Finite Element Analysis Of The Influence Of External Forces On Spine Orthopaedic

Scoliosis brings not only physical harm and even psychological obstacles to patients. Therefore, it is very important to treat spine deformity better and relieve pain for patients as soon as possible. This topic is a cooperative project with Doctor Xie of the second affiliated hospital of kunming medical college. At present, generally use posterior spinal vertebral resection (PVCR surgery) to correct the deformity of spine. According to current operation, raise the problem of impact of external forces on spine orthopaedic from the angle of mechanics.In fact, the procedure is a mechanical straightening process meeting the medical conditions, which is conducted in accordance with the principle of Newtonian mechanics.Reconstructed the three-dimensional model of deformed spine based on the CT data provided by the hospital and ultimately established the calculation model which contains correct rods, screws and other simplified parts combined with the actual operation. Then, analyzed the influence of external forces on PVCR surgery to coronal and sagittal plane deformity by finite element method. Discussed the problem under the ideal and actual conditions in total of24kinds of loading formation, and eventually obtained the following conclusion:(1) The greater the orthopedic load, the greater the elongation, and the greater the stress of spine pedicle. In actual operation, there exits friction between operation table and human skin, human spine occurs displacement with the nail and rod system,spinal elongation is smaller than ideal conditions; the soft tissue between sternum and skin leans; the human skin does not occur any displacement.(2) The stress of screw decreases from the proximal to distal, the stress of proximal screw is the maximum and the stress of distal screw is the minimum. If the external force is too large, the proximal screw may nail more easily. The friction between the table and human skin makes stress of screws increase, and the screws nail more easily, it will cause serious consequences, so it is necessary to impose a proper auxiliary force in the operation.(3) Under the same load and the same boundary conditions, spine elongation are almost identical, so the spine elongation of different coordinate surfaces after orthopaedic is mainly decided by the value of the loads.In this paper, while ignoring the influence of other parts such as muscle, but the structure and loading manner are very close to the real operation, and obtained some conclusions with reference value, which can provide some certain mechanics for spinal orthopedic surgery guidance.