Advances in artificial joint testing driven by in situ mechanical characterization: From permeability of porous structures to dynamic wear monitoring.

With the acceleration of global population aging, joint diseases such as osteoarthritis have become a major public health issue leading to disability among the elderly population. As a core treatment for joint damage, total joint replacement surgery has experienced continuously growing clinical demand. Traditional ex vivo testing methods, constrained by static and single-load analysis models, fail to realistically replicate the mechanical responses and progressive damage processes of artificial joints within complex physiological environments. This limitation has become a critical bottleneck restricting improvements in long-term performance and clinical optimization of implants. In situ mechanical characterization techniques, offering advantages of real-time and multiscale testing, provide a key technological pathway to overcome this challenge. This review outlines the development trajectory and research advancements in in situ mechanical characterization-driven testing technologies for artificial joints. It compares principles, core advantages, limitations, and application scenarios of various in situ characterization techniques across three pivotal dimensions: the in situ micro-characterization framework, in situ testing of effective properties in porous structures, and interfacial wear behavior and service failure mechanisms. The study elaborates on how in situ mechanical characterization drives material selection, structural optimization, and biomechanical mechanism analysis for artificial joints. Research indicates that modern characterization techniques enable comprehensive multiscale characterization spanning from atomic to macroscopic dimensions, effectively revealing the evolution of permeability in porous structures, dynamic mechanical responses of biomaterials, interfacial wear mechanisms, and failure progression pathways under complex loading conditions during physiological service. This provides methodological support and theoretical foundations for optimizing implant performance and evaluating long-term service safety. Additionally, the review identifies core challenges in clinical translation of current in situ testing technologies and envisions future development directions emphasizing multimodal integration and experimental-numerical coupling, thereby offering a reference framework for subsequent research in this field.