Polydactyly of Fingers Symptoms & Causes

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At Boston Children’s Hospital, our orthopedic and plastic surgery teams 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:

Polydactyly of fingers •   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)

Are there different forms degrees of severity of polydactyly?

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.

Causes

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.

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 Boston Children’s Center for Families can provide you with important resources and referrals.

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.

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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?

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Polydactyly glossary

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•   Hale Family Center for Families: 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
•   prenatal (fetal) ultrasound: ultrasound performed at several stages of pregnancy; can detect polydactyly in
    the fetus
•   polydactyly: a deformity in which the hand has one or more extra fingers
•   post-operative (post-op): occurring after surgery
•   pre-operative (pre-op): occurring before surgery
•   range of motion (ROM) exercises:physical therapy exercises designed to improve or restore flexion and
    extension of joints
•   radial (pre-axial) polydactyly: an extra thumb; thumb duplication
•   reconstructive surgery: surgery performed to repair and/or restore a body part to normal or as near
    normal as possible
•   sporadic: occurring without apparent genetic cause
•   thumb duplication: another term for polydactyly of the thumb
•   ulnar (post-axial) polydactyly: an extra little finger
•   x-rays: a diagnostic test that uses invisible ionizing radiation to produce images of internal tissues, bones,
    and organs onto film

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