Classification

Congenital syndactyly may be classified according to the:

• isolated anomaly or syndromic association
• tissues fused:
  • simple - soft tissue alone from the proximal end of the digit
  • complex - bone synostosis (metacarpal or phalangeal) and soft tissue
  • acrosyndactyly - complex syndactyly characterised by fusion of the bones distally but not proximally; fenestrations are usually present between the bones proximally and associated with constriction ring syndrome
• extent of fusion proximal-to-distal:
  • complete - fusion from web space to distal interphalangeal joints; can be associated with synonychia which is a shared or common fingernail
  • incomplete
• number of digits affected eg single versus multiple
• unilateral or bilateral
• site affected:
  • hand
  • foot
  • both