This lecture provides a systematic approach to interpreting bone marrow edema (BME) patterns in large joints on MRI by classifying them into traumatic, mechanical, inflammatory, infectious, metabolic, iatrogenic, and neoplastic etiologies. It emphasizes that BME is a nonspecific imaging finding and that accurate diagnosis relies on correlating MRI morphology with patient demographics, clinical history, lesion distribution, and associated imaging findings. Particular attention is given to differentiating transient osteoporosis, subchondral insufficiency fracture, and avascular necrosis, as these entities may appear similar but have distinct prognoses and management implications.

Learning Objectives

• Recognize the major causes of bone marrow edema in large joints and differentiate traumatic, mechanical, inflammatory, infectious, metabolic, iatrogenic, and neoplastic patterns based on clinical and imaging features.
• Differentiate transient osteoporosis, subchondral insufficiency fracture, and avascular necrosis by identifying their characteristic MRI findings, including fracture lines, the double-line sign, lesion morphology, and typical patient populations.
• Identify associated imaging findings—such as cartilage defects, synovitis, enthesitis, calcifications, tophi, fractures, or tumor-related changes—that help establish the underlying etiology of bone marrow edema.
• Apply a structured diagnostic approach by integrating patient history, lesion distribution, and accompanying MRI features to narrow the differential diagnosis and guide appropriate clinical management.