Cells, growth factors and bioactive surface properties in a mechanobiological model of implant healing

Abstract

Interface conditions are of prime importance for implant fixation in the early post-operative period and modelling of specific biochemical interactions at implant surface is still missing. We hypothesized that updating osteoblast adhesion properties and growth factor source in an active zone located at the implant surface was relevant to model biochemical interactions of implant with its environment. We proposed an innovative set of diffusive-convective-reactive equations which relevant parameters were the cell decay factor, the cell motility and the growth factor balance. Initial comparison with histomorphometic results from a stable PMMA canine implant model provided an encouraging base to implement a numerical sensitivity analysis to evaluate the role of three types of bioactive surfaces: acid-etched titanium, coarse grit-blasted acid-etched titanium and coarse grit-blasted acid-etched titanium with RGDS peptide. We found that cell diffusion decrease (acid-etched+RGDS peptide vs. PMMA), and increase of local growth factor fraction (PMMA vs. acid-etched+RGDS peptide), significantly improved the amount of mineralized tissue on the implant surface. When the variation of structural fraction to cell motility and growth factor synthesis was investigated, an envelope pattern with an optimum was obtained but this could be exceeded for strong surface modifications and/or for high growth factor concentrations. The model also confirmed that implant bioactive properties should play a limited role to reduce heterogeneity of new-formed tissue. In conclusion, we suggested that our innovative theoretical approach was relevant to investigate implant fixation and could potentially help in reduction of implant revision.

Experimental and Numerical Models of Complex Clinical Scenarios; Strategies to Improve Relevance and Reproducibility of Joint Replacement Research

“…Computationally unwieldy models can occur even with simplified loading, simplified boundary conditions, simplified geometry and heterogeneity of tissue distribution and assumptions on the nature of the interface connections. While numerical models for predicting bone and tissue adaptation traditionally focus on mechanical and structural analysis, it is important to consider the contribution of other factors such as biologic and biochemical [36,37]. Incorporating complex mixed mechanics (solid þ fluid, poromechanics, reactive media) carries the challenge of providing rigorous validation on clinically relevant measures [38][39][40][41].…”

Wave front migration of endothelial cells in a bone-implant interface

“…The theory inspired by works in implant fixation (Ambard and Swider, 2006;Gué rin et al, 2009) and tumors angiogenesis (Anderson and Chaplain, 1998) was completed by source terms to take into account the proliferation and diffusive terms to enhance the prediction of growth factor migrations. It was applied to a canine experimental model and extended by a parametric sensitivity analysis.…”

Sensitivity analysis of periprosthetic healing to cell migration, growth factor and post-operative gap using a mechanobiological model

“…It is observed that sensitivity to surface topology is significant (Neidlinger-Wilke et al 1994;Fermor et al 1998;Pessková et al 2007) and generally, osteoblastic proliferation decreases when surface roughness increases (Martin et al 1995;Mustafa et al 2001;Rosa and Beloti 2003). We previously proposed a preliminary model of interactions with bioactive surfaces (Guérin et al 2009). Osteoblast adhesion properties and growth factor source were locally updated to model biochemical interactions of implant with its environment.…”

“…A preliminary model of local interactions with the implant bioactive surface of implant has been proposed (Guérin et al 2009) and this will be completed by relevant source terms involving the post-operative neovascularisation.…”