After a baby is born, one of the first things proud parents do is count the infant's fingers and toes. What happens when those digits look fused or stuck together?
Medically, that condition is known as syndactyly. It occurs when skin fuses two or more fingers or toes, making them look "webbed." Bones and other soft tissues might also be affected. Syndactyly is diagnosed at birth, or sometimes even earlier during prenatal ultrasound screenings.
Webbed fingers or toes can affect each person differently. Here's what you need to know about the types of webbing that occur to fingers and toes and some of their common causes, risk factors, and treatments.
What Causes Webbed Fingers or Toes?
As a baby develops in the uterus, their hands and feet first form in flipper-like paddle shapes. Around week 10 of pregnancy, the fetus’s fingers and toes should separate, elongate, and lose their webbing. Syndactyly happens when fingers or toes don't separate or develop normally at this time.
Webbed fingers and toes usually happen on their own as an isolated birth defect but sometimes there is a genetic component to your likelihood of having syndactyly. It's estimated that between 10% and 40% of people with syndactyly have family histories of webbed fingers and toes.
Sometimes syndactyly is part of a larger health problem. Webbed fingers and toes can be a symptom of many other genetic syndromes like Apert, Chotzen, and Poland syndromes.
What Are the Different Types of Webbed Fingers and Toes?
Each person with webbed fingers or toes develops differently and has a unique genetic makeup that can influence the severity and type of syndactyly that affects them. While syndactyly refers to skin webbing, there are variations of the condition that include skin, bone, and connecting tissues.
There are four groupings of syndactyly based on hand or foot symptoms:
- Simple syndactyly. Fingers or toes are joined together with skin and other soft tissues.
- Complex syndactyly. Some bones are also fused under the skin.
- Complicated syndactyly. A person has extra, missing, or undeveloped bones with abnormal tendons and ligaments.
- Incomplete syndactyly. Part of the skin between fingers and toes are webbed.
Syndactyly is also grouped into several types depending on which fingers or toes are affected:
Type 1. This is the most common kind of webbing between fingers and toes that's not related to other genetic syndromes. Often the third and fourth fingers or second and third toes are affected. This type of webbing usually affects both right and left hands or both feet.
Type 2. This type of webbing commonly affects the third and fourth fingers and the fifth toe. People with this variation of webbing often have extra fingers or toes. It can also cause the fifth finger to be curved, crooked, or shortened.
Type 3. This variation usually affects the fourth and fifth fingers of the hands. The third — or middle — finger might also be fused, missing, or undeveloped. Type 3 syndactyly does not affect feet.
There are many other types of syndactyly that affect the skin and bones of fingers and toes. Your doctor will be able to diagnose the severity and type by using physical exams, X-rays, or genetic testing.
How Common Are Webbed Fingers or Toes?
Syndactyly is a fairly common birth defect, but if you don’t have a family history of webbed fingers or toes, having a child that does can take you by surprise.
About one in every 2,000 to 3,000 newborns have webbed fingers or toes. Type 1 is the most common, and usually only affects the skin and soft tissues. Other types are much rarer, including those caused by genetic syndromes that have other serious health effects.
Syndactyly usually will affect both hands in about half of babies born with the condition. Caucasian male babies are born with webbed fingers and toes more often than female, Black, or Asian babies.
What Is the Treatment for Webbed Fingers and Toes?
Mild finger webbing that doesn’t interfere with your child’s development and webbing between the toes can usually be left untreated.
All other types of syndactyly can be repaired surgically, usually when the child is between ages 1 and 2. By then, a child is young enough that the chances of normal development increase and old enough that risks from anesthesia are decreased.
During the surgery, your doctor will split your child’s skin evenly between the webbed fingers and carefully separate the tissue. This is usually done in a zig-zag pattern to help reduce the need for skin grafts. If extra skin is needed, it can be taken from other parts of the body. Often it will come from the wrists or elbows to reduce visible scarring.
If your child has multiple webbed fingers and toes or a more severe form of syndactyly, they might have to have more than one surgery.
After surgery, your child will wear a cast for several weeks. Rubber spacers might be needed to keep your child's fingers separated while they heal. There will be regular, follow-up doctor visits to check on your child's progress, answer questions, and help plan the next steps to take. Your child might also need physical therapy to help improve hand and finger movements.