Response to treatment of osteoid osteoma after radio frequency ablation and a comparison between drilling and curettage techniques before radio frequency ablation

Osteoid osteoma is a painful benign osteoblastic lesion occurring mainly in the long bones. On the one hand, some studies have declared that post-treatment CT cannot determine the success or failure of radiofrequency ablation, on the other hand, some studies have stated that imaging follow-up can be helpful or even mandatory in some cases. The present study aims to evaluate Osteoid Osteoma's imaging features before or after radiofrequency ablation with or without curettage and during the follow-up period.

In this retrospective and cross-sectional study, we reviewed twenty seven Osteoid Osteoma patients with radiofrequency ablation who were assessed via drilling with or without curettage from March 2015 to December 2019 at Nemazi Hospital, Shiraz University of Medical Sciences.

Radiofrequency ablation with drilling was used in 22(81.5%) patients, and for the rest 5(18.5%), radiofrequency ablation with curettage and drilling was performed as a treatment procedure. The overall clinical success rate was 92.6%(25/27), with a low complication rate (7.4%). The mean diameter of nidus in pre/pos treatment was 3.46±2.02 and 2.22±1.75 mm, respectively. Femur 12(44.4%) was the most common bone in the patients. Significant differences between pre/post treatment follow up examinations in nidus size (P=0.03), nidus diameter (P=0.02), bone and calcification size (P=0.005) were detected. Additionally, it depicts that the mean values of tumor size and cortical thickening decreased after treatment.

It is noteworthy that the present study had some limitations, including the small sample size and the relatively short follow-up period. There is no significant difference between radiofrequency ablation after drilling and curettage in treating Osteoid Osteoma. It is concluded that although there was a significant difference in pre/post-treatment imaging, there is no need for continuous imaging follow-up in treated patients without clinical complications such as pain to mitigate radiation dose risks and healthcare expenses.