Humero-radial synostosis is a rare, genetic, congenital joint formation defect disorder characterized by uni- or bilateral fusion of the humerus and radius bones at the elbow level, with or without associated ulnar and carpal/metacarpal deficiency, leading to loss of elbow motion and, in many cases, functional arm incapacity. Bowing of radius may be additionally present.

Underdevelopment of the patella.