Advancements in Biomedical Sensors for Early Detection of Failure in Hip and Knee Implants: Scoping Review on Potential Sensors for Implant Integration

Purpose: Despite significant advancements in hip and knee joint implant technology, 6.4% of implants fail within the first ten years due to aseptic loosening, instability, and/or infection. Implants equipped with sensors show promise in early failure detection, enabling early and reduced intervention. This scoping review aims to provide an overview of biomedical sensors and their potential for integration into hip- and knee implants. 

Methods: A comprehensive search of databases PubMed and Embase was performed. Inclusion criteria were sensors to detect failure causes infection, inflammation, loosening or wear; developed for biomedical applications; ex vivo, in vivo and/or in vitro studies. The sensors were analysed based on criteria per sensor characteristics (e.g. accuracy, durability, response time) relevant for implant integration. 

Results: 49 articles were included presenting 52 sensors: 24 pressure and force, 6 strain, 15 acidity, 4 temperature, and 3 bacterial detection (3 dual sensing elements). Among these, three sensors were specifically designed for hip- and knee implants. The remaining 46 were developed for other biomedical applications. Our analysis identified two strain and seven acidity sensors that met the criteria for detecting hip- and knee implant failure. Two bacteria sensors showed potential for short-term use post-implantation, aligning with the critical period for periprosthetic infection, but the reporting frequency was too low to draw proper conclusions. No wear (particle) sensor was found. 

Conclusion: We found a significant gap in sensors that can detect wear particles. Future work on continuous implant monitoring should focus on reducing risk and the enhancement of sensor durability and longevity.