Mechanic Evaluate Percutaneous Vertebroplasty With Finite Element Analysis

Objectives To establish three-dimensional finite element model of lumbar osteoporosis vertebral compression fracture(OVCF) and analysis von misses stress changes of the percutaneous vertebroplasty (PVP).Methods Get 20 lumbar CT data from zhujiang hospital ,all these data was permitted .exclude the data which exist some deformities .The available data were imported into computers to establish L1/L2/L3 three-dimensional geometric model by mimics 11.1. The geometric model was imported into simpleware to establish the finite element (FE) model of osteoporosis vertebral compression fracture (only L2 fractured) .The FE model were import into abaqus 6.51 to analysis the mise stress distribution. For simulating PVP, first restore the height of L2, and then column-like PAMA mass was placed into L2 vertebra unilaterally and bilaterally. 500N press was loaded on the upper endplate of L1,and 15Nm moment was loaded too to simulating the lumbar anteflexion ,extension ,lateral bending and rotation. The von mise stress changes on endplate, cancellous bone and cement before and after the operation were recorded and analysis respectively.Results The model builded by mimics,simpleware and abaqus has a excellent geometric similarity. After 30% reduction of modulus of elasticity, the model can truly meet the need the biomechanics of osteoporosis vertebral compression fracture. And it is a good FE model of osteoporosis vertebral compression fracture. To evaluate the PVP, we found after operation, the von mise stress of the L2 vertebra endplate did not reduce greatly, nor did the cancellous bone. The von mise stress of bilateral group was a little smaller than the unilateral group. The mise stress of L1 endplate did not vary with the operation. But with the height restoration, the mise stress of L1 endplate reduced and the mise stress of L3 endplate increased.Conclusions 1.The model builded by mimics,simpleware and abaqus is a good FE model of osteoporosis vertebral compression fracture. 2.After PVP, parts of von mise stress of the endplate transferred to the cement, the mise stress of the endlpate reduced, but mise stress of the cancellous bone did not decrease. So little changes between unilateral group and bilateral group, they almost can be neglected .PVP would not increase the mise stress of the adjacent vertebral body. But with the height restoration, the mise stress of L1 endplate reduced and the mise stress of L3 endplate increased. on the contrary ,with L2 compression fracture, the mise stress of L1 endplate increased and the mise stress of L3 endplate increased reduced.