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