Vertebroplasty is a common and effective treatment for symptomatic osteoporotic vertebral compression fractures. However, the cemented and adjacent vertebras have a risk of recollapse due to largely unassured mechanisms, among which excessive stiffness of bone cement may be an important risk factor. This study aimed to find the most appropriate range of bone cement stiffness by analyzing its biomechanical effects on the augmented and adjacent vertebras of individual patient after vertebroplasty. A three-dimensional finite element model of T11-L1 osteoligamentous vertebras was reconstructed according to individual computed tomography data and validated by post mortem human subject experiment in literatures. Bone cement of varying stiffness was injected into the trabecular core of the T12 vertebra simulatively. The maximum von Mises stresses on cancellous and cortical bones of T11-L1 vertebras were analyzed under the loading conditions of flexion, extension, bending, and torsion. For the adjacent T11 and L1 vertebras, the stepwise elevation of the bone cement elastic modulus increased the maximum von Mises stress on the cancellous bone, but its effect on cortical bone was negligible. For the augmented T12 vertebra, the stresses on cancellous bone increased slightly under the loading condition of lateral bending and remained no impact on cortical bone. The linear interpolation revealed that the most suitable range of cement elastic modulus is 833.1 and 1408.1 Mpa for this patient. Increased elastic modulus of bone cement may lead to a growing risk of recollapse for the cemented vertebra as well as the adjacent vertebras. Our study provides a fresh perspective in clinical optimization of individual therapy in vertebroplasty. Graphical abstract ᅟ.
Keywords: Bone cement; Elastic modulus; Finite element analysis; Osteoporotic fracture; Vertebroplasty.