Thermal influence of radiofrequency ablation for bone: an experimental study in normal rabbit bone.

Yamamoto, Shuichi; Kaminou, Toshio; Ono, Yuichi; Hashimoto, Masayuki; Ohuchi, Yasufumi; Yoshida, Haruhiko; Ogawa, Toshihide

OBJECTIVE To evaluate the heat effects of radiofrequency ablation (RFA) on normal bone by mechanical testing, MRI, and histology. MATERIALS AND METHODS The institutional animal care and use committee approved the animal study. Thirty-two adult Japanese white rabbits were included in our study. Bone biopsy needles were inserted from the distal end of the right (RFA side) and the left (control side) femurs using a fluoroscopic guide. A 17-gauge internally cooled RFA electrode with a 2-cm active tip was inserted through the needle to the right femur, and RFA was performed for 12 min using a 200-W generator. Animals were divided into four groups and 8 animals from each group were euthanized on day 1, day 7, day 30, and day 60 after RFA. MRI was performed prior to euthanasia. Three-point bending test was performed to measure flexural strength. Student's t test was used to evaluate for significant differences between RFA and control side for each group. Femurs underwent histological examination by hematoxylin and eosin staining after the bending test. RESULTS MRI showed a high-intensity rim around the bone on T2WI. Three-point bending test showed no statistically significant differences (P < 0.05) between the RFA and the control side in any of the groups. Histologically, osteocytes of cortical bone showed cell death, but the lamellar structure was preserved in all groups and bone remodeling was observed. CONCLUSION Heat by RFA did not change normal bone strength within 2 months, despite the heat effects in the cortical bone and cell death.