Polydactyly: Symptoms, causes, and treatments

• Updated on: 2018-04-26
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The name comes from the Greek poly (many) and dactylos (finger). The extra fingers or toes are described as "supernumerary," which means "more than the normal number." For this reason, the condition is sometimes called supernumerary digit.

A range of treatments is available depending on the type of polydactyly, and the cause is often genetic.

Polydactyly is a condition where a person is born with extra fingers or toes on one or both of their hands and feet.

The way polydactyly presents can vary. It may appear as a:

There are three main types including:

Polydactyly may be passed down in families.

When polydactyly is passed down, it is known as familial polydactyly. This form of polydactyly typically happens in isolation, meaning a person may not experience any associated symptoms.

Polydactyly may also be associated with a genetic condition or syndrome, which means it may be passed down along with a genetic condition. If polydactyly is not passed down, it occurs due to a change in a baby's genes while it is in the womb.

Some types of polydactyly are more likely to be passed down. Others are more likely to be associated with a genetic condition.

Small finger duplication is often hereditary. This form of the condition is 10 times more common among African-American people than other groups.

In African-Americans, small finger duplication tends to occur in isolation, inherited from a specific dominant gene. In Caucasians, it is more likely to be associated with a genetic condition or syndrome.

Thumb duplication often occurs in isolation and on only one hand or foot.

People who have central polydactyly may also have webbed hands or feet.

Doctors will examine a person and use X-ray imaging to diagnose polydactyly. This helps them to see the bone structure of the affected hand or foot.

Each type of polydactyly has subtypes that depend on how formed the extra digit is and where it is positioned. An X-ray helps the doctor to identify these.

The doctor will also ask questions about their family and medical history to help them to diagnose the cause.

A doctor may also carry out further tests including:

Sometimes, polydactyly is diagnosed during the first 3 months of pregnancy. This is done using an ultrasound or embryo fetoscopy.

Treatment depends on which type of the condition a person has:

Small finger duplication may not require treatment, as it does not usually affect how people can use their hand. However, they may still want to treat it for cosmetic reasons.

If an extra small finger is only partially formed and does not contain any bones, it may be easy to remove. A doctor may do this by tying a tight string around the base of the extra finger. This cuts off the blood supply, allowing excess soft tissue to fall away naturally. This procedure often takes place in the first year after birth.

If an extra small finger is more fully-formed or functional, it may require surgery to remove.

Treatments for thumb duplication are more complicated because the extra thumb may affect the function of the other thumb.

For this reason, it may not be possible to remove the extra thumb simply. Surgery may be needed to reconstruct one functioning thumb, using parts of both thumbs.

There are a variety of different surgical options available depending on the position and formation stage of the extra thumb.

There are some surgical options for central polydactyly. These include:

The doctor will discuss these options with the person who has polydactyly. Together they can decide the most appropriate treatment.

Complications from surgery are rare but may include:

There are many surgical options available for polydactyly. Most are simple and usually have positive outcomes.

Small finger duplication, which is the most common type of polydactyly, may not require treatment. If it does, this is generally for cosmetic reasons.

If someone has polydactyly due to an underlying genetic condition, this may require additional treatment. A doctor can help a person find the best way to manage their condition.