Abstract
BackgroundThe surgical success of cementless implants is determined by the evolution of the biomechanical properties of the bone–implant interface (BII). One difficulty to model the biomechanical behavior of the BII comes from the implant surface roughness and from the partial contact between bone tissue and the implant. The determination of the constitutive law of the BII would be of interest in the context of implant finite element (FE) modeling to take into account the imperfect characteristics of the BII. The aim of the present study is to determine an effective contact stiffness left( {K_{c}^{text{FEM}} } right) of an osseointegrated BII accounting for its micromechanical features such as surface roughness, bone–implant contact ratio (BIC) and periprosthetic bone properties. To do so, a 2D FE model of the BII under normal contact conditions was developed and was used to determine the behavior of K_{c}^{text{FEM}}.ResultsThe model is validated by comparison with three analytical schemes based on micromechanical homogenization including two Lekesiz’s models (considering interacting and non-interacting micro-cracks) and a Kachanov’s model. K_{c}^{text{FEM}} is found to be comprised between 1013 and 1015 N/m3 according to the properties of the BII. K_{c}^{text{FEM}} is shown to increase nonlinearly as a function of the BIC and to decrease as a function of the roughness amplitude for high BIC values (above around 20%). Moreover, K_{c}^{text{FEM}} decreases as a function of the roughness wavelength and increases linearly as a function of the Young’s modulus of periprosthetic bone tissue.ConclusionsThese results open new paths in implant biomechanical modeling since this model may be used in future macroscopic finite element models modeling the bone–implant system to replace perfectly rigid BII conditions.
Highlights
The surgical success of cementless implants is determined by the evolu‐ tion of the biomechanical properties of the bone–implant interface (BII)
The aim of this study is to develop a multiscale model of the biomechanical behavior of an osseointegrated BII, which is modeled as an imperfect interface, taking into account its microscopic properties: the bone–implant contact ratio (BIC) ratio, the implant surface roughness and the bone properties
Voigt–Reuss bounds Figure 1 shows the variation of the effective contact stiffness obtained using the numerical approach described in “Numerical resolution” section as a function of the BIC in the reference configuration (∆ = 5 μm, λ = 80 μm, Eb = 2 GPa), which is compared with the Voigt–Reuss bounds
Summary
The surgical success of cementless implants is determined by the evolu‐ tion of the biomechanical properties of the bone–implant interface (BII). Endosseous cementless implants have been used clinically for more than 40 years and have allowed considerable progresses in dental, maxillofacial and orthopedic surgery, to replace missing organs or to restore joints functionality. Despite their routine clinical use, implant failures still occur and remain difficult to predict. When the primary stability is not sufficient, micro-movements may appear, preventing good healing conditions and leading to the formation of fibrous tissue and eventually to surgical failure [9, 10]. Micromotions at a relatively low level may be responsible for biomechanical stimulation of bone remodeling
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