Modeling the debonding process of osseointegrated implants due to coupled adhesion and friction

Abstract

Cementless implants have become widely used for total hip replacement surgery. The long-term stability of these implants is achieved by bone growing around and into the rough surface of the implant, a process called osseointegration. However, debonding of the bone–implant interface can still occur due to aseptic implant loosening and insufficient osseointegration, which may have dramatic consequences. The aim of this work is to describe a new 3D finite element frictional contact formulation for the debonding of partially osseointegrated implants. The contact model is based on a modified Coulomb friction law by Immel et al. (2020), that takes into account the tangential debonding of the bone-implant interface. This model is extended in the direction normal to the bone-implant interface by considering a cohesive zone model, to account for adhesion phenomena in the normal direction and for adhesive friction of partially bonded interfaces. The model is applied to simulate the debonding of an acetabular cup implant. The influence of partial osseointegration and adhesive effects on the long-term stability of the implant is assessed. The influence of different patient- and implant-specific parameters such as the friction coefficient $$\mu _\text {b}$$ μ b , the trabecular Young’s modulus $$E_\text {b}$$ E b , and the interference fit $$I\!F$$ I F is also analyzed, in order to determine the optimal stability for different configurations. Furthermore, this work provides guidelines for future experimental and computational studies that are necessary for further parameter calibration.

Active osseointegration in an ex vivo porcine bone model

“…Osseointegrative implants are used across orthopaedic, oral (Buser et al, 2017), and craniofacial surgery (Granstrom, 2007) to treat millions of patients with severely disabling degenerative conditions, traumatic injuries, and congenital disorders. Initial stability of an osseointegrative implant is established by interference fit to the host bone (Immel et al, 2023). The secondary biological process wherein the bone adapts to establish long-term stability is complex (Trindade et al, 2016), typically lasting three to 6 months, with success dependent on patient metabolism (Jamsen et al, 2014), the properties of the implant biomaterial (Kaur and Singh, 2019), and the stability of initial fixation (Kohli et al, 2021).…”

Indentation and Detachment in Adhesive Contacts between Soft Elastomer and Rigid Indenter at Simultaneous Motion in Normal and Tangential Direction: Experiments and Simulations

“…Computational studies of friction and adhesion between polymers at the nanoscale are typically performed within the framework of molecular dynamics (MD) simulations where special approaches for tangential contacts were also developed (see, for example, [20,21]). As another illustrative example of the modeling of tangential adhesive contact, we can refer to the model based on traction-separation laws developed in [22], the n-point asperity model proposed in [23], the fracture mechanics model [24] and many others (see, for example, [25,26]).…”