Polydactyly.

Polydactyly, when there is an extra finger or thumb

If your baby has been born with an extra finger or thumb, it can feel surprising and overwhelming at first. But polydactyly is one of the more common hand differences, it is well understood, and there is a calm, well-trodden path to caring for it.

What polydactyly is

Polydactyly simply means “more than the usual number of digits.” A hand may have an extra little finger (on the side of the hand), an extra thumb (on the thumb side), or, less often, an extra finger in the middle. The extra digit can range from a small, soft skin tag with no bone, to a fully formed, working finger. {{CONFIRM with Holly}}

Why it happens

Like other hand differences, polydactyly forms early in pregnancy as the hand is taking shape. It often runs in families, an extra little finger in particular can be passed down through generations, and sometimes it appears on its own. It is not caused by anything that happened during pregnancy. {{CONFIRM with Holly: association with syndromes, when relevant.}}

Again: this is not your fault.

How it varies

Polydactyly is usually grouped by where the extra digit sits:

• Little-finger side (ulnar / post-axial), the most common type, especially common and often inherited. {{CONFIRM with Holly}}
• Thumb side (radial / pre-axial), an extra or split thumb, which needs careful planning so the remaining thumb is strong and well-aligned.
• Central, an extra finger among the middle fingers; less common and more complex.

When and how it is treated

The approach depends entirely on the type and on how fully formed the extra digit is.

• A small skin tag with no bone may be dealt with simply. {{CONFIRM with Holly: ligation vs surgical removal, Holly to confirm current practice.}}
• A more fully formed extra digit, or an extra thumb, is addressed with a planned operation that supports the most natural, comfortable function, sometimes reconstructing the remaining thumb so it works beautifully. {{CONFIRM with Holly}}

Timing is planned around your child. Many procedures are carried out in the first year or two of life, but there is no single right age. {{CONFIRM with Holly}}

Recovery & what to expect

1. A first conversation, gentle examination, all your questions answered, no rush.
2. A clear plan, drawn out, explained with simple drawings, never jargon.
3. The procedure, usually a day case; the approach matched to your child’s hand. {{CONFIRM with Holly}}
4. Healing and follow-up, close, friendly aftercare, with hand therapy if it helps.

Questions parents ask

Does the extra finger need to be removed? Not always, and never without good reason. The aim is the best possible function and comfort for your child; we talk through the options together.

Will the hand look and work normally? The goal is a hand that grips, points and moves naturally. For thumb-side polydactyly especially, careful planning helps the remaining thumb be strong and well-aligned. {{CONFIRM with Holly}}

Is polydactyly linked to anything else? Most often it occurs on its own. Occasionally it can be associated with other conditions, which is one reason a careful assessment is helpful. {{CONFIRM with Holly}}