A study on the factors affecting the temperature distribution within intervertebral disc during electrothermal therapy

Intradiscal electrothermal therapy, a new and minimally invasive technique for the treatment of discogenic low back pain, is introduced recently. This procedure involves the percutaneous threading of a flexible catheter into the disc under fluoroscopic guidance. The catheter, composed of thermal resistive coil, heats the posterior annulus of the disc, causing contraction of collagen fibers and destruction of afferent nociceptors. This study tries to investigate the effects of the important factors of this procedure such as heat source temperature and heat loading time on the temperature distribution within the intervertebral disc. This study utilized both finite element analysis and the experiment. The results showed that when the heat source temperature was kept up 80°C for 1,020 seconds, the temperature of inner annulus reached at 45°C up to the distance of 15.6mm from heat source, which explains the coagulation of inner annulus. When the same heat source was used, the temperature of inner nucleus reached at 60°C up to the distance of 9mm from heat source, which explains the contraction of inner nucleus.