Radiofrequency thermal ablation of osteoid osteomas of the proximal femur. Usefulness of ultrasound guidance in selected cases.

To review symptoms and imaging findings of proximal femoral osteoid osteomas (OO); to analyse the results of a thermal ablation technique for radiofrequency of the nidus in this location; and to describe usefulness of ultrasound guidance in selected cases.Descriptive and retrospective study consisting of 8 patients with OO in the proximal epiphysis of the femur, which were treated by thermal ablation of the nidus with radiofrequency waves from 1998 to 2004.The mean pain period until the performance of the thermal ablation was 11.5 months (range 5-18 months). There were no complications, and all patients stated that the pain was gone by the day following the procedure, with some discomfort during the first week, except for one where it lasted more than one month due to technique difficulties. At present, with a mean follow up of 6 years and 2 months (range 6-190 months), all patients remain asymptomatic and live a rigorous normal life.Thermal ablation with CT-guided radiofrequency waves is a safe, effective and efficient procedure.Normal appearance of a proximal femoral OO does not differ significantly from other location osteomas and its diagnosis is easier with previous knowledge. Thermal ablation of the nidus with radiofrequency waves, that may be performed using ultrasound guidance, appears to be the elective treatment of choice due to its efficiency and minimum morbidity.