Intra-articular osteoid osteoma.

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Abstract

[Indexed for MEDLINE] 12. Codman Triangle. McDonald J, DenOtter TD(1). In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026 Jan–. 2023 Jul 25. Author information: (1)Creighton University Codman triangle is a radiologic sign seen most commonly on musculoskeletal plain films. It is the name given to a periosteal reaction that occurs when bone lesions grow so aggressively that they lift the periosteum off the bone and do not allow the periosteum to lay down new bone. It is a pattern of interrupted periosteal reaction where the periosteum gets lifted at either end of the aggressive lesion, and the central aspect of the lesion does not have any overlying ossification. This state gives the appearance on plain films of a raised triangle of periosteum along the edges of the lesion. In this reaction, the periosteum may become lifted by the leading edge of the tumor, pus, or hemorrhage. Copyright © 2026, StatPearls Publishing LLC.