Congenital Hand Differences

What it is

A congenital hand difference is a hand that formed differently than expected before birth. Examples include webbed or fused fingers (syndactyly), extra fingers or a duplicated thumb (polydactyly), missing or underdeveloped parts, curved fingers, and parts that are larger or smaller than usual.

What causes it

Many steps are needed to form an arm and hand. Some differences are genetic, but many have no known cause. Importantly, no research suggests that hand differences result from anything a parent did or did not do during pregnancy.

Evaluation

Hand differences are sometimes misdiagnosed at birth, so evaluation by a hand specialist is important. Some are associated with other conditions, and a genetics referral may be recommended.

Treatment

Treatment is guided by the family's and child's goals. Children can take part in medical decisions from around age eight, and including them matters. Working with a fellowship-trained hand surgeon is important because these differences have many nuances.

• Surgery: for example, separating webbed fingers, removing an extra finger, or moving the index finger into the thumb position when a thumb is missing. Some procedures work best when the child is young; others can wait until a need arises.
• Prosthetics: devices fitted by a prosthetist, used full-time, for specific tasks, or not at all
• Occupational therapy: strategies, adaptive tools, and exercises for daily activities, and help relearning hand use after surgery or with a prosthesis

Current treatment cannot replace a hand or arm, so setting realistic expectations is part of planning.

Support for families

Shock, anger, or guilt are common and valid reactions when parents learn their child has a hand difference, and almost always nothing could have prevented it. Around age eight, children may go through similar feelings as they notice their difference. Your care team can point you to support groups and help children handle staring and introduce themselves confidently. ASSH's The Hand Book is a guide for parents and caregivers.