Work

Characterization of nonlinear stress relaxation of the femoral and tibial trabecular bone for computational modeling

Year: 2025

Type: article

Abstract: • Trabecular bone from the femur and tibia show similar bone relaxation levels • On average, 54% stress relaxation of the trabecular bone was observed in 24 hours • The level of stress relaxation was independent on the applied strain or the BMD • Stress relaxation tests were replicated in sample-specific FE simulations • The average level of stress relaxation was implemented in the FE simulations Computational models of orthopedic reconstructions are reliant on bone material properties, but viscoelastic behavior of trabecular bone is often ignored in numerical simulations. The inclusion of stress relaxation could be of importance for the accuracy of models simulating the primary stability of cementless implants. In this study, a material model to describe the nonlinear viscoelastic behavior of human trabecular bone was constructed based on uniaxial stress relaxation experiments. The relationship of bone mineral density (BMD) and stress relaxation was explored, and the material model was implemented in sample-specific finite element (FE) simulations. Cylindrical trabecular human bone specimens, from the distal femur and proximal tibia, were subjected to stress relaxation tests, undergoing compression with strains from 0.2% to 0.8% for 30 minutes on four consecutive days. The experimental data were extrapolated to 24 hours. Similar levels of stress relaxation were found for femoral and tibial specimens, with an average 54.4% stress relaxation and a maximum level of 81.6%. Using a modified superposition model, the specimen-specific nonlinear stress relaxation behavior was captured. However, when the samples were considered collectively, no correlation was found between applied strain, BMD and the viscoelastic response. Therefore, the average level of stress relaxation in combination with existing BMD-stiffness relationships were implemented in FE simulations for each individual specimen. While the FE models, on average, overestimated the overall stiffness by 64%, they were able to adequately capture the stress relaxation response.

Source: Medical Engineering & Physics

DOI: 10.1016/j.medengphy.2025.104324

Authors: Thomas Gersie, Thom Bitter, David Wolfson, Robert Freeman, Nico Verdonschot, Dennis Janssen

Institutions: Radboud University Medical Center, University of Twente

Language: English

Topic: Bone health and osteoporosis research

Subfield: Orthopedics and Sports Medicine

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $3,170