Challenges in using OpenSim as a multibody design tool to model, simulate, and analyze prosthetic devices: a knee joint case-study

Abstract

The human knee is comprised of many elements including ligaments, articular cartilage, menisci and muscles, which are capable of bearing and transferring load during physical activities. Unfortunately, the knee joint is quite susceptible to injury and disease, because of the high loads to which it is subjected. In view of this fact, identifying and quantifying the loads placed on the anatomical tissues that surround the human knee is critical for understanding and studying knee joint pathologies. Experiments cannot measure clinically important quantities such as muscle and articular contact forces. Hence, muscle-actuated dynamic models are becoming a feasible approach for determining how musculoskeletal elements interact to generate movement. In general, these models combine a dynamic skeletal model with individual muscle models, but they rarely include articular contact models due to their high computational cost and complexity. OpenSim is a freely available software program, developed within a multibody dynamics framework, that enables the construction and simulation of musculoskeletal models, the visualization of measured and simulated motion, and the extraction of useful information for simulations. Given the capabilities of the OpenSim, the present work explored the use of this computational tool to study the dynamic response of a biomechanical model of a prosthetic knee. Thus, a conceptual framework for contact and muscle force modeling using OpenSim was described. The aim of this work was to investigate the potential for using this computational multibody tool to the design of medical devices, i.e., to assess how modeling approaches could complement experiment studies, mainly for the prediction of contact and muscle forces.