Syndactyly (from Greek συν- = “together” plus δακτυλος = “finger”) is a condition where two or more digits are fused together. It occurs normally in some mammals, such as the siamang, but is an unusual condition in humans.
Syndactyly of the border digits (thumb/ index finger or ring/ small fingers) is treated at early age to prevent the larger digit from curving towards the smaller digit with growth. Typically, syndactyly of these digits is treated at 6 months of age. The treatment of syndactyly of the other digits is elective and is more commonly performed when the digits have grown, at 18– 24 months of age.
Because the circumference of the conjoined fingers is smaller than the circumference of the 2 separated fingers, there is not enough skin to cover both digits once they are separated at the time of surgery. Therefore, the surgeon must bring new skin into the area at the time of surgery. This is most commonly done with a skin graft (from groin or anterior elbow). Skin can also be utilized from the back of the hand by mobilizing it (called a “graftless” syndactyly correction).
The most common problem with syndactyly correction is creeping of the skin towards the fingertip over time. This is likely due to tension at the site of the repair between the digits. Additional surgery may be required to correct this. One critique of using skin grafts is that the grafts darken in the years after surgery and become more noticeable. Also, if the skin grafts are harvested from the groin area, the skin may grow hair. Finally, the fingers may deviate after surgery. This is most commonly seen in complex syndactyly (when there has been a bony joining of the fingers).