Stelling Classification

The Stelling Classification describes the general features of polydactyly in relation to an extra digit. It was originally described in relation to ulnar (post-axial) polydactyly:

• type I: there is an extra soft tissue mass or digit that is attached by a soft tissue bridge
• type II: an extra digit (partial or complete) that articulates with a normal metacarpal or phalanx
• type III: an extra digit articulating with an extra metacarpal

Type I is the most common. The most frequent site for type I is on the ulnar border of the little finger at the level of the proximal phalanx.

The Stelling Classification is useful in that it provides a broad framework for treatment:

• type I:
  • traditionally ligated with a suture, now best treated surgically
  • a ligaclip can be applied to the stalk, but this may result in a residual nubbins after healing and a potentially tender neuroma from the nerve within the stalk
  • best treated with formal excision and burying of the neurovascular pedicle to prevent neuroma; may be safely done in a young, starved child without the need for general anaesthesia by administration of a distracting feed
• type II:
  • complete excision of digit using flap of skin from removed part to close base of digit
• type III:
  • excision of phalanges and metacarpal
  • redraping of soft tissue envelope
  • recreation of intermetacarpal ligament for central anomalies