28 August 2018

In the Journal of Orthopaedic Research, Karlijn Groenen, Dennis Janssen and colleagues reported on their subject-specific non-linear finite element models for predicting vertebral collapse of the metastatically affected spine.

Abstract
Current finite element (FE) models predicting failure behavior comprise single vertebrae, thereby neglecting the role of the posterior elements and intervertebral discs. Therefore, this study aimed to develop a more clinically relevant, case-specific non-linear FE model of two functional spinal units able to predict failure behavior in terms of (i) the vertebra predicted to fail; (ii) deformation of the specimens; (iii) stiffness; and (iv) load to failure. For this purpose, we also studied the effect of different bone density-mechanical properties relationships (material models) on the prediction of failure behavior. Twelve two functional spinal units (T6-T8, T9-T11, T12-L2, and L3-L5) with and without artificial metastases were destructively tested in axial compression. These experiments were simulated using CT-based case-specific non-linear FE models. Bone mechanical properties were assigned using four commonly used material models. In 10 of the 11 specimens our FE model was able to correctly indicate which vertebrae failed during the experiments. However, predictions of the three-dimensional deformations of the specimens were less promising. Whereas stiffness of the whole construct could be strongly predicted (R2  = 0.637-0.688, p < 0.01), we obtained weak correlations between FE predicted and experimentally determined load to failure, as defined by the total reaction force exhibiting a drop in force (R2  = 0.219-0.247, p > 0.05). Additionally, we found that the correlation between predicted and experimental fracture loads did not strongly depend on the material model implemented, but the stiffness predictions did. In conclusion, this work showed that, in its current state, our FE models may be used to identify the weakest vertebra, but that substantial improvements are required in order to quantify in vivo failure loads.

Publication
Case-specific non-linear finite element models to predict failure behavior in two functional spinal units
Groenen KHJ, Bitter T, van Veluwen TCG, van der Linden YM, Verdonschot N, Tanck E, Janssen D.

Karlijn Groenen and Dennis Janssen are both members of theme Reconstructive and regenerative medicine.

Related news items


Valentine’s day spectacle at the Radboud Research Rounds

21 February 2019

This year’s Valentine’s day in the Radboudumc was focused on the RRR of the Tumors of the Digestive Tract. In the biannual Paper Award session the big prize went to Daniel Garza from the Center for Molecular and Biomolecular Informatics, for his paper on “the environmental metabolome”.

read more

New infection route resistant hospital bacteria discovered

21 February 2019

In a case study on JAMA Network Open, physician microbiologist Joost Hopman describes how the rare bacterium Pseudomonas aeruginosa could spread infection from shower drains in patient rooms.

read more

Optimal dosing of anti-HIV drug darunavir in pregnant women

21 February 2019

In the Journal of Antimicrobial Chemotherapy Stein Schalkwijk, Rob ter Heine, Angela Colbers and David Burger investigated how pregnant women should be treated with the anti-HIV drug darunavir.

read more

RIHS awardees 2017 and 2018 Koek & Zopie ceremony

20 February 2019

And the winners are: Joanne de Hullu, Jonne Doorduin, Stein Schalkwijk, Vincent Aengevaeren, Florieke Eggermont and the initiators of the Citizen's panel.

read more

Research Integrity Round: The ConScience App 15 February 2019

14 February 2019

To introduce the new Netherlands Code of Conduct for Research Integrity we invited ‘Het Acteursgenootschap’ to perform ‘The ConScience App’, a theatre piece designed to move the debate on scientific knowledge. All Radboudumc researchers are invited to attend this event.

read more

Prevalence of sexual harassment in academic medicine

7 February 2019

In JAMA Internal Medicine Sabine Oertelt-Prigione described how sexual harassment is a pervasive phenomenon that can affect anyone in the workplace.

read more