Development and Application of a Novel Dynamic Loading Device for Molecular Transport in Articular Cartilage

This study presents the development of a force-flow coupling mass transfer device, designed to explore the potential clinical applications of dynamic loading and osteochondral interface fluid flow in supporting drug therapy for cartilage injury repair. The device's stiffness was first validated under dynamic loading, followed by a quantitative analysis of tracer concentrations in cartilage using force-flow coupling. Hydrogel scaffolds were then evaluated for their mass transfer performance, with different peak stresses applied to investigate molecular transport mechanisms within cartilage. Experimental results showed that the stress-time curve of the device was consistent with that of the original fixture. Under the same peak stress, tracer concentration during peristaltic pump-driven bone-to-cartilage fluid transport was 1.40 times higher than that without flow. Mass transfer experiments with cartilage-hydrogel constructs further demonstrated that hydrogel scaffolds exhibited higher molar flow rates when the pump was activated compared to the static state, showing superior mass transfer performance relative to native cartilage. Peak stress regulation experiments revealed that dynamic loading enhanced tracer transport into the deep cartilage layer under constant flow conditions. The newly developed device facilitates experimental investigations of both native and artificial cartilage, elucidating the complex interactions between mechanical loading and osteochondral interface fluid dynamics. This technology provides crucial technical support for understanding cartilage repair mechanisms, optimizing drug delivery strategies, and evaluating the mass transfer performance of artificial cartilage under physiological loading conditions.