Osteonecrosis, transient osteoporosis, and transient bone marrow edema: current concepts.

Osteonecrosis, transient osteoporosis, and transient bone marrow edema are closely related diseases that may have an overlapping clinical and radiographic presentation, thus creating difficulty in establishing a diagnosis. Close scrutiny of MR images may aid in distinguishing the pattern of osteonecrosis from other conditions, but in other cases careful clinical and radiologic follow up may be required. The pathogenesis, radiologic diagnosis, and clinical relevance of these conditions are described and reviewed in this article.