Air-blocking ablation of osteoid osteoma; a technical note.

Osteoid osteoma accounts for approximately 10-12% of all benign bone tumors. Surgery was the treatment of choice for osteoid osteomas until percutaneous radiofrequency ablation (RFA) was introduced in 1992. Although RFA is generally considered curative in the treatment of osteoid osteoma, disease recurrence after ablation has been reported. We report a case in which RFA was delayed by the presence air surrounding the ablation probe. In this case, ablation could only be performed after the probe was removed and saline was injected through the introducer needle to displace the air. Air is reported to decrease radiofrequency energy transmission; a simple measure like injecting saline through an introducer could prevent such a complication. We also suggest that partial air in the ablation bed surrounding the ablation probe could decrease the energy transmission and may be one of the causes of early recurrences. Saline injection could be helpful in providing a more reliable environment for ablation.