Polydactyly

Polydactyly literally means “extra digits.” There may be an extra thumb, small finger, or, less commonly, an extra digit in the central part of the hand. Polydactyly is one of the most common congenital hand anomalies.

Common Questions

Does polydactyly cause my baby any pain?

No, typically there is no pain associated with polydactyly.

What are the different types of polydactyly?

Radial, or pre-axial polydactyly means that there is an extra thumb; there are several different types of radial polydactyly. Ulnar, or post-axial polydactyly means that there is an extra small finger; there may be a well-formed extra small finger, or just a poorly-formed extra digit attached by a thin stalk of soft tissue. Central polydactyly means that the extra digit is in the central part of the hand, between the thumb and small finger.

Who gets polydactyly?

Polydactyly can occur in any newborn infant. Most types of radial polydactyly are not inherited. Postaxial polydactyly with a small, poorly-formed extra digit is ten times more common in African-Americans than in Caucasians and is inherited as an autosomal dominant trait (that is, there is a 50% chance of polydactyly in the children of an affected individual). However, postaxial polydactyly with a well-formed extra digit is equally common in all ethnicities. Central polydactyly is inherited as an autosomal dominant condition with variable expression, meaning that it may be more or less severe from one generation to the next.

What causes polydactyly?

When the hands and feet are developing in the womb, they start out as flat “paddles” that then normally separate into five digits. Polydactyly occurs when this separation process is excessive, and an extra “segment” is created. This may be caused by a genetic abnormality or by environmental influences.

What are the main issues related to polydactyly?

The primary issue in most types of polydactyly is function of the hand and digits; appearance of the hand is also an issue, but is secondary to function.

Are there other problems that occur commonly with polydactyly?

Certain rare types of preaxial polydactyly are associated with other problems, such as blood disorders, heart abnormalities, or craniofacial abnormalities. Postaxial polydactyly in which the extra digit is well-formed is associated with polydactyly of the feet, also.

What is the treatment for babies with polydactyly?

Polydactyly is treated surgically. In preaxial polydactyly, a single thumb must be reconstructed from the two duplicated, or split, thumbs. This procedure involves reconstructing the skin and soft tissues, the tendons, joints, and ligaments to create a single thumb. In postaxial polydactyly, when the extra digit is attached only by a narrow stalk of soft tissue, this may be removed either with a minor operation or, if the stalk is narrow enough, by ligating the stalk in the nursery. When the extra digit is well-formed, the surgery is more involved and may involve reconstruction of soft tissues, tendons, joints, and ligaments as in preaxial polydactyly. Finally, central polydactyly requires a complex surgical procedure to reconstruct the hand. Again, the soft tissues, tendons, ligaments, and joints must be reconstructed. In some of these cases, more than one operation is required.

What is done between the time my baby is born and the first surgery?

You will meet with your surgeon soon after your baby is born. In some cases, the diagnosis is made prenatally by ultrasound exam, and you may have the opportunity to meet your surgeon before your baby is born. Your surgeon will examine your baby and take xrays of the affected hand. Your baby will be examined in the clinic periodically during the months before surgery. The treatment plan and the details of the surgical procedures will be carefully explained to you by your surgeon. Usually, no special treatment or therapy is required before surgery.

What sorts of specialists will be involved in my baby’s care?

At the very least, your child will be treated by the hand surgeon and a certified hand therapist. In addition, a geneticist and developmental pediatrician are sometimes involved in the care of babies with polydactyly.

Will we get to know our surgeon?

Ideally, you will meet your surgeon either prenatally or soon after your baby is born. You will meet with your surgeon several times before surgery, and will get to know him quite well.

Blog Posts: Polydactyly (Extra Fingers)

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Polydactyly: That extra digit needn’t be a problem