Changes in Lumbar Endplate Area and Concavity Associated With Disc Degeneration

Association between vertebral cross-sectional area and lumbar disc displacement - a population-based study

PURPOSE

Vertebral dimensions may constitute a potential risk factor for degenerative changes in the spine. Previous studies have found a positive association between vertebral height and both type 2 Modic changes and intervertebral disc height loss. Also, vertebral endplate size has been associated with disc degeneration. However, only a few studies have investigated the association between vertebral dimensions and lumbar disc displacement (LDD). This study aimed to investigate the association between vertebral cross-sectional area (CSA) and LDD among the general middle-aged Finnish population. We hypothesized that larger vertebral CSA is associated with LDD.

MATERIALS AND METHODS

The study was conducted by using data from the Northern Finland Birth Cohort 1966 (NFBC1966). At the age of 46, a subpopulation of NFBC1966 underwent clinical examinations including magnetic resonance imaging (MRI) (n = 1249). MRI scans were used to measure L4 CSA and evaluate the presence of LDD (bulge, protrusion, and extrusion/sequestration) in the adjacent discs. The association between L4 CSA and LDD was analysed using logistic regression, with adjustment for sex, education, body mass index, leisure-time physical activity, smoking, diet, and L4 height.

RESULTS

Larger L4 CSA was associated with LDD; an increase of 1 cm2 in vertebral CSA elevated the odds of LDD relative to no LDD by 10% (adjusted odds ratio 1.10, 95% CI 1.01-1.19). The association was similar among either sex.

CONCLUSIONS

Larger L4 vertebral CSA was associated with LDD in our study sample. Even though smaller vertebral size exposes our vertebrae to osteoporotic fractures, it simultaneously seems to protect us from LDD.

Intermittent cyclic mechanical compression promotes endplate chondrocytes degeneration by disturbing Nrf2/PINK1 signaling pathway-dependent mitophagy

An abnormal mechanical load is a pivotal inducer of endplate cartilage degeneration, which subsequently promotes intervertebral disc degeneration. Our previous study indicated that intermittent cyclic mechanical compression (ICMC) promotes endplate chondrocyte degeneration, but the mechanism underlying this effect is unclear. In this study, we investigated PTEN-induced kinase 1(PINK1) dependent mitophagy during ICMC-induced endplate chondrocyte degeneration. Furthermore, we determined whether NF-E2-related factor 2 (Nrf2) activation correlated with PINK1-dependent mitophagy regulation and increased oxidation resistance of endplate chondrocytes under ICMC application. First, we generated a mechanical compression-induced endplate chondrocyte degeneration model in vitro and in vivo. ICMC was found to promote endplate chondrocyte extracellular matrix degradation. PINK1-mediated mitophagy was suppressed in the ICMC-stimulated endplate chondrocytes, while increased mitochondrial reactive oxygen species generation suggested that mitophagy is involved in the protective effect of mechanical strain on endplate chondrocytes. Moreover, Nrf2 expression, interaction with Kelch-like ECH-associated protein (Keap1), and nuclear translocation were inhibited by ICMC. Nrf2 overexpression inhibited reactive oxygen species production and reversed ICMC-induced endplate chondrocyte degeneration. Transfection with PINK1 shRNA abolished this effect and partially blocked Nrf2-induced mitophagy. Our findings suggested that ICMC could inhibit the Nrf2/PINK1 signaling pathway to reduce the mitophagy levels which significantly promote oxidative stress and thereby endplate chondrocyte degeneration. Therapeutic regulation of the Nrf2/PINK1 signaling pathway may be an efficient anabolic strategy for inhibiting this process.

A novel method to estimate adult age from the lumbar vertebral body using 3D PMCT images in Japanese

This study evaluated the age-related changes in the vertebral body using 3D Postmortem CT (PMCT) images and proposed an alternative age estimation formula. The PMCT images of 200 deceased individuals aged 25 to 99 years (126 males, 74 females) were retrospectively reviewed and included in the study. Using the open-source software ITK-SNAP and MeshLab, a 3D surface mesh of the fourth lumbar vertebral body (L4) and its convex hull models were created from the PMCT data. Using their inbuilt tools, volumes (in mm3) of the L4 surface mesh and convex hull models were subsequently computed. We derived VD, defined as the difference in volumes between the convex hull and L4 surface mesh normalized by L4 mesh volume, and VR, defined as the ratio of L4 mesh volume to convex hull volume based on individual L4. Correlation and regression analyses were performed between VD, VR, and chronological age. A statistically significant positive correlation (P < 0.001) between chronological age and VD, (r_s = 0.764, males; r_s = 0.725, females), and a significant negative correlation between chronological age and VR (r_s = -0.764, males; r_s = -0.725, females) was obtained in both sexes. The lowest standard error of the estimate was demonstrated by the VR at 11.9 years and 12.5 years for males and females, respectively. As such, their regression models to estimate adult age were Age = 248.9-2.5VR years, males; Age = 258.1-2.5VR years, females. These regression equations may be useful for estimating age in Japanese adults in forensic settings.

Influence of the geometric and material properties of lumbar endplate on lumbar interbody fusion failure: a systematic review

Background

Lumbar interbody fusion (LIF) is an established surgical intervention for patients with leg and back pain secondary to disc herniation or degeneration. Interbody fusion involves removal of the herniated or degenerated disc and insertion of interbody devices with bone grafts into the remaining cavity. Extensive research has been conducted on operative complications such as a failure of fusion or non-union of the vertebral bodies. Multiple factors including surgical, implant, and patient factors influencing the rate of complications have been identified. Patient factors include age, sex, osteoporosis, and patient anatomy. Complications can also be influenced by the interbody cage design. The geometry of the bony endplates as well as their corresponding material properties guides the design of interbody cages, which vary considerably across patients with spinal disorders. However, studies on the effects of such variations on the rate of complications are limited. Therefore, this study aimed to perform a systematic review of lumbar endplate geometry and material property factors in LIF failure.

Methods

Search keywords included ‘factor/cause for spinal fusion failure/cage subsidence/cage migration/non-union’, ‘lumbar’, and ‘interbody’ in electronic databases PubMed and Scopus with no limits on year of publication.

Results

In total, 1341 articles were reviewed, and 29 articles were deemed suitable for inclusion. Adverse events after LIF, such as cage subsidence, cage migration, and non-union, resulted in fusion failure; hence, risk factors for adverse events after LIF, notably those associated with lumbar endplate geometry and material properties, were also associated with fusion failure. Those risk factors were associated with shape, concavity, bone mineral density and stiffness of endplate, segmental disc angle, and intervertebral disc height.

Conclusions

This review demonstrated that decreased contact areas between the cage and endplate, thin and weak bony endplate as well as spinal diseases such as spondylolisthesis and osteoporosis are important causes of adverse events after LIF. These findings will facilitate the selection and design of LIF cages, including customised implants based on patient endplate properties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-022-03091-8.

Diagnostic Role of Magnetic Resonance Imaging in Low Back Pain Caused by Vertebral Endplate Degeneration

Low back pain (LBP) is a common health issue worldwide with a huge economic burden on healthcare systems. In the United States alone, the cost is estimated to be $100 billion each year. Intervertebral disc degeneration is considered one of the primary causes of LBP. Moreover, the critical role of the vertebral endplates in disc degeneration and LBP is becoming apparent. Endplate abnormalities are closely correlated with disc degeneration and pain in the lumbar spine. Imaging modalities such as plain film radiography, computed tomography, and fluoroscopy are helpful but not very effective in detecting the causes behind LBP. Magnetic resonance imaging (MRI) can be used to acquire high-quality three-dimensional images of the lumbar spine without using ionizing radiation. Therefore, it is increasingly being used to diagnose spinal disorders. However, according to the American College of Radiology, current referral and justification guidelines for MRI are not sufficiently clear to guide clinical practice. This review aimed to evaluate the role of MRI in diagnosing LBP by considering the correlative contributions of vertebral endplates. The findings of the review indicate that MRI allows for fine evaluations of endplate morphology, endplate defects, diffusion and perfusion properties of the endplate, and Modic changes. Changes in these characteristics of the endplate were found to be closely correlated with disc degeneration and LBP. The collective evidence from the literature suggests that MRI may be the imaging modality of choice for patients suffering from LBP. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY STAGE: 3.

Morphologic analysis of Chinese lumbar endplate by three-dimensional computed tomography reconstructions for helping design lumbar disc prosthesis

Lumbar disc prostheses have been used increasingly in recent years. The successful design of lumbar disc prostheses depends on accurate morphometric parameters. However, the morphologic dimensions of lumbar endplate area have not been investigated in Chinese population.A total of 1800 lumbar endplates were retrospectively accessed in 150 Chinese adults. Eighteen parameters of each lumbar segment were measured by three-dimensional computed tomography reconstructions from T12/L1 to L5/S1. These obtained parameters were compared between genders, bilateral sides, vertebral segments, and different populations.Endplate length and width increased in general, and there was a significant decrease for length/width ratio from T12 to S1 (P = .03). The average concavity depth of the lower lumbar endplate (2.09 ± 0.93 mm) was usually larger than that of the upper lumbar endplate (1.61 ± 0.74 mm) (P = .02). The percentage of the most concave point of the upper and lower lumbar endplate was 50.01 ± 10.76% and 56.41 ± 9.93%, respectively. Anterior, medium, or posterior intervertebral endplate height was severally 10.01 ± 1.98 mm, 10.46 ± 2.03 mm, and 6.41 ± 1.74 mm, and increased among vertebral segments (P = .01).The intervertebral endplate angle significantly increased from T12-L1 to L5-S1 (P = .01). Parameters displayed significant difference between genders. The morphometric parameters of different populations also showed differences.In conclusion, there is a morphologic discrepancy in dimensions of lumbar endplate regarding genders, vertebral segments, and different populations. It is essential to design the lumbar disc prosthesis suited for Chinese patients specially, for which the morphometric parameters in our study can be utilized.

Inactivation of FAM20B causes cell fate changes in annulus fibrosus of mouse intervertebral disc and disc defects via the alterations of TGF-β and MAPK signaling pathways

Intervertebral disc (IVD) disorder is often caused by the defect of annulus fibrosus (AF), especially that of the outer AF. Studies about the mechanisms governing the development of the outer AF are needed for a better understanding of pathogenesis of IVD defects. Glycosaminoglycans (GAGs) are essential components of extracellular matrix (ECM) in AF. FAM20B is a newly identified xylose kinase that catalyzes the biosynthesis of GAGs. In this study, we created Fam20B conditional knockout (cKO) mice in which FAM20B was inactivated in type I collagen-expressing cells, the main type of cells in the outer AF of IVD. The cKO mice showed severe spine deformity and remarkable IVD defects associated with AF malformation. The AF of cKO mice had a lower level of chondroitin sulfate and heparan sulfate, and the outer AF cells lost their normal fibroblast-like morphology and acquired chondrocyte phenotypes, expressing a higher level of Sox 9 and type II collagen along with a reduced level of type I collagen. The level of phospho-Smad 2 and phospho-Smad 3, and that of scleraxis, a downstream target molecule of canonical TGF-β signaling pathway were significantly lower in the AF of cKO mice. The AF in cKO mice also manifested altered levels in the molecules associated with the activations of MAPK pathway; the changes included the increase of phospho-P38 and phospho-ERK and a decrease of phospho-JNK. These results indicate that FAM20B plays an essential role in the development of AF by regulating the TGF-β signaling and MAPK signaling pathways.

[Changes in shape and signal intensity of high intensity zone in lumbar intervertebral discs on magnetic resonance images: a longitudinal study]

OBJECTIVE

To investigate changes over time in the shape and signal intensity of high intensity zone (HIZ) in the lumbar intervertebral discs on magnetic resonance images in patients with low back pain.

METHODS

The imaging data were collected from 27 patients with low back pain, who underwent lumbar magnetic resonance (MR) imaging examinations that identified HIZ lesions and received follow-up MR examinations at least 1.5 years later over the period from January 2009 to January 2017. The initial and follow-up MR T2WI images of the patients were read by two experienced radiologists to categorize the changes in the shape of the HIZ lesions into enlarged, unchanged, shrunk, and disappeared. The volume and signal/cerebrospinal fluid signal intensity (T2/CSF) ratio of the HIZ were measured on sagittal MR images using ImageJ software.

RESULTS

Of the 43 HIZ lesions found in the initial examinations, 22 (51.2%) remained unchanged in the follow-up examinations, 10 (21.3%) were enlarged, 9 (20.9%) shrank, and 2 (23.3%) disappeared. The follow-up examinations revealed 4 new HIZ lesions in the intervertebral discs. The volumes of these lesions did not vary significantly in the follow-up examinations (P=0.653), but the T2/CSF ratio was significantly higher in the follow-up than in the initial examinations (P=0.043).

CONCLUSIONS

After observation for an average of 3 years and 3 months, most of the HIZ lesions in the lumbar intervertebral discs of the patients with low back pain remained stable in shape, but their signal intensity on MR images increased.