With an estimated incidence of 1:1,000,000 - melorheostosis is a rare and progressive disorder characterized by thickening of the bone, also affecting the joints and overlying soft tissue and skin. Melorheotosis can result in severe functional limitation, extensive pain, soft tissue contractures (malformed and/or immobilized joints, tendons, ligaments), and limb, hand and/or foot deformity.  The age of diagnosis is typically based on severity of onset and symptoms.

Melorheostosis Association - http://www.melorheostosis.org