Thumb Duplication (Pre-Axial Polydactyly) | Diagnosis & Treatments

Diagnosing thumb duplication (pre-axial polydactyly)

At Boston Children's Hospital, we understand that the first step to treating your child is obtaining an accurate, timely and thorough diagnosis. Experts in our Orthopedic Center's Hand and Orthopedic Upper Extremity Program and our Plastic Surgery Department's Hand and Reconstructive Microsurgery Program provide comprehensive care — including evaluation, diagnosis, consultation, surgery, and follow-up care.

A baby’s thumb duplication can sometimes be seen prenatally in ultrasound, and it’s apparent at the baby’s birth. Your doctor will:

  • take a thorough medical and family history
  • conduct a careful physical exam
  • use x-rays to assess the underlying structure of your baby’s thumb and hand and determine a course of treatment

Surgery for thumb duplication

Our orthopedic surgeons and plastic surgeons treat children with thumb duplication by surgically removing the extra digit and reconstructing the hand — typically, when the child is between 1 and 2 years old — young enough that he won't miss milestones such as grasping (prehension) and fine motor development, but old enough to be able to tolerate anesthesia and surgery very well.

Removing your child's extra thumb (radial polydactyly, thumb duplication) can be complex. A thumb is of primary importance in a child's hand function, and radial polydactyly can negatively impact the thumb's position (angle), shape, and function.

  • Just removing the extra thumb is not usually enough.
  • Each of the split thumbs has elements (shared functions) that need to be combined to recreate one fully functional thumb.
  • The procedure usually involves remodeling the remaining thumb, with special attention to its soft tissues, tendons, joints, ligaments, and fingernails.
  • Even after treatment, the reconstructed thumb may be smaller than a normal thumb.

After surgery for thumb duplication

Complications after surgery

Complications after surgery are uncommon and often minor, and include scarring, stiffness, instability, and late deformity. Most remaining cosmetic or functional issues can be addressed in later corrective surgery.

Caring for your child after surgery

If the surgery to remove the extra thumb is fairly complex, it can also involve your child's bone, ligaments, and tendons. If that's the case, your child may need to wear a cast for a few weeks.

Your doctor may recommend occupational or physical therapy to help reduce scarring, stiffness, and swelling, and improve function. If needed, your child's team will work with you and your child to learn home exercises that are important to his recovery. He may need to wear a cast or splint in some circumstances.

What's my child's long-term outlook?

After surgery, your child should have a very functional thumb and an improved appearance of his thumb and hand. His treated thumb may be a bit smaller than the other thumb, but it should have normal or near-normal function.

Your child may need to be followed for a number of months or years to:

  • ensure that he is healing
  • check that your child's thumb and hand have full or acceptable function
  • determine whether additional surgery is needed to improve the function or appearance of your child's thumb and hand

It's possible that in a severe case, your child may need additional reconstructive surgery to recover or retain full function and improve the hand's appearance. Also, it's rare but possible that the condition can come back, so your child may need an additional operation later in life.

Coping and support

At Boston Children's Hospital, we understand that a hospital visit can be difficult, and sometimes overwhelming. So, we offer many amenities to make your child's — and your own — hospital experience as pleasant as possible. Visit the Hale Family Center for Families for all you need to know about:

In particular, we understand that you may have a lot of questions when your child is diagnosed with thumb duplication. Will this affect my child long term? Will he be able to play sports and do regular activities? Boston Children's can connect you with extensive resources to help you and your family through this stressful time, including:

  • Patient education: From doctor's appointments to physical therapy and recovery, our nurses and physical therapists will be on hand to walk you through your child's treatment and help answer any questions you may have — Why will my child need surgery? Are there non-surgical options? How long will his recovery take? How should we manage home exercises and physical therapy? We'll help you coordinate and continue the care and support your child received while at Boston Children's.
  • Parent-to-parent: Want to talk with someone whose child has been treated for thumb duplication (pre-axial polydactyly)? We can often put you in touch with other families who've been through the same process that you and your child are facing, and who will share their experiences.
  • Faith-based support: If you're in need of spiritual support, we'll connect you with the Boston Children's chaplaincy. Our program includes nearly a dozen clergy— representing Protestant, Jewish, Muslim, Roman Catholic, and other faith traditions—who will listen to you, pray with you and help you observe your own faith practices during your hospital experience.
  • Social work: Our social workers and mental health clinicians have helped many families in your situation. We can offer counseling and assistance with issues such as coping with your child's diagnosis, stresses relating to coping with illness, and dealing with financial difficulties.

International patients seeking care

As an international pediatric orthopedics center, Boston Children’s cares for young patients from all over the world. Our International Center assists families residing outside the United States: facilitating the medical review of patient records; coordinating appointment scheduling; and helping families with customs and immigration, transportation, hotel, and housing accommodations.