Effect of the material’s stiffness on stress-shielding in osseointegrated implants for bone-anchored prostheses: a numerical analysis and initial benchmark data

Abstract

Purpose: This study attempted to establish the link between design of implants for bone-anchored prostheses and stress-shielding, affecting the stability of the bone-implant coupling using numerical approach. The objectives were to share a numerical model capable to evaluate the long-term stability of implants and to use this model to extract data sets showing how shape and material stiffness of threaded, press-fit and modular press-fit implants affect stress-shielding intensity. Methods: Three designs were considered: threaded, press-fit and modular press-fit. The effect of shape and material stiffness of each design on stress-shielding intensity was assessed using Young’s modulus (10 to 210 GPa). Furthermore, the impact of the diameter of percutaneous part (10 to 18 mm) and thickness of medullar part (5 to 1 mm) was investigated for the modular press-fit implant. Results: The threaded design generated 4% more bone mass loss at the distal femur but an overall loss of bone mass was by 5% lower to press-fit design. The influence of Young’s modulus on bone mass changes was noticeable for modular press-fit implant, depending on diameter of percutaneous or medullary part. A 20 GPa change of stiffness caused a bone mass change from 0.65% up to 2.45% and from 0.07% up to 0.32% for percutaneous parts with 18 mm and 10 mm diameter, respectively. Conclusions: Results suggested that threaded implant provides greater stability despite an increased bone loss at the distal femur. Altogether, this work provided an initial model that could be applied in subsequent studies on the long-term stability of current and upcoming implants.

Load applied on osseointegrated implant by transfemoral bone-anchored prostheses fitted with state-of-the-art prosthetic components

“…Further studies could associate the loading profiles with complementary mechanical (e.g., dynamics, kinematics, kinetics characteristics), physiological (e.g., electromyography of residuum muscles, metabolic energy consumption) and participant's experience (e.g., comfort score) information (Butowicz et al, 2020;Dumas et al, 2009;Dumas et al, 2017;Frossard et al, 2011b;Kaufman et al, 2018;Pantall et al, 2011). Establishing how prosthetic loading with state-of-the-art components influence the development of osseointegration around the implant and overall stability will be particularly valuable (e.g., modelling) (Helgason et al, 2009;Lee et al, 2008a;Newcombe et al, 2013;Prochor et al, 2020;Robinson et al, 2020a;Schwarze et al, 2014).…”

Health Service Delivery and Economic Evaluation of Limb Lower Bone-Anchored Prostheses: A Summary of the Queensland Artificial Limb Service’s Experience

“…45 Fittings of BAP must be made with additional constraints to limit unwanted loads, leading to increased risks for the boneimplant interface (e.g., loosening, breakage of connector and safety device, periprosthetic fractures, infection, removal). [46][47][48][49][50] Altogether, this study showed that the provision of BAP has the potential to be slightly outside the usual scope of practice of prosthetists. 51 Training opportunities by qualified experts, guidelines from suppliers of implants, and formal recommendations from governing bodies about prosthetic care of consumers fitted with BAP and business management that could help reduce risks are sparse, or even missing, in some jurisdictions.…”

The effect of cortical thickness and thread profile dimensions on stress and strain in bone-anchored implants for amputation prostheses

“…The intention was to provide knowledge on how the careful selection of design features can minimize the risk of bone or implant fracture during use. This study contrasts earlier FEbased studies which have been either case studies with subject specific anatomy [25]- [32], studies focused exclusively on bone remodelling around the implant [31], [33], or FE-implementations with too low resolution to accurately capture the stress in the threaded region [25], [27]- [30], [32], [34]- [37].…”