A generalized approach to compute entraining velocity of knee joint during walking

In the knee joint, tangential motion between articular surfaces is commonly described in lubrication analysis through the entraining velocity u_e. Due to the complexity of joint geometry and kinematics, simplified assumptions are often introduced when modeling this quantity. This study presents a workflow to compute the entraining velocity in the knee joint. The proposed approach combines three-dimensional joint geometry derived from medical imaging with experimentally obtained motion data to characterize both the spatial configuration of the articular surfaces and their relative motion throughout the gait cycle. The method provides a consistent framework to estimate u_e without relying on prescribed functional forms. The computed velocity is compared with reference results available in the literature, showing similar trends while avoiding abrupt variations observed in some models. Although developed for the knee joint, the approach can be extended to other lubricated human joints. At the same time, its reliance on subject-specific inputs makes it suitable for personalized modeling of joint lubrication.