Polydactyly is a relatively common congenital condition, according to hand surgeon Dr. Terry Light of the Loyola University Medical Center. It can take several forms. Extra digits can be located next to the thumb, next to the little finger or in the middle of the hand. The digits typically are smaller and abnormally developed. Some babies have two thumbs on each hand, while other babies have seven or eight fingers and no thumb.
In the easiest cases, the extra digit is soft, floppy tissue with no bone. The pediatrician or hand surgeon ties a suture around the base and the digit falls off after a few days. This is how Girl Arterton's polydactyly was treated. "It's my little oddity that I'm really proud of," Arterton told Esquire magazine. "It makes me different."
More complex cases involve a digit that has split into two fingers or two thumbs, neither of which is normal. A split thumb, for example, has a Y shape. The surgeon combines parts of both branches to create one thumb. The most complicated cases involve hands with seven fingers and no thumb. The surgeon removes two of the extra fingers. Another finger is moved to where the thumb should be. The surgeon fashions this digit into a thumb, by shortening it and rotating it to face the fingers, Light said. Polydactyly occurs in at least 1 in 1,000 newborns, making it one of the most common congenital hand conditions. About 40 percent to 50 percent of cases have a genetic cause.
