Radiofrequency ablation of a difficult accessible osteoblastoma of the first sacral vertebrae: Fluoroscopic-guided electrode placement using a challenging posterior transpedicular approach

Abstract

Background Context Osteoblastoma is a benign primary bone tumour >1,5 cm in size, histologically related to osteoid osteoma, and the potential for progressive growth. Between 7-17% of osteoblastomas involve the sacrum with clinically presentation of localized pain and neurological deficits. Resection is often impeded by close localization to vulnarable structures with a high risk of procedural complications. Purpose To present a patient with a sacral osteoblastoma located at the difficult accessible anterior aspect of the S1 vertebral body using a technical demanding transpedicular approach for radiofrequency ablation (RFA). Study design Case report Methods A 16 years old male patient presented with an eighteen months history of severe sacral back pain pretreated with nonsteroidal anti-inflammatory drugs. Native computed tomography revealed an osteoblastoma, 2 x 2 cm in diameter, of the S1 vertebral body, that was histologically confirmed. A challenging surgical anterior approach by laparotomy was precluded because of the increased risk of injury to vascular and intestinal structures. RFA and subsequent alcohol injection was performed by a transpedicular approach of the S1 vertebral body under fluoroscopic guidance combined with flat panel CT for probe position. Result A significant pain reduction could be achieved when the patient leaved the hospital after 6 hours. At follow-up examination 3 months after RFA full daily activity was resumed and pain completely disappeared. Conclusion The use of a biplane x-ray system with flatpanel-CT for RFA allows spatial orientation for the anatomically very complex transpedicular access to the anterior aspect of the S1 vertebral body that can surgically only be reached with an increased risk of procedural morbidity. Key words Osteoblastoma, S1 vertebral body, radiofrequency ablation, transpedicular access, biplane x-ray system with flatpanel-CT, alcohol injection