What are duplicated thumbs?

Duplicated thumbs are a congenital hand defect that is characterised by the presence of more than one thumb on a child's hands when they are born. This is a type of polydactyly, an abnormality characterised by the development of extra digits in the hands and feet at birth.

Duplicated thumbs may appear as partially developed or fused together. They can also affect either one or both hands. Though there is no specific cause for the condition, it can be a genetic defect in some cases where duplicated thumbs develop generation after generation in a family. In most cases, however, duplicated thumbs occur at random, or sporadically during the development of the hands in the womb.

Despite not having a direct cause, duplicated thumbs are one of the most common congenital hand defects and, in more severe cases, can affect the way children learn to write and use their hands.

How are duplicated thumbs treated?

Though not painful, duplicated thumbs can affect the way children learn motor skills as they grow. This can affect their ability to write, play sports and interact with others. Duplicated thumbs can also impact their social lives too. Surgery is always required to correct the defect and ensure normal development and functioning of the thumb.

When treating duplicated thumbs, Dr Carter will first examine the affected hands through a series of tests and x-rays. This will help Dr Carter understand the severity of the birth defect and how best to repair it surgically. The surgery is usually performed when a child is between 1 and 2 years old.

During surgery, Dr Carter will work to remove the extra thumb and reconstruct the remaining thumb so that the child can have full use of their hand. This process will involve reworking the bones, tendons, ligaments and tissue of the thumb to ensure that it functions properly after surgery. The child may also need to wear a cast for some time after the surgery and engage in physical therapy to adapt to the new thumb. Sometimes, the reconstructed thumb can appear smaller than a normal thumb.