Knee joint diathermy using microwave technology

Abstract: Microwave diathermy (MD) improves knee osteoarthritis pain and function. However, non-adherence to this therapy remains a major concern. The equipment is expensive and requires substantial deployment; thus, it's only available in professional physiotherapy facilities. Consequently, the practicality and widespread applicability of this heating therapy are limited. Therefore, the purpose of this study was to present a new modality treatment of MD specialized for knee joints by developing an applicator that operates at 433.78 MHz with high quality factor (~6000), for localized heating using a re-entrant microwave cavity (RMC). RMC was designed and simulated using COMSOL Multiphysics®4.4. Simulation results have shown the capability of this heating system to develop localized heating at the knee joint and peri-articular structures with a very high-power absorption rate. ~95% of the delivered power to the applicator has been absorbed by the knee joint owing to its high-quality factor. The relatively small volume over which the electric energy is focused makes it an attractive and viable candidate for manufacturing as a small and portable device to be available for patients to use it at home.