Abstract : This paper describes the heating properties of the resonant cavity applicator for treatment of osteoarthritis inside the knee joint. Thermotherapy is widely used for musculoskeletal disorders as a physical therapy in the clinic. Hot packs, paraffin baths, microwaves and heating devices with ultra-short waves are generally used, as well as therapeutic exercises for joint such as osteoarthritis. These methods are easy, simple and effective in inhibiting osteoarthritis progression at the early stage. However, it is not easy to heat the deep tissue by using these methods. Therefore, a successful thermotherapy for osteoarthritis has not yet been realized.
To overcome these problems, we proposed a new heating method using the resonant cavity applicator for osteoarthritis. In this new heating method, a human knee is placed between two inner electrodes. Two cylindrical metal shields are used to protect the leg from the electromagnetic energy, but the knee is uncovered to focus the heating energy on the diseased joint. The human knee is non-invasively heated with electromagnetic fields stimulated inside the cavity.
In the present paper, first, a method of constructing a three-dimensional (3-D) anatomical human knee model from two-dimensional (2-D) medical images for calculating temperature distributions is described. Second, temperature distributions using the finite element method (FEM) for several therapeutic heating methods used in the clinic are presented. Third, comparisons of the calculated temperature distributions during osteoarthritis treatments are discussed.
From these results, it was found that proposed heating method using the resonant cavity applicator is useful for treatment of osteoarthritis inside the knee joint.

View full abstract