Near-physiological fatigue behaviors of orthopedic implants in vitro

The fatigue performance of orthopedic implants is a critical factor determining their clinical service life and reliability. Developing the in vitro testing systems that can closely simulate the real mechanical loading and physiological environment of orthopedic implants is essential for investigating their near-physiological fatigue behaviors. Such studies are of great significance for accurately predicting the implant fatigue life to provide guidance for structural optimization. This paper reviews the advances of in vitro research on the near-physiological fatigue behaviors of orthopedic implants. The construction methods of in vitro testing systems and techniques used to characterize the near-physiological fatigue behaviors of orthopedic implants were summarized. The influencing factors and corresponding mechanisms of the near-physiological fatigue behaviors of orthopedic implants were analyzed. Although substantial progress has been made in this field, existing in vitro testing systems still have limitations in simulating the complex physiological loading, dynamic bodily fluid circulation, and tissue regeneration process. Future efforts should focus on developing multi-factor coupled testing platforms enabling the integrated simulation of complex physiological loading, dynamic bodily fluid circulation, and tissue regeneration to simulate the interactions among mechanical-chemical-biological stimuli. Such advancements will facilitate the precise prediction of the near-physiological fatigue behavior of orthopedic implants and provide guidance for their performance optimization. (Figure presented.)