Type Description[17][18] Characteristics[18] I Normal web Thumb web space not narrowed IIA Mildly narrowed web Thumb web space mildly narrowed IIB Severely narrowed web Thumb web space severely narrowed III Syndactylized web Thumb and index rays syndactylized, web space obliterated IV Merged web Index ray suppressed, thumb web space is merged with the cleft V Absent web Thumb elements suppressed, ulnar rays remain, thumb web space no longer present