Design of a lower extremity exoskeleton to improve gait in elderly patients with knee osteoarthritis by reducing knee joint loading




Vaidyanathan, Vijay
Cao, Jennifer


Journal Title

Journal ISSN

Volume Title



Introduction: Knee osteoarthritis (OA) is the second most common diagnosis in the United States, affecting over 51.8 million people. It is characterized by joint pain and stiffness due to irreversible articular cartilage breakdown, resulting in often fatal falls or the inability to walk. There are 744,000 hospitalizations annually for elderly fall-related injuries, with each one averaging $17,483 in healthcare costs. Despite the abundance of low-cost, conservative treatments for knee OA, including braces and orthotics, a combination of patient non-compliance and lingering joint pain result in the need for an alternative treatment that reduces knee joint pain while facilitating movement of the joint by providing compensatory support during gait. The purpose of this study is to design a passive lower extremity exoskeleton that offloads the medial compartment of the knee joint while also delivering stability to the ankle-foot junction. This passive design is inspired by commercially available unloader braces for knee OA treatment, in combination with ankle-foot orthoses designed to mechanically realign the tibiofemoral junction. Methods: The initial device prototype will allow 1 degree of freedom each in the knee and ankle joints (sagittal plane) and will be modeled primarily for a 75kg adult male with a rehabilitative walking speed of 1.5-3.5 km/h. The device will be competitively lightweight with current exoskeletons with 5 or less rigid interfaces between the body and exoskeleton to allow for maximum comfort. Results: Modeling, stress and failure analysis of the prototype will be accomplished using Autodesk Inventor Design Studio. Gait parameters taken from simulation subjects wearing the device, such as walking speed, knee joint angle, and medial joint force will be measured, processed, and compared to control parameters. Conclusion: We hypothesize that an exoskeleton combining medial joint offloading and lower extremity stabilizing methods will provide the necessary joint pain relief and compensatory support to facilitate walking in the elderly.