Thiemann disease is a very rare genetic necrotic bone disorder characterized clinically by painless swelling of the proximal interphalangeal joints associated with osteonecrosis of epiphyses followed by osteoarthritic changes, with onset before 25 years of age and often a benign course. The disease is Thiemann disease, familial form (Monarch Disease Ontology identifier MONDO_0008142). Also known as: Osteochondrosis of phalangeal epiphyses, aseptic necrosis of phalangeal epiphyses, osteochondritis of phalangeal epiphyses.