Heating rabbit joint by microwave applicator.

Heating the joint to high temperatures using a microwave device may inhibit metabolic activity of the synovial tissue and enable higher penetration of antiinflammatory drugs into the joint cavity. To measure the temperature distribution of local thermotherapy, the hind joints of eight rabbits were heated by a 915 MHz microwave power source, using a special applicator. Temperatures of 44.0 +/- 2.8C, 36.1 +/- 3.8C, 39.6 +/- 2.3C, and 35.2 +/- 1.5C were measured after heating in the joint cavity, cartilage, muscle, and skin, respectively. The only significant increase in the temperature was recorded in the heated joint cavity (p less than 0.01). This new microwave device can be a therapeutic tool in treating joint diseases because of its advantage of heating the target organ only, eg, synovium, while sparing the adjacent tissues.