Polydactyly (Extra Fingers)

What is polydactyly?

Polydactyly—or extra fingers or toes—is one of the most common congenital hand conditions. It often runs in families. Extra fingers can be located anywhere on the hand:

  • When the extra finger is located on the thumb side of the hand, the condition is called radial polydactyly or pre-axial polydactyly.
  • When the extra finger is located on the pinky finger side of the hand, the condition is called ulnar polydactyly or post-axial polydactyly.
  • When the extra finger is located in the middle of the hand, the condition is called central polydactyly.

Extra fingers are usually smaller than a fully formed finger. They can range anywhere from a bump on another finger to a finger with a bone connecting it to the rest of the hand. When a fetus is developing in the mother’s womb, the hand first forms in the shape of a paddle and eventually splits into fingers. Sometimes, an extra finger forms during this process, resulting in polydactyly. Researchers are not sure why this happens, although some cases of polydactyly are genetic, and others happen alongside other hand conditions, such as syndactyly (webbed fingers).

How is polydactyly diagnosed?

Your child’s doctor can diagnose polydactyly after hearing about your child’s medical history and doing a physical exam. X-rays are often helpful in confirming the diagnosis and showing the doctors if any other bones in the hands or fingers are involved.

How is polydactyly treated?

Treatment varies based on the type and location of the extra finger, but surgery is usually recommended to remove the extra finger. For children with post-axial polydactyly (when the extra finger is located on the pinky side of the hand), surgery can vary from a minor procedure in the clinic to a more involved reconstructive surgery if the extra finger is fully developed.

For children with an extra thumb (radial or pre-axial polydactyly), reconstructive surgery is recommended, usually after age 1 so that the thumb is large enough to operate on precisely.

Depending on the type of surgery required, your child may need to wear a cast until the area heals. Occupational therapy may also help reduce stiffness and swelling after surgery, and follow-up visits will help ensure that your child’s hand function returns to normal.