Percutaneous radiofrequency ablation for osteoid osteoma Osteoid osteoma is a small benign bone tumor that commonly affects young people. Ninety percent of the population is under 30 years of age, and the majority of patients are male. The femur and tibia are the preferred sites. The main symptom is pain, which is worse at night and can be relieved by taking aspirin. Due to the constant pain caused by osteoid osteoma, patients usually need to undergo surgical treatment. Finding the exact site during surgery is difficult, so extensive bone resection is usually required to ensure complete treatment, which largely increases the rate of surgical disability. The first use of percutaneous radiofrequency ablation for osteoid osteoma was reported by Rosenthal et al in 1992. This method has been practiced in several central cities worldwide. Because it was reported to significantly reduce the rate of disability, we also adopted this technique in 2000. We conducted a study of patients who were diagnosed with osteoid osteoma between August 2000 and February 2005 and who underwent percutaneous radiofrequency ablation at St. Vincent’s Hospital in Melbourne, Australia. Vincent Hospital in Melbourne, Australia, who underwent percutaneous radiofrequency ablation in a retrospective survey of 24 patients. Of these, 6 were female patients and 18 were male patients with a mean age of 20 years. All patients agreed to undergo percutaneous radiofrequency ablation to relieve pain and remove the lesion. After general anesthesia was applied to the patients, the surgical operation was performed by a combination of surgeons and interventional radiologists from the CT room. The resting pulse rate of the patients was 10-20 beats per minute when the electrode needle was inserted into the lesion and the ablation procedure was started. All patients were discharged and allowed to walk “weight-bearing” within 12 hours of recovery from anesthesia. Immediately after the procedure, 23 patients experienced immediate relief of pain symptoms, 7 patients experienced relief followed by worsening of symptoms, and 1 patient did not experience relief. The recurrence of symptoms was mostly 8 months after surgery. Seven patients underwent multiple RFA procedures, six of whom were pain-free again, and one patient had a recurrence 7 months after the second procedure, which was successfully treated after a third RFA was performed on him. Of the eight patients who recurred, five had lesions ≥10 mm. The average time taken to follow this group of patients was 26 months. Follow-up was interrupted in one of the patients due to travel abroad, but there were no data to show a recurrence within 2 years after surgery. By the end of follow-up, all 23 patients were pain free except for one patient who was still awaiting further treatment. Percutaneous radiofrequency ablation for osteoid osteoma is a recent therapy. After performing multiple treatments, our treatment success rate was 96%, while the recurrence rate was 35%, which is higher than the recurrence rate reported therein. We noted that patients with lesions ≥10 mm had a significantly higher recurrence rate than other patients. The site treated by radiofrequency ablation was approximately 10 mm in diameter, and although multiple ablations were performed for lesions larger than 10 mm, it is likely that ablation was incomplete for tumors outside these ranges due to overlapping ablation patterns. the larger the lesion, the higher the recurrence rate, according to Woertler et al. Vanderschueren et al. recommended multiple ablations for lesions with a maximum diameter of ≥10 mm to reduce the recurrence rate. We agree with this statement and believe that recurrence and residual pain are caused by the unablated residual tissue and not by the appearance of new lesions in situ. Radiofrequency ablation therapy has several advantages over other therapies for the treatment of osteoid osteoma. Previously, surgical resection has been the treatment of choice for this disease. Accurate localization of the lesion is difficult during surgical resection, and the entire resection often requires a large incision, as well as internal fixation to prevent fracture of the surgical site. After surgical resection, hospitalization is usually required for more than 4 days, whereas our patients treated with RFA were discharged within 12 hours after surgery. After surgical resection, patients with lesions in the lower extremities are often required to “weight-bear” for a certain period of time, while patients treated with RFA can “weight-bear” without restriction after surgery. (Figure: Osteoid osteoma of the mid-femur) The difficulty in localizing the lesion is a recognized disadvantage of surgical resection for osteoid osteoma, whereas in RFA, the lesion can be precisely localized under CT guidance. In conclusion, we believe that percutaneous radiofrequency ablation is a simple and effective method for the treatment of osteoid osteoma, and has significant advantages over traditional surgical resection. Therefore, we believe that radiofrequency ablation therapy, coupled with appropriate assessment of the risk of recurrence in patients with large lesions, should be the treatment of choice for osteoid osteoma of the limb.