Previous studies indicate that occupational activities that require high knee-flexion, such as kneeling and squatting, are associated with a higher prevalence of knee osteoarthritis (OA). Excessive high kneeflexion postures may lead to increased knee joint loading, potentially contributing to the onset and development of OA. The study of the mechanism underlying the work-related OA will mostly rely on the biomechanical analysis, which will need the measurements of the dynamic thigh-calf contact forces. Furthermore, previous measurements determined only the normal component of the contact forces due to the limitations of the experimental technique. The complete thigh-calf contact forces including both tangential and normal force components during dynamic deep squatting tasks have not been evaluated previously. The purpose of this study was to quantify the time-dependent thigh-calf contact forces during high knee-flexion tasks that contain both normal and tangential components. To demonstrate the application of the proposed approach, the dynamic thigh-calf contact forces collected from a subject for deep squatting tasks were analyzed. The participant performed two sets of five continuous slow deep squats in two different postures: one set with heels grounded and another with heels raised. Our results showed that the time-histories of the thigh-calf contact forces collected from the subject were effectively characterized using a linear rotational spring model. The time-histories of the thigh-calf contact forces during the deep squatting, as calculated by the model, align closely with the corresponding experimental measurements.
Wu et al. (Fri,) studied this question.