Biomechanical Finite Element Analysis Of Adjacent Vertebral Bodies After Percutaneous Kyphoplasty

ObjectiveThree-dimension finite element models about thoracolumbar osteoprosis vertebra (T12-L1-L2), L1 compress fracture and L1 after PKP was bulit. To determine the correlations between Percutaneous kyphoplasty on adjacent vertebral endoplates stresses pressure under physiologianl load and a new fracture of adjacent vertebral body in physiological load.Material and methodsAn old female osteoporotic patient was choosed, computed tomography (CT) data was got. A three-dimensional finite element model of the osteo-porotic thoracolumbar spine T12-L1-L2 was created by using kinds of computer aided sesign softwares. T12-L1-L2 functional spinal units was got. The height of vertebral L1 was compressed by 60% to simulated the compressed fracture, and the height of L1 became the 90% of normal to simulate the replacement, two symmetrical columns-like PAMA mass (L1, 4.0ml) was placed in vertebral L1 to simulate PKP. The stress on inferior endplate of T12 and superior endplate of L2 was compared with three models.Results1. Three-dimensional finite-element model of thoracolumbar vertebral compression fractures was built in osteoporotic parameters. The model has familiar appearance with reality.2. The maximum stress in the adiacent vertebral bodies endplates increased by 76% for L1 compress fracture model and increased by 27% for kypho-plasty, respectively. The stress on the posterior part of vertebral body after PKP have an average increase of 13.2%, of which 4.5% increase in the pedicle, isthmus, and 6.15% increased in the key points 25.6%, but with the wedge-shaped fracture of L1 vertebral body compared to the model, PKP after pedicle, isthmus and the articular process have reduced stress. The results show that the stess value of T12's inferior endplate and L2's upper vertebral endplate after kyphoplasty increased compared with normal vertebrae in various states.Conclusions1. Three-dimensional finite element model of thoracolumbar vertebral compression fractures was built in osteoporotic parameters. The model has familiar appearance with reality.2. The stress on inferior endplate of T12 and superior endplate of L1 increased after PKP under all loading conditions. Increased stess may lead endplate fracture, and increase the risk of adjacent vertebral body fracture. Further researches are needed to support the conclusion. Key words Minimally Invasive;Kyphoplasty; Finite element analysis (FEA); Vertebral compression fracture (VCF); Stress; Biomechanics...