As with most medical conditions, congenital anomalies of the upper extremity have a wide range of severity. No two conditions are the same although most can be categorized into groups with similar findings. Patients with an extra thumb (also called duplicated thumb, split thumb, or radial polydactyly) can be severely affected as demonstrated below. These pictures are of two different patients with extra thumbs that will be a challenge to reconstruct in surgery.
 |
| Extra thumbs on both sides, quite different |
 |
| Radial polydactyly on the right |
This child has very different anomalies on each side. On the right, the outer thumb is clearly small and should be excised. However, the “main” thumb is limited also. It stays in a bent position and has three joints which makes it somewhat like a finger. On the left, the two thumbs are “merged” together and will be difficult to separate. Both are smaller than normal and if we simply remove one thumb, it will be very small. Combining the two thumbs has the best chance to make one reasonably sized thumb.
 |
| Another difficult radial polydactyly |
This thumb is also difficult to reconstruct. It is a “Type 4” extra thumb with a zig- zag deformity. The surgery is far more than just removing one thumb- the other thumb must be stabilized, tendons may need to be moved, and the bone may need to be cut and realigned.