QCT/FEA predictions of femoral stiffness are strongly affected by boundary condition modeling

Abstract

Quantitative computed tomography-based finite element models of proximal femora must be validated with cadaveric experiments before using them to assess fracture risk in osteoporotic patients. During validation, it is essential to carefully assess whether the boundary condition (BC) modeling matches the experimental conditions. This study evaluated proximal femur stiffness results predicted by six different BC methods on a sample of 30 cadaveric femora and compared the predictions with experimental data. The average stiffness varied by 280% among the six BCs. Compared with experimental data, the predictions ranged from overestimating the average stiffness by 65% to underestimating it by 41%. In addition, we found that the BC that distributed the load to the contact surfaces similar to the expected contact mechanics predictions had the best agreement with experimental stiffness. We concluded that BC modeling introduced large variations in proximal femora stiffness predictions.

Keywords::

• hip fracture
• osteoporosis
• quantitative computed tomography

Acknowledgements

The authors thank Samad Javid, Pascal Swider, and Iwona Jasiuk for their review and comments.

Conflict of interest statement

None of the authors have conflicts of interest to disclose.

Additional information

Funding

The study was financially supported by National Institutes of Health (NIH) [grant number AR027065Z-30S1] and the Grainger Foundation: Grainger Innovation Fund. The CT imaging of the femora was performed through the Opus CT Imaging Resource of Mayo Clinic [NIH construction grant number RR018898]. This publication was made possible by CTSA [grant number UL1 TR000135] from the National Center for Advancing Translational Sciences (NCATS), a component of the NIH. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NIH.