Morphological changes in the human cervical intervertebral disc post trauma: response to fracture-type and degeneration grade over time

Comparison of the Outcomes between AO Type B2 Thoracolumbar Fracture with and without Disc Injury after Posterior Surgery

Objective

The type AO B2 thoracolumbar fracture is a kind of flexion‐distraction injury and the effect of disc injury on treatment results of patients with B2 fracture remains unclear. The objective of the current study was to compare and analyze the outcomes in AO Type B2 thoracolumbar fracture patients with and without disc injuries in terms of the Cobb angle of kyphosis, the incidence of complication, and the rate of implant failure.

Methods

This is a retrospective study. Of the 486 patients with thoracolumbar fractures who underwent posterior fixation, 38 patients with AO type B2 injuries were included. All the patients were divided into two groups according to changes in the adjoining discs. Disc injury group A included 17 patients and no disc injury group included 21 patients. Clinical and radiologic parameters were evaluated before surgery, after surgery, and at follow‐up. Clinical outcomes included visual analogue scale (VAS) scores, incidence of complications, and incidence of implant failure. Radiologic assessment was accomplished with the Cobb angle (CA), local kyphosis (LK), percentage of anterior vertebral height (AVBH%), intervertebral disc height, and intervertebral disc angle. Fisher's precision probability tests were employed and chi square test were used to compare categorical variables. Paired sample t tests and independent‐sample t tests were used to compare continuous data.

Results

Disc injury mainly involved the cranial disc (15/19, 78.9%). The mean follow‐up period for the patients was 30.2 ± 20.1 months. No neurologic deterioration was reported in the patients at the last follow‐up. Radiological outcomes at the last follow‐up showed significant differences in the CA (18.59° ± 13.74° vs 8.16° ± 9.99°, P = 0.008), LK (12.74° ± 8.00° vs 6.55° ± 4.89°, P = 0.006), and %AVBH (77.16% vs 90.83%, P = 0.01) between the two groups.Implant failure occurred after posterior fixation in five patients with disc injury who did not undergo interbody fusion during the initial surgery. Additionally, in the subgroup analysis, interbody fusion in the implant failure group were significantly different than in the no implant failure group (0% vs 75%, P = 0.009).

Conclusions

AO B2 fracture patients with disc injury have higher risk of complications, especially implant failure after posterior surgery. Interbody fusion should be considered in AO type B2 fracture patients with disc injury.

Neonatal Enthesis Healing Involves Noninflammatory Acellular Scar Formation through Extracellular Matrix Secretion by Resident Cells

Wound healing typically recruits the immune and vascular systems to restore tissue structure and function. However, injuries to the enthesis, a hypocellular and avascular tissue, often result in fibrotic scar formation and loss of mechanical properties, severely affecting musculoskeletal function and life quality. This raises questions about the healing capabilities of the enthesis. Herein, this study established an injury model to the Achilles entheses of neonatal mice to study the effectiveness of early-age enthesis healing. Histology and immunohistochemistry analyses revealed an atypical process that did not involve inflammation or angiogenesis. Instead, healing was mediated by secretion of collagen types I and II by resident cells, which formed a permanent hypocellular and avascular scar. Transmission electron microscopy showed that the cellular response to injury, including endoplasmic reticulum stress, autophagy, and cell death, varied between the tendon and cartilage ends of the enthesis. Single-molecule in situ hybridization, immunostaining, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays verified these differences. Finally, gait analysis showed that these processes effectively restored function of the injured leg. These findings reveal a novel healing mechanism in neonatal entheses, whereby local extracellular matrix secretion by resident cells forms an acellular extracellular matrix deposit without inflammation, allowing gait restoration. These insights into the healing mechanism of a complex transitional tissue may lead to new therapeutic strategies for adult enthesis injuries.

Fate of the intervertebral disc and analysis of its risk factors following high-energy traumatic thoracic and lumbar fractures: MRI results of minimum five years after injury

OBJECTIVE

Disc degenerative disease is regarded as the primary cause of low back pain. The purpose of this study was to clarify the fate of Intervertebral disc (IVD) following the traumatic event through long-term follow-up and to identify the risk factors for irrevocable degeneration.

METHODS

78 non-operative patients who had traumatic fracture of the thoracic or lumbar at minimum 5 years before were enrolled. Disc degeneration was assessed by modified Pfirrmann grading system. The Acceleration of disc degeneration (ADD) was defined as the difference of grade between IVD adjacent to fractured vertebra and their neighbors with increasing grade from 0 to 7. A novel classification of Endplate injury (EPI) with increasing severity from type I to III was proposed based on the injured morphology. The long-term fate of IVD adjacent to fractured vertebra and risk factors for ADD were analyzed.

RESULTS

The mean time of last follow-up was 15.4 ± 10.8 years (range 5-49 years) after injury. 138 (68.66%) IVDs were graded 0 of ADD, 44 (21.89%) were 1-3 and 19 (9.45%) were 4-7. Multivariate binary logistic regression analyses showed that injured posterior ligamentous complex (PLC) and EPI type III were independent risk factors for ADD.

CONCLUSIONS

Injured PLC and EPI type III were independent risk factors for ADD in patients with traumatic thoracic or lumbar fracture. For such patients without risk factors for ADD, the non-intervertebral fusion should be given a priority if surgery is necessary.

Traumatic vertebra and endplate fractures promote adjacent disc degeneration: evidence from a clinical MR follow-up study

OBJECTIVES

The integrity of endplate is important for maintaining the health of adjacent disc and trabeculae. Yet, pathological impacts of traumatic vertebra and endplate fractures were less studied using clinical approaches. This study aims to investigate their effects on the development of adjacent disc degeneration, segmental kyphosis, Modic changes (MCs), and high-intensity zones (HIZs).

MATERIALS AND METHODS

Magnetic resonance (MR) images of patients with acute traumatic vertebral compression fractures (T11-L5) were studied. On MR images, endplate fractures were evaluated as present or absent. Disc signal, height, bulging area, sagittal Cobb angle, MCs, and HIZs were measured on baseline and follow-up MR images to study the changes of the disc in relation to vertebra fractures and endplate fractures.

RESULTS

Ninety-seven patients were followed up for 15.4 ± 14.0 months. There were 123 fractured vertebrae, including 79 (64.2%) with endplate fractures and 44 (35.8%) without. Both the adjacent and control discs decreased in signal and height over time (p < 0.001), and the disc adjacent to vertebral fractures had greater signal and height loss than the control disc (p < 0.05). In the presence of endplate fractures, the adjacent discs had greater signal decrease in follow-up (p < 0.05), as compared to those without endplate fractures. Sagittal Cobb angle significantly increased in segments with endplate fractures (p < 0.05). Vertebra fractures were associated with new occurrence of MCs in the fractured vertebra (p < 0.001) but not HIZs in the adjacent disc.

CONCLUSIONS

Traumatic vertebral fractures were associated with accelerated adjacent disc degeneration, which appears to be further promoted by concomitant endplate fractures. Endplate fractures were associated with progression of segmental kyphosis.

Degenerative Cervical Myelopathy: Insights into Its Pathobiology and Molecular Mechanisms

Degenerative cervical myelopathy (DCM), earlier referred to as cervical spondylotic myelopathy (CSM), is the most common and serious neurological disorder in the elderly population caused by chronic progressive compression or irritation of the spinal cord in the neck. The clinical features of DCM include localised neck pain and functional impairment of motor function in the arms, fingers and hands. If left untreated, this can lead to significant and permanent nerve damage including paralysis and death. Despite recent advancements in understanding the DCM pathology, prognosis remains poor and little is known about the molecular mechanisms underlying its pathogenesis. Moreover, there is scant evidence for the best treatment suitable for DCM patients. Decompressive surgery remains the most effective long-term treatment for this pathology, although the decision of when to perform such a procedure remains challenging. Given the fact that the aged population in the world is continuously increasing, DCM is posing a formidable challenge that needs urgent attention. Here, in this comprehensive review, we discuss the current knowledge of DCM pathology, including epidemiology, diagnosis, natural history, pathophysiology, risk factors, molecular features and treatment options. In addition to describing different scoring and classification systems used by clinicians in diagnosing DCM, we also highlight how advanced imaging techniques are being used to study the disease process. Last but not the least, we discuss several molecular underpinnings of DCM aetiology, including the cells involved and the pathways and molecules that are hallmarks of this disease.

Elevated lymphotoxin-α (TNFβ) is associated with intervertebral disc degeneration

Background

Intervertebral disc degeneration (IVDD) is a primary cause of degenerative disc diseases; however, the mechanisms underlying the degeneration remain unclear. The immunoinflammatory response plays an important role in IVDD progression. The inflammatory cytokine lymphotoxin-α (LTα), formerly known as TNFβ, is associated with various pathological conditions, while its role in the pathogenesis of IVDD remains elusive.

Methods

Real-time quantitative polymerase chain reaction (RT-qPCR), Western blotting (WB), and enzyme-linked immunosorbent assays were used to assess the levels of LTα in human nucleus pulposus (NP) tissues between degeneration and control groups. The plasma concentrations of LTα and C-reactive protein (CRP) were compared between healthy and IVDD patients. Rat primary NP cells were cultured and identified via immunofluorescence. Methyl-thiazolyl-tetrazolium assays and flow cytometry were used to evaluate the effects of LTα on rat NP cell viability. After NP cells were treated with LTα, degeneration-related molecules (Caspase-3, Caspase-1, matrix metalloproteinase (MMP) -3, aggrecan and type II collagen) were measured via RT-qPCR and WB.

Results

The levels of both the mRNA and protein of LTα in human degenerated NP tissue significantly increased. Plasma LTα and CRP did not differ between healthy controls and IVDD patients. Rat primary NP cells were cultured, and the purity of primary NP cells was > 90%. Cell experiments showed inversely proportional relationships among the LTα dose, treatment time, and cell viability. The optimal conditions (dose and time) for LTα treatment to induce rat NP cell degeneration were 5 μg/ml and 48 ~ 72 h. The apoptosis rate and the levels of Caspase-3, Caspase-1, and MMP-3 significantly increased after LTα treatment, while the levels of type II collagen and aggrecan were decreased, and the protein expression levels were consistent with their mRNA expression levels.

Conclusions

This study demonstrated that elevated LTα is closely associated with IVDD and that LTα may induce NP cell apoptosis and reduce important extracellular matrix (ECM) proteins, which cause adverse effects on IVDD progress. Moreover, the optimal conditions for LTα treatment to induce NP cell degeneration were determined.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03934-7.

Differential proteomic analysis of fetal and geriatric lumbar nucleus pulposus: immunoinflammation and age-related intervertebral disc degeneration

BACKGROUND

Intervertebral disc degeneration (IVDD) is a major cause of low back pain. Although the mechanism of degeneration remains unclear, aging has been recognized as a key risk factor for IVDD. Most studies seeking to identify IVDD-associated molecular alterations in the context of human age-related IVDD have focused only on a limited number of proteins. Differential proteomic analysis is an ideal method for comprehensively screening altered protein profiles and identifying the potential pathways related to pathological processes such as disc degeneration.

METHODS

In this study, tandem mass tag (TMT) labeling was combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for differential proteomic analysis of human fetal and geriatric lumbar disc nucleus pulposus (NP) tissue. Parallel reaction monitoring (PRM) and Western blotting (WB) techniques were used to identify target proteins. Bioinformatic analyses, including Gene Ontology (GO) annotation, domain annotation, pathway annotation, subcellular localization and functional enrichment analyses, were used to interpret the potential significance of the protein alterations in the mechanism of IVDD. Student's t-tests and two-tailed Fisher's exact tests were used for statistical analysis.

RESULTS

Six hundred forty five proteins were significantly upregulated and 748 proteins were downregulated in the geriatric group compared with the fetal group. Twelve proteins were verified to have significant differences in abundance between geriatric and fetal NP tissue; most of these have not been previously identified as being associated with human IVDD. The potential significance of the differentially expressed proteins in age-related IVDD was analyzed from multiple perspectives, especially with regard to the association of the immunoinflammatory response with IVDD.

CONCLUSIONS

Differential proteomic analysis was used as a comprehensive strategy for elucidating the protein alterations associated with age-related IVDD. The findings of this study will aid in the screening of new biomarkers and molecular targets for the diagnosis and therapy of IVDD. The results may also significantly enhance our understanding of the pathophysiological process and mechanism of age-related IVDD.

Disk injury in patients with vertebral fractures-a prospective diagnostic accuracy study using dual-energy computed tomography

OBJECTIVES

Using magnetic resonance imaging (MRI) as the standard of reference, we aimed to evaluate the diagnostic accuracy of dual-energy computed tomography (DECT) in assessing disk injuries in patients aged more than 50 years with vertebral fractures.

METHODS

This prospective study was approved by the local ethics committee (EA1/372/14), and all patients gave written informed consent. Patients with suspected fractures underwent spinal DECTs and MRIs. Three readers scored DECT collagen maps for the presence or absence of disk injuries and also scored MR images according to the Sander classification (0-3). Only disks at risk (target disks) were included in the analysis. Sensitivity and specificity were calculated. Fleiss's κ was used to evaluate interrater agreement. Attenuation, in Hounsfield units, was compared between affected and unaffected disks in DECT.

RESULTS

Analyzing 295 disks in 67 patients, DECT was both sensitive (0.85) and specific (0.75). Sensitivity varied with the severity of disk damage, as assessed using the Sander scale (grade 1, 0.80; 2, 0.85; and 3, 0.98). Fleiss's κ was 0.41 for MRI and 0.51 for DECT. In the DECT collagen maps, attenuation was lower in injured disks compared to that in normal disks (80.3 ± 35.2 vs. 97.9 ± 41.0, p < 0.001).

CONCLUSIONS

Compared to conventional CT, DECT collagen maps can yield more diagnostic information, allowing identification of disk injuries in elderly patients with vertebral fractures.

KEY POINTS

• Dual-energy computed tomography allows vertebral disk injuries to be detected in elderly patients with vertebral fractures. • Dual-energy computed tomography yields more diagnostic information about vertebral disks compared to conventional CT. • Dual-energy computed tomography can be used as an alternative imaging modality for patients unwilling or unable to undergo MRI.

Role of magnetic resonance imaging in acute spinal trauma: a pictorial review

Magnetic resonance imaging (MRI) has been playing an increasingly important role in the spinal trauma patients due to high sensitivity for detection of acute soft tissue and cord injuries. More and more patients are undergoing MRI for spinal trauma in the emergency settings, thus necessitating the interpreting physicians to be familiar with MRI findings in spinal trauma. In this pictorial review, we will first describe the normal anatomy of various ligamentous structures. Indications of MRI in spinal trauma as well as the role of MRI in diagnosing spinal cord and soft tissue injuries will then be discussed. Illustrated cases are mainly of cervical spine trauma, but thoracolumbar spine injuries are also included where appropriate in our review.