What Is Polydactyly?
Medically reviewed by Jonathan B. Jassey, DO
Polydactyly is a condition in which a baby is born with one (or more) additional fingers or toes. It is relatively common, with an estimated incidence of 1 in every 500 to 1,000 births. If treatment is needed, it can usually be done before it impacts a child’s motor development.
This article will outline the symptoms, causes, diagnosis, and treatment of this frequently seen congenital (present at birth) condition.
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Types of Polydactyly
Polydactyly is generally classified into the following three categories that are based on where the extra digit is located:
Preaxial polydactyly: The extra digit is situated beside the child’s thumb (also called radial polydactyly) or big toe (also called tibial polydactyly).
Postaxial polydactyly: The extra digit is located outside of the fifth finger (also known as ulnar polydactyly) or fifth toe (also called fibular polydactyly).
Central polydactyly: The extra digit grows in the middle of the hand or foot between the other fingers or toes.
Polydactyly Symptoms
The primary symptom of polydactyly is the presence of an extra digit on the hand or foot. This genetic condition usually occurs on only one side of the body. The extra finger or toe is typically smaller than the other digits and may be shaped differently. Internally, the growth may contain some combination of:
Skin and soft tissue
Skin, soft tissue, and bones
Skin, soft tissue, bones, and joints
Causes
Polydactyly occurs when the limb buds fail to properly separate during finger or toe development. As a fetus grows in the uterus, the hands and feet initially develop as paddle-shaped structures. These structures ultimately separate and are divided into fingers and toes.
In the case of polydactyly, this division process takes longer than normal, and a single finger (or toe) divides into multiple digits.
Outdated Term
Anatomic differences present at birth, such as polydactyly, were previously termed "birth defects." That terminology has been replaced with terms such as congenital conditions, anatomic variations, and anatomic differences.
Polydactyly is frequently an inherited disorder and can vary in its appearance based on your genetic makeup. For example, Black children with this condition will most likely have an extra digit near their little finger or toe. White or Asian children more commonly present with an additional digit by their thumb or big toe.
This condition can occur on its own or in combination with other birth defects as part of a syndrome. Syndromes associated with polydactyly, include:
Greig cephalopolysyndactyly syndrome
Short-rib polydactyly
Related: Common Foot Problems and Anatomic Differences in Newborn Babies
Diagnosis
Polydactyly can sometimes be identified while the fetus is still in utero during a fetal ultrasound. Once a baby is born, a healthcare provider will formally diagnose the condition by visually examining the baby’s hands and feet to look for extra digits.
An X-ray is also typically ordered if additional fingers or toes are seen. This type of imaging helps the healthcare provider determine the anatomical makeup of the extra digit and ultimately decide on the best course of treatment.
Related: Newborn Screening for Genetic and Metabolic Disorders
Treatment
If treatment is desired, polydactyly usually is addressed by removing the additional digit in one of two ways.
In some cases, a small vascular clip is used to cut off the blood supply to the extra finger or toe, causing it to shrivel and fall off. Clipping is usually only an effective treatment if the finger or toe is small, poorly formed, and doesn’t contain a bone.
A child with a more developed case of polydactyly may require corrective surgery. Depending on the makeup of the digit, the procedure can involve cutting through soft tissue, muscles, or even bones to remove it.
Occasionally, anatomical structures may also need to be repaired to ensure the hand or foot functions properly. This type of operation is typically performed in an outpatient setting when the child is very young (between the ages of 1 and 2).
Coping
Following a polydactyly operation, your child will typically receive stitches to close the incision. Surgical glue may also be applied over the stitches to protect the area. Your child’s stitches are usually dissolvable and do not need to be removed.
While most polydactyly procedures cause only mild amounts of soreness, over-the-counter pain medications may be recommended to help manage your child’s symptoms.
More complex surgeries occasionally require surgical pinning in the hand or foot. In these cases, a splint or cast is typically worn by the child while the area heals. Before the cast or splint can be removed, follow-up X-rays are usually ordered to ensure that the procedure was successful.
Following this, outpatient occupational therapy may be needed to help the child recover function in the affected area.
Prognosis
Because polydactyly is usually treated when the child is very young, most kids with this condition ultimately recover full functioning in their hand or foot. Advancing surgical techniques have also helped to ensure that the affected area looks relatively typical in appearance.
As the child gets older, their pediatrician will monitor their development to ensure that they are meeting their expected motor milestones. They will also perform follow-up examinations to assess whether additional interventions are needed to improve the function or appearance of the affected area.
Summary
Polydactyly is a congenital anomaly where a child is born with an extra finger or toe. This condition is relatively common and is frequently genetically inherited. Visual inspection and X-rays are used to make a definitive diagnosis early in a child’s life.
Treatment options include vascular pinning and outpatient surgery. Most kids who are born with this condition make a full functional recovery.
Correction - September 7, 2023: This article was updated to include syndromes associated with polydactyly.
Read the original article on Verywell Health.
