups. On the other hand, the PMF measured at L4-5 and L5-S1 showed a significant difference among the three groups, and the value of the fracture group was lower than that of the control group. Logistic regression analysis showed that the PMF value, not the CSA, of the multifidus muscle at L4-5 and L5-S1 affected the risk of OVCFs, with and without adjusting for other significant factors.

CONCLUSIONS

High percentage of fatty infiltration of the multifidus muscle increases the spinal fracture risk. Therefore, preserving the quality of the spinal muscle and bone density is essential for preventing OVCFs.

The Reliability of Rehabilitative Ultrasound Imaging of the Cross-sectional Area of the Lumbar Multifidus Muscles in the PNF Pattern

[Purpose] The primary purpose of this study was to evaluate the intraclass correlation coefficient (ICC) in obtaining the cross-sectional area of the lumbar multifidus muscles in patients with chronic low back pain (LBP) at rest and during contractions facilitated by PNF patterns by ultrasound imaging. [Subjects] The subjects were 15 (4 males, 11 females) who had chronic LBP on one side for more than 6 months. [Methods] Subjects were asked to lie on their sides with the painful side facing up. They then rested or received a front or backward lower pelvic pattern of PNF treatment. The cross-sectional area of the multifidus muscle was measured twice using ultrasonography. [Results] The intraclass correlation coefficient of the cross-sectional area of the multifidus muscle measured by ultrasonography was excellent. [Conclusion] Our results show that measurement with ultrasound imaging can be used in the treatment of LBP as an objective assessment.

Computed tomography evaluation of fat infiltration ratio of the multifidus muscle in chronic low back pain patients

Background and objectives

Fat infiltration of multifidus muscle is an important parameter to assess the efficacy of spinal stabilization training in chronic low back pain (LBP) patients. As a CT scan shows a specific attenuation value for fat, it can be used as a ratio to evaluate fat infiltration of the muscle relative to its cross-sectional area. This study aims to compare the fat infiltration ratio of multifidus muscle between subjects with and without chronic LBP in Indonesia.

Methods

Comparative cross-sectional study of 20 subjects with chronic LBP and 20 subjects without LBP. Fat infiltration ratio calculation of the multifidus muscle was obtained from the database of abdominal CT at the level of the superior and inferior endplate of L4 and L5 vertebral body.

Results

The fat infiltration ratio of multifidus muscle in the chronic LBP subjects group was significantly higher than the subjects group without NPB (p < 0.05). The cut-off value of the fat infiltration ratio at the level of the inferior endplate of L4 was 0.125 (75 % sensitivity and 80 % specificity).

Conclusion

The calculation of the multifidus muscle fat infiltration ratio at the inferior endplate L4 using CT is a potential method to evaluate multifidus muscle quality in chronic LBP patients.

Pedicled Multifidus Muscle Flap To Treat Inaccessible Dural Tear In Spine Surgery: Technical Note And Preliminary Experience

OBJECTIVE

To assess the usefulness, feasibility, and limitations of pedicled multifidus muscle flaps (PMMFs) for the treatment of inaccessible dural tears during spine surgery.

METHODS

The technique of PMMF harvesting was investigated together with relevant anatomy. We prospectively evaluated 8 patients treated with the PMMF technique between January 2017 and December 2019. Results were compared with a retrospective series of 9 patients treated with a standard technique between January 2014 and December 2016. Inclusion criteria were inaccessible dural tear or dural tear judged not amenable to direct repair because of tissue loosening. Exclusion criteria were surgical treatment of intradural disease. Clinical and demographic data of all patients were collected. Clinical evaluations were performed according to American Spinal Injury Association criteria and Oswestry Disability Index. Preoperative and postoperative computed tomography was performed in all patients. The primary end point was wound healing (cerebrospinal fluid leakage, infection, and fluid collection); secondary end points were neurologic outcome and complications.

RESULTS

Control group: 1 death as a result of wound infection secondary to cerebrospinal fluid fistula and 2 patients needed lumbar subarachnoid drain; neurologic outcome: 3 patients improved and 6 were unchanged. Flap group: no wound-related complications were observed; neurologic outcome: 3 patients improved and 5 were unchanged. No flap-related complications were described. Flap harvesting was feasible in all cases, with an average 20 minutes adjunctive surgical time.

CONCLUSIONS

The PMMF technique was feasible and safe; in this preliminary experience, its use is associated with lower complications as a result of dural tears but larger series are needed to confirm its effectiveness.

Fat quantification of multifidus muscle using T2-weighted Dixon: which measurement methods are best suited for revealing the relationship between fat infiltration and herniated nucleus pulposus

OBJECTIVE

To reveal the best-suited method for fat quantification of lumbar multifidus to demonstrate its relationship to herniated nucleus pulposus (HNP) using T2-weighted Dixon.

MATERIALS AND METHODS

One hundred eight patients who underwent MRI for low back pain were enrolled. Two readers independently analyzed the fat fraction (Ff) using axial two-dimensional (D), coronal 2-D, and coronal 3-D measurement. Pearson's correlation coefficient was calculated between age, body mass index (BMI), and the Ff, and age, sex, BMI, and Ff were compared between 'HNP group' and 'no HNP group'. Multivariate logistic regression analysis was performed to identify factors associated with HNP.

RESULTS

Coronal 2-D Ff showed the highest correlation with age (r = 0.536, P < 0.001). Coronal 2-D Ff, and coronal 3-D Ff were significantly higher in those with HNP (coronal 2-D: 18.9 ± 2.9, coronal 3-D: 19.7 ± 2.6, respectively) than those without HNP (coronal 2-D: 17.2 ± 3.2, coronal 3-D: 17.4 ± 3.2, respectively). Ff of all three measurements were significantly higher in those with HNP ≥ 3 levels (axial 2-D: 20.7 ± 3.0, coronal 2-D: 21.1 ± 2.7, coronal 3-D: 21.6 ± 2.5, respectively) than those with HNP <3 levels (axial 2-D: 17.5 ± 4.3, coronal 2-D: 18.5 ± 2.7, coronal 3-D: 19.3 ± 2.5). The BMI was an independent predisposing factor to HNP (P = 0.011). Age and coronal 2-D Ff were significant predictors for multilevel HNP (P = 0.028 and 0.040, respectively).

CONCLUSIONS

The Ff of the multifidus muscle on T2-weighted Dixon was associated with age, sex, and HNP. The coronal 2-D measurement was the best suited for fat quantification in multifidus muscle among three measurement methods.

Multifidus muscle size in adolescents with and without back pain using ultrasonography

OBJECTIVE

The purposes of this study were; a) to compare multifidus muscle cross sectional area (CSA) in male adolescents suffering from low back pain (LBP) with healthy male adolescents using ultrasonography (US), and b) to assess the correlation between multifidus muscle size and demographic variables.

METHODS

A random sample of 40 healthy boys (as a control group) and 40 boys with LBP (as an experimental group) at the age range of 15-18 years was recruited in the present cohort study. Multifidus muscle dimensions including CSA, antero-posterior and medio-lateral dimensions were measured at level of L5 in both groups using US.

RESULTS

The results of an independent t-test to compare multifidus muscle size between the experimental and control groups showed a significant difference between the two groups in terms of CSA, antro-posterior and medio-lateral dimensions so that the experimental group had smaller muscle size than the control group. A significant correlation was found between height, weight and body mass index (BMI) and multifidus muscle size, but no significant correlation was observed between age and muscle size. Pain intensity and functional disability index was significantly correlated with muscle size in the experimental group.

CONCLUSIONS

According to the results, multifidus muscle size was decreased in 15-18 years old male adolescents suffering from LBP compared with their healthy counterparts. Further studies are needed to support the findings of the present study.

Clinical Research and Technique Note of TLIF by Wiltse Approach for the Treatment of Degenerative Lumbar

Objective

To assess the clinical efficacy and share the technique notes of Wiltse Approach TLIF for the treating single segment degenerative lumbar spinal disease.

Method

In this retrospective controlled study, 780 patients with single segment degenerative lumbar disease who were operated in our hospital from January 2016 to December 2020 were analyzed retrospectively. The patients were randomly assigned to Wiltse approach group (group A, 410 cases) and conventional open approach group (group B, 370 cases). Patient's assessment of pain and disability were evaluated by the visual analogue scale (VAS) and the Oswestry disability index (ODI) before and after surgery. The incision length, operative time, exposure time, intraoperative blood loss, hidden blood loss, time to ambulation, total length of hospitalization, serum creatine kinase, X‐rays, CT and MRI were also evaluated.

Results

There were no differences in sex, age, pre‐operative ODI score, VAS score between the two groups (P > 0.05). The Wiltse approach group had a shorter incision length with 7.69 ± 0.44 cm compared to the conventional group with 11.13 ± 0.36 cm (P < 0.01). The average operative time was 119.20 ± 14.64 min with exposure time of 16.20 ± 3.42 min in the Wiltse approach group and 145.65 ± 16.98 min with 29.20 ± 3.42 min in the conventional group (P < 0.05, P < 0.01). Comparing the intraoperative blood loss, hidden blood loss, serum creatine kinase, time to ambulation, total length of hospitalization, the Wiltse approach group was less than the conventional open approach group (P < 0.05). The VAS score of the two groups decreased significantly with time, and the VAS score of the Wiltse group was significantly lower than that of the conventional open approach group (P < 0.05). At last investigation after operation, ODI scores of the two groups were significantly decreased compared with that before operation. Wiltse approach group was significantly lower than that of the conventional open approach group (P < 0.05). The multifidus of the two groups of patients had a certain degree of atrophy. But the Wiltse approach group multifidus muscle atrophy rate is significantly lower than the conventional open approach group.

Conclusion

The Wiltse approach TLIF significantly reduces the damage to the paravertebral muscles and the postoperative incidence of chronic low back pain.

Effects of Push-ups Plus Sling Exercise on Muscle Activation and Cross-sectional Area of the Multifidus Muscle in Patients with Low Back Pain

[Purpose] The purpose of this study was to examine the effect of lumbar stability exercises on chronic low back pain by using sling exercise and push-ups. [Subjects] Thirty adult subjects with chronic back pain participated, with 10 adults being assigned to each of 3 exercise groups: general physical therapy (PT), lumbar stability using sling exercises (Sling Ex), and sling exercise plus push-ups (Sling Ex+PU). Each group trained for 30 minutes 3 times a week for 6 weeks. The Oswestry Disability Index (ODI), surface electromyographic (sEMG) activity of the lumbar muscles, and cross-sectional area of the multifidus muscle on computed tomography (CT) were evaluated before and at 2, 4, and 6 weeks of therapy. [Results] A significant decrease in ODI was seen in all therapy groups, and this change was greater in the Sling Ex and Sling Ex+PU groups than in the PT group. No changes in sEMG activity were noted in the PT group, whereas significant increases in the sEMG activities of all lumbar muscles were found in the other 2 groups. The increases in the sEMG activities of the rectus abdominis and internal and external oblique muscles of the abdomen were greater in the Sling Ex+PU group than in the other 2 groups. [Conclusion] These findings demonstrate that Sling Ex+PU, similar to normal lumbar stabilization exercise, is effective in activating and improving the function of the lumbar muscles. These results suggest that Sling Ex+PU has a positive impact on stabilization of the lumbar region.

Multifidus muscle fatty infiltration as an index of dysfunction in patients with single-segment degenerative lumbar spinal stenosis: A case-control study based on propensity score matching

The multifidus muscle morphology and its relation to the function of patients with degenerative lumbar spinal stenosis (DLSS) remains unclear. This study aimed to investigate the multifidus muscle morphology in patients with DLSS and to determine its relations to the patients function. Sixty-two patients with single-segment DLSS at L4-5 and sixty control patients with non-spinal-derived low back pain were retrospectively enrolled and further matched based on propensity scores. The Oswestry Disability Index (ODI) and bodily pain using the Short-Form Health Survey were evaluated. The cross-sectional area (CSA), CSA of fatty free (CSAF), and fatty infiltration rate [FIR; i.e., (1- CSAF/CSA) × 100%] of the multifidus muscle were measured on magnetic resonance images using ImageJ software. Adjustment for confounders was performed using generalized linear models. The FIR at L5-S1 in controls was statistically significant but slightly less than the DLSS group. The between-groups difference was 5% (p < 0.001), and 2.8% (p = 0.036) in the complete and matching cohorts, respectively, after adjustment. Statistically significant differences were not observed in other multifidus muscle parameters between the groups. FIR > 20% at L5-S1 was independently associated with ODI ≥ 41 in patients with DLSS [Retaining demography as control block or not, Odds ratio (OR) = 8.4, p = 0.023; OR = 12.3, p = 0.030]. The multifidus muscle at L5-S1 demonstrated slightly greater fatty infiltration in patients with L4-5 single-segment DLSS than controls. Significant fatty infiltration in the multifidus muscle at L5-S1 may be correlated with poor function in patients with L4-5 single-segment DLSS.

Lumbar lordosis reduction and disc bulge may correlate with multifidus muscle fatty infiltration in patients with single-segment degenerative lumbar spinal stenosis

OBJECTIVES

To investigate the correlation between fatty infiltration in the multifidus muscle related to the involved nerve root and structural parameters associated with stenosis in patients with degenerative lumbar spinal stenosis (DLSS).

PATIENTS AND METHODS

Sixty-four patients with single-segment DLSS at L4-5 were retrospectively enrolled. The fatty infiltration rate (FIR) of the multifidus muscle at L5-S1, lumbar lordosis and the cross-sectional area (CSA) of the structural parameters at L4-5, such as dural sac, disc bulge, ligamentum flava and vertebral body of L5 were measured on magnetic resonance images using ImageJ software. All enrolled patients were divided into an FIR < 25 % group and an FIR ≥ 25 % group according to the FIR of the multifidus muscle at L5-S1. The propensity scores matching and adjustment of potential covariates were performed to reduce the confounding bias between the two groups.

RESULTS

Lumbar lordosis in the FIR ≥ 25 % group was significantly lower than that in the FIR＜25 % group in both cohorts. The mean differences in lumbar lordosis of 14.16 degrees between the two groups in the complete cohort and of 14.23 degrees in the matched cohort remained significant after adjustment. The disc bulge CSA/ vertebral body CSA in the FIR ≥ 25 % group was greater than that in the FIR＜25 % group in both cohorts. The mean differences in the disc bulge CSA/ vertebral body CSA between the two groups of 0.67 in the complete cohort and 0.96 in the matched cohort were statistically significant after adjustment. There was no significant difference in the dural sac CSA/ vertebral body CSA and ligamentum flava CSA/ vertebral body CSA between the two groups in either cohort regardless of adjustment. Logistic regression analysis for FIR ≥ 25 % in the multifidus muscle at L5-S1 exhibited that the disc bulge CSA/ vertebral body CSA were independent risk factors with odds ratio (OR) of 8.52, while lumbar lordosis were independent protective factors (OR = 0.72).

CONCLUSIONS

The disc bulge at the stenosis segment and lumbar lordosis reduction may be correlated with fatty infiltration in the multifidus muscles at L5-S1 in patients with L4-5 single-segment DLSS.

Diagnostic accuracy of multifidus muscle spontaneous activity by needle electromyography for the detection of lumbar foraminal and lateral exit-zone stenosis

PURPOSE

The medial branch of the posterior ramus of the lumbar spinal nerve is well known to be innervated independently and to end in the multifidus muscle without anastomosis. This prospective cohort study aimed to determine the diagnostic specificity and sensitivity of multifidus muscle denervation (MMD) by needle electromyography (N-EMG) for lumbar foraminal and lateral exit-zone stenosis (LF/LEZS).

METHODS

We enrolled 61 consecutive patients experiencing unilateral dysesthesia and/or leg pain in the L4 or L5 regions with suspicious LF/LEZS. The Japanese Orthopedic Association (JOA) score, Visual Analog Scale (VAS) for leg pain, and N-EMG were examined. In this study protocol, all patients received at least 3 months of conservative therapy. Surgery was performed on patients who experienced less than 50% VAS pain relief compared with their initial score after confirming the responsible level by lumbar nerve root block. The specificity of N-EMG was the proportion of patients who improved with conservative therapies (non-surgery) after 3 months. The sensitivity of N-EMG was the proportion of patients who improved with surgical therapies (surgery) after more than 12 months.

RESULTS

Twenty-three patients underwent surgery. The initial lower JOA, positive Kemp test and motor weakness were significantly higher in the surgery group. The MMD by N-EMG indicated that 34 of 38 patients were negative in the non-surgery group. In the surgery group, 21 of 23 patients were positive. The diagnostic sensitivity and specificity were 91.3 and 92.1%, respectively.

CONCLUSIONS

Needle electromyography is a simple and available additional method for the diagnosis of LF/LEZS.

Morphological changes of cervical musculature in relation to chronic nonspecific neck pain: a systematic review and meta-analysis

BACKGROUND

Chronic neck pain is a common musculoskeletal disorder. Previous studies have found that chronic neck pain is associated with changes in neck muscle morphology and fat infiltration (FI). This systematic review summarizes and analyzes all studies on neck muscle morphology in patients with chronic nonspecific neck pain (CNNP).

OBJECTIVES

The main objective of this study was to review and analyze measurements of neck muscles in all patients with CNNP, including morphological changes in the multifidus muscle (MF), longus colli muscle (LC), and semisspinalis capitis muscle (SCa) in patients with CNNP compared with controls.

STUDY DESIGN

Systematic review with meta-analysis METHODS: A comprehensive search of online databases, including PubMed, Web of Sciences, Embase, and Medline was conducted to identify relevant studies reporting changes in neck muscle morphology in patients with chronic neck pain versus healthy controls. Search scope from inception to June 30, 2022, no language restrictions. Two reviewers participated in the screening process independently. Due to the lack of relevant data from other studies, only studies were selected to report morphological changes of MF, LC and SCa in patients with CNNP, including muscle cross-sectional area (CSA), lateral diameter (LD), and anteroposterior diameter (APD). A modified Newcastle-Ottawa scale was used to assess study quality and risk of bias. A total of 11 studies were included based on inclusion and exclusion criteria, of which 8 were included in the meta-analysis.

RESULTS

The results showed that the CSA of LC was slightly smaller in CNNP patients (MD = -0.23, 95%CI = -0.37 to -0.08), and the multiplied linear dimensions (MLD: LD*APD) of SCa was slightly smaller (MD =-0.19, 95%CI = -0.34 to -0.03). There was no difference in MF muscle size between CNNP patients and healthy controls.

CONCLUSIONS

LC and SCa sizes were slightly smaller in CNNP patients, there was no difference in MF muscle size between the two groups. And no conclusions could be drawn in fat infiltration due to insufficient evidence. In summary, CNNP has influence on neck muscle morphology, but the evidence is limited.