Thermotherapy for rheumatoid arthritis using resonant cavity applicator

This paper discusses the new heating method for rheumatism rehabilitation using resonant cavity applicator with a cylindrical shield made of an aluminum alloy and a water bolus. Thermotherapy is widely used for musculoskeletal disorders as a physical therapy in clinical settings. Hyperthermia with hot packs, paraffin baths, ultra-short waves and microwaves are generally performed as well as therapeutic exercises for joint diseases such as osteoarthritis (OA) and rheumatoid arthritis. However, all of them have advantages and disadvantages, and a successful heating method for deeply tissue has not yet been realized. In this new heating system, the human knee is covered with the cylindrical shield, except for the heated area. The human knee is placed in the gap between two inner electrodes. And it is then covered with the water bolus to concentrate the heating power in deep tissue. In this study, to evaluate the effectiveness of the proposed methods, specific absorption rate (SAR) distributions of this heating system were calculated by FEM with the 3-D anatomical human body model reconstructed from MRI images. From these results, it was found that our heating method is useful for heating deep places in the knee joint.