The narrowing of the lumbar spinal canal during loaded MRI: the effects of the disc and ligamentum flavum

Analysis of complications of minimally invasive approaches for symptomatic lumbar spinal stenosis

INTRODUCTION

Current treatment modalities of lumbar spinal stenosis range from conservative medical management and physical therapy to open surgical decompression. Minimally invasive lumbar decompression (MILD) and Superion interspinous spacers (SISS) Vertiflex offer the promise of effective pain relief with shorter recovery time and lesser potential complications compared with open surgical decompression procedures and general anesthesia. Despite their increasing utilization, their complication profile is not well established in the literature.

METHODS

We searched the FDA's Manufacturer and User facility Device Experience (MAUDE) database for all entries on MILD product code 'HRX' and SISS product code 'NQO'. MAUDE database was queried from 2010 to 2021. Duplicate entries were removed, and complications were classified based on the event descriptions.

RESULTS

For the MILD procedure, a total of 10 entries were found in the MAUDE database. Among these, 8 were classified as surgical complications and 2 were device related. On the other hand, a total of 919 reports were found in the MAUDE database for Vertiflex, with 385 medical device reports were included in the analysis. Device-related were the most reported complication, accounting for 189 cases.

CONCLUSION

As with any new intervention, we must proceed with caution and evaluate the procedure performance over time. Such data should aid physicians to make informed decisions before choosing either technique for their patients. The findings from this study provide insight into the complication profile associated with both MILD and Vertiflex procedures, highlighting the need for continued evaluation and careful consideration in clinical decision-making.

Analysis of the Thickness of Ligamentum Flavum and Its Relationship With Degenerative Disc Changes at L3-4, L4-5, and L5-S1 Levels in Patients Undergoing Magnetic Resonance Imaging (MRI) of the Lumbosacral Spine

Background Low back pain (LBP) is the leading cause of disability among working-age adults, with its prevalence increasing with age and peaking in the 45-54 age group. It is common practice for clinicians to conduct advanced imaging procedures, such as computed tomography (CT) and magnetic resonance imaging (MRI) when a patient presents with LBP. The objective of this study was to measure and analyze the width of the ligamentum flavum (LF) on each side and the extent of degeneration of the disc at the L3-4, L4-5, and L5-S1 levels. Methods The current investigation was a cross-sectional descriptive-analytical effort carried out in the radiodiagnosis department of Sri Devaraj Urs Medical College, Tamaka, Kolar, from July 2024 to September 2024. The study's inclusion criteria were participants in age groups ranging from 20 to 60 years who were referred for an MRI of the lumbosacral spine and had a prior history of LBP. Results Out of 60 subjects, 26 (43.3%) individuals were females, and 34 (56.7%) individuals were males. Out of the maximum number of patients, 23 (38.3%) were within the age range of 31-40 years. The medial and lateral aspects of the LF measurements showed an increase with age, with lateral values being greater than the medial measurements (p = 0.001). The mean thickness of the ligament and the mean height of the disc showed significant variations at all levels. Statistically significant differences were seen in the thickness of the LF of male patients (4.82, 0.62 mm) compared to female patients (4.89, 0.72 mm). A statistically significant positive Pearson association was observed between the thickening of the LF and Pfirrmann grading of degenerative disc disease (DDD). Conclusion The LF thickness is significantly associated with disc degeneration, especially at the L4-L5 level, contributing to spinal canal stenosis, which is critical for the management of LBP.

Comparison of Predictive Performance for Pedicle Screw Loosening Between Computed Tomography-Based Hounsfield Units and Magnetic Resonance Imaging-Based Vertebral Bone Quality Score After Lumbar Surgery

OBJECTIVE

To compare predictive performance for pedicle screw loosening between computed tomography (CT)-based Hounsfield units (HU) and magnetic resonance imaging (MRI)-based vertebral bone quality score (VBQ) after lumbar surgery.

METHODS

A retrospective study was conducted on patients who received transforaminal lumbar interbody fusion continuously at our institution from May 2018 to September 2020. On the basis of 12 months' follow-up lumbar radiographs, screw loosening was defined as a clear zone of minimal thickness of ≥1 mm around the pedicle screw on radiography. VBQ score and HU value were measured using preoperative MRI and CT, respectively. Then, we evaluated the predictive performance of these 2 parameters by comparing the receiver operating characteristic curve.

RESULTS

In all patients, area under the curve (AUC) of the VBQ score (AUC = 0.752; 95% confidence interval [CI] 0.663-0.841; P < 0.001) was larger than those of the CT HU value (AUC = 0.652; 95% CI 0.558-0.746; P = 0.005), but there was no significant difference between them (PAUC = 0.076). In patients with lumbar spinal stenosis, AUC of VBQ score (AUC = 0.863; 95% CI 0.764-0.961; P < 0.001) was larger than those of the CT HU value (AUC = 0.673; 95% CI 0.513-0.833; P = 0.043), with significant difference (PAUC = 0.003).

CONCLUSIONS

MRI-based VBQ score and CT-based HU value have similar performance in predicting pedicle screw loosening after lumbar surgery. Furthermore, in patients with lumbar spinal stenosis, VBQ score demonstrated better predictive ability than HU value.

Buckling of the Ligamentum Flavum in Patients with Lumbar Spinal Canal Stenosis

STUDY DESIGN

Experimental study.

OBJECTIVE

We sought to elucidate the association between ligamentum flavum thickening and tissue buckling, and the clinical and imaging factors related to buckling by comparing the ligamentum flavum thickness on MRI images and within the actual tissue.

SUMMARY OF BACKGROUND DATA

Ligamentum flavum thickening is a main contributor to lumbar spinal canal stenosis. Buckling of the tissue may contribute to ligamentum flavum thickening along with tissue hypertrophy; however, this association has not been established conclusively.

MATERIALS AND METHODS

Ligamentum flavum samples (135 ligament samples) from 70 patients with lumbar spinal canal stenosis were evaluated. The ligamentum flavum thicknesses on magnetic resonance imaging (MRI) and in the tissue samples were compared to assess for the presence of buckling. The ligamentum flavum samples were divided into groups with or without buckling based on the difference between their thicknesses on MRI and in the tissues. The Pearson correlation coefficient test was used to assess the relationships between the LF thicknesses on MRI and in the tissues, MRI-tissue difference and LF thickness in the tissues, and MRI-tissue difference and LF thickness on MRI. Further, differences between the buckling+ and buckling- groups were compared using the unpaired t-test (LF thickness on MRI, LF thickness in the tissues, age, disc angle, and disc height) and χ2 (disc level, disc degeneration, and receival/nonreceival of dialysis) test.

RESULTS

The ligamentum flavum thickness on MRI and in the tissues had a positive linear relationship, although the thickness was estimated to be significantly larger on MRI than in the tissues themselves. The ligamentum flavum with buckling had a larger thickness on MRI, less tissue hypertrophy, more severe disc degeneration, and was present in patients with a higher rate of dialysis. There were no differences in age and disc height, angle, or level between the two groups.

CONCLUSIONS

Buckling of the ligamentum flavum coexists with tissue hypertrophy and contributes to perceived ligamentum thickening on imaging. Buckling of the ligamentum flavum tends to occur in less hypertrophied tissues and is associated with the grade of disc degeneration and the presence of other characteristics associated with spinal degeneration.

Prevalence of and factors associated with stenotic thoracic ligamentum flavum hypertrophy

INTRODUCTION

Stenotic thoracic ligamentum flavum hypertrophy can cause leg and/or low back pain similar to that caused by lumbar spinal stenosis. However, the thoracic spine may occasionally be overlooked in patients with leg and/or low back pain. An accurate understanding of the prevalence of stenotic thoracic ligamentum flavum hypertrophy and its associated factors is necessary.

METHODS

In this prevalence study, we reviewed whole-spine MRI scans of patients who visited the pain clinic complaining of leg and/or low back pain between 2010 and 2019. We analyzed the overall prevalence and prevalence according to the age group, sex, grade of lumbar disc degeneration, and thoracic level. In addition, we identified factors independently associated with stenotic thoracic ligamentum flavum hypertrophy occurrence.

RESULTS

Among 1896 patients, the overall prevalence of stenotic thoracic ligamentum flavum hypertrophy was 9.8% (185/1896), with the highest prevalence observed in the ≥80-year-old age group among all age groups (15.9%, 14/88). The region with the highest prevalence was the T10/11 level (3.0%, 57/1896). Multivariable logistic regression analysis revealed that when compared with the <50-year-old age group, all other age groups were significantly associated with stenotic thoracic ligamentum flavum hypertrophy (p<0.01). In addition, grade 5 of lumbar disc degeneration was significantly associated with stenotic thoracic ligamentum flavum hypertrophy (p=0.03).

CONCLUSIONS

Given the possibility for missed stenotic thoracic ligamentum flavum hypertrophy to potentially result in neurological complications, extending lumbar spine MRI covering the lower thoracic region may be considered for patients over 50 years of age with suspected severe lumbar disc degeneration.

The MOTION study: Two-year results of a real-world randomized controlled trial of the mild® procedure for treatment of lumbar spinal stenosis

OBJECTIVE

The MOTION study is designed to measure the impact of percutaneous image-guided lumbar decompression as a first-line therapy on patients otherwise receiving real-world conventional medical management for lumbar spinal stenosis with neurogenic claudication secondary to hypertrophic ligamentum flavum. This prospective, multicenter randomized controlled trial uses objective and patient-reported outcome measures to compare the combination of the mild® percutaneous treatment and nonsurgical conventional medical management (CMM) to CMM-Alone.

METHODS

Test group patients received the mild procedure after study enrollment. Test and control groups were allowed conventional conservative therapies and low-risk interventional therapies as recommended by their physicians. Subjective outcomes included the Oswestry Disability Index, Numeric Pain Rating Scale, and Zurich Claudication Questionnaire. Objective outcomes included a validated Walking Tolerance Test, the rate of subsequent lumbar spine interventions, and safety data.

RESULTS

Two-year follow-up included 64 mild + CMM and 67 CMM-Alone patients. All outcome measures showed significant improvement from baseline for mild + CMM, whereas the majority of CMM-Alone patients had elected to receive mild treatment or other lumbar spine interventions by 2 years, precluding valid 2-year between-group comparisons. Neither group reported any device- or procedure-related adverse events.

CONCLUSIONS

The durability of mild + CMM for this patient population was demonstrated for all efficacy outcomes through 2 years. Improvements in walking time from baseline to 2 years for patients treated with mild + CMM were significant and substantial. The lack of reported device or procedure-related adverse events reinforces the strong safety profile of the mild procedure. These results provide support for early interventional treatment of symptomatic LSS with the mild procedure.

Lumbar Spinal Stenosis and Minimally Invasive Lumbar Decompression: A Narrative Review

Background

Lumbar spinal stenosis (LSS) is a common pain condition that causes lumbar back pain, radiating leg pain, and possible functional impairment. MILD is an emerging minimally invasive treatment for LSS. It is an image-guided percutaneous procedure designed to debulk hypertrophied ligamentum flavum. However, the exact short- and long-term efficacy, safety profile, indication criteria, and certain procedure details reported in medical literature vary.

Objective

This narrative review was to elucidate efficacy, safety profile, certain procedure details, advantages, and limitations of MILD.

Study Design

This is a narrative review.

Setting

All included articles are clinic trials including analytic studies and descriptive studies.

Methods

PubMed, Cochrane Library, and Scopus were searched. Only clinical trials of MILD procedure were included. Information of indications, contraindications, VAS scores, ODI scores, effective rate, efficacy durations, and certain procedure details was focused on.

Results

According to the literature, for the MILD procedure, the VAS score could be reduced from a pre-treatment level of 6.3-9.6 to a post-treatment level of 2.3-5.8. The ODI score could be reduced from a pre-treatment level of 38.8-55.3 to a post-treatment level of 27.4-39.8. The effective rate of the MILD procedure was reported to be 57.1%-88%. A 2-year postoperative stability of efficacy was also supported. One RCT study testified superior efficacy of MILD over epidural steroid injection.

Limitations

There is few high-quality literature in the review. Moreover, the long-term efficacy of MILD cannot be revealed according to the current literature.

Conclusion

Based on the reviewed literature, MILD is an effective and safe procedure. MILD can reduce pain intensity and improve functional status significantly. Therefore, it is a preferable option for LSS patients who failed conservative treatments, but not for those who require immediate invasive decompression surgery.

Cervical Foraminal Changes in Patients with Intermittent Arm Radiculopathy Studied with a New MRI-Compatible Compression Device

Diagnosing cervical foraminal stenosis with intermittent arm radiculopathy is challenging due to discrepancies between MRI findings and symptoms. This can be attributed to the fact that MRI images are often obtained in a relaxed supine position. This study aims to evaluate the feasibility of the Dynamic MRI Compression System (DMRICS) and to assess possible changes in cervical foramina, with both quantitative measurements and qualitative grading systems, with MRI during a simulated Spurling test. Ten patients (five women and five men, ages 29-45) with previously confirmed cervical foraminal stenosis underwent MRI scans using DMRICS. MRI images were acquired in both relaxed and provoked states. A radiologist assessed 30 foramina (C4-C7) on the symptomatic side in both patient positions. Quantitative and qualitative measures were performed, including the numeric rating scale (NRS) and the Park and Kim grading systems. The provoked state induced concordant neck and arm pain in 9 of 10 patients. Significant shifts in Park and Kim foraminal gradings were noted: 13 of 27 Park gradings and 9 of 27 Kim gradings escalated post provocation. No quantitative changes were observed. This pilot study indicates that the DMRICS device has the potential to improve diagnostic accuracy for cervical radiculopathy, demonstrating induced cervical foraminal changes during a simulated Spurling test while performing MRI.

An in vivo model of ligamentum flavum hypertrophy from early-stage inflammation to fibrosis

Multi-joint disease pathologies in the lumbar spine, including ligamentum flavum (LF) hypertrophy and intervertebral disc (IVD) bulging or herniation contribute to lumbar spinal stenosis (LSS), a highly prevalent condition characterized by symptomatic narrowing of the spinal canal. Clinical hypertrophic LF is characterized by a loss of elastic fibers and increase in collagen fibers, resulting in fibrotic thickening and scar formation. In this study, we created an injury model to test the hypothesis that LF needle scrape injury in the rat will result in hypertrophy of the LF characterized by altered tissue geometry, matrix organization, composition and inflammation. An initial pilot study was conducted to evaluate effect of needle size. Results indicate that LF needle scrape injury using a 22G needle produced upregulation of the pro-inflammatory cytokine Il6 at 1 week post injury, and increased expression of Ctgf and Tgfb1 at 8 weeks post injury, along with persistent presence of infiltrating macrophages at 1, 3, and 8 weeks post injury. LF integrity was also altered, evidenced by increases in LF tissue thickness and loss of elastic tissue by 8 weeks post injury. Persistent LF injury also produced multi-joint effects in the lumbar IVD, including disc height loss at the injury and adjacent to injury level, with degenerative IVD changes observed in the adjacent level. These results demonstrate that LF scrape injury in the rat produces structural and molecular features of LF hypertrophy and IVD height and histological changes, dependent on level. This model may be useful for testing of therapeutic interventions for treatment of LSS and IVD degeneration associated with LF hypertrophy.

Differentiating Lumbar Spinal Etiology from Peripheral Plexopathies

Clinicians have managed and treated lower back pain since the earliest days of practice. Historically, lower back pain and its accompanying symptoms of radiating leg pain and muscle weakness have been recognized to be due to any of the various lumbar spine pathologies that lead to the compression of the lumbar nerves at the root, the most common of which is the radiculopathy known as sciatica. More recently, however, with the increased rise in chronic diseases, the importance of differentially diagnosing a similarly presenting pathology, known as lumbosacral plexopathy, cannot be understated. Given the similar clinical presentation of lumbar spine pathologies and lumbosacral plexopathies, it can be difficult to differentiate these two diagnoses in the clinical setting. Resultingly, the inappropriate diagnosis of either pathology can result in ineffective clinical management. Thus, this review aims to aid in the clinical differentiation between lumbar spine pathology and lumbosacral plexopathy. Specifically, this paper delves into spine and plexus anatomy, delineates the clinical assessment of both pathologies, and highlights powerful diagnostic tools in the hopes of bolstering appropriate diagnosis and treatment. Lastly, this review will describe emerging treatment options for both pathologies in the preclinical and clinical realms, with a special emphasis on regenerative nerve therapies.

Japanese Orthopaedic Association (JOA) clinical practice guidelines on the management of lumbar spinal stenosis, 2021 - Secondary publication

BACKGROUND

The Japanese Orthopaedic Association (JOA) guideline for the management of lumbar spinal stenosis (LSS) was first published in 2011. Since then, the medical care system for LSS has changed and many new articles regarding the epidemiology and diagnostics of LSS, conservative treatments such as new pharmacotherapy and physical therapy, and surgical treatments including minimally invasive surgery have been published. In addition, various issues need to be examined, such as verification of patient-reported outcome measures, and the economic effect of revised medical management of patients with lumbar spinal disorders. Accordingly, in 2019 the JOA clinical guidelines committee decided to update the guideline and consequently established a formulation committee. The purpose of this study was to describe the formulation we implemented for the revision of the guideline, incorporating the recent advances of evidence-based medicine.

METHODS

The JOA LSS guideline formulation committee revised the previous guideline based on the method for preparing clinical guidelines in Japan proposed by the Medical Information Network Distribution Service in 2017. Background and clinical questions were determined followed by a literature search related to each question. Appropriate articles based on keywords were selected from all the searched literature. Using prepared structured abstracts, systematic reviews and meta-analyses were performed. The strength of evidence and recommendations for each clinical question was decided by the committee members.

RESULTS

Eight background and 15 clinical questions were determined. Answers and explanations were described for the background questions. For each clinical question, the strength of evidence and the recommendation were both decided, and an explanation was provided.

CONCLUSIONS

The 2021 clinical practice guideline for the management of LSS was completed according to the latest evidence-based medicine. We expect that this guideline will be useful for all medical providers as an index in daily medical care, as well as for patients with LSS.

The current state of radiodiagnostics of degenerative changes in the lumbar spine (literature review)

Examination of the spine using radiological methods remains the most frequently conducted study in the outpatient practice of almost any radiologist. In most cases, changes in the spine are degenerative and dystrophic in nature. These changes in the spine are the leading cause of loss of activity among adults and the elderly, and cover a wide range of age-related structural changes. It is of great importance to understand the possibilities and limitations of radiological methods of diagnostics. The description of morphological changes observed in degenerative and dystrophic changes requires the use of unified terminology and classifications among clinicians and radiologists.The aim. To present modern concepts in the assessment of degenerative changes of the spine using radiological methods. A description of the standardized international nomenclature of intervertebral disc pathology and current classifications of spinal canal stenosis are presented.Material and methods. For literature search, we used electronic databases MEDLINE (PubMed), eLibrary, EMBASE and Cochrane Library with a selection of sources published from 2000 to 2021. We analyzed the works devoted to the diagnosis of degenerative changes in lumbar spine and to degenerative stenosis.Conclusion. The key to productive communication between physicians is the uniformity or standardization of terminology and definitions used. It is important that the protocol of description, its terms, semantic expressions be uniform and understandable to specialists who are involved in the diagnosis and treatment of the spine. Magnetic resonance imaging is a valuable method in the diagnosis of degenerative changes of the spinal column, but it has its limitations.

The American Society of Pain and Neuroscience (ASPN) Evidence-Based Clinical Guideline of Interventional Treatments for Low Back Pain

Introduction

Painful lumbar spinal disorders represent a leading cause of disability in the US and worldwide. Interventional treatments for lumbar disorders are an effective treatment for the pain and disability from low back pain. Although many established and emerging interventional procedures are currently available, there exists a need for a defined guideline for their appropriateness, effectiveness, and safety.

Objective

The ASPN Back Guideline was developed to provide clinicians the most comprehensive review of interventional treatments for lower back disorders. Clinicians should utilize the ASPN Back Guideline to evaluate the quality of the literature, safety, and efficacy of interventional treatments for lower back disorders.

Methods

The American Society of Pain and Neuroscience (ASPN) identified an educational need for a comprehensive clinical guideline to provide evidence-based recommendations. Experts from the fields of Anesthesiology, Physiatry, Neurology, Neurosurgery, Radiology, and Pain Psychology developed the ASPN Back Guideline. The world literature in English was searched using Medline, EMBASE, Cochrane CENTRAL, BioMed Central, Web of Science, Google Scholar, PubMed, Current Contents Connect, Scopus, and meeting abstracts to identify and compile the evidence (per section) for back-related pain. Search words were selected based upon the section represented. Identified peer-reviewed literature was critiqued using United States Preventive Services Task Force (USPSTF) criteria and consensus points are presented.

Results

After a comprehensive review and analysis of the available evidence, the ASPN Back Guideline group was able to rate the literature and provide therapy grades to each of the most commonly available interventional treatments for low back pain.

Conclusion

The ASPN Back Guideline represents the first comprehensive analysis and grading of the existing and emerging interventional treatments available for low back pain. This will be a living document which will be periodically updated to the current standard of care based on the available evidence within peer-reviewed literature.

Diagnostic Technology for Spine Pathology

Diagnostic techniques for spinal pathologies have been developed in accordance with advances in technology. Accurate diagnosis of spinal pathology is essential for appropriate management of spinal diseases. Since the development of X-rays in 1895 and computed tomography (CT) in 1967, several diagnostic imaging modalities have been utilized for detecting spinal pathologies, including radiography, CT, magnetic resonance imaging, and radionuclide imaging. In addition to diagnostic imaging technologies, electrodiagnostic tests, including electromyography and nerve conduction studies, play a significant role as diagnostic tools, as spinal diseases are mostly profoundly associated with pathologies of the neural structures, such as the spinal cord and nerve root, and extent of injury at the structure cannot be adequately detected by conventional imaging techniques. In patient-specific treatment strategies, usage of diagnostic modalities is of great importance; thus, we should be aware of the basic details and approaches of the different diagnostic modalities. In this review, the authors discuss the details of the technologies that aid in the diagnosis of spinal pathologies.

Histological difference in ligament flavum between degenerative lumbar canal stenosis and non-stenotic group: A prospective, comparative study

BACKGROUND

Ligament flavum (LF) hypertropy is the main etiopathogenesis of lumbar canal stenosis (LCS). The purely elastic LF undergoes a morphological adaptation including a reduction in the elastic fibers and a consequent increase in the collagen content, fibrosis, cicatrization, and calcification. However, the morphometric analysis can delineate the LF in patients with LCS from those without LCS, which would help in better understanding LCS pathogenesis.

AIM

To compare the histopathological changes in LF between the degenerative LCS and non-stenotic (non-LCS) group.

METHODS

The present prospective study was conducted in 82 patients who were divided into two groups, namely LCS and non-LCS. Demographic details of the patients such as duration of symptoms, level of involvement, and number of segments were recorded. The LF obtained from both groups was histopathologically examined for the fibrosis score, elastic fiber degeneration, calcification, and chondroid metaplasia. Morphometrical details included a change in elastin and collagen percentages, elastin/collagen ratio, elastic fiber fragmentation, and ligamentocyte numbers. All parameters were compared between the two groups by using the independent t test, Chi-square test, and Pearson’s correlation test.

RESULTS

Out of 82 cases, 74 were analysed, 34 in LCS and 40 in non-LCS group. The mean ± SD age of presentation in LCS and non- LCS group was 49.2 ± 8.9 and 43.1 ± 14.3 respectively. The LCS group (n = 34) exhibited significant differences in fibrosis (P = 0.002), elastic fiber degeneration (P = 0.01), % elastic fragmentation (66.5 ± 16.3 vs 29.5 ± 16.9), % elastic, content (26.9 ± 6.7 vs 34.7 ± 8.4), % collagen content (63.6 ± 10.4 vs 54.9 ± 6.4), reduction of elastic/collagen (0.4 ± 0.1 vs 0.6 ± 0.1), and ligamentocyte number (39.1 ± 19.1 vs 53.5 ± 26.9) as compared to non-LCS group (n = 40). The calcification (P = 0.08) and Pearson’s correlation between duration and loss of elastin was not significant. The difference in LF morphology is consistent in patient’s ≥ 40 years of age among the groups as found in subgroup analysis. Similarly in the patents < 40 and > 40 in the non-LCS group.

CONCLUSION

LF is vital in the pathogenesis of LCS. The purely elastic LF undergoes a morphological adaptation that includes a reduction in the elastic fibers with a consequent increase in the collagen content, fibrosis, cicatrization, and calcification. The present study provides a detailed morphometric analysis to semiquantitatively delineate the LF changes in patients with LCS from those in patients without LCS.

The cervical sagittal curvature change in patients with or without PCSM after laminoplasty

Objective

After laminoplasty, the cervical sagittal curvature of some patients tend to be lordotic, this phenomenon cannot be explained by the theory of laminoplasty, and the reason remains unknown. We explored the possible role played by pinching cervical spondylotic myelopathy (PCSM) in the cervical sagittal curvature change in patients after laminoplasty.

Methods

From April 2017 to May 2019, we studied 122 patients undergoing laminoplasty with cervical spondylotic myelopathy (CSM). All patients were divided into Group A (anterior compression only, without PCSM) and Group B (both anterior and posterior compression, with PCSM). The visual analogue scale (VAS) was used to measure pain, and modified Japanese Orthopedic Association (mJOA) score was derived. The cervical global angle (CGA) and the range of cervical motion (ROM) were compared. The clinical and imaging results were compared between Group A and Group B.

Results

After laminoplasty, both the mean VAS and mJOA scores improved significantly in Group A and Group B, the mJOA recovery rate of Group B was better than that of Group A (P < 0.05). The mean CGA and ROM decreased in Group A, but increased in Group B. MRI revealed that the ligamentum flavum of Group A was significantly thinner than that of Group B (P < 0.05).

Conclusions

Because of the hypertrophic and folded ligamentum flavum compressing the dorsal spinal cord, patients with PCSM may maintain a compulsive kyphotic posture. After laminoplasty, the cervical sagittal curvature of these patients tend to be lordotic due to the release of dorsal spinal cord compression.

Factors Associated with Thickening of the Ligamentum Flavum on Magnetic Resonance Imaging in Patients with Lumbar Spinal Canal Stenosis

STUDY DESIGN

Experimental study of the ligamentum flavum (LF) thickness among patients with lumbar spinal canal stenosis (LSCS).

OBJECTIVES

To elucidate the factors associated with thickening of the LF on magnetic resonance imaging (MRI).

SUMMARY OF BACKGROUND DATA

Thickening of the LF is a major contributor to LSCS. This thickening is attributed to tissue hypertrophy or buckling of the ligament, and there may be several associated factors on MRI; however, these factors remain unclear.

METHODS

We studied the LF in 56 patients (a total of 106 ligaments) with LSCS, who underwent decompressive surgery; among them, 23 were receiving haemodialysis. The Pearson correlation coefficient was used to assess relationships between the thickness of the LF on MRI and the thickness of the LF tissue, age, disc height, disc degeneration, and disc level. Patients were also categorised into 2 groups based on whether they were undergoing haemodialysis, and the relationships were assessed similarly.

RESULTS

Among patients with LSCS, the thickness of the LF on MRI showed a significant positive linear relationship with the thickness of the LF tissue, and no association with disc height. Except for in those receiving haemodialysis, the thickness of the LF on MRI showed a significant positive relationship with age, disc degeneration, and disc level among patients with LSCS.

CONCLUSION

In patients with LSCS, thickening of the LF on MRI appears to represent tissue hypertrophy. The association between the thickness of the LF on MRI and age, disc degeneration, and disc level may indicate simultaneous alterations of spine components along with aging that was cancelled by the effects of haemodialysis.

Best Practices for Minimally Invasive Lumbar Spinal Stenosis Treatment 2.0 (MIST): Consensus Guidance from the American Society of Pain and Neuroscience (ASPN)

Introduction

Methods

Results

Discussion

Conclusion

Axial Loading during MRI Induces Lumbar Foraminal Area Changes and Has the Potential to Improve Diagnostics of Nerve Root Compromise

Lumbar foraminal stenosis is a common cause of lumbar radiculopathy and conventionally assessed with magnetic resonance imaging (MRI) in supine-positioned patients. An MRI acquired during spine loading may unmask pathology not otherwise revealed in a relaxed position. Therefore, we investigated how spine loading during MRI affects lumbar foramina. In 89 low-back pain patients’ lumbar, MRIs were performed in a relaxed supine position and during axial loading using a Dynawell^® compression device. The smallest area of all intervertebral foramina at levels L3/L4–L5/S1 (534 foramina) was determined using a freehand polygonal tool in parasagittal T2-weighted sequences. The grading system described by Lee et al. was also used to qualitatively assess foraminal stenosis. Overall, a mean reduction of 2.2% (mean −0.89 cm² and −0.87 cm², respectively) was observed (p = 0.002), however for individual foramina large variations, with up to about 50% increase or decrease, were seen. Stratified for lumbar level, an area reduction was found for L3/L4 and L4/L5 foramina (mean change −0.03 cm²; p = 0.036; and −0.03 cm²; p = 0.004, respectively) but not for L5/S1. When comparing the measured area changes to qualitative foraminal grading, 22% of the foramina with a measured area decrease were evaluated with a higher grading. Thus, detailed information on foraminal appearance and nerve root affection can be obtained using this method.

The MOTION Study: A Randomized Controlled Trial with Objective Real-World Outcomes for Lumbar Spinal Stenosis Patients Treated with the mild® Procedure: One-Year Results

OBJECTIVE

The purpose of this study is to provide Level-1 objective, real-world outcome data for patients with lumbar spinal stenosis suffering from neurogenic claudication secondary to hypertrophic ligamentum flavum.

DESIGN

The MOTION Study is a prospective, multicenter, randomized controlled trial comparing the mild® Procedure (minimally invasive lumbar decompression; Vertos Medical, Aliso Viejo, CA, USA) as a first-line therapy in combination with nonsurgical conventional medical management (CMM) vs CMM alone as the active control.

METHODS

Patients in the test group received the mild Procedure at baseline. Both the mild+CMM group and the control group were allowed unrestricted access to conventional real-world therapies. Patient-reported outcomes included the Oswestry Disability Index, the Zurich Claudication Questionnaire, and the Numeric Pain Rating Scale. A validated Walking Tolerance Test, the incidence of subsequent lumbar spine interventions, and the occurrence of adverse events were used to measure objective outcomes.

RESULTS

Sixty-nine patients in each group were analyzed at 1-year follow-up. No device- or procedure-related adverse events were reported in either group. Results from all primary and secondary outcome measures showed statistical significance in favor of mild+CMM.

CONCLUSIONS

One-year results of this Level-1 study demonstrated superiority of mild+CMM over CMM alone for patients with lumbar spinal stenosis who were suffering from neurogenic claudication secondary to hypertrophic ligamentum flavum. Use of the validated Walking Tolerance Test to objectively measure increased ability to walk without severe symptoms provided evidence of statistically significantly better outcomes for mild+CMM than for CMM alone. With no reported device or procedure-related adverse events, the long-standing safety profile of the mild Procedure was reaffirmed. mild is a safe, durable, minimally invasive procedure that has been shown to be effective as an early interventional therapy for patients suffering from symptomatic lumbar spinal stenosis.

Expression and function of fibroblast growth factor 1 in the hypertrophied ligamentum flavum of lumbar spinal stenosis

BACKGROUND

Fibrosis is one of the main pathologies caused by hypertrophy of the ligamentum flavum (LF), which leads to lumbar spinal stenosis (LSS). The fibroblast growth factor (FGF) family is a key mediator of fibrosis. However, acidic fibroblast growth factor (FGF-1) expression and function are not well understood in LF. This study sought to evaluate FGF-1 expression in the hypertrophied and non-hypertrophied human LF, and to investigate its function using primary human LF cell cultures.

METHODS

We obtained hypertrophied lumbar LF from LSS patients and non-hypertrophied lumbar LF from control patients during surgery. Immunohistochemistry and qPCR were performed to evaluate FGF-1 expression in LF tissue. The function of FGF-1 and transforming growth factor beta 1 (TGF-β1) was also investigated using primary LF cell culture. The effects on cell morphology and cell proliferation were examined using a crystal violet staining assay and MTT assay, respectively. Immunocytochemistry, western blotting, and qPCR were performed to evaluate the effect of FGF-1 on TGF-β1-induced myofibroblast differentiation and fibrosis.

RESULTS

Immunohistochemistry and qPCR showed higher FGF-1 expression in hypertrophied LF compared to control LF. Crystal violet staining and MTT assay revealed that FGF-1 decreases LF cell size and inhibits their proliferation in a dose-dependent manner, whereas TGF-β1 increases cell size and promotes proliferation. Immunocytochemistry and western blotting further demonstrated that TGF-β1 increases, while FGF-1 decreases, α-SMA expression in LF cells. Moreover, FGF-1 also caused downregulation of collagen type 1 and type 3 expression in LF cells.

CONCLUSION

FGF-1 is highly upregulated in the LF of LSS patients. Meanwhile, in vitro, FGF-1 exhibits antagonistic effects to TGF-β1 by inhibiting cell proliferation and decreasing LF cell size as well as the expression of fibrosis markers. These results suggest that FGF-1 has an anti-fibrotic role in the pathophysiology of LF hypertrophy.

High-resolution, three-dimensional magnetic resonance imaging axial load dynamic study improves diagnostics of the lumbar spine in clinical practice

BACKGROUND

The response to axial physiological pressure due to load transfer to the lumbar spine structures is among the various back pain mechanisms. Understanding the spine adaptation to cumulative compressive forces can influence the choice of personalized treatment strategies.

AIM

To analyze the impact of axial load on the spinal canal’s size, intervertebral foramina, ligamenta flava and lumbosacral alignment.

METHODS

We assessed 90 patients using three-dimensional isotropic magnetic resonance imaging acquisition in a supine position with or without applying an axial compression load. Anatomical structures were measured in the lumbosacral region from L1 to S1 in lying and axially-loaded magnetic resonance images. A paired t test at α = 0.05 was used to calculate the observed differences.

RESULTS

After axial loading, the dural sac area decreased significantly, by 5.2% on average (4.1%, 6.2%, P < 0.001). The intervertebral foramina decreased by 3.4% (2.7%, 4.1%, P < 0.001), except for L5-S1. Ligamenta flava increased by 3.8% (2.5%, 5.2%, P < 0.001), and the lumbosacral angle increased.

CONCLUSION

Axial load exacerbates the narrowing of the spinal canal and intervertebral foramina from L1-L2 to L4-L5. Cumulative compressive forces thicken ligamenta flava and exaggerate lumbar lordosis.

Axial loading during supine MRI for improved assessment of lumbar spine: comparison with standing MRI

BACKGROUND

There are no studies comparing the morphologic changes of lumbar spines between supine axial-loaded and 90° standing magnetic resonance imaging (MRI) examinations of patients with spinal stenosis.

PURPOSE

To determine whether axial-loaded MRI using a compression device demonstrated similar morphology of intervertebral disc, dural sac, and spinal curvature as those detected by 90° standing MRI in individuals with suspected spinal stenosis.

MATERIAL AND METHODS

A total of 54 individuals suspected of having spinal stenosis underwent both axial-loaded and standing MRI studies. The outcome measures included seven radiologic parameters of the lumbar spine: measures of the intervertebral disc (i.e. cross-sectional area [DA], disc height [DH], and anteroposterior distance [DAP]), dural sac (cross-sectional area [DCSA]), spinal curvature (i.e. lumbar lordosis [LL] and L1-L3-L5 angle [LA]), and total lumbar spine height (LH).

RESULTS

For agreement between the two methods, intraclass correlation coefficient (ICC) ≥ 0.8 was found for all seven radiologic parameters. Supine axial-loaded MRI underestimated LL but remained correlated (ICC = 0.83) with standing MRI. Minor differences between the two methods (≤5.0%) were observed in DA, DCSA, DAP, LA, and LH, while a major difference was observed in LL (8.1%).

CONCLUSION

Using a compression device with the conventional supine MRI to simulate weight-bearing on the lumbar spine generated MRI morphology, which was strongly correlated with those from a standing MRI.

Hypertrophy of the ligamentum flavum in lumbar spinal canal stenosis is associated with abnormal accumulation of specific lipids

Ligamentum flavum hypertrophy (HLF) is the most important component of lumbar spinal canal stenosis (LSCS). Analysis of hypertrophied ligamentum flavum (HLF) samples from patients with LSCS can be an important que. The current study analyzed the surgical samples of HLF samples in patients with LCSC using quantitative and qualitative high performance-liquid chromatography and mass spectrometry. We collected ligamentum flavum (LF) tissue from twelve patients with LSCS and from four patients with lumbar disk herniation (LDH). We defined LF from LSCS patients as HLF and that from LDH patients as non-hypertrophied ligamentum flavum (NHLF). Total lipids were extracted from the LF samples and evaluated for quantity and quality using liquid chromatography and mass spectrometry. The total lipid amount of the HLF group was 3.6 times higher than that of the NHLF group. Phosphatidylcholines (PCs), ceramides (Cers), O-acyl-ω-hydroxy fatty acids (OAHFAs), and triglycerides (TGs) in the HLF group were more than 32 times higher than those of the NHLF group. PC(26:0)+H+, PC(25:0)+H+, and PC(23:0)+H+ increased in all patients in the HLF group compared to the NHLF group. The thickness of the LF correlated significantly with PC(26:0)+H+ in HLF. We identified the enriched specific PCs, Cers, OAHFAs, and TGs in HLF.

Lumbosacral spinal compression device with the use of a cushion back support in supine MRI

BACKGROUND

We hypothesized that axial-loaded magnetic resonance imaging (MRI), modified with the use of a cushion placed behind the lower back (i.e. BS-MRI method), would simulate the standing position more accurately than an axial-loaded MRI without a cushion back support (BS).

PURPOSE

To determine whether the BS-MRI method demonstrated similar morphologies on intervertebral disc (IVD), dural sac, and spinal curvature as those detected on 90° standing MRIs in individuals with suspected spinal stenosis.

MATERIAL AND METHODS

Twenty-five subjects underwent a BS-MRI, as well as axial-loaded and standing MRI studies. Outcome measures were four radiographic parameters of the lumbar spine: IVD height (DH); dural sac cross-sectional area (DCSA); and spinal curvature (i.e. lumbar lordosis [LL] and L1-L3-L5 angle [LA]).

RESULTS

Major differences (>5%) between standing MRI and BS-MRI methods were observed in DCSA, DH, and LL. Major differences between standing and axial loaded MRIs were observed only in DCSA and LA. Although BS-MRIs demonstrate an image of the lumbar spine curvature (i.e. LA) which is closer to that when standing than axial-loaded MRIs, it is likely to overestimate both narrowing of dural sac and extent of LL.

CONCLUSION

Using a compression device with a BS to simulate weight-bearing on the lumbar spine is not recommended due to: (i) overestimation of the narrowing of the dural sac and extent of LL; and (ii) underestimation of loss of disc height. Supine axial-loading produced DCSA and DH which were strongly correlated with those detected with standing MRIs. Exceptions were that LL and LA were underestimated.

A Retrospective, Single-Center, Quantitative Analysis of Adverse Events in Patients Undergoing Spinal Stenosis with Neurogenic Claudication Using a Novel Percutaneous Direct Lumbar Decompression Strategy

Introduction

Low-back pain with accompanying neurogenic claudication is a common diagnosis in pain and spine centers around the world, with an evolving algorithm of treatment. One option for the treatment of neurogenic claudication by decompressive strategies centers on percutaneous direct decompressive techniques. Although commonly employed in clinical practice, there have been no formal investigations looking at safety of percutaneous direct decompression without the use of an epidurogram and relying on osteal landmarks. The purpose of this study was to investigate the safety of percutaneous direct decompression performed without the use of the epidurogram.

Methods

After an IRB exemption had been obtained from the Western Investigational Review Board, data were retrospectively analyzed from July 2018 to August 2020 on patients that had undergone percutaneous direct decompression using the Mild procedure in a single center by a single physician. Data were analyzed quantitatively for reported complications within 3 months of the procedure, including nerve injury, hematoma, infection, death, or allergic reaction to contrast use.–

Results

Chart review yielded 147 individual patients who had undergone percutaneous direct decompression from July 2018 to August 2020. In this data set, women outnumbered men, with an average age of 76 years, with L4–L5 followed by L3–L4 being the most common levels decompressed. Of the 147 patients was performed, utilizing an epidurogram versus no epidurogram for decompression, with no complications. These data are the first to describe the safety of percutaneous direct lumbar decompression without the use of contrast.

Conclusion

This study strongly suggests the use of an epidurogram is not necessary for the safe decompression of a patient with symptomatic spinal stenosis and neurogenic claudication utilizing percutaneous direct decompression.

Objective Real-World Outcomes of Patients Suffering from Painful Neurogenic Claudication Treated with the mild® Procedure: Interim 6-Month Report of a Randomized Controlled Trial

Background

Lumbar spinal stenosis (LSS) is a serious degenerative condition of the spine that can cause significant functional disability. Therapies for these patients generally begin with conservative management, since more invasive interventions such as open surgery and spinal implants are associated with higher complication rates. Early in the treatment algorithm for LSS patients, multiple conventional medical management (CMM) therapies are often combined as an initial low-risk treatment strategy. This composite first-line treatment plan may include conservative care together with early interventional treatment options such as epidural steroid injections, radiofrequency ablation and the mild^® Procedure.

Methods

This prospective randomized controlled trial evaluates patients aged 50 to 80 years treated with mild plus CMM, compared to those treated with CMM alone, as the active control. Walking tolerance test outcomes and incidence of subsequent disallowed procedures provided objective real-world outcome data. The incidence of device or procedure-related adverse events was analyzed. Follow-up includes 6-month, 1-year and 2-year assessments, with 1-year being primary. Patients in the mild+CMM group are followed at 3, 4, and 5 years. This is a report of interim 6-month outcomes.

Results

Of 155 patients enrolled at 19 US interventional pain management centers, 78 were allocated to CMM-Alone, and 77 to mild+CMM. At 6-months, the validated walking tolerance test demonstrated statistical superiority of mild+CMM versus CMM-Alone (p<0.001). The incidence of patients receiving a subsequent disallowed procedure, and thereby considered treatment failures in their study group, was statistically significantly higher in CMM-Alone versus mild+CMM (p<0.001). There were no device or procedure-related adverse events in either group.

Conclusion

At 6-months, the mild Procedure combined with CMM provided statistically superior objective real-world outcomes versus CMM-Alone. There were no device or procedure-related adverse events reported in either study group. With its excellent safety profile and superior efficacy, mild is uniquely positioned as early first-line therapy.

The new imaging findings: "Passing spine" without kissing

Case-control studies by examining the lumbar spine computed tomography (CT) findings focusing on the spinous processes."Passing spine" was defined as a lumbar degenerative change observed on CT images. In contrast, kissing spine, which is also an image finding, has been acknowledged as an established clinical condition. Therefore, we compared the passing spine group and the kissing spine group to investigate whether the 2 groups belong to a similar disease group; this would help explain the clinical and imaging characteristics of patients with passing spine.Previous studies have described the gradual increase in the height and thickness of the lumbar vertebral spinous processes that can occur in individuals aged >40 years, and reported that this progressive degeneration can lead to a condition termed "kissing spine."We examined the CT imaging of 373 patients with lumbar spinal disease and divided patients into 2 groups, the kissing spine (K) group and the passing spine (P) group, and compared the clinical (age, sex, presence/absence of lower extremity pain) and imaging data (localization of kissing or passing spine, intervertebral disc height at the level of kissing or passing spine, lumbar lordosis (LL) angle, presence/absence of vacuum phenomenon (VP) in the intervertebral discs and spondylolisthesis at the level of kissing or passing spine between the 2 groups.Compared with patients with kissing spine, patients with passing spine had an increased incidence of lower extremity pain, lower intervertebral disc height at the level of passing spine, relatively static LL, and VP commonly observed in the intervertebral discs at the level of passing spine.Because the clinical and imaging characteristics of patients with passing spine are different from those of patients with kissing spine, passing spine might be a pathological condition distinct from kissing spine.

The durability of minimally invasive lumbar decompression procedure in patients with symptomatic lumbar spinal stenosis: Long-term follow-up

Background

Minimally invasive lumbar decompression (mild^®) has been shown to be safe and effective for the treatment of lumbar spinal stenosis patients with hypertrophic ligamentum flavum as a contributing factor. This study examines the long‐term durability of the mild procedure through 5‐year follow‐up. Pain relief and opioid medications utilization during 12‐month follow‐up were also assessed.

Methods

All patients diagnosed with lumbar spinal stenosis secondary to ligamentum flavum hypertrophy who underwent mild from 2010 through 2015 at the Cleveland Clinic Department of Pain Management were included in this retrospective longitudinal observational cohort study. The primary outcome measure was the incidence of open lumbar decompression surgery at the same level(s) as the mild intervention during 5‐year follow‐up. Secondary outcome measures were the change in pain levels using the Numeric Rating Scale and opioid medications utilization using Morphine Milligram Equivalent dose per day from baseline to 3, 6, and 12 months post‐mild procedure. Postprocedural complications (minor or major) were also collected.

Results

Seventy‐five patients received mild during the protocol‐defined time period and were included in the study. Only 9 out of 75 patients required lumbar surgical decompression during the 5‐year follow‐up period. Subjects experienced statistically significant pain relief and reduction of opioid medications utilization at 3, 6, and 12 months compared to baseline.

Conclusion

Based on our analysis, the mild procedure is durable over 5 years and may allow elderly patients with symptomatic lumbar spinal stenosis to avoid lumbar decompression surgery while providing significant symptomatic relief.

Weight-Bearing Magnetic Resonance Imaging as a Diagnostic Tool That Generates Biomechanical Changes in Spine Anatomy

Weight-bearing magnetic resonance imaging (MRI) is a unique modality in diagnostic imaging that allows for the assessment of spinal pathology in ways considered previously inaccessible or insufficient with the conventional MRI technique. Due to limitations in positioning within the MRI machine itself, difficulties would be posed in determining the underlying cause of a patient’s pain or neurological symptoms, as the traditional supine position utilized can, in many cases, alleviate the severity of presented symptoms. Weight-bearing MRI addresses this concern by allowing a clinician to position a patient (to a certain degree) into flexion, extension, rotation, or side-bending with an axial load that can mimic physiologic conditions in order to replicate the conditions the patient experiences in order to give clinicians a clearer understanding of the anatomical relationship of the spine and surrounding tissues that may lead to a particular presentation of symptoms. These findings can then guide treatment approaches that are better tailored to a patient’s needs in order to initiate treatment earlier and shorten the duration of treatment necessary for patient benefit. The goal of this review is to describe and differentiate weight-bearing MRI from conventional MRI as well as examine the advantages and disadvantages of either imaging modality. This will include assessing cost-effectiveness and improvements in clinical outcomes. Further, the advancements of weight-bearing MRI will be discussed, including potentially unique clinical applications in development.

Could compression and traction loading improve the ability of magnetic resonance imaging to identify findings related to low back pain?

BACKGROUND

Diagnostic imaging is routinely used to depict structural abnormalities in people with low back pain (LBP), but most findings are prevalent in people with and without LBP. It has been suggested that LBP is related to changes induced in the spine due to loading. Therefore, new imaging measurements are needed to improve our ability to identify structures relating to LBP.

OBJECTIVES

To investigate the response of the lumbar spine to compression and traction in participants with and without chronic LBP using MRI T₂-mapping.

METHOD

Fifteen participants with chronic LBP were matched for age, weight, and gender with 15 healthy volunteers. All participants underwent MRI under three loading conditions maintained for 20 min each: resting supine, followed by compression and traction, both using 50% body weight. Participants were imaged in the last 5 min of each loading condition. Disc morphometric and fluid-based measurements from T₂-maps were obtained.

RESULTS

Traditional MRI measurements (i.e. disc height, width and mean signal intensity) were not able to capture any differences in the changes measured in response to loading between individuals with and without pain. The location of the T₂ weighted centroid (WC) was able to capture the difference between groups in response to compression in the horizontal (p < 0.01) and vertical direction (p < 0.01), and in response to traction in the vertical direction (p < 0.01). While the location of T₂WC moved anteriorly (Effect Size (ES): 0.44) and inferiorly with compression in those with pain (ES: 0.34), it moved posteriorly (ES: -0.14) and superiorly (ES: -0.05) in the group without pain. In response to traction, the vertical location of T₂WC moved superiorly in both groups but the change was larger in those with pain (ES _Pain = -0.52; ES _{No Pain}: -0.13).

CONCLUSION

The novel measurements of the location of the T₂WC in the intervertebral discs were the only measurements capturing differences in response to loading between those with and without low back pain.

Minimally invasive lumbar decompression: a review of indications, techniques, efficacy and safety

Lumbar spinal stenosis is a common degenerative spine condition. In properly selected patients, minimally invasive lumbar decompression ( mild®) may be an option to improve outcomes. This review provides an in-depth description of the mild procedure and a comprehensive examination of safety and efficacy. Two randomized controlled trials, together with 11 other controlled clinical studies, have established the efficacy of mild, which is a minimally invasive procedure that does not involve implants and has demonstrated excellent efficacy and safety. With an established safety profile equivalent to epidural steroid injections, and efficacy that has been shown to be superior to such injections, mild can reasonably be positioned early in the treatment algorithm for these patients. Based on extensive review of the literature, robust safety and efficacy through 2 years, and in accordance with minimally invasive spine treatment guidelines, mild is recommended as the first intervention after failure of conservative measures for lumbar spinal stenosis patients with neurogenic claudication and ligamentum flavum hypertrophy.

Ligamentum flavum fibrosis and hypertrophy: Molecular pathways, cellular mechanisms, and future directions

Hypertrophy of ligamentum flavum (LF), along with disk protrusion and facet joints degeneration, is associated with the development of lumbar spinal canal stenosis (LSCS). Of note, LF hypertrophy is deemed as an important cause of LSCS. Histologically, fibrosis is proved to be the main pathology of LF hypertrophy. Despite the numerous studies explored the mechanisms of LF fibrosis at the molecular and cellular levels, the exact mechanism remains unknown. It is suggested that pathophysiologic stimuli such as mechanical stress, aging, obesity, and some diseases are the causative factors. Then, many cytokines and growth factors secreted by LF cells and its surrounding tissues play different roles in activating the fibrotic response. Here, we summarize the current status of detailed knowledge available regarding the causative factors, pathology, molecular and cellular mechanisms implicated in LF fibrosis and hypertrophy, also focusing on the possible avenues for anti-fibrotic strategies.

The Impact of Age on the Outcomes of Minimally Invasive Lumbar Decompression for Lumbar Spinal Stenosis

Background and Purpose

Minimally invasive lumbar decompression (mild^®) is an effective long-term therapy for patients with symptomatic lumbar spinal stenosis (LSS) resulting primarily from hypertrophic ligamentum flavum (HLF). Most subjects in clinical studies of the mild procedure have been older adults (age≥65). While the incidence of LSS increases with age, a substantial number of adults (age<65) also suffer from neurogenic claudication secondary to HLF. In this report, outcomes of mild were compared between adults and older adults.

Patients and Methods

All prospective studies of the mild procedure with a 1-year follow-up completed since the beginning of 2012 that allowed the inclusion of adult patients of all ages were reviewed. Outcomes of visual analog scale (VAS), Oswestry Disability Index (ODI), Pain Disability Index (PDI), Roland Morris Low Back Pain and Disability Questionnaire (RMQ), standing time and walking distance were compared for adults and older adults.

Results

Four studies met the inclusion criteria, resulting in an analysis of 49 adults and 160 older adults. Patients in both age groups experienced significant mean improvements in all but one outcome measure at 6- and 12-month follow-up. Differences between the two age groups in all scores at 6 and 12 months were not statistically significant.

Conclusion

Analysis of the four studies indicated that symptom improvements for adults and older adults were significant from baseline, and no statistically significant difference was observed between the two age groups. These results illustrate that mild can be an effective treatment for LSS due primarily to HLF, regardless of the adult patient age.

Relationship between the location of ligamentum flavum hypertrophy and its stress in finite element analysis

Objective

To quantitatively describe the stress of the ligamentum flavum (LF) using the finite element method and to compare the stress at different parts of the healthy LF.

Methods

Based on the high resolution computed tomography imaging data of a healthy 22‐year‐old man, three‐dimensional nonlinear L_4–5 lumbar finite element model (FEM) representing intact condition was developed. The LF, as the object of the present research, was incorporated into the spinal model in the form of solid three‐dimensional structure. The model’s validity is verified by comparing its biomechanical indices, such as range of motion and axial compression pressure displacement, with published results under specific loading conditions. To authenticate the accuracy of the solid LF, the lamina attachments, the central cross‐section, and other anatomy indicators were compared with figures in the published literature. After the average and maximum von Mises stress on the surface of LF under various working conditions were measured using ANSYS and AutoCAD software, the surface stress difference in the LF between the ventral and dorsal sides as well as the lateral and lamina parts were determined.

Results

The FEM predicted a similar tendency for biomechanical indices as shown in previous studies. The lamina attachments, the central cross‐section, and the height as well as the width of the LF in the healthy FEM were in accordance with published results. In the healthy model, the average and maximum von Mises stress in the shallow layer of the LF were, respectively, 1.40, 2.28, 1.76, 1.48, 1.38 and 1.79, 2.41, 1.46, 1.42, 1.71 times that in the deep layer under a compressive preload of 500 N incorporated with flexion, extension, and lateral and rotational moments (10 Nm). The most conspicuous difference in surface stress was observed with the flexion motion, with a nearly 241% difference in the maximum stress and a 228% difference in the average stress compared to those in other states. As far as the whole dorsal side of the LF was concerned, the maximum surface stress was almost all concentrated in the dorsal neighboring facet joint portion. In addition, the maximum and average stress were, respectively, 77%, 72%, 15%, 11%, 71% and 153%, 39%, 54%, 200%, 212% higher in the lateral part than in the lamina part.

Conclusion

Based on the predisposition of LF hypertrophy in the human spine and the stress distribution of this study, the positive correlation between LF hypertrophy and its stress was confirmed.

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.

[Classification and diagnosis of lumbar spinal stenosis]

BACKGROUND

Lumbar spinal stenosis is caused by various pathological conditions. With the diagnostic tools available, a precise classification of the condition should be made, which enables a consistent and appropriate therapeutic approach.

OBJECTIVES

In the present article, the currently used classifications of lumbar spinal stenosis are discussed and the diagnostic tools are presented, focussing on the imaging descriptions of morphological changes.

MATERIALS AND METHODS

This article is based on a PubMed literature search of the past 60 years and our own experiences.

RESULTS

Lumbar spinal stenosis is caused mainly by degenerative changes to the spine. MR tomographic imaging can result in precise anatomical illustration and classification of the stenosis.

CONCLUSIONS

Although modern imaging procedures deliver a very precise illustration of lumbar spinal stenosis, clinical symptoms make a considerable contribution to therapeutic decision-making. With the anatomical classification, differentiated surgical decompression of the spinal canal can be planned.

Increased advanced glycation end products in hypertrophied ligamentum flavum of diabetes mellitus patients

BACKGROUND CONTEXT

Ligamentum flavum (LF) hypertrophy plays a dominant role in lumbar spinal stenosis (LSS). Although LSS prevalence is known to be higher in patients with diabetes mellitus (DM), the underlying pathomechanisms are not well understood. Abnormal advanced glycation end products (AGEs) formation occurs in DM and promotes tissue damage in various organs through degeneration and inflammation.

PURPOSE

To analyze and compare LF histology focused on AGE status between control patients, LSS patients with DM, and LSS patients without DM.

STUDY DESIGN/SETTING

Basic research study design utilizing human LF tissue for histologic analyses.

PATIENT SAMPLE

LF tissue samples were collected from patients who underwent lumber decompression surgery for LSS in the author's institution.

OUTCOME MEASURES

Quantitative visualization of Masson's Trichrome (MT) stains, and AGE immunohistochemistry (IHC) for the three groups.

METHODS

Ten LF specimens from LSS patients with DM (DM group, mean age 71.4 years), 10 from LSS patients without DM (non-DM group, mean age 71.2 years), and 9 from patients with lumbar disc herniation or cauda equina tumor (control group, mean age 49.0 years) were harvested during surgery and histologically analyzed. Percentage of elastic fiber areas (%EF) was measured with MT staining, and the percentage of AGE immuno-positive areas (%AGEs) was measured with IHC.

RESULTS

The average %EFs were 12.8 in the DM group, 17.1 in the non-DM group, and 24.9 in the control group. The decrease in the elastic fibers was significantly more in the DM group than in the non-DM (p<.01) and control groups (p<.001). Accumulation of AGEs was found mainly in the extracellular matrix in areas of elastic fiber disruption. The %AGEs were 18.3 in the DM group, 12.1 in the non-DM group, and 4.6 in the control group. These were significantly larger in the DM group than in the non-DM (p<.01) and control (p<.01) groups. The %AGEs also positively correlated with patient age (p<.01, R=0.47).

CONCLUSIONS

Accumulation of AGEs is significantly greater in the LF of DM patients and correlates with patient age. AGEs may accelerate degeneration and hypertrophy of LF with age and may lead to higher prevalence of LSS in patients with DM.

CLINICAL SIGNIFICANCE

The present results partly reveal the molecular mechanism of LF hypertrophy, suggesting that AGEs may be involved in the process of LF degeneration in the elderly and patients with DM.

Long-Term Safety and Efficacy of Minimally Invasive Lumbar Decompression Procedure for the Treatment of Lumbar Spinal Stenosis With Neurogenic Claudication: 2-Year Results of MiDAS ENCORE

BACKGROUND AND OBJECTIVES

This study evaluated the long-term durability of the minimally invasive lumbar decompression (MILD) procedure in terms of functional improvement and pain reduction for patients with lumbar spinal stenosis and neurogenic claudication due to hypertrophic ligamentum flavum. This is a report of 2-year follow-up for MILD study patients.

METHODS

This prospective, multicenter, randomized controlled clinical study compared outcomes for 143 patients treated with MILD versus 131 treated with epidural steroid injections. Follow-up occurred at 6 months and at 1 year for the randomized phase and at 2 years for MILD subjects only. Oswestry Disability Index, Numeric Pain Rating Scale, and Zurich Claudication Questionnaire were used to evaluate function and pain. Safety was evaluated by assessing incidence of device-/procedure-related adverse events.

RESULTS

All outcome measures demonstrated clinically meaningful and statistically significant improvement from baseline through 6-month, 1-year, and 2-year follow-ups. At 2 years, Oswestry Disability Index improved by 22.7 points, Numeric Pain Rating Scale improved by 3.6 points, and Zurich Claudication Questionnaire symptom severity and physical function domains improved by 1.0 and 0.8 points, respectively. There were no serious device-/procedure-related adverse events, and 1.3% experienced a device-/procedure-related adverse event.

CONCLUSIONS

MILD showed excellent long-term durability, and there was no evidence of spinal instability through 2-year follow-up. Reoperation and spinal fracture rates are lower, and safety is higher for MILD versus other lumbar spine interventions, including interspinous spacers, surgical decompression, and spinal fusion. Given the minimally invasive nature of this procedure, its robust success rate, and durability of outcomes, MILD is an excellent choice for first-line therapy for select patients with central spinal stenosis suffering from neurogenic claudication symptoms with hypertrophic ligamentum flavum.

CLINICAL TRIAL REGISTRATION

This study was registered at ClinicalTrials.gov, identifier NCT02093520.

An increase in the degree of olisthesis during axial loading reduces the dural sac size and worsens clinical symptoms in patients with degenerative spondylolisthesis

BACKGROUND CONTEXT

Previous studies have shown that axial loading during magnetic resonance imaging (MRI) significantly reduces the size of the dural sac compared with conventional MRI in patients with degenerative lumbar disease. In our previous study, axial-loaded MRI showed a significantly larger degree of olisthesis than conventional MRI in patients with degenerative spondylolisthesis (DS). Furthermore, the degree of olisthesis on axial-loaded MRI correlated more strongly with that observed on X-ray in the upright position. However, no study has investigated whether or not the increase in the degree of olisthesis during axial loading correlates with the reduction in the dural sac size and affects the severity of clinical symptoms in patients with DS.

PURPOSE

The objective of this study was to determine whether or not the increase in the degree of olisthesis correlates with the reduction of the dural sac cross-sectional area (DCSA) detected on axial-loaded MRI and worsens the severity of clinical symptoms in patients with DS.

STUDY DESIGN/SETTING

This is an imaging cohort study.

PATIENT SAMPLE

A total of 41 consecutive patients with DS were prospectively evaluated in this study.

OUTCOME MEASURES

The outcome measures include the degree of olisthesis, the DCSA, the Pearson correlation coefficient, and the severity of clinical symptoms.

MATERIALS AND METHODS

The differences in the degree of olisthesis and the DCSA between conventional and axial-loaded MRIs were determined. The Pearson correlation coefficient of the increase in the degree of olisthesis with the reduction in the DCSA during axial loading was calculated. The reduction in the DCSA and the severity of clinical symptoms in patients exhibiting a ≥2-mm increase in the degree of olisthesis were compared with those in patients exhibiting a <2-mm increase.

RESULTS

The increase in the degree of olisthesis was significantly correlated with the reduction in the DCSA during axial loading (Pearson correlation coefficient=0.63, p<.001). The reduction in the DCSA during axial loading in patients with a ≥2-mm increase in the degree of olisthesis (26±3 mm²) was significantly greater than in those with a <2-mm increase (13±2 mm²) (p<.01). Clinical symptoms such as walking distance and activity of daily living evaluated using the Japanese Orthopaedic Association score were significantly worse in patients with a ≥2-mm increase in the degree of olisthesis (117±19 m and 6.7±0.5 points, respectively) than in those with a <2-mm increase (236±36 m and 8.4±0.4 points, respectively) (p<.05).

CONCLUSIONS

The present study demonstrated that the increase in the degree of olisthesis was significantly correlated with the reduction in the dural sac size detected on axial-loaded MRI and worsened the severity of clinical symptoms in patients with DS. These results suggest that axial-loaded MRI may be a useful imaging study for detecting dynamic changes in the degree of olisthesis during axial loading to the lumbar spine related to the narrowing of the spinal canal and the severity of clinical symptoms in the assessment of patients with DS.

Dural sac area is a more sensitive parameter for evaluating lumbar spinal stenosis than spinal canal area: A retrospective study

Narrowing of the dural sac cross-sectional area (DSCSA) and spinal canal cross-sectional area (SCCSA) have been considered major causes of lumbar central canal spinal stenosis (LCCSS). DSCSA and SCCSA were previously correlated with subjective walking distance before claudication occurs, aging, and disc degeneration. DSCSA and SCCSA have been ideal morphological parameters for evaluating LCCSS. However, the comparative value of these parameters is unknown and no studies have evaluated the clinical optimal cut-off values of DSCSA and SCCSA. This study assessed which parameter is more sensitive.Both DSCSA and SCCSA samples were collected from 135 patients with LCCSS, and from 130 control subjects who underwent lumbar magnetic resonance imaging (MRI) as part of a medical examination. Axial T2-weighted MRI scans were acquired at the level of facet joint from each subject. DSCSA and SCCSA were measured at the L4-L5 intervertebral level on MRI using a picture archiving and communications system.The average DSCSA value was 151.67 ± 53.59 mm in the control group and 80.04 ± 35.36 mm in the LCCSS group. The corresponding average SCCSA values were 199.95 ± 60.96 and 119.17 ± 49.41 mm. LCCSS patients had significantly lower DSCSA and SCCSA (both P < .001). Regarding the validity of both DSCSA and SCCSA as predictors of LCCSS, Receiver operating characteristic curve analysis revealed an optimal cut-off value for DSCSA of 111.09 mm, with 80.0% sensitivity, 80.8% specificity, and an area under the curve (AUC) of 0.87 (95% confidence interval, 0.83-0.92). The best cut off-point of SCCSA was 147.12 mm, with 74.8% sensitivity, 78.5% specificity, and AUC of 0.85 (95% confidence interval, 0.81-0.89).DSCSA and SCCSA were both significantly associated with LCCSS, with DSCSA being a more sensitive measurement parameter. Thus, to evaluate LCCSS patients, pain specialists should more carefully investigate the DSCSA than SCCSA.

Indications for prophylactic lumbar decompression at the L3/4 level in patients with L4/5 responsible lumbar spinal canal stenosis

Introduction

Lumbar spinal canal stenosis (LSS) is a very common disease. When the responsible level is considered to be L4/5 despite the appearance of double-level (L3/4 and L4/5) stenosis on magnetic resonance imaging (MRI), it is difficult for spinal surgeons to decide whether prophylactic decompression should be performed at the L3/4 level. The purpose of this study was to investigate the relationship between the dural sac cross-sectional area (DCSA) at the L3/4 level and clinical symptoms in patients with double-level stenosis.

Methods

Thirty-five patients with double-level stenosis were registered in this study. All patients underwent decompression surgery at the L4/5 responsible level. The severity of patients' symptoms was evaluated by the Japanese Orthopaedic Association (JOA) score and its rate of recovery. A measurement program on MRI was used to determine the DCSA.

Results

The clinical course of LSS according to the JOA score recovery rate at the final follow-up revealed that the good group (≥50%) included 27 patients, and the poor group (<50%) included 8 patients. In the good group, the mean DCSA at the L3/4 level was 72.3 ± 32.1 mm² preoperatively and 71.3 ± 29.0 mm² at the final follow-up. In contrast, in the poor group, the mean DCSA at the L3/4 level was 49.1 ± 23.8 mm² preoperatively and 40.6 ± 14.1 mm² at the final follow-up. Significant differences were observed in the preoperative and final follow-up DCSAs at the L3/4 level between two groups.

Conclusions

Considering the present results, prophylactic decompression surgery at the L3/4 level should be performed for patients with double-level stenosis and DCSA <50 mm² at the L3/4 level.

MiR-21 promotes fibrosis and hypertrophy of ligamentum flavum in lumbar spinal canal stenosis by activating IL-6 expression

The molecular mechanism underlying the fibrosis of ligamentum flavum(LF) in patients with lumbar spinal canal stenosis(LSCS) remains unknown. MicroRNAs are reported to play important roles in regulating fibrosis in different organs. The present study aimed to identify fibrosis related miR-21 expression profile and investigate the pathological process of miR-21 in the fibrosis of LF hypertrophy and associated regulatory mechanisms. 15 patients with LSCS underwent surgical treatment were enrolled in this study. For the control group, 11 patients with lumbar disc herniation(LDH) was included. The LF thickness was measured on MRI. LF samples were obtained during the surgery. Fibrosis score was assessed by Masson's trichrome staining. The expression of miR-21 in LF tissues were determined by RT-PCR. Correlation among LF thickness, fibrosis score, and miR-21 expression was analyzed. In addition, Lentiviral vectors for miR-21 mimic were constructed and transfected into LF cells to examine the role of miR-21 in LF fibrosis. Types I and III collagen were used as indicators of fibrosis. IL-6 expression in LF cells after transfection was investigated by RT-PCR and ELISA. Patients in two groups showed similar outcomes regarding age, gender, level of LF tissue. The thickness and fibrosis score of LF in the LSCS group were significantly greater than those in LDH group (all P < 0.05). Similarly, the expression of miR-21 in LSCS group was substantially higher than that in LDH group(P < 0.05). Furthermore, the miR-21 expression exhibited positive correlations with the LF thickness (r = 0.595, P < 0.05) and fibrosis score (r = 0.608, P < 0.05). Of note, miR-21 over-expression increased the expression levels of collagen I and III (P < 0.05). Also, IL-6 expression and secretion in LF cells was elevated after transfection of miR-21 mimic. MiR-21 is a fibrosis-associated miRNA and promotes inflammation in LF tissue by activating IL-6 expression, leading to LF fibrosis and hypertrophy.

Increased sorbitol levels in the hypertrophic ligamentum flavum of diabetic patients with lumbar spinal canal stenosis

The pathomechanism of the ligamentum flavum (LF) hypertrophy in diabetic patients with lumbar spinal canal stenosis (LSCS) remains unclear. A cross-sectional study was undertaken to investigate the mechanism of LF hypertrophy in these patients. Twenty-four diabetic and 20 normoglycemic patients with LSCS were enrolled in the study. The structure of the LF in the study subjects was evaluated using histological and immunohistochemical methods, and the levels of sorbitol, pro-inflammatory cytokines, and the fibrogenic factor, TGF-β1, in the LF were analyzed. In vitro experiments were performed using NIH3T3 fibroblasts to evaluate the effect of high-glucose conditions and an aldose reductase inhibitor on the cellular production of sorbitol, pro-inflammatory factors, and TGF-β1. We found that the LF of diabetic patients exhibited significantly higher levels of sorbitol and pro-inflammatory cytokines, TGF-β1 and of CD68-positive staining than that of the normoglycemic subjects. The diabetic LF was significantly thicker than that of the controls, and showed evidence of degeneration. The high glucose-cultured fibroblasts exhibited significantly higher levels of sorbitol, pro-inflammatory factors, and TGF-β1 compared to the low glucose-cultured cells, and these levels were dose-dependently reduced by treatment with the aldose reductase inhibitor. Taken together, our data suggests that increased sorbitol levels in the LF of diabetic patients results in increased production of pro-inflammatory and fibrogenic factor, which contribute to LF hypertrophy, and could increase the susceptibility of diabetic patients to LSCS. Furthermore, aldose reductase inhibition effectively reduced the levels of sorbitol and sorbitol-induced pro-inflammatory factor expression in high glucose-cultured fibroblasts. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1058-1066, 2017.

Conventional Supine MRI With a Lumbar Pillow-An Alternative to Weight-bearing MRI for Diagnosing Spinal Stenosis?: A Cross-sectional Study

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To investigate if adding a lumbar pillow in supine position during magnetic resonance imaging (MRI) is superior to standing positional MRI for diagnosing lumbar spinal stenosis (LSS).

SUMMARY OF BACKGROUND DATA

The upright standing position and especially extension of the lumbar spine seem to worsening symptoms of LSS. However, it is unclear whether a forced lumbar extension by a pillow in the lower back during conventional supine MRI may improve the diagnostics of LSS compared with standing MRI.

METHODS

Patients suspected for LSS and referred to conventional MRI were included to an additional positional MRI scan (0.25T G-Scan) performed in: (1) conventional supine, (2) standing, (3) supine with a lumbar pillow in the lower back. LSS was evaluated for each position in consensus on a 0 to 3 semi-quantitative grading scale. Independently, L2-S1 lordosis angle, spinal cross-sectional diameter (SCSD), dural cross-sectional diameter (DCSD), and dural cross-sectional diameter (DCSA) were measured. The smallest dural diameter was defined as stenosis level and the largest control level for comparison.

RESULTS

Twenty-seven patients (60.6 years; ±9.4) were included. The lordosis angle increased significantly from supine to standing (3.2° CI: 1.2-5.2) and with the lumbar pillow (12.8° CI: 10.3-15.3). One-way analysis of variance (ANOVA) showed significant differences between positions (P < 0.001). When compared with the supine position, pairwise comparisons showed decreased SCSD, DCSD, DCSA, and increasing semi-quantitative grading, during both standing and supine with the lumbar pillow. A difference in the semi-quantitative grades was only found between standing and supine with a lumbar pillow, and the scan with a lumbar pillow was significantly more painful.

CONCLUSION

Standing MRI and supine MRI with a lumbar pillow resulted in equal changes in the lumbar spine, although standing MRI may be more sensitive in the assessment of patients suspected for LSS.

LEVEL OF EVIDENCE

2.