A user-defined element for simulating hydrogel injection into trabecular bone: Numerical simulations and experimental
Georgios F Samaras1, Vincent Dischl1, Anita Fung1
1Institute for Biomechanics, ETH Zürich, Zürich, Switzerland.
Medical Engineering & Physics
|November 1, 2025
Summary
This study developed a numerical model to simulate hydrogel injection into femurs, accurately predicting bone augmentation patterns. The model aids in safer treatment planning for osteoporosis patients.
Area of Science:
- Biomechanics
- Biomaterials Engineering
- Computational Modeling
Background:
- Hydrogel injection is a promising bone augmentation technique.
- Accurate simulation of hydrogel-bone interactions is crucial for treatment planning.
- Existing models may not fully capture the complex biomechanical and rheological factors involved.
Purpose of the Study:
- To develop and validate a comprehensive numerical model for simulating hydrogel injection into femurs.
- To investigate the influence of hydrogel properties and injection parameters on augmentation patterns.
- To assess the safety of the injection process by quantifying bone strains.
Main Methods:
- A coupled mechanical-flow formulation based on the Theory of Porous Media was implemented.
- The model was developed as an open-source Abaqus User Element (UEL) subroutine.
- Hydrogel rheological properties were calibrated against experimental data from three femurs.
Main Results:
- The model accurately predicted hydrogel volume distribution with an average Dice coefficient of 0.75.
- Simulations revealed the impact of injection flow rate and bone permeability on hydrogel patterns.
- Calculated solid strains remained below the tensile yield limit within the tested flow rate range.
Conclusions:
- The developed computational tool enhances the accuracy of bone augmentation modeling.
- This methodology can contribute to safer treatment planning for osteoporotic patients.
- The model provides insights into hydrogel-bone interactions during injection.
