Conditions & Treatments
- A to Z Guide

Polydactyly

Disease Information

In-Depth

At Children’s Hospital Boston, our orthopedic and plastic surgeryteams know that you’re concerned about your baby’s hand deformity. It might help put your mind at ease to know that we’ve developed innovative surgical and non-surgical treatments for children with all degrees of severity of polydactyly. Learning more about this condition may help you feel more confident and informed as we treat—and work toward—healing your child.

What is polydactyly?

Polydactyly is a deformity in which the hand has one or more extra fingers in any of three places of the hand:

on the small finger side—most common (ulnar)
on the thumb side, also called thumb duplication—less common (radial)
in the middle of the hand—least common (central)

In polydactyly, are there different forms and different degrees of severity?

The extra fingers are usually smaller and abnormally developed than normal and can be made up of:

skin and soft tissue—the simplest to remove
skin, soft tissue and bone but no joint—more challenging to remove/remodel
skin, soft tissue and bone with joint (closer to a fully-formed finger—most challenging to remove/remodel)

Are certain ethnic groups predisposed to have a certain type of polydactyly?

Yes, African-American children are more likely to have an extra little finger, while Asians and Caucasians are more likely to have an extra thumb.

What causes polydactyly?

During normal embryonic development (while the baby is still in the womb), the hand initially forms in the shape of a paddle, and then—at about the sixth or seventh week of gestation—splits into separate fingers. Polydactyly results if there’s an irregularity in this process: An extra finger forms when a single finger splits in two.

The vast majority of occurrences of polydactyly are sporadic, meaning that the condition occurs without an apparent cause—but some may be due to a genetic defect or underlying hereditary syndrome. African-Americans are more likely to inherit the condition than other ethnic groups.

How common is polydactyly?

Polydactyly is one of the most common congenital hand defects, affecting about one out of every 500 to 1,000 babies. Usually, only one of a child’s hands is affected.

Does polydactyly cause the baby pain?

No, an extra finger isn’t usually painful.

How is polydactyly diagnosed?

Polydactyly can be seen by ultrasound prenatally, and by eye at birth. Your doctor will use x-rays to assess the underlying structure of your baby’s finger and determine a course of treatment.

How is polydactyly treated, and at what age?

Children’s orthopedic surgeons and plastic surgeons usually treat polydactyly by surgically removing the extra finger—typically, when the child is between 1 and 2 years old, young enough that he won’t miss developmental milestones such as grasping (prehension), but late enough that he can tolerate anesthesia and surgery well.

For details, see Treatment & Care.

What’s the prognosis for my child after surgery for polydactyly?

The outlook for your child after removal of his extra digit is excellent if it occurs in isolation. Our orthopedic and plastic surgeons have vast experience treating children with polydactyly. If the condition occurs in association with a genetic syndrome, your child’s outlook depends to a large extent on the nature and severity of the syndrome.

Can there be complications after polydactyly surgery?

Complications after surgery are common but are often minor. Such minor complications include scar formation, stiffness, instability, and late deformity. Most cosmetic or functional deformities can be addressed in later corrective surgery.

Will my child be OK?

The good news is that after surgery, most of our young patients have full hand function and an improved appearance of their hand. If needed, your child’s team will work with you and your child to learn home exercises that are important to his recovery. He may need to wear a cast in some circumstances. It is possible that in a severe case, your child may need additional reconstructive surgery(ies) to recover full function and improve the hand’s appearance.

FAQ

Q: What is polydactyly?
A: Polydactyly isa deformity in which a child’s hand has one or more extra fingers in any of three places of the hand:

on the small finger side—most common (ulnar)
on the thumb side, also called thumb duplication—less common (radial)
in the middle of the hand—least common (central)

Q: What are the signs and symptoms of polydactyly?
A: Polydactyly is visible at birth. It is also usually visible in utero by fetal ultrasound.

Q: How is polydactyly usually diagnosed?
A: Polydactyly can sometimes be seen by ultrasound prenatally, and by eye at birth. Your doctor will use x-rays to assess the underlying structure of the baby’s finger and determine a course of treatment.

Q: How does Children’s treat polydactyly?
A: Except in very mild cases, at Children’s we usually treat this condition by removing the extra digit surgically.

For treatment details, see Treatment & Care.

Q: If my child has surgery for polydactyly, will he be OK?
A: Most of our young patients have full hand function and an improved appearance of the hand. If needed, your child’s team will work with you and your child to learn home exercises that are important to his recovery. He may need to wear a cast in some circumstances. It is possible that in a severe case, your child may need additional reconstructive surgery(ies) to recover full function and improve the hand’s appearance.

Q: What is Children’s experience treating polydactyly?
A: The experts in our Orthopedic Center’s Hand and Orthopedic Upper Extremity Program and our Plastic Surgery Department’s Hand and Microsurgery Reconstructive Program have treated thousands of babies and children with hand problems ranging from the simple to the highly complex. So, we can provide your child with expert diagnosis, treatment and care—as well as the benefits of some of the most advanced clinical and scientific research in the world

Causes/risks

During normal embryonic development (while the baby is still in the womb), the hand initially forms in the shape of a paddle, and then eventually—in about the sixth or seventh week of gestation—splits into separate fingers. Polydactyly results if there’s an irregularity in this process: An extra finger forms when a single finger splits in two.

The vast majority of occurrences of polydactyly are sporadic, meaning that the condition occurs without an apparent cause—while some may be due to a genetic defect or underlying hereditary syndrome. African-Americans are more likely to inherit the condition than other ethnic groups.

Signs and symptoms

Polydactyly is visible at birth. It is also sometimes visible in utero by fetal ultrasound.

When to see a specialist

Your child’s doctor will know by sight that your baby’s hand has an extra digit. The doctor will refer you to a hand specialist, who will guide you to a more detailed diagnosis and treatment plan.

Questions to ask your doctor

If your child is diagnosed with polydactyly, you may feel overwhelmed with information. It can be easy to lose track of the questions that occur to you. Lots of parents find it helpful to jot down questions as they arise—that way, when you talk to your child’s doctors, you can be sure that all of your concerns are addressed.

Some of the questions you may want to ask include:

What is happening to my child, and why?
What will x-rays reveal?
What actions might you take after you review my child’s x-rays?
Is surgery necessary? Are there alternative therapies?
Will my child be OK after surgery?
Will there be restrictions on his activities or capabilities?
What will be the long-term effects?
What can we do at home?

Complications

Complications after surgery are common but often minor. Most remaining cosmetic or functional deformities can be addressed in later corrective surgery.

Long-term outlook

Most of our young patients recover full hand function and an improved appearance of the hand. If needed, your child’s team will work with you and your child to learn home exercises that are important to his recovery. He may need to wear a cast or splint in some circumstances. It is possible that in a severe case, your child may need additional reconstructive surgery(ies) to recover full function and improve the hand’s appearance.

Your child may need to be followed for a number of months or years to:

ensure that the healing has gone well
check that function has returned to your child’s hand
determine whether additional surgery is needed to improve the function or appearance of the hand as your child grows

For parents

It’s natural for parents whose babies are born with polydactyly to feel concern. Your child’s treatment and recovery may be fairly easy. Or, the journey may be more complicated—requiring more than one surgery for your child.

Even though you understand the importance of surgery and therapy for your child, you still might experience his treatment and recovery as a stressful time. If you feel frustrated or depressed, speak to your doctor or counselor to get help. Professionals in Children’s Center for Families can provide you with important resources and referrals.

Polydactyly glossary

The Center for Families at Children’s: dedicated to helping families find the information, services and resources they need to understand their child’s medical condition and take part in their care

central polydactyly: an extra finger in the middle of the hand

congenital: present at birth

embryonic development: development of the fetus in the womb

in utero: in the womb (uterus)

MRI (magnetic resonance imaging): produces detailed images of organs and structures within the body; does not use ionizing radiation

occupational and physical therapy: services offered by trained professionals to help restore function or (re)teach basic life skills, like walking or grasping objects

orthopedics: the medical specialty concerned with diagnosing, treating, rehabilitating and preventing disorders and injuries to the spine, skeletal system and associated muscles, joints and ligaments

orthopedic surgeon, orthopedist: a physician specializing in surgical and non-surgical treatment of the spine, skeletal system and associated muscles, joins and ligaments