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Assessment of Human Vertebrae Stiffness Variability Under Anterior Wedge Compression
Assessment of Human Vertebrae Stiffness Variability Under Anterior Wedge Compression
The most common vertebral fracture among the elderly and post-menopausal women is the anterior wedge-shape compression fracture. This in part due to the loss of bone mineral density (BMD) as is the case in osteoporosis. Many surgical procedures aimed to manage this condition clinically can cause mechanical behavioral changes to the vertebral stiffness along the human spine, thus increasing the risk of subsequent fractures. In spine augmentation procedures, it has been shown that volume and stiffness of the cement affect the load transfer and causes adjacent vertebrae to fail, due in part to a stiffness mismatch between the treated and intact vertebra. Hence, our objective is to assess the mechanical stiffness of human vertebrae and its variability along the spine when subject to different loading conditions. Since most common fractures are the wedge-shape fractures and they occur most frequently in the thoracic spine, our analysis is strictly limited to this region.
The most common vertebral fracture among the elderly and post-menopausal women is the anterior wedge-shape compression fracture. This in part due to the loss of bone mineral density (BMD) as is the case in osteoporosis. Many surgical procedures aimed to manage this condition clinically can cause mechanical behavioral changes to the vertebral stiffness along the human spine, thus increasing the risk of subsequent fractures. In spine augmentation procedures, it has been shown that volume and stiffness of the cement affect the load transfer and causes adjacent vertebrae to fail, due in part to a stiffness mismatch between the treated and intact vertebra. Hence, our objective is to assess the mechanical stiffness of human vertebrae and its variability along the spine when subject to different loading conditions. Since most common fractures are the wedge-shape fractures and they occur most frequently in the thoracic spine, our analysis is strictly limited to this region.
Thoraco-lumbar spine compression project
Thoraco-lumbar spine compression project
Prediction of strength and fracture pattern of thoraco-lumbar spine is a serious challenge for patients who have osteoporosis, which is considered a significant health problem for the aging population. This study aimed to confirm if CT- based finite element models be used to measure strength and stiffness of vertebrae under compression loading and to predict failure patterns/locations. the results of the study showed that the experimental fracture cracks and their locations in the specimens agreed reasonably well with those of the CT/FEA analyzed element failure. The FE model showed high predictive capability for vertebral strength and moderate prediction for stiffness. Based on results, porcine spine can be a good substitute models for human cadaveric specimens.
Prediction of strength and fracture pattern of thoraco-lumbar spine is a serious challenge for patients who have osteoporosis, which is considered a significant health problem for the aging population. This study aimed to confirm if CT- based finite element models be used to measure strength and stiffness of vertebrae under compression loading and to predict failure patterns/locations. the results of the study showed that the experimental fracture cracks and their locations in the specimens agreed reasonably well with those of the CT/FEA analyzed element failure. The FE model showed high predictive capability for vertebral strength and moderate prediction for stiffness. Based on results, porcine spine can be a good substitute models for human cadaveric specimens.
The effect of screw diameter to pedicle size ratio on toggling and pullout strength of pedicle screws
Spinal stabilization with pedicle screws is recommended for various spinal disorders such as trauma, deformity, and tumor. The stabilization performance of the pedicle screw is affected by toggling. Toggling of the pedicle screws is a cycling loading mechanism that impacts the fixation capacity of the screw and leads to loosening or failure of the screw. The selection of the pedicle screws is one of the biggest challenges in the clinic. An undersized screw can decrease the pull-out strength, increasing the probability of failure due to loosening. Conversely, an oversized pedicle screw can reduce the toggling force but also can compromise the stability of the pedicle by breaking it. The results of this study aim to determine the best pedicle screw diameter to reduce toggling force compared to pedicle diameter.
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