Paediatric
Polydactyly
Extra digit
What it is
Polydactyly is an extra digit present at birth. What it means differs a great deal depending on which side of the hand is involved.
On the thumb side it is usually a duplication: two partial thumbs, neither of them completely normal. On the little-finger side it ranges from a small skin tag to a fully formed finger.
Symptoms
A duplicated thumb is usually narrower, stiffer and less stable than a normal thumb, and pinch between thumb and index lacks strength. The thumb often deviates off its axis.
A tag on the little-finger side generally causes no functional limitation, but it catches on clothing and becomes tender if knocked.
Non-operative treatment
There is no non-surgical treatment that corrects a duplication. The waiting period is used for planning and for assessing the stability and movement of each element.
One point about small tags on the little-finger side: tying them off in the nursery, once common, is now less favoured, because it frequently leaves a small tender lump at the end of the stump. A clean surgical excision is preferable.
Surgical treatment
A thumb duplication is not treated by simply removing the smaller part. The better-formed thumb is kept and then reconstructed: bone, joint, nail, ligament and tendon elements are recentred and rebalanced, and the collateral ligament is reconstructed to give a stable pinch.
Surgery is usually carried out around one year of age. A well-formed extra digit on the little-finger side is removed with ligament reconstruction of the finger that remains.
Recovery expectations
A cast is worn for four to six weeks, followed by splinting and therapy. Children go back to using the hand spontaneously and quickly.
The reconstructed thumb usually stays slightly smaller and slightly stiffer than the one on the other hand. Deviation can reappear with growth; that is the reason for follow-up to skeletal maturity, where a further correction is sometimes offered.
These pages give general information for patients and referring physicians. They do not replace an individual assessment: the treatment plan is decided in consultation, based on your examination and your goals.