Polydactyly (Extra Fingers or Toes)
What You Need to Know
- The most common type of polydactyly results in an extra small finger or extra little toe.
- Another form of polydactyly causes an extra thumb or extra big toe.
- Treatment for polydactyly involves removing the extra digit. Most children have fully functioning hands or feet after treatment.
What is polydactyly?
Polydactyly (pahl-ee-DAK-til-ee) occurs when a baby is born with extra fingers or toes (digits). “Poly” means many; “dacytlos” refers to digits. Usually, only one hand or foot has extra digits. The extra digit is usually small and not well formed. It may not function like other digits.
Also called hyperdactyly, polydactyly is the most common congenital (present at birth) limb difference.
- Polydactyly of the hand is a type of congenital hand difference.
- Polydactyly of the foot is the most common congenital difference affecting the front part of the foot.
Types of Polydactyly
The location of the extra digit determines the type of polydactyly. The three types include:
Postaxial Polydactyly
Postaxial polydactyly is the most common type. It affects approximately 1 in 3,000 newborns.
An infant with postaxial polydactyly may have an extra:
- small finger (ulnar polydactyly)
- Small toe (fibular polydactyly)
Preaxial Polydactyly
Preaxial polydactyly occurs in about 1 in 7,000 newborns. An infant with preaxial polydactyly may have an extra:
- Big toe (tibial polydactyly)
- Thumb (radial polydactyly or thumb duplication)
Central Polydactyly
An infant with central polydactyly has one or more extra digits between their thumb and little finger, or between their big toe and little toe. Central polydactyly is the least common type. Some digits may fuse together (syndactyly), creating a weblike appearance.
What causes polydactyly?
For some children, polydactyly occurs without a known reason. Sometimes the condition can affect members of the same family. A child inherits a changed gene (mutation) from a parent that causes one or more extra digits.
Race and biological sex may also play a role. The condition is 22 times more common in Black females than white females. Black males are 10 times more likely to have an extra digit than white males.
Children with these conditions are also more prone to having extra digits:
- Asphyxiating thoracic dystrophy
- Chondroectodermal dysplasia (Ellis-van Creveld syndrome)
- Craniofacial abnormalities, including Carpenter syndrome
- Diamond-Blackfan anemia
- Down syndrome (trisomy 21)
- Fanconi anemia
- Laurence-Moon syndrome
- Rubinstein-Taybi syndrome
- Smith-Lemli-Opitz syndrome
- Trisomy 13
- VACTERL association
Polydactyly Signs and Symptoms
A newborn with polydactyly has one or more extra fingers or toes. The extra digit may be a:
- Fully formed digit that functions as it should
- Short, underdeveloped digit that doesn’t function
- Small, raised bump (nubbin)
How is polydactyly diagnosed?
A prenatal (before birth) ultrasound often detects an extra finger or toe. If not detected on ultrasound, the extra digit is noticeable at birth. Your child will get an X-ray to see how the extra digit attaches to the hand or foot. This information helps guide treatment. Your child may also get a genetic test (a type of blood test) to check for gene mutations and conditions associated with polydactyly.
Polydactyly Treatments
Treatment for polydactyly often takes place when a child is between Infancy and 1–2 years of age, depending on the complexity of the extra digit. The treatment type depends on how the digit attaches to the hand or foot. Small, unformed digits that attach with just skin and soft tissue are easier to remove at a younger age. Fully formed digits that attach by bone, blood vessels and soft tissues are more complicated to remove.
Treatments for polydactyly include:
Cauterization for Polydactyly
Cauterization removes small, unformed digits (usually fingers) attached by skin and soft tissues. A child receives a numbing injection so they don’t feel pain. A doctor uses a device to deliver a safe electric current to the base of the extra digit. The current heats and destroys the skin and tissue that connects the digit. It also seals (cauterizes) the skin to reduce bleeding and promote healing.
Ligature for Polydactyly
Ligature uses a tight band to cut off the blood supply to the extra digit. It is usually only done if the extra digit does not have bone or connective tissues. The process does not hurt the child, and in about two weeks the extra digit will fall off.
Polydactyly Surgery
A child with an extra toe or more complex polydactyly that includes bones and blood vessels needs surgery to remove the extra digit. The type and complexity of the surgery depends on a child’s unique diagnosis. A child may wear a splint or cast after surgery while their hand or foot heals.
Physical and Occupational Therapy for Polydactyly
Many children with polydactyly benefit from physical therapy, occupational therapy or hand therapy after surgery. These therapies can improve mobility and function of the digits, as well as the hand or foot.
What is the outlook for children with polydactyly?
Depending on the severity of the condition, a child may not be able to fully bend or use an affected joint after treatment. However, most children have good use and typical appearance of their hands or feet after treatment. They shouldn’t need ongoing physical or occupational therapies throughout life.
