Department of hand surgery & Microsurgery.

Thumb duplication

What is thumb duplication?

Thumb duplication is a form of polydactyly (an extra digit in the hand or foot) in which your child’s hand (usually just one side) has more than one thumb.

How is thumb duplication diagnosed?

An extra thumb can often be seen by ultrasound prenatally, and by eye at birth. Your doctor will use x rays to assess the underlying structure of your baby’s finger and determine a course of treatment.

Causes of thumb duplication (pre-axial polydactyly)

During normal prenatal development (while the baby is in the womb), the hand initially forms in the shape of a paddle, and then eventually — in about the sixth or seventh week of gestation — splits into separate fingers. Thumb duplication and other forms of polydactyly result if there’s an irregularity in this process: An extra digit forms when a single digit splits in two.

The vast majority of the time, this occurs sporadically, meaning that the condition happens without an apparent cause. Some may result from a genetic defect or underlying hereditary syndrome, particularly if your child has a thumb with three bones instead of two

When to see a specialist

Your child’s doctor will know by sight that your baby’s hand has an extra thumb. The doctor will refer you to a hand specialist, who will guide you to a more detailed diagnosis and treatment plan

How we care for thumb hypoplasia

The Orthopedic Center’s hand surgery and microsurgery unit have undergone special training to deal with such problems. We are experienced in treating conditions that range from routine to highly complex, and can provide your child with expert diagnosis, treatment, and care.