The "thickened" ligamentum flavum: is it buckling or enlargement?

Inflammatory Biomarkers in Smokers: Implications for Ligamentum Flavum Hypertrophy

BACKGROUND Ligamentum flavum (LF) hypertrophy is a key contributor to spinal pathologies such as lumbar and cervical disc herniations and spinal stenosis. Smoking, as a modifiable lifestyle factor, is implicated in systemic inflammation and oxidative stress, potentially exacerbating LF hypertrophy. This study aimed to compare the expression of alpha-1 antitrypsin (AAT), interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) in the lumbar ligamentum flavum from 27 smokers and 31 non-smokers. MATERIAL AND METHODS LF tissue samples were collected during spinal surgeries. Demographic, anthropometric, and clinical data were recorded. ELISA was used to quantify levels of AAT, IL-1ß, IL-6, and TNF-alpha. Statistical analyses included t-tests, Mann-Whitney U tests, and receiver operating characteristic (ROC) curve analyses. Statistical significance was set at p<0.05. RESULTS Smokers exhibited significantly higher levels of IL-1ß (p<0.001), IL-6 (p=0.004), and TNF-alpha (p<0.001), while AAT levels were significantly lower (p<0.001) compared to non-smokers. ROC analysis identified IL-1ß (AUC=0.828; p<0.001) and TNF-alpha (AUC=0.801; p<0.001) as highly effective markers for distinguishing smokers from non-smokers, while IL-6 (AUC=0.730; p=0.003) showed moderate diagnostic accuracy. AAT (AUC=0.867; p<0.001) demonstrated excellent sensitivity (96.3%) for detecting smoking-related effects. CONCLUSIONS Smoking contributes significantly to systemic inflammation and oxidative stress, leading to biochemical changes that may drive LF hypertrophy. These findings underscore the importance of smoking cessation as a modifiable risk factor in the management of spinal pathologies.

Imaging review of the atypical spinal epidural space pathologies

Pathologies affecting the spinal epidural space (SES) comprise various abnormalities. However, they all have the potential to cause thecal sac narrowing or spinal cord compression. In this review, we group these pathologies into degenerative, infective, neoplastic, vascular, traumatic, and others, focusing on their imaging features. Degenerative pathologies of the SES range from disc to facet disease, with a particular emphasis on the less common degenerative pathologies in this review. Infective pathologies affecting the epidural space include spondylodiscitis and associated epidural phlegmon and abscess. Neoplasms arising from typical SES components include neurofibroma, hemangioma, and liposarcoma. MRI is the best modality to assess the anatomy and abnormalities of the epidural space. MRI, combined with computed tomography, or a radiograph, is useful for the evaluation of bones or radiopaque foreign bodies.

Prevalence and distribution of ossification of the ligamenta flava in a 16th-18th century skeletal population sample from Poland

OBJECTIVE

This study aimed to determine the prevalence of the ossification of the ligamenta flava (OLF) among skeletal remains from Poland.

MATERIALS AND METHODS

124 skeletons aged 25 years and older were analyzed. The presence and size of OLF were observed macroscopically. OLF was recorded at the cranial and caudal attachment sites of each vertebra. The following factors were analyzed: age at death, sex, and presence of other spondyloarthropathies.

RESULTS

The crude prevalence of OLF in the analyzed series was 68.55 %. OLF was located most frequently in the lower thoracic spine. A statistically significant relationship was observed between the presence of OLF and age at death. OLF coincided with degenerative spondyloarthropathies of the thoracolumbar spine.

CONCLUSIONS

The results of this study indicate that OLF was not a rare condition in past populations of European ancestry. Analysis of OLF prevalence in skeletal materials can contribute to reconstruction of the conditions and lifestyles of past people.

SIGNIFICANCE

This study shed new light on the prevalence of OLF and provides information on the variability of OLF in past European populations. The evaluation of the prevalence of OLF represents an important contribution to the field of paleopathology in understanding disease changes in prehistoric and historic human populations.

LIMITATIONS

The analyzed material came from unknown populations without demographic data. Sex and age at death were assessed using standard anthropological methods.

SUGGESTIONS FOR FURTHER RESEARCH

It is important to understand the influence of sociocultural factors and physical activity patterns on the development of OLF.

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.

Load-Bearing Shifts in Laminar and Ligament Morphology: Comparing Spinal Canal Dimensions Using Supine versus Upright Lumbar MRI in Adults without Back Pain

Purpose  The effects of weight bearing on lumbar spinal canal dimensions are not well reported the low back pain (LBP) literature. Since axial loading induces changes in anatomical configuration of the lumbar spine, supine spine imaging may not uncover dimensional changes associated with physiological weight bearing that could be demonstrated in imaging in the upright position. Methods  This study compared anteroposterior spinal canal dimensions measured at the level of the intervertebral discs in the supine and upright lumbar spine magnetic resonance images in adults without a history or current back pain. Additionally, interlaminar distances were measured between the centers of adjacent laminae involving a spinal segment. These parameters were utilized to ascertain the deformation incurred at the ligamentum flavum due to load bearing. Results  Within and between-sessions t -tests, factorial and repeated-measures analysis of variance showed significant alterations in canal dimensions at certain levels, secondary to the upright positioning of the spine. Measurement reliability assessed between sessions and scanning positions using intraclass correlation coefficients demonstrated strong agreement. Conclusion  Imaging studies involving physiological weight bearing may be useful to understand the potential etiological effects of such changes in mechanical LBP.

Ligamentum flavum analysis in patients with lumbar discus hernia and lumbar spinal stenosis

The normal ligamentum flavum (LF) is a well-defined elastic structure with specific innervation. Several studies investigated LF in patients with lumbar spinal stenosis (LSS) and used lumbar discus hernia (LDH) patients as control group, only on the presumed thesis that LF in this patients have normal morphology. In patients with LSS thickening of the LF is the main cause of stenosis, which is most often presented with neurogenic claudication, whose pathophysiological mechanism is not completely understood. We conducted observational cohort study of 60 operated patients divided into two groups. The first group of 30 patients underwent micro-discectomy (LSH group), and second group with 30 patients underwent decompression, after which analysis of harvested LF was performed. Patients from the LDH group and LSS group differed significantly in the frequencies of chief complaints, duration of symptoms, physical examination, and specific morphological/radiological parameters. The LF analysis showed that the groups differed significantly in the amount of collagen and elastic fibers, as well as in the histological appearance/architectonics of elastic fibers. Also, groups differ in the presence of LF nerve fibers. Our findings speak in favor of the recently postulated inflammatory theory in the origin of spinal neurogenic claudication's.

Administration of N-Acetylcysteine to Regress the Fibrogenic and Proinflammatory Effects of Oxidative Stress in Hypertrophic Ligamentum Flavum Cells

Ligamentum flavum hypertrophy (LFH) is a major cause of lumbar spinal stenosis (LSS). In hypertrophic ligamentum flavum (LF) cells, oxidative stress activates intracellular signaling and induces the expression of inflammatory and fibrotic markers. This study explored whether healthy and hypertrophic LF cells respond differently to oxidative stress, via examining the levels of phosphorylated p38 (p-p38), inducible nitric oxide synthase (iNOS), and α-smooth muscle actin (α-SMA). Furthermore, the efficacy of N-acetylcysteine (NAC), an antioxidant, in reversing the fibrogenic and proinflammatory effects of oxidative stress in hypertrophic LF cells was investigated by assessing the expression levels of p-p38, p-p65, iNOS, TGF-β, α-SMA, vimentin, and collagen I under H2O2 treatment with or without NAC. Under oxidative stress, p-p38 increased significantly in both hypertrophic and healthy LF cells, and iNOS was elevated in only the hypertrophic LF cells. This revealed that oxidative stress negatively affected both hypertrophic and healthy LF cells, with the hypertrophic LF cells exhibiting more active inflammation than did the healthy cells. After H2O2 treatment, p-p38, p-p65, iNOS, TGF-β, vimentin, and collagen I increased significantly, and NAC administration reversed the effects of oxidative stress. These results can form the basis of a novel therapeutic treatment for LFH using antioxidants.

Retrodural space of Okada in the posterior ligamentous complex region: clinical and anatomical findings relevant to lumbar interlaminar epidural injection

Background

The retrodural space of Okada is a potential space posterior to the ligamentum flavum that allows communication with the bilateral facet joints. However, the actual anatomy of this space has not been clearly visualized to date. We sought to investigate the characteristics of patients showing contrast spreading to the facet joint space during epidural injection and to clarify the anatomical structures of the retrodural space and adjacent ligamentous tissues in cadaveric specimens.

Methods

Fluoroscopic images of patients who underwent fluoroscopy-guided lumbar interlaminar epidural injection were assessed for contrast flow to the facet joints. Patient demographics, preprocedural imaging study findings, and epidural approaches were analyzed. The anatomical study included the sectional dissection, micro-CT imaging, and histological evaluation of lumbar spine specimens from 16 embalmed cadavers.

Results

Fluoroscopic images of 605 epidural injections were analyzed. Among them, 36 with inadvertent spread into the facet joints (5.9%) were identified. Multivariate analysis revealed that facet joint pathologies were significantly associated with inadvertent spread into the facet joints (OR 4.382; 95% CI 1.160 to 16.558; p=0.029). Micro-CT and histological findings consistently showed a retrodural space between the ligamentum flavum and interspinous ligament. Various anatomical communication routes in the posterior ligamentous complex leading to this space were observed in specimens with degenerative and pathological changes.

Conclusion

Degenerative and pathological facet joint changes were associated with a higher incidence of spread into the retrodural space during epidural injection. Our findings confirm anatomical evidence for a false loss of resistance before the needle enters the epidural space.

Ligamentum Flavum Buckling vs Hypertrophy in Cervical Myelopathy Using Dynamic Imaging: Are Instability and Loss of Disc Height the Culprits?

BACKGROUND

The literature has not distinguished between LF "hypertrophy" and "buckling" when addressing cervical spondylotic myelopathy. The identification of buckling on dynamic magnetic resonance imaging can determine the levels for decompression more accurately and modify the surgical plan accordingly. No studies have been performed in the cervical spine to analyze the factors affecting LF buckling.

PURPOSE

Our objective was to investigate the factors affecting static ligamentum flavum (LF) "hypertrophy" and dynamic LF "buckling."

STUDY DESIGN

Retrospective cohort study.

METHODS

We conducted a retrospective study of hospital records and imaging database from January 2014 to January 2020. The relation of age, disc height, and intervertebral instability to LF hypertrophy and buckling were assessed.

RESULTS

Measurements were performed from C2-3 to C7-T1 in 169 patients who satisfied the eligibility criteria, making a total of 1014 levels. The samples were divided into 2 groups: 798 levels with buckling <1 mm (group A) and 216 levels with buckling >1 mm (group B). Of those, 161 levels satisfied the criteria for radiological instability (sagittal translation/rotation). No correlation was observed between age/disc height and buckling. Intervertebral instability showed significant association (P = 0.046) with buckling. No correlation was found between age/intervertebral instability and hypertrophy.

CONCLUSION

LF buckling but not hypertrophy is related to intervertebral instability in the cervical spine. LF buckling in the cervical spine is not related to age or disc height in the cervical spine.

CLINICAL RELEVANCE

Intervertebral instability on dynamic x-ray imaging of the cervical spine can be a predictor of ligamentum flavum buckling and can be utilized for surgical planning.

LEVEL OF EVIDENCE: 3

Intervertebral disc degeneration relates to biomechanical changes of spinal ligaments

BACKGROUND CONTEXT

The ligamentum flavum (LF), the inter- and supraspinous ligament (ISL&SSL) and the intertransverse ligament (ITL) are relevant spinal structures for segmental stability. The biomechanical effect of degeneration and aging on their biomechanical properties remains largely unknown.

PURPOSE

The aim of this study was to assess the material properties of the ITL, ISL&SSL and LF and to correlate parameters of biomechanical function with LF-thickness, intervertebral disc (IVD) degeneration and age.

STUDY DESIGN

Biomechanical cadaveric study.

METHODS

MRI- and CT-scans of 50 human lumbar segments (Th12-L5) were used to assess the ISL (acc. to Keorochana), the grade of IVD degeneration (acc. to Pfirrmann) and to quantify LF-thickness. The ITL, ISL&SSL and LF were resected in the neutral position of the spinal segment with a specifically developed method to conserve initial strain. Ramp to failure testing was performed (0.5 mm/s) to record initial tension, slack length, stiffness and ultimate strength. The relationship between the biomechanical characteristics and age and radiological parameters were analyzed. There are no study-specific conflicts of interest and no external funding was received for this study.

RESULTS

With aging, a significant reduction in initial tension (r=-0.5, p<.01) and ultimate strength (r=-0.41, p<.01) of the LF was observed, while the effect on LF-stiffness and the characteristics of the other ligaments was non-significant. IVD-degeneration was correlated with a significant reduction in stiffness (r=-0.47, p=.001; r=-0.36, p=.01) and ultimate strength (r=-0.3, p=.04; r=-0.36, p=.01) of the LF and ISL&SSL respectively and a significant reduction in initial tension (r=-0.4, p<.01) of the LF. For the ITL, no significant correlation was observed. Comparing Pfirrman 2 to 5, this reduction was 40% to 80% for stiffness 60% to 70% for ultimate strength and 88% for initial tension of the LF. ISL&SSL-stiffness between Kerorochana grade A and D differed significantly (p=.03), while all other comparisons were non-significant (p>.05). LF-thickness did not correlate with the biomechanical properties of the LF (p>.05).

CONCLUSIONS

Aging is primarily related to biomechanical changes to the LF. IVD-degeneration is related to a relevant reduction in stiffness and ultimate strength of the LF and ISL&SSL, with a similar trend for the ITL. The ISL-specific Keorochana grading system provides only minimal biomechanical information and LF-thickness does not provide biomechanical information.

CLINICAL SIGNIFICANCE

Patient age and the degenerative state of the IVD can be used to evaluate the biomechanical characteristics of the dorsal spinal ligaments, which can be helpful in selecting the optimal surgical procedure (e.g. in decompression surgery) for a specific situation.

Oxidative stress mediates age-related hypertrophy of ligamentum flavum by inducing inflammation, fibrosis, and apoptosis through activating Akt and MAPK pathways

The role of oxidative stress in ligamentum flavum (LF) hypertrophy has not been elucidated. We hypothesize that oxidative stress induces inflammatory responses and the subsequent fibrotic processes in LF, via activation of the Akt and MAPK pathways. Specimens of LFs were collected during surgeries for lumbar disc herniation (LDH) or lumbar spinal stenosis (LSS). Part of the LF specimens underwent analyses for ROS, fibrotic markers, and inflammatory mediators, with the remainder minced for cell cultures. The cell cultures were treated with H₂O₂, after which the cells were lysed and analyzed via western blotting. The specimens of the LSS patients showed increased infiltration of inflammatory cells and were stained positively for MMP-3, MMP-9, vimentin, and fibronectin. The LF of the LSS patients had increased oxidative stress and inflammation compared to that of the LDH patients. In vitro analyses demonstrated that oxidative stress rapidly activated the Akt and MAPK pathways. Inflammatory mediators, iNOS and NF-κB, and fibrotic markers, including TGF-β, β-catenin, α-SMA and vimentin, were significantly upregulated after induction of oxidative stress. Oxidative stress activated the intrinsic apoptotic pathway. These findings revealed that oxidative stress is one of the etiological factors of LF hypertrophy, which might provide new insights into treatment approaches.

Dorsal Spinal Ligamentum Flavum Thickening: A Magnetic Resonance Imaging Study

Study Design

A retrospective radiological study of the ligamentum flavum (LF).

Purpose

We determined the relationship of dorsal spinal LF thickening with age and sex using magnetic resonance imaging (MRI). We also determined whether LF thickening has a predominant tendency to occur at a specific dorsal level and on a specific side.

Overview of Literature

Many researchers have studied LF thickness at dorsal levels in patients with compressive myelopathy. However, there is a dearth of literature pertaining to the study of dorsal LF thickness in patients without myelopathy.

Methods

LF thickness was measured at dorsal levels from T1 to T12 on both sides using MRI in 100 individuals. The patients were divided into three groups based on age: 20 to 40, 41 to 60, and >60 years. On axial T2-weighted imaging at the mid-disc level, LF thickness was measured perpendicular to the lamina border, either at half the length of LF or at maximum thickness, whichever was greater.

Results

We found that LF thickness does not increase significantly with increasing age and there was no significant disparity in LF thickness between the sides and sexes. We also found that there was a significant increase in LF thickness at the T10–T11 level (mean value, 3.27±0.94 mm).

Conclusions

LF thickness does not appear to have any side/sex dominance. LF thickening has a predominant tendency to occur specifically at the T10–T11 level. This may be due to maximum tensile strength and mobility at this level. Because there is an increased tendency for LF thickening at the T10–T11 level, this may be used as a reference point for counting the vertebral levels.

Hypertrophy of the ligamentum flavum and expression of transforming growth factor beta

Objective

To explore the relationship between cellular apoptosis and hypertrophy of the ligamentum flavum in the lumbar region.

Methods

Thirty patients with lumbar spinal stenosis were evaluated. Hypertrophy of the ligamentum flavum was present in 15 patients and absent in 15. Hematoxylin–eosin staining and transforming growth factor beta (TGF-β) immunohistochemical testing were applied to compare these two groups.

Results

Derangement of fibrous alignment, fibrocartilage changes, and infiltration of inflammatory cells were observed in the patients with hypertrophy of the ligamentum flavum, while fibrous alignment was normal and few inflammatory cells were observed in patients without hypertrophy. Immunohistochemical studies showed positive expression of TGF-β in patients with hypertrophy, while expression was negative in patients without hypertrophy. The integrated optical density was 2.6556708 in the hypertrophy group and 23104671 in the normal controls.

Conclusions

Expression of TGF-β was closely related to hypertrophy of the ligamentum flavum. Appropriate application of the TGF-β expression level can be used to predict progression of hypertrophy of the ligamentum flavum.

Classification of spondylolytic clefts in patients with spondylolysis or isthmic spondylolisthesis using positional MRI

Background Posterior instability is a pathologic movement occurring in the spondylolytic cleft. Purpose To present a new classification system for the evaluation of spondylolytic cleft by positional magnetic resonance imaging (MRI) and determine the prevalence of the different types. Material and Methods A total of 176 segments of the lumbar spine with spondylolysis or isthmic spondylolisthesis were examined using positional MRI. Scans were obtained in neutral sitting, flexion, and extension positions. No visible movement in the cleft was defined as type A, fluid displaced into the cleft as type BI, displacement of the flava ligaments at the level of the cleft as type BII, and intraspinal cysts arising from the spondylolytic cleft as type BIII. The movements were characterized by a radiologist and a neurosurgeon experienced in positional MRI. Clinical findings were correlated with the different types of instability. Results A high agreement was found between the two observers. In total, 131 segments were characterized as type A, six as type BI, 24 as type BII, and 10 as type BIII. In five segments, the type differed between the right and the left side. Two patients had a mixed type BI/II, another two patients had a mixed type BII/III, and one patient had a mixed type BI/III. Patients with type BII and BIII instabilities suffered more often from radicular symptoms compared to patients without any instability. Conclusion The presented classification might help to better understand and study changes encountered in the spondylolytic cleft in patients with spondylolysis and isthmic spondylolisthesis using positional MRI.

Ligamentum flavum thickening at lumbar spine is associated with facet joint degeneration: An MRI study

OBJECTIVE

Degenerative changes in posterior elements of the spine such as thickening or hypertrophy of the ligamentum flavum (LF) may result in spinal stenosis. In the present study, we aimed to investigate the potential factors including age, intervertebral disc degeneration (IDD), facet joint degeneration (FJD), end plate degeneration (EPD), which may affect LF thickening and to reveal the relationship among those factors at each level of lumbar spine by evaluating the magnetic resonance images (MRI).

METHODS

A total of 200 individuals with low back and/or leg pain complaints who had undergone lumbar MRI were included in this study. The thickness of LF, FJD, IDD and EPD were assessed at all lumbar levels.

RESULTS

Totally 1000 end plates, 1000 intervertebral discs and 2000 facet joints were evaluated and the thicknesses of 2000 LFs were measured from MRI images of 200 patients (100 males and 100 females). The mean age was 46.87 ± 12.47 years. LF thickness was strongly associated with FJD especially on the ipsilateral side. Age and IDD were correlated at whole vertebral levels. The age related changes (LF thickness, FJD, IDD and EPD) were more prominent at L4-L5 vertebral level. However, gender had no effect on LF thickness.

CONCLUSION

The results of this study suggest that LF thickening may occur independently or could be associated with FJD especially on the ipsilateral side and this relationship is due to the vertebral level. The degree of disc degeneration increases with age and age related changes may be predominantly observed at L4-L5 vertebral level.

Asymmetric Facet Joint Osteoarthritis and Its Relationships to Facet Orientation, Facet Tropism, and Ligamentum Flavum Thickening

STUDY DESIGN

The degrees of osteoarthritis of the left and right facet joints were evaluated by using computerized tomography among elderly patients with low back or leg pain.

OBJECTIVE

To reveal the phenomenon of asymmetry regarding facet joint osteoarthritis (FJOA) in old patients and establish its relationships to spinal level, facet orientation, facet tropism and ligamentum flavum (LF) thickening.

SUMMARY OF BACKGROUND DATA

There were few reports regarding left-right asymmetry among severity of FJOA and its relationships to spinal level, facet orientation, facet tropism, and LF thickening remained unclear.

METHODS

The grade of bilateral FJOA was evaluated using 4-grade scale on computerized tomography images at the L3-4, L4-5, and L5-S1 levels of patients with age ranging from 60 to 80 years. All subjects were divided into 2 groups: symmetric FJOA group (FJOA I-II on both sides or FJOA III-IV on both sides) and asymmetric FJOA group (FJOA I-II on one side and FJOA III-IV on the other side). The relationships of FJOA to spinal level, facet orientation, facet tropism, and LF hypertrophy were evaluated.

RESULTS

No association between asymmetric FJOA and spinal level was noted (P>0.05). In asymmetric FJOA group, significant difference in facet orientation between 2 sides was observed at the L4-5 (P=0.018) and L5-S1 levels (P=0.033). Compared with symmetric FJOA, asymmetric FJOA showed significant difference in prevalence of facet tropism at the L5-S1 level (P<0.001). The LF showed significantly thicker on the side of FJOA III-IV than the side of FJOA I-II at each level in asymmetric FJOA group (P<0.05). However, no difference was found in thickness between 2 sides in symmetric FJOA group (P>0.05).

CONCLUSIONS

Asymmetric FJOA is associated with facet orientation and tropism, but not with spinal level. There is a close relationship between severity of FJOA and LF thickness.

The paradoxical relationship between ligamentum flavum hypertrophy and developmental lumbar spinal stenosis

Background

Ligamentum flavum (LF) hypertrophy is a common cause of lumbar spinal stenosis and is thought to be degeneration-driven. Developmental spinal stenosis (DSS) is characterized by pre-existing narrowed spinal canals and is likely a developmental problem that occurs in childhood. In these cases, the LF may demonstrate different characteristics as compared to degeneration-driven stenosis. Thus, this study aimed to investigate the relationship between histological changes of LF and canal size.

Methods

Patients who had surgical decompression for lumbar spinal stenosis were prospectively recruited and divided into three groups (critical DSS, relative DSS and non-DSS) based on previously defined anteroposterior bony spinal canal diameter measurements on MRI. The degree of disc degeneration and LF thickness were also measured from L1 to S1. Surgical LF specimens were retrieved for histological assessment of fibrotic grade and area of fibrosis.

Results

A total of 19 females and 15 males (110 LF specimens) with an overall mean age of 65.9 years (SD ± 9.8 years) were recruited. DSS was found to have a significant negative correlation (p < 0.001) with LF thickness, its fibrotic grade and area of fibrosis (%). Non-DSS exhibited a significant positive relationship with the degree of LF fibrosis. Disc degeneration and LF thickness had no correlation with LF histology.

Conclusions

Our study is the first to definitively note that degeneration is the cause of LF fibrosis in non-DSS patients; however, in contrast, an inverse relationship exists between canal size and LF fibrosis in DSS patients, suggesting a different pathomechanism. Hence, despite a similar degree of LF thickness, DSS patients have LF with less fibrosis compared with non-DSS patients. Further investigation of the cause of LF changes in DSS is necessary to understand this relationship.

Thickness of the ligamentum flavum: correlation with age and its asymmetry-an magnetic resonance imaging study

Study Design

A retrospective radiological study of the ligamentum flavum (LF).

Purpose

This study is an attempt to measure and compare the thickening of the LF on both the sides with the use of magnetic resonance imaging, to investigate if there is a predominant tendency to thicken a specific side and also to determine if a correlation between the thickening of the LF and increasing age exists.

Overview of Literature

Even though many studies measured the thickness of the LF, very few have compared it on each side, or determined its correlation with age.

Methods

The thickness of LF was measured at the L3-4, L4-5, L5-S1 levels on both sides using the magnetic resonance images of 200 patients (n=1,200). The sample population was divided into three groups: 21-40 years, 41-60 years, and 61-80 years. The data was analyzed statistically, comparing the thickness of LF on both sides and in various age-groups.

Results

The thickness of the LF was found to increase with age; however, there were several younger instances with thicknesses >4 mm. The mean thickness of the right LF at different spinal levels was measured (L3-L4=3.38±0.94 mm, L4-L5=3.70±1.16 mm, and L5-S1=3.65±1.16 mm) while the mean thickness of the left LF was higher (L3-L4=3.52±0.99 mm, L4-L5=3.84±1.12 mm, and L5-S1=3.78±1.24 mm).

Conclusions

The LF thickness does not appear to have any side dominance; however, it tends to thicken with increasing age.

Thickness of the ligamentum flavum of the spine and its relationship with disc degeneration

Objective: This study investigates whether the thickening of the ligamentum flavum (LF) is correlated with disc degeneration. Methods: This retrospective study was conducted with 98 patients with chronic low back pain treated in a spinal surgery service between January 2012 and January 2013. All patients underwent magnetic resonance imaging (MRI) and the images were evaluated by a spinal surgeon to measure the thickness of the LF and evaluate the degree of disc degeneration by the Pfirrmann grading system, according to the spinal levels (L3 -L4, L4-L5, L5-S1). An association was sought between LF hypertrophy and disc degeneration, age, sex and disc height. Results: The mean age of the patients was 53.6 years, and the majority were women (59.2%). The thickness of the LF and disc height varied according to the spinal level, the greatest LF thickness being found between L4-L5, and the greatest disc height at L5-S1. Women had statistically thicker ligaments in L3/L4 than men. The degree of disc degeneration was inversely correlated with the height at all the levels evaluated, i.e., the greater the degree of degeneration, the lower the disc height. Conclusions: The thickening of LF is not related to disc height or degree of disc degeneration. Therefore, there is no deformation of the LF within the spinal canal secondary to disc degeneration.

Dynamic changes of the ligamentum flavum in the cervical spine assessed with kinetic magnetic resonance imaging

The purpose of this article is to quantify changes in thickness of the ligamentum flavum (LF) associated with motion of the cervical spine and to compare the thickness of the LF at each cervical level using kinetic magnetic resonance imaging (kMRI). Two hundred fifty-seven symptomatic patients (129 men; 128 women) underwent kMRI in neutral, flexion, and extension positions. Midsagittal images were digitally marked and electronically analyzed by spine surgeons. Thickness of LF in the cervical region from C2-3 to C7-T1 was measured in all three positions. LF at C7-T1 was significantly thicker than C2-3 to C6-7 in neutral, flexion, and extension positions (p < 0.05). LF was significantly thicker in extension than in flexion at C3-4 to C6-7. LF thickness increases with extension and decreases with flexion. LF is uniquely thick at C6-7 and at C7-T1 in the extension position, which may predispose these levels to cord compression syndromes and associated neuropathies.

Imaging of spinal stenosis: neurogenic intermittent claudication and cervical spondylotic myelopathy

Spinal stenosis in either the cervical or lumbar spinal segments is one of the most common indications for spine imaging and intervention, particularly among the elderly. This article examines the pathophysiology and imaging of the corresponding clinical syndromes, cervical spondylotic myelopathy or neurogenic intermittent claudication. The specificity fault of spine imaging is readily evident in evaluation of spinal stenosis, as many patients with anatomic cervical or lumbar central canal narrowing are asymptomatic. Imaging also may be insensitive to dynamic lesions. Those imaging features that identify symptomatic patients, or predict response to interventions, are emphasized.