SCIENTIFIC ARTICLE Percutaneous radiofrequency ablation: relationship between different probe types and procedure time on length and extent of osteonecrosis in dog long bones J. Martel & A. Bueno & M. P. Domínguez & P. Llorens & J. Quirós & C. Delgado Received: 23 May 2007 / Revised: 7 September 2007 / Accepted: 17 October 2007 / Published online: 23 November 2007 # ISS 2007 Abstract Purpose We have been using radiofrequency ablation for the percutaneous treatment of osteoid osteoma since 2001. Frequently, lesions are located near the joint surface, involve the vertebral body or are close to major nerves. We seek to determine whether radiofrequency ablation (RFA) can be used safely in these cases. Materials and methods A total of 65 lesions were induced in 4 dogs. Each dog underwent RFA on the diaphysis of long bones, as well as femoral and humeral heads. Four different sessions were carried out by using 1- and 2-cm probes with or without a cool-tip system and by varying the timing of the procedure. Plain film, CT, and MRI were obtained. All bone samples were examined histologically. Results The dogs’ activity after the procedure was normal. No pathologic fractures occurred despite unrestricted activity of the animals. Cortical bone was always respected; therefore, articular cartilage has not been damaged. Radio- logical findings were characteristic. There were no signif- icant differences in lesion size, probe type, and the duration of the procedure. The mean lesion diameter perpendicular to the electrode was 18.5 mm. Conclusions Our study confirms the insulative effect of cortical bone. RFA can be safely performed close to the joint surface without damaging the cartilage. Keywords Radiofrequency ablation . Bone . Experimental study Introduction Percutaneous radiofrequency ablation (RFA) of osteoid osteoma has been widely used since the initial description by Rosenthal et al. [1]. Although this method has replaced classical surgical treatment in the majority of the hospitals there is a lack of knowledge about the possible adverse effects on neighboring structures including joint cartilage, spinal cord, nerve roots, and vessels. Most investigations relating to the side effects of RFA have been performed in livers or other solid organs, but infrequently in bone [2–11]. Variable results have been published, possibly relating to the insulating effect of cortical bone [3]. The purpose of this investigation was to evaluate the extent of RFA-related necrosis in different treatment schedules (cooling versus no cooling, 4 min vs. 8 min), to demonstrate effects of RFA on cortical bone, articular cartilage, and adjacent soft tissue, and to perform imaging– pathological correlation. Materials and methods Approval of the Committee of Ethics of the School of Veterinary Medicine was obtained before the study. Four healthy dogs were used, weighing between 15 and 20 kg. Skeletal Radiol (2008) 37:147–152 DOI 10.1007/s00256-007-0416-1 J. Martel (*) : A. Bueno Departamento de Diagnóstico por Imagen, Fundación Hospital Alcorcón, Avda. de Budapest s/n, 28922 Alcorcón, Madrid, Spain e-mail: jmartel@fhalcorcon.es M. P. Domínguez Departamento de Patología, Fundación Hospital Alcorcón, Alcorcón, Madrid, Spain P. Llorens : J. Quirós : C. Delgado Facultad de Veterinaria, Universidad Complutense, Madrid, Spain