Preliminary study on biomechanics of vertebroplasty: a computational fluid dynamics and solid mechanics combined approach.
METHODS
Algorithm development for the automatic finite element modeling of patient vertebra.


OBJECTIVE
To present a technique for automatic generation of patient specific computational fluid dynamics (CFD) models for intraosseous PMMA cement flow simulation. The secondary objective is to demonstrate the possibility of using resultant PMMA cement distribution for post-PVP stress-strain analyses.


BACKGROUND
There are no noninvasive methods for the visualization of PMMA cement flow. In addition, optimum volume and distribution of PMMA cement are still not known. Computational models that allow patient specific intraosseous PMMA cement flow visualization as well as postvertebroplasty mechanical evaluation would be advantageous.


METHODS
We developed an algorithm coded into a custom platform that inputs patient CT datasets. Hounsfield unit values were used to assign permeability values as well as modulus to the finite element model before analyses. Several user inputs are required, and these reflect the decisions made by physicians that practice vertebroplasty. As a case study, we isolated a single L1 vertebra from patient CT dataset and used our platform for model generation. Simulated vertebroplasty was performed for different PMMA cement volumes and at different placements to study the effects of varying distribution.


RESULTS
Increased needle injection pressure was observed as the volume of PMMA increases and as the distribution of PMMA is in close proximity to the cortical walls. Stiffness of augmented vertebral body also increases with increased volume of PMMA administered. Varying distributions, for the same volume, of PMMA cement did not alter stiffness drastically.


CONCLUSIONS
Our custom platform and technique for modeling vertebral bodies may contribute significantly to the science of vertebroplasty. Intraosseous PMMA cement flow can be visualized before vertebroplasty, and needle position altered for optimization. Also, parametric computational studies on the postvertebroplasty biomechanical effects of vertebroplasty are now enhanced with such a modeling capability.
Teo
Jeremy
J
Department of Diagnostic Radiology, National University Hospital, Singapore. g0305846@nus.edu.sg
Wang
Shih Chang
SC
Teoh
Swee Hin
SH
D000465:Algorithms; D001696:Biomechanical Phenomena; D001843:Bone Cements / Q000493:pharmacokinetics*; D003198:Computer Simulation; D016208:Databases, Factual; D006801:Humans; D007267:Injections; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000502:physiology / Q000601:surgery*; D019060:Minimally Invasive Surgical Procedures; D008954:Models, Biological; D009339:Needles; D019904:Polymethyl Methacrylate / Q000008:administration & dosage / Q000493:pharmacokinetics*; D012212:Rheology; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed
D001843:Bone Cements; D019904:Polymethyl Methacrylate