Periprosthetic Joint Infection in Revision Total Hip Arthroplasty: Infection Prevention and Mode of Action by a New Antimicrobial Implant Coating

In hip revision arthroplasty, periprosthetic joint infection remains a severe complication and is the main reason for re-revision procedures within two years [Davis2022]. Patient-specific factors such as age, sex, BMI and comorbidities have a significant impact on the infection-related probability of hip revision surgery [EPRD2021]. For an innovative ultra-thin antimicrobial IP (Infection Prevention) coating an overview will be given on the journey from pre-clinical material and biomechanical testing, over different dedicated animal model studies towards a pre-CE clinical study with an IP coated THA revision system. A biodegradable ultra-thin antimicrobial IP coating is applied to orthopaedic implants for hip revision surgery. The IP coating contains pure metallic silver aggregates embedded in a polysiloxane matrix. Upon water contact, the silver aggregates start to release silver ions, which inhibit bacterial colonization on the implant surface [Lansdown2010, Chernousova2013]. The antimicrobial activity of the coating is intended as infection prevention in aseptic revision surgery, as well as supporting treatment of periprosthetic joint infection (PJI) in infected revision. Pre-clinical testing of the ultra-thin antimicrobial IP coating has been performed in the areas of material characterisation, packaging and sterilisation as well as biomechanical testing including usability aspects, like the implantation procedure in human donor bones. The antimicrobial effect has been investigated in in vitro tests for bacterial adhesion and surface growth [Fabritius2020]. In an rabbit model the stability and degradation of the IP coating on titanium alloy K-wires over a 24-week period was evaluated. The degradation over time was determined by measurement of the silver and silicon content as relevant molecular markers, as well as by measurement of the antimicrobial effectiveness of the coating. In dedicated animal in vivo models the antibacterial activity of the ultra-thin antimicrobial IP coating has been proven [vanHoogstraten2024] and it has been demonstrated that the IP coating is biocompatible and does not inhibit osseointegration on implant materials [Smets2017, Stein2020]. In the IP coating stability and degradation study on titanium K-wires implanted into rabbits, the presence of the IP coating and a residual antimicrobial activity after 12 weeks could be demonstrated. Together with the good biocompatibility of the IP coating and the continuously low silver values detected in the bone tissue, this in vivo model allows good conclusions regarding the safety, degradation behaviour and antimicrobial efficiency of the IP coating. Based on the pre-clinical evidence and promising results from customised orthopaedic implants a pre-CE study is initiated.