Convergence analysis and validation of a discrete element model of the human lumbar spine

Degenerative diseases of the spine can lead to or hasten the onset of additional spinal problems that significantly reduce human mobility. The spine consists of vertebral bodies and intervertebral discs. The most degraded are intervertebral discs. The vertebral body consists of a shell (cortical bone tissue) and an internal content (cancellous bone tissue). The intervertebral disc is a complex structural element of the spine, consisting of the nucleus pulposus, annulus fibrosus, and cartilaginous plates. To develop numerical models for the vertebral body and intervertebral disc, first, it is necessary to verify and validate the models for the constituent elements of the lumbar spine. This paper, for the first time, presents discrete elements-based numerical models for the constituent parts of the lumbar spine, and their verification and validation. The models are validated using uniaxial compression experiments available in the literature. The model predictions are in good qualitative and quantitative agreement with the data of those experiments. The loading rate sensitivity analysis revealed that fluid-saturated porous materials are highly sensitive to loading rate: a 1000-fold increase in rate leads to the increase in effective stiffness of 130 % for the intervertebral disc, and a 250-fold increase in rate leads to the increase in effective stiffness of 50 % for the vertebral body. The developed model components can be used to create an L4-L5 segment model, which, in the future, will allow investigating the mechanical behavior of the spine under different types of loading.

Laser Reconstruction of Spinal Discs Experiments and Clinic

Degenerative disease of the intervertebral discs (DDD) is currently a serious problem facing the world community. The surgical methods and conservative therapy used today, unfortunately, do not stop the pathological process, but serve as a palliative method that temporarily relieves pain and improves the patient’s quality of life. Therefore, at present, there is an active search for new methods of treating DDD. Among new techniques of treatment, biological methods, and minimally invasive surgery, including the use of laser radiation, which, depending on the laser parameters, can cause ablative or modifying effects on the disc tissue, have acquired considerable interest. Here, we analyze a new approach to solving the DDD problem: laser tissue modification. This review of publications is focused on the studies of the physicochemical foundations and clinical applications of a new method of laser reconstruction of intervertebral discs. Thermomechanical action of laser radiation modifies tissue and leads to its regeneration as well as to a long-term restoration of disc functions, elimination of pain and the return of patients to normal life.

Neck pain: diagnostic and therapeutic features

Neck pain is a fairly common complaint when visiting a doctor, its occurrence frequency is 10–21% per year, and neck pain takes the 4th place among the causes of disability; almost 50% of patients continue to experience unpleasant sensations or repeated pain episodes. The elderly people are the most prone to the neck pain, this is associated with the progressive degenerative changes in the facet joints and intervertebral discs. However, reasons of this symptom can be of different kinds. Cervicalgia diagnosis is directed primarily to eliminate symptomatic pains associated with severe somatic pathology, immune diseases, infections and oncology. Comorbid diseases and risk factors can combine with each other causing the polyetiologic pain syndrome. Main steps of the cervicalgia diagnostic algorithm are the following: collection of complaints and anamnesis in detail, physical and neurological examination, and also use of visualization methods. Visualization and electrodiagnostic methods are not always informative for patients with chronic cervicalgia and in the degenerative etiology of the syndrome. MRI and the surgeon consultation must be recommended to patients with deteriorating neurological symptoms or with long-term constant pain. Conservative therapy of cervicalgia implies a combination of non-drug methods (compliance with regime, orthopedic treatment, leaf, physiotherapy, etc.) and pharmacotherapy. The last depends on the presence of a neuropathic component of pain and the duration of pain syndrome. The pain therapy with a nociceptive nature is usually implies a combination of non-steroidal anti-inflammatory remedies, non-opioid analgesics and muscle relaxants. Whereas neuropathic pains first-line preparations are tricyclic antidepressants, duloxetine, venlafaxine, pregabalin, gabapentine. The therapy success depends on the proper individual estimation of the pain factors, pain chronization and possible treatment complications. The therapeutic forecast of the acute nonspecific cervicalgia is usually good, but it becomes less predictable if the pain acquires chronic character.

Tomodensitometric Bone Anatomy of The Intervertebral Foramen of The Lower Cervical Spine: Measurements and Comparison of Foraminal Volume in Healthy Individuals and Patients Suffering from Cervicobrachial Neuralgia Due to Foraminal Stenosis.

Purpose Degenerative foraminal stenosis of the cervical spine can lead to cervicobrachial neuralgias. Computed tomography (CT)-scan assists in the diagnosis and evaluation of foraminal stenosis. The main objective of this study is to determine the bony dimensions of the cervical intervertebral foramen and to identify which foraminal measurements are most affected by degenerative disorders of the cervical spine. These data could be applied to the surgical treatment of this pathology, helping surgeons to focus on specific areas during decompression procedures. Methods A descriptive study was conducted between two groups: an asymptomatic one (young people with no evidence of degenerative cervical spine disorders) and a symptomatic one (experiencing cervicobrachial neuralgia due to degenerative foraminal stenosis). Using CT scans, we determined a method allowing measurements of the following foraminal dimensions: foraminal height (FH), foraminal length (FL), foraminal width in its lateral part ((UWPP, MWPP and IWPP (respectively Upper, Medial and Inferior Width of Pedicle Part)) and medial part (UWMP, MWMP and IWMP (respectively Upper, Medial and Inferior Width of Medial Part)), and disk height (DH). Foraminal volume (FV) was calculated considering the above data. Mean volumes were measured in the asymptomatic group and compared to the values obtained in the symptomatic group. Results Both groups were made up of 10 patients, and a total of 50 intervertebral discs (100 intervertebral foramina) were analyzed in each group. Comparison of C4C5, C5C6 and C6C7 levels between both groups showed several significant decreases in foraminal dimensions (p< 0,05) as well as in foraminal volume (p <0.001) in the symptomatic group. The most affected dimensions were UWPP, MWPP, UWMP, MWMP and FV. The most stenotic foraminal areas were the top of the uncus and the posterior edge of the lower plate of the overlying vertebra. Conclusion Using a new protocol for measuring foraminal volume, the present study refines the current knowledge of the normal and pathological anatomy of the lower cervical spine and allows us to understand the foraminal sites most affected by degenerative stenosis. Those findings can be applied to foraminal stenosis surgeries. According to our results, decompression of the foramen in regard of both uncus osteophytic spurs and inferior plate of the overlying vertebra might be an important step for nerve roots release.

Intervertebral disc degeneration in warmblood horses: Histological and biochemical characterization

Gross morphology of healthy and degenerated intervertebral discs (IVDs) is largely similar in horses as in dogs and humans. For further comparison, the biochemical composition and the histological and biochemical changes with age and degeneration were analyzed in 41 warmblood horses. From 33 horses, 139 discs and 2 fetal vertebral columns were evaluated and scored histologically. From 13 horses, 73 IVDs were assessed for hydration, DNA, glycosaminoglycans, total collagen, hydroxyl-lysyl-pyridinoline, hydroxylysine, and advanced glycation end-product (AGE) content. From 7 horses, 20 discs were assessed for aggrecan, fibronectin, and collagen type 1 and 2 content. Histologically, tearing of the nucleus pulposus (NP) and cervical annulus fibrosus (AF), and total histological score (tearing and vascular proliferation of the AF, and chondroid metaplasia, chondrocyte-like cell proliferation, presence of notochordal cells, matrix staining, and tearing of the NP) correlated with gross degeneration. Notochordal cells were not seen in IVDs of horses. Age and gross degeneration were positively correlated with AGEs and a fibrotic phenotype, explaining gross degenerative changes. In contrast to dogs and humans, there was no consistent difference in glycosaminoglycan content and hydration between AF and NP, nor decrease of these variables with age or degeneration. Hydroxylysine decrease and collagen 1 and AGEs increase were most prominent in the NP, suggesting degeneration started in the AP. In caudal cervical NPs, AGE deposition was significantly increased in grossly normal IVDs and total collagen significantly increased with age, suggesting increased biomechanical stress and likelihood for spinal disease in this part of the vertebral column.

Mechanism of Long Noncoding RNA HOTAIR in Nucleus Pulposus Cell Autophagy and Apoptosis in Intervertebral Disc Degeneration

Objective. Intervertebral disc degeneration (IDD) contributes to cervical and lumbar diseases. Long noncoding RNAs (lncRNAs) are implicated in IDD. This study explored the mechanism of lncRNA HOTAIR in IDD. Methods. Normal and degenerative nucleus pulposus (NP) cells were isolated from NP tissues obtained in intervertebral disc surgery. Cell morphology was observed by immunocytochemistry staining and toluidine blue staining. NP cell markers were detected by RT-qPCR. Proliferation was detected by MTT assay. Autophagy-related proteins were detected by Western blot. Autophagosome was observed by monodansylcadaverine fluorescence staining. Apoptosis was detected by TUNEL staining and flow cytometry. si-HOTAIR and/or miR-148a inhibitor was introduced into degenerative NP cells. Binding relationships among HOTAIR, miR-148a, and PTEN were predicted and verified by dual-luciferase reporter assay and RNA pull-down. Finally, IDD rat models were established. Rat caudal intervertebral discs were assessed by HE staining. Expressions of HOTAIR, miR-148a, and PTEN were determined by RT-qPCR. Results. HOTAIR was highly expressed in degenerative NP cells p < 0.05 . si-HOTAIR inhibited degenerative NP cell apoptosis and autophagy p < 0.05 . HOTAIR upregulated PTEN as a sponge of miR-148a. miR-148a was poorly expressed in degenerative NP cells. miR-148a deficiency partially reversed the inhibition of si-HOTAIR on degenerative NP cell autophagy and apoptosis (all p < 0.05 ). In vivo assay confirmed that si-HOTAIR impeded autophagy and apoptosis in intervertebral disc tissues, thus improving pathological injury in IDD rats (all p < 0.05 ). Conclusion. LncRNA HOTAIR promoted NP cell autophagy and apoptosis via promoting PTEN expression as a ceRNA of miR-148a in IDD.

MRI RESEARCH OF THE CAUSES OF PAIN SYNDROMES IN THE BACK AND OSTEOCHONDROSIS OF THE SPINE

The aim of the study was to search for organic changes in the tissues of the spine that are the cause of pain syndromes in the back and spine. With the help of MRI, the state of the muscular corset of the spine was diagnosed and the violations found were compared with the localization of pain syndromes in the back and the localization of dystrophic manifestations in the vertebrae and intervertebral discs. In 70 patients who underwent MRI examinations of areas with pain syndromes in the back, it was shown that osteochondrosis of the spine is preceded by spastic conditions of the intervertebral muscles, leading to disruption of trophism of the vertebrae and intervertebral discs, as well as to the development of pain syndromes.