Intra-articular osteoid osteoma of the proximal ulna.

Osteoid osteoma is a common benign osteogenic bone neoplasm characterized histologically by increased osteoid tissue formation with an intracortical nidus surrounded by cortical thickening and vascular fibrous stroma and sclerosis. The clinical presentation classically includes severe nocturnal pain that is improved with nonsteroidal anti-inflammatory drugs. Younger men (second and third decades) have the highest incidence, with the most frequent sites of involvement being the long bones or axial skeleton. Osteoid osteoma may be missed due to the lesion occurring in an atypical location or due to failure to obtain advanced imaging studies such as computed tomography (CT). Intralesional or wide excision, or CT-guided radiofrequency ablation if available, leads to predictable and rapid pain relief. The authors report the case of a 24-year-old man who had a painful flexion contracture of his dominant right elbow for 1.5 years, secondary to an intra-articular osteoid osteoma. Attempted motion, passive or active, produced a marked exacerbation of pain. Previous surgeries, including an elbow synovectomy and an ulnar nerve transposition, had been unsuccessful in relieving his pain. Plain radiographs demonstrated a small area of periosteal thickening adjacent to the sublime tubercle. Fine-cut CT scan demonstrated an osteoid osteoma within the articular surface of the trochlear notch of the olecranon, adjacent to the sublime tubercle. Because of a perceived risk to the surrounding articular cartilage, CT-guided radiofrequency ablation was not performed. Wide en bloc surgical excision of the nidus was performed, with complete resolution of pain and rapid return to normal function.