A 30-year-old man presented with a painful intraarticular lesion in the knee, clinically simulating osteoid osteoma. Pretherapeutic imaging disclosed a focal articular cartilage defect located in the medial femoral condyle and surrounded by extensive bone marrow edema. The defect was inaccessible for arthroscopic treatment because of its unusual posterosuperior location. Percutaneous radiofrequency ablation was then performed under computed tomography guidance, resulting in complete resolution of symptoms. Magnetic resonance imaging follow-up found resolution of the bone marrow edema pattern around the lesion and growth of fat in the site of the previous lesion.