Syndactyly: Causes, Symptoms, and Treatment
Medically reviewed by Harsha Moole, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor treats Syndactyly?
Syndactyly is often found during a child's health exam. A plastic or orthopedic surgeon with extra training in hand surgery typically performs the repair. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What is syndactyly?
Webbing of the fingers or toes is called syndactyly. It refers to the connection of 2 or more fingers or toes. Most of the time, the areas are connected only by skin. In rare cases, the bones may fuse together.
It is called simple syndactyly when only skin and soft tissue are joined. It is called complex syndactyly when finger bones next to each other are also joined. Syndactyly is the most common congenital hand deformity, which means a hand difference present at birth. It occurs in about one in every 2000 to 3000 births. Polysyndactyly describes both webbing and extra fingers or toes.
Symptoms
The main sign is webbing, a connection between fingers or toes.
- The web connections most often go up to the first joint of the finger or toe.
- However, they can run the length of the finger or toe.
- In its most common form, webbing occurs between the 2nd and 3rd toes.
- In the hand, more than half of cases involve the third web space, between the middle and ring finger.
Syndactyly can interfere with normal hand function. About half of all cases are bilateral, which means both sides are affected. Some cases are much less severe and involve only minor webbing.
Causes and who gets it
Most cases of syndactyly have a genetic basis, which means it is linked to changes in genes. Between 10% and 40% of cases have a family history of syndactyly. The most common form, webbing between the second and third toes, is often inherited and is not unusual. Syndactyly happens when the web between the digits does not go away around week six of the baby's development, as it usually does.
Syndactyly can also occur along with other birth defects involving the skull, face, and bones. More common causes include Down syndrome and hereditary syndactyly. Very rare causes include Apert syndrome, Carpenter syndrome, Cornelia de Lange syndrome, Pfeiffer syndrome, and Smith-Lemli-Opitz syndrome. Use of the medicine hydantoin (phenytoin) during pregnancy is also a very rare cause. Syndactyly is a feature of over 300 different syndromes.
Syndactyly is seen twice as often in males as in females.
How doctors diagnose it
Your child's health care provider will do a physical exam and ask about the child's medical history. The provider may ask which fingers or toes are involved and whether other family members have had this problem. Syndactyly is a clinical diagnosis, which means it is based on the exam. An x-ray (also called a radiograph) must also be done, both to confirm it and to look for hidden extra fingers or other differences within the web space.
An infant with webbing may have other symptoms that together point to one syndrome or condition. Chromosome tests and lab tests for certain proteins may be done. Complex syndactyly is often part of a syndrome, so a full exam is done to look for one.
Treatment
Surgery may be done to separate the fingers or toes. Surgery is typically required to regain hand function. Function, rather than looks, is the number one goal of syndactyly release surgery. Very mild cases where function is not impaired may not need surgery.
Repair is typically done between six to 18 months of age, depending on the type of syndactyly. The surgery is typically performed in an outpatient setting. The surgeon trims fat from the finger flaps, separates the digits, and closes the skin with absorbable stitches.
Surgeons may cover the gap with a skin graft or a synthetic dermal substitute. Complications of the surgery include contracture, web creep, and the need for a second surgery. Scarring may occur. Follow-up visits may last for many years.
When to see a doctor
Syndactyly is normally discovered at birth while the baby is in the hospital. If you notice webbing of your child's fingers or toes later, ask your child's health care provider to examine it. After surgery, parents must be counseled in recognizing signs of complications. Ask the surgeon which warning signs to watch for.
How a direct primary care or concierge doctor fits in
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance. Either can examine your child, explain the findings, and refer you to a hand surgeon when needed.
Common questions
Does syndactyly always need surgery?
No, some cases are much less severe and may not require surgery at all. Almost all cases, however, call for surgery.
What causes syndactyly?
Most cases of syndactyly have a genetic basis. Down syndrome is one of the more common causes. Between 10% and 40% of cases have a family history of syndactyly.
When is syndactyly surgery done?
Syndactyly repair is typically done between six to 18 months of age, depending on the type. Apart from very mild or very complex cases, the repair is done before school age.
What are the risks of syndactyly surgery?
Complications of the surgery include contracture, web creep, and the need for a second surgery. Scarring may occur, and function rather than looks is the main goal.
Sources
- MedlinePlus - Webbing of the fingers or toes
- PubMed Central - Syndactyly in the Pediatric Population: A Review of the Literature
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
