Three-dimensional finite element analysis of optimal distribution model of vertebroplasty.

Background: Establishment of a three-dimensional (3D) finite element model of osteoporosis, the simulation fluid was used to enter the vertebral body to study the stiffness recovery of injured vertebral body under different perfusion and distribution conditions, and the stress analysis of adjacent vertebral body after percutaneous vertebroplasty (PVP) was carried out.

Methods: A healthy male volunteer was selected. Computed tomography (CT) scanning was performed from T11 to L2. MIMICS 15.0 and ABAQUS 6.11 software was used to extract CT findings, and a vertebral model of osteoporotic fracture was established. The flow physical field and conduction and diffusion physical field were coupled to simulate the process and parts of the bone cement injection into the vertebral fracture model. The quantities of bone cement injected into the vertebral fracture model were 2, 4, and 6 mL, respectively. The diffusion range of bone cement was simulated on the simulated image, and the postinjection model of bone cement was obtained. For the simulation of vertebral movement, vertical downward, forward, and backward pressure of 300 N was applied on the model's surface. The stress changes in the upper and lower vertebrae and diseased vertebrae were calculated under different conditions.

Results: It was revealed that the von Mises stress in the endplate under T12 was the highest in the three different states before and after fracture. The von Mises stress in the intervertebral discs and endplates was significantly higher after fracture than before fracture. When PVP was applied, the von Mises stress in adjacent endplates was increased with the increase of cement injection, while the von Mises stress was decreased in the adjacent endplates with cement injection compared with diseased vertebrae.

Conclusions: A reliable biomechanical model of lumbar vertebral fracture can be established through numerical simulation of CT scanning data. Vertebral fracture and vertebroplasty may cause biomechanical changes in adjacent vertebrae. The influence of biomechanical changes may notably increase along with the amount of bone cement injected. In this study, PVP revealed 4 mL to be the optimal amount for cement injection.