Fig. 1.

Study design overview; (A) Hyaluronic acid (HA) supplementation at the joint level was examined using a passive pendulum friction setup (upper row), while the load application for the stance and swing phases were derived from a human gait cycle [24]. A viscous friction model was applied on the decaying passive knee joint motion in flexion–extension to calculate the damping time (tD) and to quantify the energy loss in terms of viscous damping (c) and friction processes (µ). (B) Testing of HA supplementation at the tissue level where meniscus against cartilage (tribosystem Meniscus) and tibial against femoral cartilage (tribosystem Cartilage) samples were examined using a dynamic pin-on-plate tribometer under gait-like loading conditions [19], while the coefficient of friction (CoF) was separately calculated for both, the stance and swing phases