7.P.11 CT GUIDED RADIO FREQUENCY ABLATION OF PEDIATRIC OSTEOID OSTEOMA UTILIZING A WATER-COOLED TIP

Radiofrequency (RF) ablation carries success rate of 70–90% in the treatment of Osteoid Osteoma (OO). Failures are related to incomplete ablation which might be caused by the probe’s small heating radius (0.5–0.8 cm). Water cooled tips were developed in order to prevent charring of the tip and adjacent tissues and to allow for a larger, up to 3cm ablation diameter. To our knowledge safety and efficiency of this probe in the treatment of pediatric OO were never reported. Our goal was to examine if this technique, when added to conventional RF ablation, improves the clinical results and whether it carries any additional risks in the pediatric population. Twenty two OO patients, 15 males and 7 females, 3 years and 6 months to 18 years old, were treated using the Cool-tip™ Tyco probe in a cooled mode followed immediately by conventional RF cycle under general anesthesia, in the CT suite. Fifteen of the lesions were in the femur, 2 in the tibia and the remainder lesions were located in the humerus, talus, calcaneus, 2nd metatarsus and sacrum. The OO was intraarticular in 5 patients: femur (3), calcaneus and Talus. Follow-up period averaged 38.5 months (range 16–66 months). All patients but one had their symptoms resolved immediately following a single treatment (95.5% success rate). One patient had partial relief and underwent second successful ablation. There were one recurrence after 18 months and one superficial infection. No fractures, neurovascular complications or growth disturbances were encountered. We conclude that the addition of a Cool-tip cycle to conventional RF ablation in children is safe, efficient and reduces the risk of recurrence without adverse effects specific to this age group. We attribute this success to the larger diameter of heat distribution occurring due to cooling of the tip and the prevention of probe and tissue charring.