Main Content

Syndactyly

What is syndactyly?

Sometimes, a baby is born with two or more fingers or toes that are joined together. They may look webbed. This condition is called syndactyly (sin-DAK-tuh-lee).

It is a very common abnormality, affecting about 2 in 2,000 births. The place that is most likely to be fused is between the second and third toes in the feet, and between the middle and ring fingers on the hands. The condition happens with toes more than fingers.

What causes syndactyly?

In the early stages of development in the womb, a baby’s fingers and toes are covered all the way around by a loose layer of tissue. Normally, between the sixth and eighth week of development, the tissue between the fingers and toes goes away, a process called apoptosis. Syndactyly happens when apoptosis fails to take place. So, syndactyly isn’t when fingers or toes grow together; instead, it’s when they fail to separate.

Experts don’t fully understand why syndactyly occurs, but it appears to happen in one of three ways. It can be:

• A random abnormality that happens as a baby develops in the womb.
• A trait that is passed down from a parent. It’s possible for a parent to have no symptoms of syndactyly and still pass down the gene that can cause it.
• Part of a syndrome that affects several different parts of the body. Some syndromes that include syndactyly are Poland syndrome, Apert syndrome and Carpenter syndrome.

Boys are twice as likely to have syndactyly as girls. It can affect one or both hands/feet. The number of fingers and/or toes that are joined, and how much they are joined can be different for every child.

How is syndactyly diagnosed?

Joined fingers and/or toes are visible at birth. Doctors will likely order X-rays to see how much of the bones and tissues in the joined area are involved. Sometimes X-rays will show extra fingers or toes beneath the skin.

As part of a physical exam, a doctor may manipulate the joined area to see if the joined fingers or toes can be moved separately. This will help determine if the bones are joined, or only the flesh.

Also, because syndactyly can sometimes be part of a syndrome, they may also order tests to determine if there are symptoms of a syndrome in other parts of the body. Doctors may also ask questions about the baby’s family medical history. Depending on what the joined area looks like and other test results, they may recommend that the baby’s family speak with a genetic specialist.

With the diagnosis, doctors may also classify the syndactyly to describe how much fusion or other problems there may be in the joined area. This can help them determine the best treatment. There are different ways to classify syndactyly, but in general it can be:

• Simple or complex: This refers to whether or not the bones are fused or only the soft tissue. Simple syndactyly only involves the tissue; complex syndactyly involves bone and tissue.
• Complete or incomplete: Fingers or toes that are joined all the way to the tip, including the nails, are complete syndactyly. If the webbing only goes part of the way, that is considered incomplete.
• Complicated: If there are deeper abnormalities, such as extra fingers/toes or bones that aren’t shaped correctly, the syndactyly is considered complicated. In a complicated case, there may be fusion in the nerves and blood vessels as well.

Usually, a simple syndactyly with no other problems anywhere else is not part of a syndrome.

How is syndactyly treated?

Treatment for syndactyly depends on where it is, how severe it is and any other medical concerns there may be about a baby’s overall health.

Simple syndactyly in the toes may not cause a problem. In this situation, some families may decide against treatment.

In the fingers, syndactyly can affect a child’s ability to use the hand. Treatment for syndactyly in the fingers is to separate the joined fingers, with a goal of giving the child a complete range of motion in the hand, and to improve the hand’s appearance.

In the case of complicated syndactyly, where the fusion can include bones, nerves and blood vessels, some doctors may not recommend surgery. This is because separating the fingers might not make things better. Overall, surgery may not be recommended if it would not improve the overall function of the fingers and hand.

When surgery is recommended, doctors must decide the best timing for the procedure. They have to consider a number of factors, including how babies’ hands grow and when they start learning how to move their hands. For example, a baby’s hand doubles in size during the first year, and this can affect the decision about certain kinds of syndactyly.

In general, for simple cases, surgery is performed when the baby is between 12 and 18 months old. For more complicated cases, surgery may be recommended earlier. For example, if two fingers of greatly different lengths are joined, such as the ring finger and the little finger, there is a chance that the little finger would “tether” the ring finger and keep it from growing straight. In cases like this, surgery may be performed when the baby is around 6 months old. If more than one set of fingers are joined, sometimes treatment may take multiple surgeries done in stages 3 to 6 months apart.

After fingers are separated during surgery, there is often skin missing where the fingers were joined. Because of this, surgeons often have to perform skin grafts in those areas. This involves taking skin from other areas of the body and placing it into the new area. Grafts used to treat syndactyly are usually taken from the groin, palm/wrist, inside of the elbow or the inside of the foot.

After surgery, when the stitches have healed, children benefit from hand therapy. This helps them gain movement and helps keep any scar tissue from becoming too tight.

For the best outcomes, treatment for syndactyly should be done at centers that have all the specialists needed to offer the full range of care. Some of the specialists who may treat children with syndactyly include:

• Pediatric plastic/orthopedic surgeons
• Pediatric hand surgeons
• Pediatric geneticist/genetic counselors
• Pediatric physical and occupational therapists
• Social workers

What is the outlook for syndactyly?

Every child and every case are different. Children usually do well recovering from the surgery itself. Overall, surgery helps children gain better hand movement and, as they grow, do well in school and in social settings.

Outcomes for simple cases of syndactyly may be more straightforward than complex ones. Potential complications can include scar tissue getting very tight and causing the hand to bend abnormally. In some children, the webbed area starts to grow back in. For any of these reasons, and others, additional surgery is sometimes needed.

Additionally, children who have syndactyly as part of a syndrome may have other issues that also need to be addressed as they grow. No matter the case, simple or complex, a skilled care team with good follow-up helps with long-term good outcomes.

Get help at Children’s of Mississippi

Children’s of Mississippi’s pediatric plastic surgeons lead care teams that include all the specialties that children with syndactyly need for the best possible outcomes. If your child has syndactyly, you can schedule a consultation with a pediatric plastic surgeon to discuss all the possible options for your child. They will be happy to talk with you and help you understand your next steps. Schedule an appointment online.

Last reviewed 10/15/2026.