Effect of microwave oven induced mild hyperthermia on bone viability and strength.

Extracorporeal hyperthermia treatment of bone followed by reimplantation may be an option for treating bone tumors. However, intensive heat treatment, such as autoclaving, causes a decline of mechanical and biologic functions of bone tissue. In the current study, a microwave oven was used for minimal hyperthermic treatment, and it was found that complete eradication of all viable cells in rat bone could be achieved with minimal reduction in mechanical function. When the cells were evaluated histologically by special lactate dehydrogenase activity staining, complete bone cell death occurred after 60 seconds of heating in an empty Petri dish and after 30 seconds when heated in a Petri dish containing normal saline. Mechanical stiffness and strength of the bones, tested in three-point bending, showed no decrease after this heating. Microwave oven induced hyperthermia eradication of viable cells without significant damage to the mechanical properties may have clinical relevance in limb salvage tumor surgery.