What is polydactyly?

Polydactyly 3

Hand of a child with an extra digit next to their little finger.

Having an extra finger or toe is called polydactyly (pahl-ee-DAK-til-ee). The extra  may range from a small, raised bump to a complete working finger or toe. Most of the time, it’s smaller than the other digits and not well formed.

Sometimes the extra digit is only skin (a nubbin), and it connects to the hand or foot with only a narrow stalk of tissue. If the digit is better formed, it may have all the normal tissues, such as bone, muscles, blood vessels and nerves. In this case, it connects to the hand or foot deep inside.

This is a fairly common condition. It happens in about 1 in 1,000 babies. It’s passed down in some families (inherited). Often it happens to only 1 person in a family because of changes in their .

Usually there’s an extra digit on only 1 hand or 1 foot. Some babies are born with an extra digit on both hands or both feet. Less often, babies are born with extra digits on both hands and both feet.

Many babies with polydactyly have no other differences in their bodies and no health problems. But this condition can happen along with other hand or foot conditions, such as syndactyly (then it’s called polysyndactyly) or with other  conditions or syndromes.

Polydactyly is also called supernumerary digit. “Supernumerary” means “more than the typical number.”

  • Types of polydactyly

    There are 3 types of polydactyly based on where the digit is:

    • The extra digit is outside the thumb or big toe (preaxial polydactyly). When the digit is outside the thumb, it’s called radial polydactyly. When it’s outside the big toe, it’s called tibial polydactyly.
    • The extra digit is outside the little finger or little toe (postaxial polydactyly). When the digit is outside the little finger, it’s called ulnar polydactyly. When it’s outside the little toe, it’s called fibular polydactyly.
    • The extra digit is between other fingers or toes (central polydactyly).  

Why choose Seattle Children’s for polydactyly treatment?

Polydactyly is among the most common conditions treated by the experts in our Hand and Upper Extremity Program and our Foot and Ankle Deformities Program. Each year we see many babies with this condition in our clinics.

Our doctors, surgeons and are experienced in the range of treatment options for polydactyly. We create a treatment plan custom-made for your child to get the best results for them.

  • The hand and foot experts you need are here
    • Your child’s team includes doctors, surgeons, and nurses from Orthopedics and Sports Medicine as well as Plastic Surgery if needed.
    • For many of our patients, treatment means surgery — sometimes highly complex surgery to remove a fully formed digit. Our surgeons are experienced at performing this type of surgery in children. We have surgeons with expanded fellowship training in upper extremity surgery and foot and ankle conditions.
    • If your child needs occupational therapy after surgery to gain the best use of their hands or feet, we have the largest team of occupational therapists in the Pacific Northwest who specialize in the care of babies, children, teens and young adults.
    • We also work with families who choose not to have their child’s extra digit removed. We talk with you about the risks and benefits of treatment as well as your wishes and beliefs so you can decide what’s right for your family.


  • Care from before birth through young adulthood
    • We specialize in caring for kids. This means our experts have the knowledge, training and skills to treat the youngest patients, including babies and young children with extra digits. At Seattle Children’s, your child’s team has special training in the medical, surgical, emotional and social needs of young people.
    • If your child is diagnosed with polydactyly before birth based on an , we offer prenatal consultations to talk with you about your baby’s condition.
    • Babies and children are still developing. When we evaluate your child’s condition, plan their treatment and provide their care, we carefully consider their growth. We think about how growth may affect your child’s hands and feet over time. We also consider how an extra digit — and treatment to remove it — may affect the rest of their development and health.
    • If your child needs imaging that uses radiation, we use the lowest amount possible (PDF) to make the best image. We have a low-dose radiation X-ray machine, called the EOS. It makes safer full-body images. We also have the largest group of  pediatric radiologists in the Northwest.



  • Support for you and your family
    • We know it can be stressful to have a child with a hand or foot difference and to find the treatment they need. Everyone at Seattle Children’s works to make your experience here as easy as we can on your whole family.
    • Your child’s team does more than plan and provide care for your child. We also make sure you and your child understand your child’s condition and treatment options.
    • Seattle Children’s supports your family with a range of resources. Our Child Life specialists, Family Resource Center and Guest Services are here to help.
  • Research to improve care
    • Seattle Children’s takes part in the CoULD Registry for congenital upper limb differences. A registry is a place where researchers keep information about people who have a certain condition so they can learn more about it. CoULD connects researchers from children’s hospitals around the country to study treatments and improve life for kids born with arms and hands that aren’t typical.
    • Learn more about current orthopedics research at Seattle Children’s.


What are the symptoms of polydactyly?

Children with polydactyly are born with 1 or more extra fingers or toes.

The extra digit may be: 

  • A small, raised bump or a piece of skin that looks like a small finger or toe that isn’t fully formed (nubbin)
  • A complete working finger or toe 

For some children, polydactyly is only 1 feature of a more complex genetic condition or syndrome. These children will have other signs and symptoms.

How is polydactyly diagnosed?

If your child is born with an extra finger or toe, the doctor will examine your child carefully. During the exam, the doctor will check for other signs to tell whether your child has a more complex condition.

Your child may need an to see if there are bones in the extra digit and to see how the extra digit connects to the rest of the hand or foot. If the doctor thinks your child might have other genetic problems, your child might have tests to check their chromosomes.

Diagnosis before birth

Sometimes doctors can diagnose polydactyly based on what they see during an before a baby is born (prenatally). If this happens, talk with your healthcare team about what they can tell from the ultrasound and what it may mean for you and your baby. Our team at Seattle Children’s is here to provide prenatal consultations to talk with you about your baby’s condition.

How is polydactyly treated?

In most cases, doctors remove an extra finger or toe in early childhood. The goal of treatment is to give your child a hand or foot that works well and looks typical. There are also practical concerns, such as removing an extra toe so your child’s foot fits well into shoes.

Your child’s care team will talk with you about the risks and benefits of each treatment option — as well as the option to leave the extra digit if you want to consider this.

The method for removing an extra digit depends on how it connects to the hand or foot. An extra digit may connect with only a narrow stalk of tissue, or it may connect more deeply and share bones, muscles and other tissues with the hand or foot.

  • Vascular clip

    If the digit is poorly formed and contains no bone, sometimes the treatment is as simple as attaching a vascular clip at the base during a clinic visit. The clip stops blood flow to the digit so it will fall off, like the stump of the belly button does soon after birth. After attaching the clip, the doctor puts a bandage on your child’s hand or foot. In a couple of weeks, your child comes back to the clinic to have the bandage removed.

  • Surgery

    If the digit is more fully formed, a surgeon removes it in the operating room when your child is about 1 year old. This is done as a . Your child’s surgery will be based on their exact condition. More complex cases may require complex surgery.

    The surgery may involve carefully cutting through or around bones, , muscles,  and other tissues to remove the extra digit. Then the surgeon may move or reconnect some structures before closing the skin so the whole hand or foot works well and looks typical.

    After surgery, your child may need to wear a cast or splint on their hand or foot while it heals. The doctor will want your child to come back for follow-up visits to make sure they are healing well. Some children who have extensive surgery with cutting through many tissues may have occupational therapy to help with swelling, scarring and stiffness.

Contact Us

Contact Orthopedics and Sports Medicine at 206-987-2109 for an appointment, a second opinion or more information.

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