Thumb Duplication

What Is Thumb Duplication?

Thumb duplication is a congenital defect in which a child is born with two thumbs on one hand. Thumb duplication is also called pre-axial polydactyly, radial polydactyly, or supernumerary thumbs.  

However, the name thumb duplication can be misleading because the muscles, tendons, ligaments, blood vessels, and nerves are often divided between each of the abnormal thumbs, and they appear fused together rather than as two individual thumbs.

As a parent, you probably have a number of concerns and questions about your child’s condition and the treatment process. Our specialists will work closely with you, providing detailed answers to make sure you feel comfortable every step of the way.  

Causes of Thumb Duplication

So far, the cause of duplicate thumb is unknown. In most cases, polydactyly of the thumb occurs sporadically as the fetus forms without any known genetic predisposition. Often parents have feelings of guilt and frustration when their child is the first to carry a genetic mutation. However, it is important to know that there is no known link between anything done in pregnancy and the cause of the polydactyly. 

In other cases, the defect is inherited and parents have or have known someone in their family who has thumb duplication. 

Thumb duplication occurs in about 1 out of every 1,000 live births. Males tend to be affected more than females, and the condition occurs more frequently in Caucasians, Asians, and Native Americans.

Treatments for Thumb Duplication

The only treatment for thumb duplication is surgery, which generally begins around age one.

At the Yale Hand and Microsurgery Program, we know how scary it can be to have your child undergo surgery. Your child will be cared for by some of the top surgeons in the country, using the most advanced techniques to recreate the best possible thumb.

Before the surgery, we will discuss your child’s customized treatment plan with you so you understand the process and know what to expect.