Osteoid osteoma is treated primarily by radiofrequency
(RF) ablation. However, there is little information about the distribution
of heat in bone during the procedure and its safety. We constructed
a model of osteoid osteoma to assess the distribution of heat in
bone and to define the margins of safety for ablation. Cavities
were drilled in cadaver bovine bones and filled with a liver homogenate
to simulate the tumour matrix. Temperature-sensing probes were placed
in the bone in a radial fashion away from the cavities. RF ablation
was performed 107 times in tumours <
10 mm in diameter (72 of
which were in cortical bone, 35 in cancellous bone), and 41 times
in cortical bone with models >
10 mm in diameter. Significantly
higher temperatures were found in cancellous bone than in cortical
bone (p <
0.05). For lesions up to 10 mm in diameter, in both
bone types, the temperature varied directly with the size of the
tumour (p <
0.05), and inversely with the distance from it. Tumours
of >
10 mm in diameter showed a trend similar to those of smaller
lesions. No temperature rise was seen beyond 12 mm from the edge
of a cortical tumour of any size. Formulae were developed to predict
the expected temperature in the bone during ablation. Cite this article:
Percutaneos radiofrequency (RF) ablation of osteoid osteoma has been proved as an effective treatment. However, there is limited data regarding other tumors. It also has been described in the treatment of other benign and malignant tumors like chondroblastoma and metastasis. In fact, one of the reported cases of chondroblastoma that were treated with RF was radiological small lesion erroneously diagnosed prior to treatment as osteoid osteomas. It was diagnosed as chondroblastoma only retrospectively. The aim of this study is to describe the success of RF as a definitive treatment and as an alternative to traditional surgery for the treatment of large chondroblastoma and chondromyxoid-fibroma which were diagnosed as such prior to ablation. From April 2006 to April 2007, 3 patients with chondroblastoma and 1 patient with chondromyxoid-fibroma were treated with RF ablation using cool-tip probe. Three procedures were done in the CT suit and one in the operating room. There were 3 girls and 1 boy. Mean age was 12 y 9 m (range 11 y 6 m – 14 y 6 m). Clinical and radiological follow-up was performed to assess outcome. The mean follow-up was 23.25 months (range 20–32 months). Three patients healed after single treatment and one needed repeated treatment. No immediate or delayed complications were observed. Follow up MRI showed no enhancement in the lesion and an extra-lesional sclerotic ream signifying RF effect beyond the lesion area. All patients returned to complete normal painless function. In spite of the small number of patients, percutaneous RF ablation was shown to be an effective and safe minimally invasive procedure for the treatment of chondroblastoma and chondromyxoid-fibroma, avoiding the morbidity of commonly used wide excision surgeries.
