A particle-based model for prediction of cement diffusion during osteoporotic hip augmentation surgery: Theory and validation

Elderly patients with preexisting osteoporotic hip fracture are at high risk of a subsequent fracture in their contralateral hip. Current preventive approaches commonly have a long delay in restoring bone strength leaving patients at continued risk despite preventive efforts. Femoroplasty - injection of bone cement into the proximal femur - has been proposed as a potential preventive approach. However, it can cause complications because of extravasation of the cement into unwanted regions of the bone and an increased pressure within the bone, if not controlled and planned carefully. Therefore, precise modeling of the diffusion of the bone cement in osteoporotic bone and control over the injection process is of substantial importance. This paper presents a patient-specific fluid dynamics model to simulate the diffusion of the bone cement inside femur. The model is based on the smoothed particle hydrodynamics (SPH) method for particle-based modeling of fluids. The Navier-Stokes equations were built into the SPH formulations and viscosity effects were added to model the flow of cement inside porous media. To validate the model, a new prototype automatic injection device was used to inject acrylic silicone into a porous foam block. Results of simulation of the injection show close matching with experimental data. The model is therefore promising for further development of optimized and fully controlled femoroplasty procedures.