Maria came into the clinic with her first born son Rafael for evaluation of a duplicated thumb. Her face was clouded with worry and guilt. “Was it something that I did during pregnancy?” We smiled and responded “you did a great job, already your child is an overachiever just like you.” Like a ray of sunshine, a smile came to her face.

What is a bifid thumb?

Duplicated or polydactylous thumbs are seen in many forms. Occasionally they are only a fleshy nubbin on the side of a normal thumb or can range up to a fully formed, fully functional “twin” of a thumb.

Are bifid thumbs common?

Thumb polydactyly can be part of a variety of syndromes, but these syndromes do not occur very frequently. Simple bifid thumb is found in fewer than 1 per 1000 births.

What causes a bifid thumb?

When duplication occurs alone, it is usually on one side and not an inherited condition. When bilateral or associated with other polydactylies of the hand or feet it is typically an inherited or genetic condition.

What are the symptoms of a bifid thumb?

Typically there is no pain and the duplicated thumb has normal sensation. Parents may be worried about a small dangling thumb getting caught on blankets or clothing but this doesn’t occur because the child’s sensory system protects the thumb.

How is a bifid thumb diagnosed?

Diagnosis is made by examination of the hand. Occasionally x-rays will be necessary to determine the extent and stability of the duplicated digit.

How is a bifid thumb treated?

Surgery is the mainstay for management of the bifid thumb. In most situations the preserved thumb is smaller in comparison to the thumb on the opposite hand. Surgeries are usually timed to minimize the risks associated with anesthesia. For most children the surgery is around one year of age. Ligaments and tendons are utilized from the extra thumb to augment the remaining thumb if needed.

What is the long-term outlook for my child?

Hand function is usually normal and pain-free. A small thumb after reconstruction will remain small at maturity but it will grow proportionally with the rest of the hand. Sometimes instability and growth disturbances have been noted over the long term but most are treatable with follow-up procedures when the child is older.

We were light-hearted in imagining the advantages of the extra thumb. Rafael could perhaps throw a speedy curve ball or be an exceptional concert pianist. However, the day to day problems he would experience, especially with glove wear in the winter, indicated to us that reconstruction would be the best choice. Even without the extra digit, the curve ball or piano expertise wouldn’t be outside of his possibilities.