| Intervertebral disc degeneration is one of the most common causes of low back pain. Major surgical measures, including discectomy and spine fusion, were used to treat conditions related to the disc degeneration. But as surgical treatments, both of these interventions alter the biomechanics of the spine, leading that complications arise, possibly leading to further degeneration of the surrounding tissues and the discs at adjacent levels. A treatment measure is needed to restore the nature biomechanics of the segment after disc degeneration and disc excision, relieving pain and preventing further degeneration at the adjacent segment. Artificial intervertebral disc is developed to replace the degenerated disc. Artificial disc replacement is acting as a surgical measure as well as discectomy and fusion, but many problems need be studied deeply, especially the problems related to long-term implantation. Although many reports about the disc replacment have been published, because of the shorter history of clinical application, the follow-up peri elds are still not enough long to evaliate the measure with a all round conclusion. Biomechanical ananlysis and test could provide datas to explain the clinical effect and predict long-term effect, helping the development of artificial disc design, while long-term follow-up is depending on the future time and may have some limilations to explain the related mechanisms.To data, there have been but a few attampts to analysis and test the biomechanical changes in whole spine after discectomy and disc replacement, fewer about the changes in adjacent segments and stress distribution in the prosthesis after replacement; more seldom reports about the optimizational design analysis on the structures materials and geometry to aim at the existent disc prosthesis, and the changes of compressive loading in adjacent level segments after discectomy and disc prosthesis replacement, especially in proximal segment, which may be thecause of abnormal stress distribution and movements of adjacent segments, and the cause of possibal benefits of disc replacment even in whole spine. These articles now presented are to examine the factors above, as attempts to provide foundations for knowledging the characteristics of the prosthesis and effects in spine after replacement, hoping to be helpful to future design and prediction long-term clinical effect in adjacant segments, even whole spine.On the basis of background, data and the experimental objectives, the three-dimensional solid model was built according to the lumbar prosthesis, the finite element analysis was used to biomechanical analysis the characteristics of the sturcture, geometry^ materiel and mechanics, their cross relationships were included. Topological Optimization was done to aim at the existent lumbar disc prosthesis. The whole human cadaveric ligamentous lumbar spine specimens were used to make three kinds of model: intact, discectomy, prosthesis replacement after discectomy. The compressive load in aproximal segment above the injury segment was measured separately in various loading cases on three modles. Various geometry parameter' s changes of operative segments and proximal segments were measured with CAD technology, including intervetebral height. Foramen area^ intervertebral area^ total space area in segment. The difference of every geometry parameter between preoperation and Postoperation were compared in operative and proximal segments. The compares of various parameters between 1 segment ARD and 2 segments ARD were done too.The three-dimensional solid model was built according to the geometry of the prosthesis, and its responses were predicted in three compression modes which simulated its different load conditions in vivo. Consideration of the mechanical properties of the prosthesis is benefit to improving understanding and the design of Artificial Intervertebral Disc. The evaluation of the mechanical properties of Artificial LumbarIntervertebral Disc was done using Finite-Element Analysis.The study usin...
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