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BACKGROUND CONTEXT The cartilaginous and bony material that can be present in herniated tissue suggests that failure can involve both cartilaginous and vertebral-endplates. How structural integration is achieved across the junction between these two distinct tissue regions via its fibril and mineral components is clearly relevant to the modes of endplate failure that occur. PURPOSE To understand how structural integration is achieved across the cartilaginous-vertebral endplate junction. STUDY DESIGN A micro- and fibril-level structural analysis of the cartilage-vertebral endplate region was carried out using healthy, mature ovine motion segments. METHODS Oblique vertebra-annulus-vertebra samples were prepared such that alternate layers of lamellar fibers extended from vertebra to vertebra. The endplate region of each sample was then decalcified in a targeted manner before being loaded in tension along the fiber direction to achieve incomplete rupture within the region of the endplate. The failure regions were then analyzed with differential interference contrast microscopy and scanning electron microscopy. RESULTS Microstructural analysis revealed that failure within the endplate region was not confined to the cement line. Instead, rupture continued into the underlying vertebral endplate with bony material still attached to the now unanchored annular bundles. Ultrastructural analysis of the partially ruptured regions of the cement line revealed clear evidence of blending/interweaving relationships between the fibrils of the annular bundles, the calcified cartilage and the bone with no one pattern of association appearing dominant. These findings suggest that fibril-based structural cohesion exists across the cement line at the site of annular insertion, with strengthening via a mechanism somewhat analogous to steel-reinforced concrete. The fibrils are brought into a close intermingling association with interfibril forces mediated via the mineral component. CONCLUSIONS This study provides clear evidence of structural connectivity across the cartilaginous-vertebral endplate junction by the intermingling of their fibrillar components and mediated by the mineral phase. This is consistent with the clinical observation that in some disc herniations bony material can be still attached to the extruded soft tissue.

Objectives To evaluate the changes of Hounsfield units (HU) value in different types of Modic changes (MCs) and to analyze the correlation between the change of HU value and area ratio of MCs region, bone mineral density (BMD), and degree of intervertebral disc degeneration. Methods One hundred fifty-eight endplates with MCs were included and analyzed. HU values of MCs regions and adjacent vertebral corresponding regions without MCs were measured. The area ratio of MCs region was defined as the area of MCs divided by the area of endplate or the vertebral sagittal plane. BMD was measured by Dual-energy x-ray absorptiometry (DXA). Degree of intervertebral disc degeneration was evaluated based on Pfirrmann classification. According to the types of variables, descriptive statistics, Kolmogorove-Smirnov test, paired t-test, Wilcoxon signed-rank test, Independent-Samples T Test, and Pearson correlation analysis were used. Results The HU values in any types of MCs are significantly higher than that of adjacent vertebral corresponding regions without MCs (P Conclusions HU values of the vertebral endplate and bone marrow were increased in most MCs regions with all types of MCs. HU value of endplates had a significantly positive correlation with BMD. Higher area ratio of MCs region is associated with more severe intervertebral disc degeneration.

This paper describes a minimally invasive technique of percutaneous intervertebral bridging cementoplasty (PIBC) to augment the fractured vertebrae and immobilize the intervertebral space with endplate-disc complex injury simultaneously. Thirty-two patients with adjacent multilevel osteoporotic thoracolumbar fractures (AMOTLFs) and vertebral endplate-disc complex injury (EDCI) treated by PIBC were retrospectively reviewed. The PIBC technique was a combination of puncture, balloon expansion and bridging cementoplasty. The clinical and radiological assessments were reviewed. The operation time was 82.8 ± 32.5 min, and blood loss was 76.9 ± 31.7 mL. A cement bridge was connected between the two fractured vertebrae across the injured intervertebral space. VAS at three time points including pre-operation, post-operation 1 day and final follow-up was 6.9 ± 0.9, 2.9 ± 0.8 and 1.7 ± 0.8, respectively; ODI at three time points was (71.1 ± 7.8)%, (18.4 ± 5.7)%, and (10.3 ± 5.7)%, respectively; Cobb angle at three time points was 46.0° ± 10.4°, 25.9° ± 8.5°, and 27.5° ± 7.1°, respectively. Compared with pre-operation, VAS, ODI and Cobb angle were significantly improved at post-operation 1 day and final follow-up (P

Melatonin is reportedly associated with intervertebral disc degeneration (IDD). Endplate cartilage is vitally important to intervertebral discs in physiological and pathological conditions. However, the effects and mechanism of melatonin on endplate chondrocytes (EPCs) are still unclear. Herein, we studied the effects of melatonin on EPC apoptosis and calcification and elucidated the underlying mechanism. Our study revealed that melatonin treatment decreases the incidence of apoptosis and inhibits EPC calcification in a dose‐dependent manner. We also found that melatonin upregulates Sirt1 expression and activity and promotes autophagy in EPCs. Autophagy inhibition by 3‐methyladenine reversed the protective effect of melatonin on apoptosis and calcification, while the Sirt1 inhibitor EX‐527 suppressed melatonin‐induced autophagy and the protective effects of melatonin against apoptosis and calcification, indicating that the beneficial effects of melatonin in EPCs are mediated through the Sirt1‐autophagy pathway. Furthermore, melatonin may ameliorate IDD in vivo in rats. Collectively, this study revealed that melatonin reduces EPC apoptosis and calcification and that the underlying mechanism may be related to Sirt1‐autophagy pathway regulation, which may help us better understand the association between melatonin and IDD.

OBJECTIVE. In the 29 years since the initial description of Modic type 1 vertebral endplate changes there has been ongoing debate regarding their cause. Studies have attributed Modic type 1 vertebral endplate changes to traumatic injury to the vertebral endplate, localized action of proinflammatory mediators, and more recently low-grade bacterial infection. Can we reconcile these conflicting data about the underlying cause of Modic type 1 vertebral endplate changes? Are we now in a position to conclude whether Modic type 1 vertebral endplate changes are secondary to injury, inflammation, or infection? CONCLUSION. We argue that the processes are not disparate but are in fact closely linked, each potentially instigating a chain of events leading to the MRI findings of Modic type 1 vertebral endplate change. A method of delineating which process is predominantly at play in an individual patient is required so that tailored treatment options can be offered with huge potential benefit to individuals and societ...

The anatomical descriptions of the IVD include the nucleus pulposus and annulus fibrosus (classic but not as evident in the young), the vertebral endplate, and the marginal listel (apophyseal ring). The IVD infrastructure consists of proteoglycans, collagen, hyaluronic acid, and water with a hydrophilic role, hydraulic shock absorber, and stress transmission according to a tensegrity model (tensional integrity). MR imaging shows the different types of herniated discs and guides the therapeutic decision. The disc pressure is measured in vivo and the endoscopic approach for radiofrequency of the fissure zone is discussed, superseding blind percutaneous approaches.

Though segmentation of spinal column from medical images have been intensively studied for decade, most of the works were concentrated on the segmentation of the vertebral body and arch, instead of the endplate. Recently, the increasing study on degeneration analysis of vertebra and intervertebral disc (IVD) make endplate segmentation as important as others. While the accurately segmentation of mice endplate from micro computed tomography (CT) images is challenging. The major difficulties include potential high system payload and poor run-time efficiency resulting from high-resolution micro-CT data, highly complicated and variable shape of the vertebra tissues, and the ambiguous segmentation boundary due to the similarity of spongy structures inside both the endplate and its adjacent vertebral body. To solve the problems, the core idea of the proposed method is to identify trabeculae between the endplate and the body through a graph-based strategy. In addition, in order to reduce the data complexity, an endplate-targeted region of interest (ROI) extraction method is introduced according to the analysis of spatial relationship and variety of bone density of vertebra. Furthermore, shape priori of endplate in both two-dimensional and three-dimensional are extracted to assist in the segmentation. Finally, an iterative cutting procedure is implemented to produce the final result. Experiments were carried out which validate the performances of the proposed method in terms of effectiveness and accuracy.

Degenerative disc disease, associated with discrete structural changes in the peripheral annulus and vertebral endplate, is one of the most common pathological triggers of acute and chronic low back pain, significantly depreciating an individual’s quality of life and instigating huge socioeconomic costs. Novel emerging therapeutic techniques are hence of great interest to both research and clinical communities alike. Exogenous crosslinking, such as Genipin, and platelet-rich plasma therapies have been recently demonstrated encouraging results for the repair and regeneration of degenerated discs, but there remains a knowledge gap regarding the quantitative degree of effectiveness and particular influence on the mechanical properties of the disc. This study aimed to investigate and quantify the material properties of intact (N = 8), trypsin-denatured (N = 8), Genipin-treated (N = 8), and platelet-rich plasma–treated (N = 8) discs in 32 porcine thoracic motion segments. A poroelastic finite element model was used to describe the mechanical properties during different treatments, while a meta-model analytical approach was used in combination with ex vivo experiments to extract the poroelastic material properties. The results revealed that both Genipin and platelet-rich plasma are able to recover the mechanical properties of denatured discs, thereby affording promising therapeutic modalities. However, platelet-rich plasma–treated discs fared slightly, but not significantly, better than Genipin in terms of recovering the glycosaminoglycans content, an essential building block for healthy discs. In addition to investigating these particular degenerative disc disease therapies, this study provides a systematic methodology for quantifying the detailed poroelastic mechanical properties of intervertebral disc.

A novel morphometric measurement of endplate degradation was compared with qualitative ratings of intervertebral disc degeneration (Pfirrmann Grading) in a double-blinded study to investigate a new, quantitative method for relating disc morphology and bony changes using MR imaging techniques known as the “Concavity Index” (CI). By adding a quantitative measure of vertebral endplate degeneration, the CI could provide further insight into structural changes related to disc breakdown and subsequent low back pain. The continuous nature of the CI may also allow medical professionals to more closely monitor a patient’s low back health. T2-weighted MRI scans of the sagittal profile of the lumbar endplates (L2-S1) were collected from 50 subjects (25 females and 25 males) whose ages ranged from 20–40 years. Three trained examiners independently measured the height and the concavity levels of each lumbar vertebrae (L2-S1) as well as assessed the health of the intervertebral discs using Pfirrmann’s lumbar disc degeneration grading method. Concavity Indices (CIs) were computed by dividing measured concavity level by disc height (CL/DH). A larger CI was hypothesized to be indicative of spinal degradation and subsequent low back pain. Intra- and inter-rater reliabilities were assessed for both the CI measurements and Pfirrmann’s lumbar disc degeneration grades. The categorical intra-observer agreement for Pfirrmann ratings ranged from 26 to 63%. However, the CI, which is a continuous measure, varied by only 2% (average absolute error) among raters. Endplate concavity is indicative of fracturing and damage and is hypothesized to lead to subsequent disc degeneration due to impediment of nutrient flow to the discs themselves. The CI shows promise as a means for potentially quantifying low back health and identifying risk for future low back pain prior to significant disc degeneration.

Vertebral fractures are among the most common of all osteoporosis related fracture types and its risk assessment is largely based on bone quality measures. Morphometric parameters are not yet considered, although endplate thickness and concavity shape were found to be important in fracture prediction in low-rate tests. We hypothesized that, under high-rate impact loading, the shape and size of the central endplate concavity are of key importance for fracture prediction. Therefore, we tested rabbit spinal segment explants in vitro under high-rate impact loading. With a combination of microCT to describe endplate morphometry, high-speed video imaging, and impact force measurement, endplate morphometry was correlated to the mechanical response. We found that endplate concavity shape and volume were important in describing the mechanical response: larger concavities caused higher failure load. We suggest a model for the fracture mechanism under high-rate impact loading, considering the morphometry of the endplates: wider and more voluminous concavities are protective whereas steeper slopes of the concavity edges and increasing bone volume fraction of the central endplate moiety are disadvantageous. Therefore, the shape and size of endplate morphometry are important in vertebral fracture prediction and should be considered included in vertebral fracture risk assessment.

STUDY DESIGN: Cross-sectional study of spine MR in a population, predominantly female, sample.OBJECTIVE: To determine the relationship between vertebral endplate defect and intervertebral disc degeneration (DD) in general population.SUMMARY OF BACKGROUND DATA: Precise understanding of the mechanisms leading to DD development is lacking. In a degenerating disc, mechanical and structural changes lead to further worsening of disc integrity. Increasing attention has been paid to vertebral endplate defects as having a possible role in the etiopathogenesis of DD.METHODS: The study population comprised 831 twin volunteers from TwinsUK (mean age 54 ± 8 years, 95.8% female). Lumbar T2-weighted magnetic resonance images were coded for endplate defects from 8310 endplates into six grades. Total endplate score (TEP score) was achieved by summing both endplate defect grades from the same disc level. DD was evaluated using two different classifications; Pfirrmann grading, and a quantitative trait for DD based on a 4-point grading systems. Multivariable regression analysis was used to determine relationships between the traits of interest and the known risk factors for DD, age and body mass index (BMI). A receiver operator curve for TEP score predicting DD was generated, and survival analysis paired with Cox proportional hazards models analysis performed.RESULTS: There was statistically significant association between DD and age and BMI. These associations lost significance when TEP score was included as predictor in multivariable model. TEP score was strongly and independently associated at every lumbar disc level with DD (Pfirmann p≤0.001; 4-point grading systems p CONCLUSIONS: Our large, population-based study has shown that endplate defect was strongly and independently associated with DD at every lumbar disc level. These results provide a mechanism by which increasing age and BMI predispose to DD.LEVEL OF EVIDENCE: 2.

The aim of this study was to develop a novel method for observing the morphology of the blood vessels in the rabbit endplate. Twenty 6-month-old rabbits were used in this study. The blood vessels in the L5 endplate in Group A were injected with iohexol and Group B with barium sulfate. Group C was the control group with saline. To optimize the study, Group B was divided into two subgroups: Group B-1 was injected with 100% (w/v) barium sulfate and Group B-2 with 50% (w/v). After injection, the L4–L5 vertebral body was excised and the cranial endplate of L5 was scanned using a micro-CT scanner. Models of the vertebral endplate and vessels were reconstructed using the 3D reconstruction software (Mimics 16.0) by calculating a bone threshold value, and then merged these two models to create a superimposed model. The 3D vessel models could not be created in Groups A and C, but they were clearly visualized in Group B. In the 3D model, the blood vessels extended from the subchondral bone to the endplate, and the density of the blood vessels in the area of the nucleus pulposus (NP) was higher than in the annulus fibrosus. The results of this study suggest that the blood vessels in the rabbit endplate can be clearly observed by the method described using barium sulfate [the 50% (w/v) gave better results compared with the 100% (w/v)]. The information from the 3D vessel structure could provide essential data to help us understand the nutrient pathways within the vertebral endplate.

It is presumed that poor intervertebral disc cell nutrition is a contributing factor in degeneration, and is exacerbated by vertebral endplate sclerosis. Yet, quantitative relationships between endplate morphology and degeneration are unavailable. We investigated how endplate bone microstructure relates to indices of disc degeneration, such as morphologic grade, proteoglycan content, and cell density. Intervertebral core samples [n = 96, 14 subjects, L1–L5 level, ages 35–85 (64 ± 16 years), degeneration grade 1 (n = 4), grade 2 (n = 32), grade 3 (n = 44), grade 4 (n = 10), grade 5 (n = 6)] that included subchondral bone, cartilage endplate, and adjacent nucleus were harvested from human cadaveric lumbar spines. The morphology of the vertebral endplate was analyzed using µCT and the adjacent nucleus tissue was collected for biochemical and cellular analyses. Relationships between vertebral endplate morphology and adjacent disc degeneration were analyzed. Contrary to the prevailing notion, vertebral endplate porosity increased between 50% and 130% and trabecular thickness decreased by between 20% and 50% with advancing disc degeneration (p

Study design Mechanically induced disruption and subsequent microscopic investigation of lumbar intervertebral discs following a previously published testing protocol, but using a much higher rate of loading. Objective To explore if loading rate affects the internal disruption mechanics of lumbar intervertebral discs. Summary of background data The failure mechanics of some bone-ligament-bone constructs vary with the rate of tensile load application. Like many ligaments, recent reports indicate that the mechanical response of the disc wall varies with strain-rate. It is possible that the internal failure mechanics of the disc wall also varies with strain-rate. Methods Nuclear pressurization was used to deliver sudden pressure impulses directly to the nucleus of ovine lumbar motion segments. Pressure impulses were delivered to 12 neutrally positioned motion segments, and 15 motion segments held at 7° flexion. Aside from loading rate, testing was conducted in the same manner as 2 previously published studies that employed a gradual nuclear pressurization regime. Following testing, the internal damage resulting to each disc was analyzed using micro-CT and serial microscopy in tandem. Results Radial tears of the medioposterior disc wall were the most frequent cause of disc failure. In most cases, radial tears involved a combination of annular and endplate disruption: Neutrally positioned discs frequently suffered tears within the superior cartilaginous endplate adjacent to the transition zone and/or inner anulus. Flexed discs frequently suffered tears adjacent to the outer anulus at the cartilaginous/vertebral endplate junction, or within the vertebral endplate. Both groups frequently suffered endplate tears adjacent to the mid anulus at the inferior cartilaginous/vertebral endplate junction. Conclusion The internal morphologies of the disc disruptions created in this study using high strain-rate impulse pressurization differed significantly from those documented previously for both neutrally positioned and flexed discs subjected to gradual low strain-rate pressurization. These morphologic differences show that the internal failure mechanics of lumbar intervertebral discs vary with the rate of internal radial load application.

Homeostasis of the intervertebral disc relies on nutrient supply and waste clearance through the dense capillary network that is in contact with the cartilage endplate (CEP). We developed a micro-computerized tomography (micro-CT) method to quantify the marrow contact channel surface (MCCS) with the CEP and to validate the hypothesis according to which MCCS was correlated to the effective permeability of the vertebral endplate (VEP) and influenced by the mechanical stimuli. The influence of compression loading on local vascularization was investigated. Six 4-week-old skeletally immature pigs were instrumented with left pedicle screws and rod at both T5-T6 and L1-L2 levels to create asymmetrical spine tethers. After 3 months of growth, three cylindrical specimens of the VEP (one central and two lateral right and left) were obtained from both the instrumented and the control levels. We used a previously validated method for measuring permeability. Micro-CT analysis (resolution 12 mu m) yielded a gray-scale 2D-image of the discal end of each specimen converted into a binary 2D-image to derive the MCCS. Correlations between MCCS and effective permeability were assessed. Effective permeability and MCCS were significantly decreased compared to the control group especially on the tethered side (-41..5%, p = 0.004 and -52.5%, p = 0.0009, respectively). Correlations were significant and showed maximal value (r(2) = 0.430, p < 0.0001) on the tethered side involving maximal compressive loadings. Mechanical stimuli, due to unbalanced growth, altered the vascularization and the convective properties of the CEP. The cascade of mechanobiological events should offer perspectives for research on disc degeneration and attempted treatment. (C) 2010 Orthopaedic Research Society.

Impaired nutrition of the intervertebral disc has been hypothesized to be one of the causes of disc degeneration. However, no causal relationship between decreased endplate perfusion and limited nutrient transport has been demonstrated to support this pathogenic mechanism. To determine the importance of endplate perfusion on solute diffusion into the nucleus pulposus and to show causality of endplate perfusion on intranuclear diffusion in large animal lumbar intervertebral discs, diffusive transport into ovine lumbar intervertebral discs was evaluated after inhibiting adjacent vertebral endplate perfusion. Partial perfusion blocks were created in vertebrae close and parallel to both endplates of lumbar discs of anaesthetized sheep. To assess diffusivity of small molecules through the endplate, N(2)O was introduced into the inhalation gas mixture and concentrations of intranuclear N(2)O were measured for 35 min thereafter. Post mortem, procion red was infused through the spinal vasculature and perfusion through the endplate was assessed by quantifying the density of dye-perfused endplate vascular buds in histology sections. Perfusion of the endplates overlying the nucleus pulposus was inhibited by almost 50% in the partially blocked discs relative to the control discs. There was also a nine-fold decreased transport rate of intranuclear N(2)O in partially blocked discs compared with control discs. The density of perfused endplate vascular buds correlated significantly to the amount of transported intranuclear N(2)O (r(2) = 0.52, P = 0.008). The vertebral endplate was demonstrated to be the main route of intravascular solute transport into the nucleus pulposus of intervertebral discs, and inhibition of endplate perfusion can cause inhibited solute transport into the disc intranuclear tissue.

Type 2 diabetes (T2D) adversely affects many tissues, and the greater incidence of discogenic low back pain among diabetic patients suggests that the intervertebral disc is affected too. Using a rat model of polygenic obese T2D, we demonstrate that diabetes compromises several aspects of disc composition, matrix homeostasis, and biomechanical behavior. Coccygeal motion segments were harvested from 6-month-old lean Sprague-Dawley rats, obese Sprague-Dawley rats, and diabetic obese UCD-T2DM rats (diabetic for 69 ± 7 days). Findings indicated that diabetes but not obesity reduced disc glycosaminoglycan and water contents, and these degenerative changes correlated with increased vertebral endplate thickness and decreased endplate porosity, and with higher levels of the advanced glycation end-product (AGE) pentosidine. Consistent with their diminished glycosaminoglycan and water contents and their higher AGE levels, discs from diabetic rats were stiffer and exhibited less creep when compressed. At the matrix level, elevated expression of hypoxia-inducible genes and catabolic markers in the discs from diabetic rats coincided with increased oxidative stress and greater interactions between AGEs and one of their receptors (RAGE). Taken together, these findings indicate that endplate sclerosis, increased oxidative stress, and AGE/RAGE-mediated interactions could be important factors for explaining the greater incidence of disc pathology in T2D.

The vasculature in the outer annulus supplies only the periphery of the disc so that nutrition to the bulk of the disc, including all the inner annulus and nucleus pulposus, is derived from the vertebral epiphyseal end arteries where nutrients diffuse across the cartilaginous endplate to reach the disc. In this regard the vertebral endplate plays an important role in disc nutrition. Compromise of diffusion of nutrients to the disc cells may play a large part in the progression or even initiation of disc degeneration. Increasing evidence suggests that estrogen deficiency also influence the severity of disc degeneration in post-menopausal females. Structural disorganization of the vertebral endplate occurs with disc degeneration, with the most common endplate changes observed clinically being Schmorl's node. Schmorl's node is more commonly seen in post-menopausal women than younger women. Osteosclerosis, osteonecrosis and fibrosis associated with Schmorl's nodes can impede nutrient diffusion into the disc as well as removal of metabolites from the disc. We hypothesize that menopause negatively affects vertebral endplate quality and induces endplate degeneration. This endplate degeneration decreases nutrients diffusion from vertebral body into discs, and also impedes removal of metabolites, leads to further disc degeneration. To confirm our hypothesis, a cross-sectional post-contrast MRI study can be performed in pre-menopausal and post-menopausal women. If the hypothesis is confirmed, then low dose hormone replacement treatment may retard disc degeneration in post menopausal women and thereby limit the consequences associated with disc degeneration such as low back pain.

It is hypothesized that, in a large number of cases of aspecific low back pain, the primary cause of the pain is a fracture of the vertebral endplate caused by compression forces. Clinical studies have shown that, in many low back pain patients, damage of the vertebral bodies and or the intervertebral disc is present. In vitro studies reveal that the most likely type of failure of this anterior part of the spine is a fracture of the endplate as a result of compression. The high incidence of aspecific low back pain concurs with the likeliness of compression fractures of the endplate to occur in everyday life. Furthermore, epidemiological findings and the natural history of low back pain appear to be in line with the proposed hypothesis.

The cartilaginous endplate (CEP) is a thin layer of hyaline cartilage positioned between the vertebral endplate and nucleus pulposus (NP) that functions both as a mechanical barrier and as a gateway for nutrient transport into the disc. Despite its critical role in disc nutrition and degeneration, the morphology of the CEP has not been well characterized. The objective of this study was to visualize and report observations of the CEP three-dimensional morphology, and quantify CEP thickness using an MRI FLASH (fast low-angle shot) pulse sequence.MR imaging of ex vivo human cadaveric lumbar spine segments (N = 17) was performed in a 7T MRI scanner with sequence parameters that were selected by utilizing high-resolution T1 mapping, and an analytical MRI signal model to optimize image contrast between CEP and NP. The CEP thickness at five locations along the mid-sagittal AP direction (center, 5 mm, 10 mm off-center towards anterior and posterior) was measured, and analyzed using two-way ANOVA and a post hoc Bonferonni test. For further investigation, six in vivo volunteers were imaged with a similar sequence in a 3T MRI scanner. In addition, decalcified and undecalcified histology was performed, which confirmed that the FLASH sequence successfully detected the CEP.CEP thickness determined by MRI in the mid-sagittal plane across all lumbar disc levels and locations was 0.77 ± 0.24 mm ex vivo. The CEP thickness was not different across disc levels, but was thinner toward the center of the disc.This study demonstrates the potential of MRI FLASH imaging for structural quantification of the CEP geometry, which may be developed as a technique to evaluate changes in the CEP with disc degeneration in future applications.

The human vertebral body and intervertebral disc interface forms the region where the cartilaginous endplate, annulus fibrosis and bone of the vertebral body are connected through an intermediate calcified cartilage layer. While properties of both the vertebral body and components of the disc have been extensively studied, limited quantitative data exists describing the microstructure of the vertebral body-intervertebral disc interface in the spine throughout development and degeneration. Quantitative backscattered scanning electron and second harmonic generation confocal imaging were used to collect quantitative data describing the mineral content and collagen fiber orientation across the interface, respectively. Specimens spanned ages 56 days to 84 years and measurements were taken across the vertebral endplate at the outer annulus, inner annulus and nucleus pulposis. In mature and healthy endplates, collagen fibers span the calcified cartilage layer in all regions, including the endplate adjacent to the central nucleus pulposis. We also observed an abrupt transition from high mineral volume fractions (35-50%) to 0% over short distances measuring 3-15 microns in width across the transition from calcified cartilage to unmineralized cartilage. The alignment of collagen fibers at the outer annulus and thickness of the CC layer indicated that collagen fiber mineralization adjacent to the bone may serve to anchor the soft tissue without a gradual change in material properties. Combining backscattered scanning electron microscopy and second harmonic generation imaging on the same sections thus enable a novel assessment of morphology and properties in both mineralized and soft tissues at the vertebral body-intervertebral disc throughout development and aging.

Study design Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts. Objectives To examine morphologic differences between vascular buds in two regions of the vertebral endplate (inner anular and nucleus pulposar). Summary of background data Vascular buds are specific structures present at the vertebral endplate that are important as nourishing channels. There is a significant difference in permeability between the lateral portion (inner anular) and the central portion (nucleus pulposar) of the endplate, the latter usually being permeable and the former being impermeable. Morphologic differences between vascular buds in the two regions have not been investigated previously. Methods Eight 20-week-old rabbits were used. Vascular buds in rabbit vertebral endplates were examined by scanning electron microscopy of corrosion casts. Results The vascular buds in the region of the inner anulus form simple loops, but those in the area near the nucleus pulposus exhibit swollen and complex coil-like loops. Although they differ structurally, the average number of vascular buds per area does not vary between the two regions. Conclusions We suggest that the morphologic difference between the vascular buds in the two regions (inner anular and nucleus pulposar) plays a principal role in permeability at the endplate.

Introduction: The cartilaginous endplate (CEP) is a thin layer of hyaline cartilage which functions as a mechanical barrier between the nucleus pulposus and the vertebral endplate and as a gateway for nutrient transport to the intervertebral disc. To date, the geometry of the CEP has not been well defined. This study visualizes the three-dimensional morphology of the CEP and quantifies CEP thickness via a semi-automatic analysis technique. Methods: Human lumbar motion segments (n=24) were imaged using an optimized 3D FLASH sequence. MRI data were evaluated in the axial and mid-sagittal imaging planes for CEP area, circumference, anterior-posterior width, lateral width, and thickness. CEP thickness was evaluated at five anterior-posterior locations. Results: There was no significant difference in CEP circumference, area, A-P width, or lateral width with respect to superior/inferior location (p>0.7) or disc level (p>0.6) except between L1L2 and L4L5 (p 0.5). Discussion: This study demonstrates the potential for MRI FLASH imaging coupled with automatic geometric quantification in evaluating the CEP as a potential contributor in the degenerative cascade.

Study Design: Comparative biomechanical study. Objective: To determine whether an angular mismatch between the vertebral body replacement (VBR) endplate and the simulated foam vertebral endplate leads to accelerated subsidence in a cyclic compression model of the VBR-vertebra interface. Summary of Background Data: One of the main complications of the VBR surgery is postoperative subsidence and collapse of the VBR implant into the adjacent vertebral bodies. Although numerous factors affecting intervertebral cage subsidence have been cited, few studies have proposed factors responsible for VBR cage subsidence. Methods: Hardwood blocks at 0–30-degree angles and polyurethane foam blocs have been used as base for this experimental setting. One end of the Synex (Synthes) expandable cage was attached to a material testing machine. The endplate of the implant was placed at a similar spot on the block in such a manner that there was an exact match between the Synex endplate and the foam block at 0 degrees, subsequent angled blocks would tilt the foam endplates by the 10-, 20-, and 30-degree increments as needed. Cyclic axial loads were applied in 9 load-unload cycles. Results: Five samples were tested at each mismatch angle (0, 10, 20, and 30 degrees), for a total of 20 trials. Implant subsidence significantly increased for each 10-degree increase in mismatch angle. This effect, however, did not follow a uniform trend at all angles. The curve appeared exponential at 0 degree of angular mismatch, became linear at 10–20 degrees of mismatch, and then demonstrated some ability to resist load at 30 degrees, leading to a plateau at the higher loads. Conclusions: Increasing mismatch angles are an important factor in leading to increased cage subsidence into polyurethane blocks. Consequently, the incidence of subsidence in the clinical setting could be reduced by paying careful attention to ensuring that both the prosthetic and bony endplates are well apposed at the end of surgery.

Adjacent segment degeneration (ASD) is considered as a long-term complication of spinal fusion procedure. Numerous clinical studies have reported some factors related with ASD, but few could address the reason why the incidence of caudal ASD is significantly lower than that of cranial ASD. Because the pedicle of vertebral arch is closer to the superior endplate of vertebrea and its cranial intervertebral disc, there might be some possibilities of malpositions of pedicle probe or screws into the superior vertebral endplate or disc during the procedure of posterior intervertebral fusion. A number of evidences have showed that puncture of intervertebral disc will result in disc degeneration. Thus the authors put forward the hypothesis that intraoperative malposition of pedicle probe or screws might be a cause of ASD at cranial segments.

Summary Introduction Degenerative disc disease (DDD) is a major health problem worldwide. Both Modic lesions and Schmorl’s nodes are considered to correlate with DDD such as low back pain. Modic lesions are the changes of degenerative vertebral endplate and adjacent bone marrow observed on magnetic resonance imaging and are divided into three types. Modic type III lesions are thought to represent extensive subchondral bone sclerosis within the bone marrow of adjacent endplate. The pathological performance of Schmorl’s nodes is cystic lesions around indistinct sclerotic margins and beneath the cartilaginous endplate. Coincidently, there are many similarities between Modic type III lesions and Schmorl’s nodes including pathological appearances, pathogenetic location and related diseases. Hypothesis We hypothesize that Modic type III lesions and Schmorl’s nodes are the same pathological changes, and Modic type III lesions may be the quiescent or incipient pathology phrase of Schmorl’s nodes. The clinical symptoms of DDD are also accompanied by emergence of these pathological changes. Testing A longitudinal study could be used to test this hypothesis. We could measure and analyze whether Modic type III lesions have increased in size or evolved into Schmorl’s nodes as time goes on. Significance This hypothesis explains the possible pathologic process of Modic type III lesions and Schmorl’s nodes. If the hypothesis were conformed, Modic type III lesions and Schmorl’s nodes will be rediscovered, which provides the new basis for the clinical treatment of DDD. In additions, this hypothesis also has crucial significances for the classification of Modic lesions.

The vertebral endplates are critical for maintaining disc function yet like other components of the disc are vulnerable to degeneration. This paper provides an overview of the development and normal function of the endplates as well as an impression of what happens when they undergo progressive degeneration. Recent research suggests that the degenerative process can be retarded or reversed.

Background: Disc degeneration and other radiological abnormalities are highly frequent among young athletes in sports with great demands on the back. It has also been reported that athletes with these abnormalities have more back pain than other athletes and non-athletes. There is, however, incomplete knowledge regarding the effect of intensive physical loading on the spine, at what age various abnormalities occur and regarding the long-term effects on the morphological abnormalities and on the occurrence of back pain. Aims: It was hypothesised that high loads on the spines of athletes are correlated to an increased frequency of abnormalities and to back pain. The aim was to study the long-term outcome with regard to MRI-abnormalities and back pain. With the aid of an experimental porcine model, an aim was also to try to elucidate the mechanisms behind traumatic displacement of the ring apophysis, disc degeneration and endplate injuries found in adolescent athletes.Methods: Clinical studies: Twenty young elite divers were studied longitudinally (5 years) regarding MRI changes in the thoracolumbar spine and back pain symptoms. The frequency of MRI changes and back pain were also studied longitudinally (15 years) in 71 athletes (weight-lifters, wrestlers, orienteers, ice-hockey players) and 21 non-athletes. Back pain was assessed by questionnaires. Experimental studies: Normal discs and discs with experimentally-induced degeneration from young pigs were mechanically loaded in axial compression, flexion compression and extension compression to failure. The compression load and angle at failure were measured. The segments were then examined for injuries using X-ray, MRI and morphological and histological techniques. Additionally, a group of intervertebral discs with experimentally-induced degeneration were histologically examined regarding reactive and degenerative changes. Results and conclusions: Clinical studies: At the baseline assessment, MRI changes (primarily reduced disc signal) were found in 65% of the young elite divers and at 5 year follow-up deterioration had occurred in half the cases. New abnormalities in previously unaffected individuals occurred in only one case. Current or previous back pain was reported in 89%. Among the four groups of athletes, an even higher prevalence of MRI changes (91%) was found, while back pain was found in 78%. Disc degeneration was the most prevalent abnormality, and it progressed in a large proportion. Experimental studies: The spine in this porcine model was more susceptible to trauma in extension compression than in flexion compression Flexion compression and extension compression caused a fracture or separation of the endplate from the vertebral body in the growth zone in both normal and degenerated discs from young pigs. Axial compression of degenerated discs caused a fracture through the endplate and dorsal part of the vertebral body. In the histological study, the main finding was the demonstration of reactive repair processes that had replaced injured and degenerative structures with vascularised scar tissue. In conclusion, elite athletes run a high risk of developing disc degeneration and back pain. The growth zone and the endplate are the weakest parts in both normal and degenerated discs in growing porcine lumbar spines, when loaded in axial compression, flexion compression and extension compression. Neo-vascularisation of the central parts of the disc is likely to be of key importance in turning the degenerative features of the remaining tissue into reactive more normal structures.

This review will acquaint the reader with normal development, structure, and function of the intervertebral disc. The disc is composed of the vertebral endplate, nucleus pulposus, and annulus fibrosus. These three functional components all serve important purposes for health and function of the disc. Nutrition and biomechanics are also discussed. The molecular basis of disc degeneration is reviewed so that biologic approaches to the reversal and or treatment of disc degeneration may be better understood.

Total disc replacement is an exciting technology that may one day replace fusion as the gold standard treatment for DDD, but it is currently an experimental procedure in the United States. Promising short- and mid-term results have been reported for TDR, but longer follow-up and randomized trials comparing TDR to fusion and nonsurgical treatment are needed to fully define the role of TDR in the spine surgeon's armamentarium. Short-term complication rates have been acceptably low, but in the long term the durability of TDR implants and the vertebral endplate will provide challenges. Finally, it is essential that practitioners understand that a limited subset of patients are good candidates for TDR and that indiscriminate application of this technology will result in poor outcomes.

Introduction Low back pain (LBP) is a common disorder in the western world and accounts for disability and considerable work absenteeism.1 Lumbar disc degeneration (DD) is associated with LBP.2 It has been suggested that different DD phenotypes should be “split” rather than “lumped” into a single phenotype (DD) so as to allow a more meaningful interrogation of the pathogenic processes underlying the constituent traits.3 One trait of special interest is vertebral endplate or Modic change (MC), which comprises vertebral endplate and bone marrow lesions seen on magnetic resonance imaging (MRI).4 This trait has been found to be associated with LBP in some,5 but not all studies.6 MC is classified into three different types: types I-III. Whether MC is entirely environmental in origin, or whether it is influenced by underlying genetic factors, has not been established. Our purpose was to study (1) the prevalence of MC, (2) the progression of MC over a 10-year follow-up, and (3) the heritability of MC prevalence in a classical twin study. Materials and Methods The study population was recruited from TwinsUK register between 1996 and 2000 when the baseline spine MRI study was performed as previously described7 and at follow-up a decade later.3 MC was evaluated from T2-weighted lumbar MRI. Both rostral and caudal endplates of each lumbar segment were coded using the same method at baseline and follow-up.8 The maximum depth and width of each MC was evaluated and the size index was calculated. Heritability was estimated using variance components analysis. MRI with appropriate data was available for 831 twins at baseline and for 436 twins at follow-up. In total, both baseline and follow-up imaging were available for 347 twins. Results Mean age of the study population at baseline was 54.1 years (range, 45.7-62.5) and females comprised 96%. The prevalence of MC at baseline was 32.1% and at follow-up was 48.4%. The incidence of new MC at any level during the 10-year follow-up was 21.6% and was most frequent at L4-L5 and L5-S1. MC regressed totally in 3.5% of twins. The volume of the MC lesions increased during follow-up: the median MC size index summary score was 10.0 (interquartile range = 5.0-18.0) at baseline and 13.5 (interquartile range = 8.0-21.75) at follow-up ( p = 0.012). Twins with prevalent MC at baseline demonstrated a higher incidence of MC at upper lumbar levels compared with twins without baseline MC ( p = 0.015). Probandwise concordance rates were higher in monozygotic (0.56) than dizygotic twin pairs (0.39) suggestive of familial influence. Heritability of MC prevalence was estimated using variance components analysis to be 30 (16-43)%. Conclusion This is the first study to assess the heritability of MC. This study suggests that MC is heritable and progressive in middle age. Further work is needed to define the relationship of MC and lumbar DD. That MC shows a degree of heritability suggests that it is reasonable to search for genetic variants. Disclosure of Interest None declared References Murray CJ, Vos T, Lozano R, et al. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012;380(9859):2197–2223 Livshits G, Popham M, Malkin I, et al. Lumbar disc degeneration and genetic factors are the main risk factors for low back pain in women: the UK Twin Spine Study. Ann Rheum Dis 2011;70(10):1740–1745 Williams FM, Popham M, Sambrook PN, Jones AF, Spector TD, MacGregor AJ. Progression of lumbar disc degeneration over a decade: a heritability study. Ann Rheum Dis 2011;70(7):1203–1207 Modic MT, Steinberg PM, Ross JS, Masaryk TJ, Carter JR. Degenerative disk disease: assessment of changes in vertebral body marrow with MR imaging. Radiology 1988;166(1 Pt 1):193–199 Jensen TS, Karppinen J, Sorensen JS, Niinimäki J, Leboeuf-Yde C. Vertebral endplate signal changes (Modic change): a systematic literature review of prevalence and association with non-specific low back pain. Eur Spine J 2008;17(11):1407–1422 Lim CH, Jee WH, Son BC, Kim DH, Ha KY, Park CK. Discogenic lumbar pain: association with MR imaging and CT discography. Eur J Radiol 2005;54(3):431–437 Sambrook PN, MacGregor AJ, Spector TD. Genetic influences on cervical and lumbar disc degeneration: a magnetic resonance imaging study in twins. Arthritis Rheum 1999;42(2):366–372 Jensen TS, Sorensen JS, Kjaer P. Intra- and interobserver reproducibility of vertebral endplate signal (modic) changes in the lumbar spine: the Nordic Modic Consensus Group classification. Acta Radiol 2007;48(7):748–754

Provocative discography is a controversial diagnostic tool for pathologic discs. Modic has identified vertebral endplate signal changes on magnetic resonance imaging (MRI) that are thought to signify advanced discogenic degeneration. These two distinct diagnostic tools are examined to determine if there is association between them. Fifty-three consecutive patients who underwent both investigations were retrospectively reviewed. In discs that had negative T1 MRI findings, 28.2% of patients had concordant pain and 17.3% had discordant pain. In discs with positive T1 MRI findings, 34.8% of patients had concordant pain and 17.4% had discordant pain. 79.5% and 74.4% of levels with patient concordant pain on discography had no endplate changes on T1- and T2 weighted MR images, respectively (compared with 84.5% and 81.7%, respectively, for levels with no patient pain on discography). Our data showed no significant relationship between these distinct diagnostic tools. Further investigation of their relative roles in this application is recommended.

A high prevalence of radiological abnormalities of the spine has been reported in some physically demanding sports. The significance and aetiology of these radiological abnormalities are still a matter of controversy and the long-term effects are not known. The injury patterns were studied in 16 adolescent human cadaveric spinal motion segments (vertebra-disc-vertebra) when axially compressed to failure. Injuries were found in the region of the growth plate of the vertebral body. This injury pattern differs from that in earlier studies of adult spines, where fractures to the spongious bone under an intact endplate were found. Adolescent porcine spinal lumbar motion segments were axially compressed to failure. In all cases, on microscopic and histological examination, a fracture line could be seen through the epiphyseal plate and through the growth zone. The fracture site was filled with material from the nucleus pulposus and there was a loss of nucleus content in the disc. The injuries could be seen on magnetic resonance imaging but not on plain radiography. By comparison, when axially compressed to failure, adult porcine motion segments did not show this type of injury. Instead there was a fracture of the vertebra or a rupture of the anulus fibrosus. Radiological changes in the thoraco-lumbar spine and the frequency of back pain were investigated in a 12-15-year follow-up study of 135 top athletes and a reference group of 28 non-athletes. Radiological abnormalities of various types were found in all the groups of athletes and non-athletes, but they were more common among athletes, especially male gymnasts and wrestlers. A deterioration in the disc height during the follow-up period was significantly more common among wrestlers than non-athletes. There was no significant correlation between the number of radiographic abnormalities and back pain. Despite a higher frequency of radiographic abnormalities among the groups of athletes, they did not report significantly more back pain than non-athletes. However, a decrease in disc height between the two examinations correlated significantly with back pain at follow-up. In conclusion, the study supports the view that the spine is most vulnerable to athletic trauma during the growth period. Injuries to the disc in particular appear to be at risk of long-term radiological deterioration and subsequent back pain.

The increase of low back problems has stimulated the development of different analysis and evaluation techniques. Among these methods, the direct linear transformation (DLT) technique is commonly used to reconstruct the spine in three dimensions by means of its known image coordinates on radiographs. Despite its efficiency and precision, general reconstruction of some standard anatomical landmarks (7-11) does not give all the necessary data for a detailed analysis of the intrinsic geometrical characteristics of lumbar vertebrae. Thus, in order to obtain such geometrical information a three-dimensional (3-D) reconstruction vertebral endplate contour technique has been developed. This technique involves 1) iterative optimization and reconstruction processes of the vertebral endplate centroid and 2) 3-D reconstruction of vertebral endplate contour. Validation based on mathematical simulations demonstrated that two or three iterations are necessary to correct (within 2 mm) the endplate centroid position for simulated error higher than 10 mm. Other validations based on 3-D reconstructions of a chamfered tube and a dry vertebra contours of known dimensions have given mean errors of 2 mm. Application on a healthy subject demonstrated the potential of this 3-D reconstruction technique. Finally, 3-D data obtained on vertebral endplates would allow the development of new clinical measurements that could be used to evaluate the lumbar spine geometrical behavior and orthoses biomechanical effects.