Thumb duplication (pre-axial polydactyly)

 (See also Polydactyly)

Please note: these pages focus on thumb duplication, or polydactyly of the thumb. For details on polydactyly of other fingers, see our web pages on polydactyly.

If your baby was born with more than one thumb on one hand, we know that you and your family may be concerned. So, please know that at Children’s Hospital Boston, we approach your child’s treatment and care with sensitivity and support.

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• Thumb duplication is a congenital condition (meaning that your baby was born with it) in which your child has two thumbs on one hand.
• Rather than a single normal thumb on each hand, your child’s duplicated thumbs are smaller and underdeveloped.
  • The thumbs may be separate or appear fused together.
  • Other fingers may be abnormal, too.
• The muscles, tendons, ligaments, blood vessels and nerves are often divided between each of the abnormal thumbs. So, surgery for thumb duplication is often more complex than for other forms of polydactyly.
• Usually, surgery for thumb duplication involves reconstruction of the hand, for both functional and cosmetic reasons.
  • Surgery is usually done when the child is between 1 and 2 years old, when he can tolerate anesthesia and surgery well.
• Usually, the condition is unilateral, meaning that it affects only one of your child’s hands.
• Thumb duplication can sometimes be detected by prenatal ultrasound, and is apparent at birth; the underlying structure of the finger and the course for treatment are determined with an x-ray.
• Research is inconclusive regarding which gender is more affected by thumb duplication.
• Asian-American, Caucasian and Native American children are more likely to have thumb duplication (polydactyly on the thumb side), African-Americans on the small finger side.
• At Children’s, surgery almost always results in a very functional hand—although for more complex variations, a second surgery may be needed as a child grows.

How Children’s Hospital Boston approaches thumb duplication

The skilled experts in our Orthopedic Center’s Hand and Orthopedic Upper Extremity Program and our Plastic Surgery Department’s Hand and Microsurgery Reconstructive Program have treated thousands of babies and children with finger and hand problems, from simple to complex. We can provide your child with expert diagnosis, treatment and care—as well as the benefits of some of the most advanced clinical and scientific research in the world.

Our Orthopedic Center is recognized as the preeminent center for the care of children and young adults with a wide range of developmental, congenital, neuromuscular, sports related, traumatic and post-traumatic problems of the musculoskeletal system.

As one of the largest pediatric plastic surgery centers in the United States, our Department of Pediatric Plastic Surgery provides comprehensive care and treatment to children with a wide variety of congenital and acquired conditions, including finger and hand anomalies.

Thumb Duplication (Pre-axial Polydactyly): Reviewed by Amir Taghinia, MD, Brian I. Labow, MD, Donald S. Bae, MD © Children’s Hospital Boston; posted in 2012