RADIOFREQUENCY THERMAL ABLATION:

This is a procedure, whereby, percutaneous ablation or destruction of an osteoid osteoma is done using radio-frequency waves. The technique involves
computer tomographic (CT) guided introduction of a probe that is connected to a radiofrequency generator. The probe is placed into the center of the lesion and the lesion is burned using radiofrequency energy. The procedure is performed on an outpatient basis and there has been excellent success in relief of the patient’s
symptoms. Due to the fact that only a small defect is created by a biopsy needle, there is virtually no compromise of the structural integrity of bone. Therefore, the patient may, almost immediately, return to normal activities.

A. AP x-ray of the leg: Osteoid osteoma in the tibia (arrow).
B. Bone scan image: Lesion with abnormal uptake (arrow).
C. CT image: Hypodense nidus (arrow) with surrounding thickened cortex
(asterisks). t = tibia f = fibula

Due to the high concentration of pain receptors within osteoid osteomas, as well as the need for the patient to remain perfectly still for an extended period of time, general anesthesia is recommended. The patient is placed in an oblique lateral position on the CT scanner in order to gain optimal access to the lesion without
neurovascular compromise. Preliminary CT images of the affected area are obtained to localize the lesion.

A. Preliminary CT scout view
(obl. lat. patient position)
B. Metal markers (white dots)
are placed on the skin in order
to localize the level of percuta
neous needle entry.
The nidus is seen on both images (arrows)

1. The skin is marked with a sterile marker and a small skin incision is made with a #11 knife blade. A coaxial bone biopsy set is selected that will accommodate the RF probe.
sheath (s), needle (n), probe (p)

2. The bone biopsy set (sheath and needle) are percutaneously inserted down to the level of the osteoid osteoma.

3. The needle is exchanged for the RF probe (p).

4. The probe is placed through the sheath into the center of the osteoid osteoma
(arrow).

After proper grounding of the patient, the electrode is connected to the generator and the lesion is ablated as the temperature is increased to 90 deg C and held at that temperature for 6 minutes.

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