What is polydactylism?

Polydactylism, or having one or more extra fingers or toes, is probably the most common abnormality of development found at birth. Polydactylism is reported in about 2 per 1000 children. The true incidence is probably even higher since simple cases are not always reported. While polydactylism can be seen in conjunction with other birth defects, the majority of cases are not associated with any other physical abnormalities.

An extra finger or toe may be nothing more than a nubbin of soft tissue with no bone involvement, it may be a full digit that forks off one of the five normal long bones of the hand or foot, or it may be a complete extra digit with its own extra long bone in the hand or foot -- or almost any variation between these possibilities.

The most common form of polydactyly is a small, soft, extra finger that contains no bone. Many of these can be easily treated at birth by the attending physician who ties a suture tightly around the base. The extra digit falls off, and the normal-appearing hand or foot heals quickly.

If there might be bone in the extra digits, X rays should be obtained to give a clear picture of what is going on. In some instances, it is still difficult to decide which digit should be removed, and close observation of the function of the hands and feet as they develop can give the answer.

Complex polydactyly is usually not repaired until a child is one year old. Generally, the digit that is best aligned with the long bones is saved. When the other digit is removed, sometimes transferring tendons from the amputated digit will make the one that remains more normal. Sometimes a joint needs to be reconstructed, or a bony prominence shaved. If the case is complex, an orthopedic or plastic surgeon with expertise in hands and feet is preferred. Usually the results are excellent.