Design And Biomechanical Analysis Of Open Shape Memory Alloy Artificial Vertebral Body

Objective To design an open shape memory alloy artificial vertebral body that can be used to reconstrut the vertebral body in spine diseases,such as thoracolumbar spine tumors, burst fracture of the vertebral,kyphotic and scoliosis.And to evaluate the biomechanical stability of lumbar functional segment unit after insertion with the shape memory alloy artificial vertebral body.Methods The research divided into two parts,(1)The development of open shape memory alloy artificial vertebral body:We collected the height of lumbar roots in normal people and according to the spine data,we made sure the size of the artificial vertebral body.Finally, we made the open nickel-titanium shape memory alloy artificial vertebral body. (2) The biomechanical analysis of open shape memory alloy artificial vertebral body:Eight normal adult fresh porcine spine specimens(thoracic 14-lumbar 5) (the pig has 15 thoracic vertebrae) was used to detect the range of motion(ROM) in four models,which were intact vertebral model, pedicle screw fixation inT15, L1, L3and L4 model, L2 total resection and reconstructed by open shape memory alloy artificial vertebral body model, lumbar 2 total resection and reconstructed by titanium mesh vertebral body model. The last two models were made by turns. All models were tested using a spinal three dimensional anlysis system (tipe:U.S. MTS-858).Undertake the data with medical statistical analysls.Results (1)The open shape memory alloy artificial vertebral body can be putted through the lumbar roots windows when be compressed in the ice water.Then when temperature rised,the elastic recovered to revive the height of the spine.So the open shape memory alloy artificial vertebral body made the operation easily. (2)Compared with the intact vertebral body model, the other three models were more stable in compression,flexion, left and right lateral bending, and rotation,there was significant difference(P0.05).Compared with the titanium mesh reconstructed model, the memory alloy artificial vertebral body reconstructed model had less degree of motion in T15-L1 and L3-L4 segments(P<0.05),but no statistic significance in L1-L3 segment.Conclusion The design of the open shape memory alloy artificial vertebral body meets the design principles.It is innovative and has a good biomechanical stability. It can be used to recover the height and stabilize the spinal segment with pedicle screw fixation.And there is less effective in the adjacent segments. It can help to reduce the stress concentration. So it can reduce the probability of failure.This study offers the bio-mechanical basis to the next phase of animal experiments and initial clinical application.