An investigation into experimental biotribology and porohyperelastic lubrication modelling to elucidate transient cartilage friction

Experimental evaluations of articular cartilage biotribology primarily rely on macroscopic metrics, such as the coefficient of friction (CoF) and bulk strain, which obscure the transient internal fluid-solid mechanics critical to joint health. To resolve these inaccessible internal fields, this study presents a novel hybrid experimental-computational framework that couples physiological matched cartilage-on-cartilage reciprocating sliding data with a two-dimensional porohyperelastic lubrication (PHEL) model. Moving beyond current specialised models, the PHEL formulation explicitly couples finite-strain poroelasticity, porous flow, contact mechanics, and thin-film elastohydrodynamic lubrication to simultaneously simulate the dynamic operating conditions of matched cartilage. Validated against macroscopic experimental CoF and deformation profiles, the model extracts spatially and temporally resolved internal metrics, including interstitial fluid pressurisation, load partitioning, and interfacial fluid flux. Results reveal that frictional behaviour is fundamentally governed by dynamic load partitioning; interstitial fluid supports 90%–95% of the applied load during active sliding, leaving the solid matrix to support the remaining 5%–10%, which maintains a hydrodynamic wedge and a minimal CoF ( ∼ 0.02). The model successfully captures the velocity-dependent oscillation of CoF, demonstrating that momentary depressurisation at stroke reversal forces the solid matrix to temporarily support up to 15% of the load. This transfer is manifested as an increase in instantaneous compressive strain, directly driving macroscopic friction peaks. Furthermore, spatially resolved flux vectors provide direct quantitative evidence of tribologically driven interfacial mass transport, illustrating that sliding-induced hydrodynamic pressure gradients drive fluid recovery into the poroelastic matrix. This PHEL framework offers a sophisticated predictive tool to bridge macro-scale tribology with micro-scale mechanobiology, underpinning the future development of biomimetic joint repair technologies.