Loading simulation of spinal vertebrae using the finite cell method

Osteoporosis compromises bone strength, increasing the risk of vertebral fractures with severe health consequences. The development of an accurate and reliable patient-specific vertebral model would be of major clinical relevance, for both the prognosis of fractures and the investigation of implant systems. In the case of spinal fusion, the peri-implant bone strains are of major interest. High forces are transmitted at the bone-implant interface and screw loosening is the major cause of surgical failure. In recent years, the finite element method has been increasingly applied to predict the biomechanical response of vertebrae. In general, quantitative CT-data is used to retrieve the geometric model and the inhomogeneous material properties. A finite element mesh is then generated for the numerical simulation. For the finite element analysis of a bone-implant system, the adequate treatment of the bone-implant interface demands the adaptive refinement of the finite element mesh for an accurate solution. In this contribution, the finite cell method (FCM), a high order embedded domain approach, is applied to simulate the biomechanical behavior of human vertebrae. The recently developed multi- level hierarchical refinement is used to enrich the FCM, allowing to resolve the highly inhomogeneous material properties of vertebrae. For the simulation of bone-implant systems, the hierarchic refinement is used to resolve the bone-implant interface appropriately. The feasibility of using FCM for predicting the biomechanical response of human vertebrae is demonstrated with numerical examples on both intact and fused vertebral segments. Furthermore, the inherent hierarchical nature of the FCM strongly supports verification and validation.     «

Osteoporosis compromises bone strength, increasing the risk of vertebral fractures with severe health consequences. The development of an accurate and reliable patient-specific vertebral model would be of major clinical relevance, for both the prognosis of fractures and the investigation of implant systems. In the case of spinal fusion, the peri-implant bone strains are of major interest. High forces are transmitted at the bone-implant interface and screw loosening is the major cause of surgical...     »