Design And Biomechanical Analysis Of Self-fixing Artificial Vertebral Body

The resection of diseased vertebra from patients of spine burst fracture, spinal tumor or tuberculosis always results in massive spinal defect. At present, artificial vertebral body replacement has been performed to repair bone defect and reestablish spinal stability. In order to strengthen the stability of spine in clinic operations, most of artificial vertebral bodies are implanted, combining with other internal fixation devices. In this thesis, a Self-fixing Artificial Vertebral Body(SAVB) linked with self-tapping thread sleeve and fixed with cross screw is designed. It can restore spinal stability without using other internal fixation devices.According to spinal physiological structure and surgical requirements, after distilled data from CT pictures and the design of CAD, the SAVB is made by Ti6A14V which has good mechanical performance and biology compatible capability. It consists of three sleeves and two ending-plates. It is hollow and symmetric. The length is adjustable. The shape of its middle conforms to spinal physiological curve. The figure of its two ending-plates match thesection of vertebral body. The ending sleeves are screwed into vertebral bodies about 1.5cm.Apply Finite Element Method (FEM) to study biomechanics of the SAVB. Mechanic model needs to be set up firstly, and then by FEM, the load on the mechanic model, such as compression, torsion and bending, is simulated, analyzed, verified and optimized. According to the stress and the strain contrasted with fore-and-aft improvements, the variational trend and the area where stress focus on are ascertained. Then the AVB is further optimized and improved so as to make stress well-distributed and to increase the system's stability. The outcomes show that the stresses focus on the ending-plates, middle-sleeves and screws. With thickness and screw's diameter increasing, the intensity increase markedly.Each of nine adult cadaver specimens of lumbar vertebrae (L1-L5) is measured biomechanical capability of the normal spine and the artificial vertebral body. Undertake the data with medical statistical analysis. There is no significant difference between artificial vertebral body fixed with Dick screw and the SAVB in stability such as compression, flexion, extension, left/right lateral bending, left/right axial torsion. Its yield strength can meet the requirement of normal spine. The sine-wave compressive loads are applied on the SAVB for one million times, there is no distortion orcrack. This indicates that its fatigue strength is sufficient.In conclusion, the SAVB has good biomechanical behavior and can be used to stabilize the spinal segments after resection of the diseased vertebral body and to reconstruct the height and stability of the anterior spinal column.Before using this prosthesis in clinic, clinical studies should be carried out to confirm its immediate and perennial curative effect and its compatibility...