Cement Injection into a Bone

Vertebroplasty is a medical spinal procedure in which bone cement is injected through a small hole in the skin into a fractured vertebra with the goal of relieving back pain caused by vertebral compression fractures. Complications from these procedures can however occur and, occasionally, are fatal. Patient specific computer simulation is an ideal tool to assess the risks of an intervention, and to provide a surgeon with recommendations for the amount of cement to be injected, and other parameters.
This type of simulation is however inaccessible to classical mesh-based CFD, as the extremely high porosity poses an unsurmountable to mesh generators. Our meshfree CFD solver has no such issues, and reproduces the full bone filling process with high accuracy.
The right image below shows a computer model, obtained through medical imaging from a damaged human vertebra. On the left image, the vertebra is cut in half to show the results of a computer simulation, showing the progress of a virtual cement injection into the bone.
 
Image courtesy Annick Baur, EPFL (Lausanne, Switzerland) for all vertebroplasty image data. In collaboration with Dr. VA Stadelmann, AO Research Institute (Davos, Switzerland).

 

The time evolution of the cement injection is shown on the animation below. The simulation predicts among others on which side of the vertebra the cement exceeds the bone if the injected amount of cement is too large.

 

The simulation results were validated against data from in vitro experiments, and found to provide predictions of exceptional quality. The image below compares the experimental and simulation profiles on a cut through the vertebra, after the injection of three millilitres of cement:

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