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IN SILICO BONE REMODELLING OF A WHOLE HUMAN VERTEBRA BEFORE AND AFTER BONE AUGMENTATION
S112
Presentation 1512 − Topic 12. Bone remodelling and adaptation
IN SILICO BONE REMODELLING OF A WHOLE HUMAN VERTEBRA BEFORE AND AFTER BONE AUGMENTATION Sandro D. Badilatti (1), Alexander Zwahlen (1), Alina Levchuk (1), Friederike A. Schulte (1), Ralph Müller (1)
1. Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
Introduction The ability of bone to adapt to changes in external loading is well known. To get better insight into the biological processes, various approaches to simulate microstructural bone remodelling have been proposed [Gerhard 2009]. Lacking required computational resources, these simulations were often restricted to 2D or to a sub-volume of the bone. Augmentation of osteoporotic bone to restore the load transfer function in the spine is widely used [Hulme 2001]. Incorporating patient specific adaptation models into treatment planning could improve the outcome of the procedure. Here, we investigated the possibility to simulate remodelling of a whole human vertebra over several years, based on high resolution imaging of the bone microstructure. In addition, we showed the potential of remodelling simulations for treatment planning of bone augmentation.
Results In the first instance, we simulated remodelling process of a whole human vertebra mimicking the progression of osteoporosis (Fig. 1). The bone adaptive process led to changes of the trabecular structures such as thickening of trabeculae, as well as removal of whole structures. Changes in the load transfer after augmentation (Fig. 2) led to an altered path in bone loss. In this case, the remodelling led to larger bone structures along the loading axis close to the bone cement.
Methods For the simulations, we used a strain-adaptive bone remodelling algorithm based on the mechanostat theory [Frost 1987]. The simulations were performed on a supercomputer (CSCS, Manno, Switzerland) and included the calculation of strain energy density (SED) as a mechanical trigger, using finite element analysis (ParFE). The simulations were run on a model generated from a high resolution micro-CT scan (Skyscan, 17.4 μm resolution) of a whole human vertebra representing the native state of the vertebra. Augmentation was then simulated by filling void spaces to match the surgical volume.
Fig 2: Different load distribution (SED) after bone augmentation.
Discussion We were able to show the feasibility of bone remodelling simulations of whole human bone at high resolution. In addition, we could also illustrate that the influence of a treatment procedure such as bone augmentation can be simulated, which may give a better insight into the success of the procedure before starting the treatment.
Acknowledgements The authors gratefully acknowledge funding from the European Union (VPHOP FP7-ICT2008223865) and computational time granted from the Swiss National Supercomputing Center (CSCS).
References Frost, The Anatomical Record, 219:1-9, 1987. Gerhard et al, Phil. Trans. R. Soc. A., 367:20112030, 2009. Hulme et al, Spine, 31:19831-2001, 2006. Fig 1: Detail of remodelled bone showing formed structures (yellow) and resorbed structures (blue). Journal of Biomechanics 45(S1)
ESB2012: 18th Congress of the European Society of Biomechanics
Presentation 1512 − Topic 12. Bone remodelling and adaptation
IN SILICO BONE REMODELLING OF A WHOLE HUMAN VERTEBRA BEFORE AND AFTER BONE AUGMENTATION Sandro D. Badilatti (1), Alexander Zwahlen (1), Alina Levchuk (1), Friederike A. Schulte (1), Ralph Müller (1)
1. Institute for Biomechanics, ETH Zurich, Zurich, Switzerland
Introduction The ability of bone to adapt to changes in external loading is well known. To get better insight into the biological processes, various approaches to simulate microstructural bone remodelling have been proposed [Gerhard 2009]. Lacking required computational resources, these simulations were often restricted to 2D or to a sub-volume of the bone. Augmentation of osteoporotic bone to restore the load transfer function in the spine is widely used [Hulme 2001]. Incorporating patient specific adaptation models into treatment planning could improve the outcome of the procedure. Here, we investigated the possibility to simulate remodelling of a whole human vertebra over several years, based on high resolution imaging of the bone microstructure. In addition, we showed the potential of remodelling simulations for treatment planning of bone augmentation.
Results In the first instance, we simulated remodelling process of a whole human vertebra mimicking the progression of osteoporosis (Fig. 1). The bone adaptive process led to changes of the trabecular structures such as thickening of trabeculae, as well as removal of whole structures. Changes in the load transfer after augmentation (Fig. 2) led to an altered path in bone loss. In this case, the remodelling led to larger bone structures along the loading axis close to the bone cement.
Methods For the simulations, we used a strain-adaptive bone remodelling algorithm based on the mechanostat theory [Frost 1987]. The simulations were performed on a supercomputer (CSCS, Manno, Switzerland) and included the calculation of strain energy density (SED) as a mechanical trigger, using finite element analysis (ParFE). The simulations were run on a model generated from a high resolution micro-CT scan (Skyscan, 17.4 μm resolution) of a whole human vertebra representing the native state of the vertebra. Augmentation was then simulated by filling void spaces to match the surgical volume.
Fig 2: Different load distribution (SED) after bone augmentation.
Discussion We were able to show the feasibility of bone remodelling simulations of whole human bone at high resolution. In addition, we could also illustrate that the influence of a treatment procedure such as bone augmentation can be simulated, which may give a better insight into the success of the procedure before starting the treatment.
Acknowledgements The authors gratefully acknowledge funding from the European Union (VPHOP FP7-ICT2008223865) and computational time granted from the Swiss National Supercomputing Center (CSCS).
References Frost, The Anatomical Record, 219:1-9, 1987. Gerhard et al, Phil. Trans. R. Soc. A., 367:20112030, 2009. Hulme et al, Spine, 31:19831-2001, 2006. Fig 1: Detail of remodelled bone showing formed structures (yellow) and resorbed structures (blue). Journal of Biomechanics 45(S1)
ESB2012: 18th Congress of the European Society of Biomechanics