Thumb Duplication (Pre-Axial 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 Boston Children’s Hospital, we approach your child’s treatment and care with sensitivity and support.

Thumb duplication is a congenital condition (meaning that your baby was born with it) in which your child has two thumbs on one hand. The muscles, tendons, ligaments, blood vessels, and nerves are often divided between each of forms of polydactyly.

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.

Thumb duplication is a congenital condition in which a child has two thumbs on one hand.

How we care for thumb duplication

The Orthopedic Center’s Hand and Orthopedic Upper Extremity Program and our Department of Plastic and Oral Surgery's Hand and Reconstructive Microsurgery Program have treated thousands of babies and children with thumb duplication and other hand problems. We are experienced treating conditions that range from routine to highly complex, and can provide your child with expert diagnosis, treatment, and care. We also offer the benefits of some of the most advanced clinical and scientific research in the world.

Our Orthopedic Center is nationally known 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.

Our Department of Plastic and Oral Surgery is one of the largest and most experienced pediatric plastic and oral surgery centers anywhere in the world. We provide comprehensive care and treatment for a wide variety of congenital and acquired conditions, including hand deformities.