An abnormal union between bones or parts of bones of the fingers. The synonymous term "symphalangism of the hand" may be translated as fusions of bones of varying digree, that involve at least one phalangeal bone of the hand. If bony fusions are referred to as "Symphalangism" the fusion occurs in a proximo-distal axis. Fusions of bones of the fingers in a radio-ulnar axis are referred to as "bony" Syndactyly. [ HPO:sdoelken ]