Periodic Reporting for period 3 - BoneImplant (Monitoring bone healing around endosseous implants: from multiscale modeling to the patient’s bed)
Reporting period: 2019-10-01 to 2021-03-31
The aim of BoneImplant is to investigate the multi-time (from the microsecond up to the month) variations of the multiscale (from the nanometer to the organ scale) biomechanical properties of the bone-implant interface as a function of the implant environment, following an approach typical from engineering sciences. BoneImplant focuses on the description of the properties of bone tissue located around the implant during osseointegration. The originality of the approach lies in: i) multiphysical multimodality measurements, ii) the development of advanced multiscale bone model accounting for remodeling phenomena, isogeometric contact analysis and iii) the fundamental nature of this problem (understanding the time evolution of the properties of an interface) with important implications in terms of public health.
In vivo experiments were realized using titanium alloy (TiAl6V4) coin-shaped implants under different conditions. The advantage of this animal model is to consider a planar implant surface, which allows: i) standardized mechanical environmental conditions and ii) a proper initiation of crack path selection. Some implants were placed at around 200 µm from the leveled cortical bone surface, leading to an initially empty cavity (bone chamber), which allows to distinguish between mature and newly formed bone tissues. The effects of surface roughness, healing time and initial bone healing distance were investigated.
A multimodality and multi-physical experimental approach has been carried out to assess the biomechanical properties of newly formed bone tissue as a function of the implant environment. Different techniques such as nanoindentation and micro Brillouin scattering were employed to assess the biomechanical properties of newly formed bone tissue around an implant. The experimental approach also allowed to estimate the effective adhesion energy and the potentiality of quantitative ultrasound imaging to assess different biomechanical properties of the interface.
New modeling approaches have been developed in close synergy with the experiments. Isogeometric mortar formulation has allow to simulate the bone-implant interface in a stable and efficient manner. Moreover, finite element modeling has been carried out, allowing to understand the biomechanical determinant of primary and secondary stability.
Results will be used to design effective loading clinical procedures of implants and to optimize implant conception, leading to the development of therapeutic and diagnostic techniques. The development of acoustic techniques to assess implant primary and secondary stability has led to the project of creation of a spin-off.