RFA of chondroblastomas offers efficacious alternative to surgery

Evidence from the largest study of its kind to date suggests that percutaneous CT-guided radiofrequency ablation is a safe and effective alternative to open surgery in selected cases of chondroblastomas, according to New York University researchers.

Chondroblastomas are benign but painful tumors affecting the epiphyses of long bones such as the femur, tibia, and humerus. Albeit rare, they occur mostly in children and can severely affect their musculoskeletal development.

Open surgery, the current treatment of choice, entails a high risk of complications including arthritis and permanent bone and articular damage. Percutaneous RFA has established a solid reputation in osteoid osteoma, a similar type of benign bone tumor. The clinical literature regarding RFA's use for the treatment of chondroblastomas, however, is thin.

Treatment with RFA does not completely take away the risk of joint collapse or other complications. But the largest study available to date shows the technique can be safely and effectively employed in selected patients as an alternative to the more expensive and risky open surgical approach, said principal investigator Dr. Leon D. Rybak, an assistant professor of radiology at NYU.

Over a 12-year period, Rybak and colleagues enrolled a total of 17 patients (13 males, mean age of 16.4 years) with confirmed diagnosis of chondroblastoma. Patients underwent percutaneous CT-guided RFA at two academic centers. The investigators assessed pain levels immediately before and after the procedure and secured long-term follow-up (range four to 45 months) from 10 patients.

All 17 patients were pain-free within 24 to 48 hours of the procedure. Only two patients experienced some form of recurrence after RFA, at eight and nine months, and these required additional surgery. Rybak presented results at the 2007 RSNA meeting.

Ablation treatment consisted of the application of a single-tip monopolar RFA probe at about 90°C during a six-minute period. The number of treatments depended primarily on lesion size (range, 0.5 cc to 10 cc) and electrode type. The treatment protocol has been enhanced in recent years to include smaller probes and shorter ablation times, Rybak said.

"Large lesions, particularly those with evidence of preprocedural collapse, may not be an ideal candidate for this procedure," he said. "If the lesion is big enough that you have to consider a multitine probe, that's a lesion you may want to stay away from."

Despite the study being the largest series to date in this setting, its small number of patients remains a limitation. Further randomized controlled research should compare the complication rates for large and small lesions as well the rate of recurrence, which sets apart chondroblastomas from other bone tumors, Rybak said.

"We know that surgery carries anywhere from 10% to 35% recurrence rate. It will be interesting to see down the line what kind of recurrence rates we get with RFA," Rybak said.

For more information from the Diagnostic Imaging archives:

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Percutaneous ablation treats bone tumors safely, effectively