Patient Outcomes Following Computed Tomography–Guided Radiofrequency Ablation of Osteoid Osteoma in a Tertiary Cancer Center

Purpose: To report the therapeutic efficacy and safety profile of radiofrequency ablation of osteoid osteoma (OO) in a comprehensive cancer center.

Materials and Methods: After local institutional review board approval, patients who underwent therapeutic percutaneous radiofrequency ablation (RFA) of OO between June 2010 and June 2017 were identified. The records were reviewed for patient demographics, lesion size and location, ablation parameters, and technical success. Pre- and postprocedural magnetic resonance imaging (MRI) scans were reviewed for the presence of bone marrow (BM) edema. Patient-specific outcomes were examined. Baseline subjective pain levels using either the numeric analog pain scale (NAS) or face pain scale (FPS), pain medication category, and daily intake frequency were recorded and compared with 1- to 3-week and 6- to 8-week postprocedural follow-ups. An un-paired t-test was conducted to examine the differences between the groups.

Results: A total of 44 patients with a solitary lesion were identified. The lesions were located in the femur (15), tibia (14), ankle or foot (6), pelvic girdle (3), humerus (3), shoulder girdle (1), fibula (1), and L1 vertebrae (1). The lesions had an average size of 6.29 mm ± 2.17 mm. All 44 patients underwent RFA as outpatients, most frequently with a single applicator for 6 minutes at temperatures up to 90°C. Technical success was achieved in all 44 (100%) RFA sessions. Average NAS or FPS score before RFA was 7.9 ± 1.6, with 43 patients taking preprocedural pain medications (nonsteroidal antiinflammatory drugs, 41; acetaminophen, 2), with an average daily intake of 2.2 ± 1.2 pills. Preprocedural MRI was available in 37 patients, with 35 of 37 (95%) patients demonstrating significant BM edema. Six- to 8-week follow-up was available in 41 of 44 of patients, in whom the average NAS or FPS score was 0.7 ± 1.83 (P <0.0001). Whereas 37 of 41 patients had stopped their chronic intake of pain medications, the other 4 decreased their intake remarkably. Six- to 8-week follow-up MRI was available in 32 patients. All 32 patients had complete coverage of the OO nidus, with resolution of BM edema in 17 of 32 patients. Fifteen patients continued to have BM edema but with remarkable decreases in 13 of 15 patients. Acute complications were minor and included skin paresthesia and temporary local discomfort at the RFA site in two patients and osteomyelitis in one patient.

Conclusions: Image-guided percutaneous RFA is a highly efficacious treatment modality for patients with OO, with a great safety profile and remarkable patient satisfaction.