Experimental rat model for cervical compressive myelopathy

Previously, a rat model of chronic compressive myelopathy that uses a water-absorbing polymer inserted under a spinal lamina was reported. However, the best size and coefficient of expansion of the polymer sheet have not yet been established. The aim of the present study was to optimize these properties in an ideal rat model of cervical compressive myelopathy. Thirty rats were used in this study. A sheet of water-absorbing polymer was inserted under the cervical laminae. Rats were divided randomly into five experimental groups by the expansion rate (350 or 200%) and thickness (0.5 or 0.7 mm) and the control. After the surgery, the severity of paralysis was evaluated for 12 weeks. At 12 weeks after the surgery, cresyl violet staining was performed to assess the number of motor neurons in the anterior horn at the C4/C5 segment and Luxol Fast Blue staining was performed to assess demyelination in the corticospinal tract at the C7 segment. ‘Slow-progressive’ paralysis appeared at 4–8 weeks postoperatively in rat models using sheets with 200% expansion. By contrast, only temporary paralysis was observed in rat models using sheets with 350% expansion. A loss of motor neurons in the anterior horn was observed in all groups, except for the control. Demyelination in the corticospinal tract was observed in rat models using sheets with 200% expansion, but not rat models using sheets with 350% expansion. A polymer sheet that expands its volume by 200% is an ideal material for rat models of cervical compressive myelopathy

A New Framework for Investigating the Biological Basis of Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 5]: Mechanical Stress, Vulnerability and Time

Study design: Literature Review (Narrative). Objective: To propose a new framework, to support the investigation and understanding of the pathobiology of DCM, AO Spine RECODE-DCM research priority number 5. Methods: Degenerative cervical myelopathy is a common and disabling spinal cord disorder. In this perspective, we review key knowledge gaps between the clinical phenotype and our biological models. We then propose a reappraisal of the key driving forces behind DCM and an individual\u27s susceptibility, including the proposal of a new framework. Results: Present pathobiological and mechanistic knowledge does not adequately explain the disease phenotype; why only a subset of patients with visualized cord compression show clinical myelopathy, and the amount of cord compression only weakly correlates with disability. We propose that DCM is better represented as a function of several interacting mechanical forces, such as shear, tension and compression, alongside an individual\u27s vulnerability to spinal cord injury, influenced by factors such as age, genetics, their cardiovascular, gastrointestinal and nervous system status, and time. Conclusion: Understanding the disease pathobiology is a fundamental research priority. We believe a framework of mechanical stress, vulnerability, and time may better represent the disease as a whole. Whilst this remains theoretical, we hope that at the very least it will inspire new avenues of research that better encapsulate the full spectrum of disease

Management of Degenerative Cervical Myelopathy and Spinal Cord Injury

The present Special Issue is dedicated to presenting current research topics in DCM and SCI in an attempt to bridge gaps in knowledge for both of the two main forms of SCI. The issue consists of fourteen studies, of which the majority were on DCM, the more common pathology, while three studies focused on tSCI. This issue includes two narrative reviews, three systematic reviews and nine original research papers. Areas of research covered include image studies, predictive modeling, prognostic factors, and multiple systemic or narrative reviews on various aspects of these conditions. These articles include the contributions of a diverse group of researchers with various approaches to studying SCI coming from multiple countries, including Canada, Czech Republic, Germany, Poland, Switzerland, United Kingdom, and the United States

Examination of a new arthrodesis technique for equine cervical vertebrae

Objectives – To investigate a new technique for fusion of equine cervical vertebrae: 1. Report the findings from a single case. 2. Examine the biomechanical properties of the construct in cadaver specimens and compare the biomechanical properties with the currently used arthrodesis technique. Study design – Case report, followed by two in vitro biomechanical investigations. Sample population – Single case for the case report then cadaveric adult equine cervical vertebral columns for biomechanical testing. Methods –A three month old foal with cervical stenotic myelopathy was deemed too small for treatment with a kerf cut cylinder, so arthrodesis was performed using a ventrally placed locking compression plate. The case was followed and reported. A test modulus was developed to allow biomechanical testing of a single cervical vertebral articulation and the biomechanical properties of different implants were investigated. The investigation was followed by further investigation in different loading directions. Results –The foal responded well to treatment and had improved 2.5 neurological grades by 30 months post-operatively. Results of the two biomechanical studies demonstrated that the biomechanical properties of the LCP construct were comparable to superior to the KCC constructs in flexion, extension and lateral flexion. Conclusions –The LCP technique has potential as an arthrodesis technique for equine cervical vertebrae. Evaluation of the technique in live adult cases is warranted

Cervical Total Level Arthroplasty System With PEEK All-Polymer Articulations

The cervical spine must provide structural support for the head, allow large range of motion and protect both the spinal cord and branching nerves. There are two types of spinal joints: the intervertebral discs which are flexible connections and the facets, which are articulating synovial joints. Both types degenerate with age. Current surgical treatments include spinal fusion and articulating disc replacement implants. If both disc and facet joints are degenerated, fusion is the only option. In spinal fusion, the disc is removed and the adjacent vertebrae are fused which causes abnormally high stress levels in adjacent discs. In disc replacement, an articulating device is inserted to restore intervertebral motion and mimic healthy spinal kinematics. Disc arthroplasty does not significantly increase adjacent level stress but the lack of rotational constraint causes increased facet contact pressures. Thus, there is a need for a cervical total level arthroplasty system (CTLAS) that has a disc implant specifically designed to preserve the facet joints and implants for facet arthroplasty that can act independently or in-unison with the disc replacement. The conceptual design of a CTLAS implant system was proposed that would replace the disc and the facet joints. To facilitate medical imaging, PEEK (polyetheretherkeytone) was selected as the structural and bearing material. In the present thesis, multi-station pin-on-plate wear testing was initiated for pairs of unfilled (OPT) and carbon-fiber-reinforced (CFR) PEEK. Wear is important in arthroplasty implant design because wear particles can cause osteolysis leading to loosening. A variety of experiments were performed to investigate the effects of load, contact geometry and lubricant composition on wear. CFR PEEK was found to have much lower and more predictable wear than OPT PEEK in the present experiments. The wear of OPT PEEK pairs showed sensitivity to lubricant protein concentration. The coefficient of friction during testing was found to be quite high (up to 0.5), which might have clinical implications. Also, some subsurface fatigue was found, exposing carbon fibers of CFR PEEK. This remains a concern for its long-term application. Further wear testing is recommended using actual implants in a spine wear simulator

Developing Experimental Models of Non-Traumatic Spinal Cord Injury

Over 50% of non-traumatic spinal cord injuries (NTSCI) are caused by mechanical compression either due to osteophytes in degenerative disease, or tumours (New et al., 2014). The pathophysiology of NTSCI is poorly understood, with no distinct injury cascade (Karadimas et al., 2013). The aim of this project was to evaluate cellular responses to mechanical insults in the context of NTSCI. In-vitro, a model was developed to apply high and low velocity compression to astrocyte-seeded collagen hydrogels. Outcomes included hydrogel contraction, GFAP expression, cellular shape, and cytokine release. In-vivo a balloon lesion model was modified to induce a non-traumatic ventral lesion, by developing an injection port and inflating over 3 days. Functional deficits and histological outcomes were assessed. In-vitro, 100 mm.s-1 compression elicited an astrogliotic and inflammatory response from day 11, indicative of TSCI. This comprised a significant increase in GFAP area per cell, astrocyte ramification, and IL-6 expression. Conversely, at <100 mm.s-1, no differences were observed. The findings of this study suggest slow compression of astrocytes alone does not induce NTSCI. In-vivo, surgery was undertaken on 10 animals (including 3 shams). In injury groups, functional deficits were observed , which increased with each inflation. Animals were grouped into mild and severe based on their motor function (severe animals exhibited paraplegia). Minimum motor function correlated with minimum cross-sectional area, and greater parenchyma disruption. In the severe group only, there was a trend of mild astrogliosis, demyelination and vasculature narrowing at the epicentre. This corresponds with the wider literature, where demyelination and disruption to the vasculature are hypothesised to be involved in NTSCI pathology. Overall, in-vitro and in-vivo models of NTSCI have been successfully developed. Physiological changes were observed in both models, with differences to TSCI. Further investigations can be undertaken to understand the pathology of NTSCI

SIMBIO-M 2014, SIMulation technologies in the fields of BIO-Sciences and Multiphysics: BioMechanics, BioMaterials and BioMedicine, Marseille, France, june 2014

Proceedings de la 3ème édition de la conférence internationale Simbio-M (2014). Organisée conjointement par l'IFSTTAR, Aix-Marseille Université, l'université de Coventry et CADLM, cette conférence se concentre sur les progrès des technologies de simulation dans les domaines des sciences du vivant et multiphysiques: Biomécanique, Biomatériaux et Biomédical. L'objectif de cette conférence est de partager et d'explorer les résultats dans les techniques d'analyse numérique et les outils de modélisation mathématique. Cette approche numérique permet des études prévisionnelles ou exploratoires dans les différents domaines des biosciences

Ultrasound imaging of cervical spine motion for extreme acceleration environments

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.Cataloged from PDF version of thesis. Vita.Includes bibliographical references (p. 52-55).Neck and back pain is one of the most common musculoskeletal complaints in personnel in variable acceleration environments such as astronauts and military pilots. Ultrasound is known for dynamic imaging and diagnostic workup of the axial and appendicular skeleton, but is not currently used to image the cervical spine, the injury of which may change the biomechanics of the cervical vertebrae, which CT and MRI (the current gold standard in cervical spine imaging) are poor at capturing. To validate ultrasound as a modality for imaging dynamic motion of the cervical spine several experiments were performed in static and dynamic human and animal (ovine) models: 1. Static analysis of ex-vivo ovine cervical spines imaged by ultrasound, MRI, and CT demonstrated that the imaging modality affected the measured intervertebral disc height (p<0.01); similar evaluation was done in-vivo in Emergency Department patients who received a CT scan as part of their clinical course that showed that ultrasound could fit into existing clinical workflows. 2. Dynamic analysis of isolated ex-vivo ovine cervical spinal segments intervertebral disc displacement with a mounted ultrasound probe demonstrated a measurement uncertainty of ± 0.2 mm and no bias at low frequency sinusoidal spinal displacement. A similar evaluation in-vivo with humans with an ultrasound probe mounted on a cervical-collar found a 0.8-1.3 mm amount of cervical spine distraction from the C4-5 Functional Spinal Unit. In human cadavers subjected to passive flexion and extension of the cervical spine, ultrasound measurements of the relative flexion/extension angles between consecutive cervical vertebrae were similar to fluoroscopy. 3. Ultrasound was able to record dynamic motion of the cervical spine in-vivo in running on a treadmill, during parabolic flight, and traveling over a rough road in a military vehicle. The ultrasound methods developed and tested in this thesis could provide an inexpensive, portable and safe technique that can identify and characterize cervical spine anatomy and pathology.Funding Acknowledgment: National Space Biomedical Research Institute, Army Research Office, Children's Hospital Orthopedic Surgery Foundationby Daniel Miller Buckland.Ph.D

Current Advances in Spinal Diseases of Elderly Patients

The rapid aging of populations in developed countries since the 2000s has placed increasing attention on the issue of musculoskeletal disorders in elderly patients. Notably, spinal disorders not only restrict the social activities of elderly patients, but they also lead to economic loss for society. “Current Advances in Spinal Diseases of Elderly Patients” is a topical collection of articles about current perspectives on diagnosis and treatment of spinal disorders including current surgical strategies. This Special Issue covers a broad range of issues, ranging from managing refractory states such as severe osteoporosis, spinal deformity, ossification of the spinal ligaments, and multiple arthropathy to managing lifestyle-related spinal diseases during the COVID-19 pandemic in elderly populations. We hope that the readers of this Special Issue find the contents interesting