What Is Polydactyly? Polydactyly (pol-ee-DAK-tuh-lee) is when a baby is born with an extra finger on the hand or an extra toe on the foot. It can be on one or both hands or feet. Polydactyly usually happens on the pinky finger side of the hand or little toe side of the foot (called "post-axial"). Less often, it happens on the thumb or big toe side ("pre-axial"). Rarely, it can be central or in the middle of the hand or foot. The extra digit is usually smaller than the other fingers or toes. What Causes Polydactyly? Polydactyly happens before a baby is born. When a baby's hands and feet are first forming, they're shaped like mittens. Then the fingers or toes form. If an extra finger or toe forms, this causes polydactyly. Who Gets Polydactyly? Any baby can be born with polydactyly. Post-axial polydactyly can run in families. Most babies who have polydactyly do not have other health problems. But sometimes, it happens as part of a genetic syndrome . How Is Polydactyly Diagnosed? Polydactyly may be seen before birth on an ultrasound. Otherwise, doctors diagnose it when the baby is born. Sometimes doctors do X-rays to see if the extra digit has bones and joints. This helps the surgeon decide what kind of treatment is needed. How Is Polydactyly Treated? Treatment for polydactyly depends on the location of the digit on the hand or foot and how it is formed. An extra pinky or little toe that is connected with a thin stalk can be removed easily, sometimes right in the surgeon's office with a surgical clip or stitch. Extra thumbs, big toes, or middle fingers or toes that contain bones and/or joints need surgery in the hospital. Looking Ahead Because surgery for polydactyly is usually done when a baby is young, most kids learn to use their hands and walk without problems. If needed, occupational therapy (OT), physical therapy (PT), and home exercises can help a child with this. Back to Articles Related Articles Symbrachydactyly Babies with symbrachydactyly are born with short often webbed fingers. Some might be missing fingers. Read More Syndactyly Syndactyly is when a baby is born with two or more fingers or toes joined or "webbed" together. Read More Thumb Duplication Babies with thumb duplication (or thumb polydactyly) are born with an extra thumb on one or both hands. Most will have surgery to fix the problem. Read More Thumb Hypoplasia Babies with thumb hypoplasia are born with a thumb that is smaller than normal, or with the thumb missing completely. Read More Radial Dysplasia Babies with radial dysplasia (also called radial club hand) are born with a short or missing radial bone. This makes the wrist turn in. Read More Ulnar Dysplasia Babies with ulnar dysplasia (also called ulnar club hand) are born with a short or missing ulnar bone. This makes the wrist turn out. Read More Bones, Muscles, and Joints Without bones, muscles, and joints, we couldn't stand, walk, run, or even sit. The musculoskeletal system supports our bodies, protects our organs from injury, and enables movement. Read More Occupational Therapy Occupational therapy can help improve kids' cognitive, physical, and motor skills and build their self-esteem and sense of accomplishment. Read More X-Ray Exam: Foot A foot X-ray can help find the cause pain, tenderness, swelling, or deformities. It also can detect broken bones or dislocated joints. Read More X-Ray Exam: Finger Doctors may order a finger X-ray to find the cause of symptoms such as pain, tenderness, or swelling, or to detect broken bones or dislocated joints. Read More X-Ray Exam: Hand A hand X-ray can help find the cause of pain, tenderness, swelling, and deformity. It also can detect broken bones or dislocated joints. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.