Entheses and enthesopathy. Anatomical, pathological, and radiological correlation

Entheses are sites of tendon and ligament attachment to bone, and enthesopathy is a disease process occurring at these sites. It may be inflammatory, degenerative, endocrine, metabolic, or traumatic in nature. Common sites of involvement include the pelvis, femoral trochanter, humeral tuberosity, patella, olecranon, and calcaneus as well as portions of the vertebral column. Specific radiographic features, including bone erosion, hyperostosis, fragmentation, and crystal deposition, may allow a precise diagnosis.