Radiofrequency ablation for non-spinal osteoid osteomas in 557 patients.

Objectives: To present the results of biopsy and computed tomography (CT) guided radiofrequency ablation (RFA) for non-spinal osteoid osteomas, and compare the results before and after procedural modifications.

Methods: We retrospectively studied 557 patients with non-spinal osteoid osteomas treated with biopsy and CT-guided RFA. In 68 patients we used 3-mm CT at 2-mm intervals, 19 G/5-mm active tip electrodes, and one 4-minute ablation at 90-93°C. In 489 patients we used contiguous 1-mm CT, 20 G/5-15-mm electrodes, ablation maintaining 60°C for 2 min followed by 14-15 min at 90-93°C, and multiple ablations in the same session for large and multiform lesions.

Results: 533/557 patients (96%) remained asymptomatic and 24/557 (4%) had recurrence; repeat RFA was successful in 22/24 patients (92%). Biopsy was non-diagnostic in 82%. With the modifications performed, success improved from 79% to 98%, recurrences reduced from 21% to 2% and complications from 5.9% to 0.2% (p < 0.001). All patients with large and multiform lesions treated with one ablation had recurrence, compared to no patient with similar lesions and multiple ablations in the same session.

Conclusion: Electrode parameters, duration of ablation, morphology and size of osteoid osteomas are important for RFA. The above modifications are recommended for improved outcome.