Thumb duplication (pre-axial polydactyly)

  • "Combining training in adult and pediatric orthopedics, hand surgery, plastic surgery and microsurgery allows our surgeons to provide a comprehensive level of care unmatched in most hospital settings."

    –Donald S. Bae, MD, associate in Orthopedic Surgery, Boston Children's Hospital; Brian I. Labow, MD, principal investigator, Plastic Surgery, Boston Children's Hospital

     (See also Polydactyly)

    Please note: these pages focus on thumb duplication, or polydactyly of the thumb. For details on polydactyly of other fingers, see our web pages on polydactyly.

    If your baby was born with more than one thumb on one hand, we know that you and your family may be concerned. So, please know that at Children’s Hospital Boston, we approach your child’s treatment and care with sensitivity and support.Thumb Duplication

    Thumb duplication is a congenital condition (meaning that your baby was born with it) in which your child has two thumbs on one hand.

    • Rather than a single normal thumb on each hand, your child’s duplicated thumbs are smaller and underdeveloped.
      • The thumbs may be separate or appear fused together.
      • Other fingers may be abnormal, too.
    • The muscles, tendons, ligaments, blood vessels and nerves are often divided between each of the abnormal thumbs. So, surgery for thumb duplication is often more complex than for other forms of polydactyly.
    • Usually, surgery for thumb duplication involves reconstruction of the hand, for both functional and cosmetic reasons.
      • Surgery is usually done when the child is between 1 and 2 years old, when he can tolerate anesthesia and surgery well.
    • Usually, the condition is unilateral, meaning that it affects only one of your child’s hands.
    • Thumb duplication can sometimes be detected by prenatal ultrasound, and is apparent at birth; the underlying structure of the finger and the course for treatment are determined with an x-ray.
    • Research is inconclusive regarding which gender is more affected by thumb duplication.
    • Asian-American, Caucasian and Native American children are more likely to have thumb duplication (polydactyly on the thumb side), African-Americans on the small finger side.
    • At Children’s, surgery almost always results in a very functional hand—although for more complex variations, a second surgery may be needed as a child grows.

    How Children’s Hospital Boston approaches thumb duplication

    The skilled experts in our Orthopedic Center’s Hand and Orthopedic Upper Extremity Program and our Plastic Surgery Department’s Hand and Microsurgery Reconstructive Program have treated thousands of babies and children with finger and hand problems, from simple to complex. We can provide your child with expert diagnosis, treatment and care—as well as the benefits of some of the most advanced clinical and scientific research in the world.

    Our Orthopedic Center is recognized as the preeminent center for the care of children and young adults with a wide range of developmental, congenital, neuromuscular, sports related, traumatic and post-traumatic problems of the musculoskeletal system.

    As one of the largest pediatric plastic surgery centers in the United States, our Department of Pediatric Plastic Surgery provides comprehensive care and treatment to children with a wide variety of congenital and acquired conditions, including finger and hand anomalies.

    Hand and Orthopedic Upper Extremity Program

    The Hand and Orthopedic Upper Extremity Program provides comprehensive care involving occupational and physical therapy, splinting, casting and reconstructive surgeries for infants, children and adolescents with complex congenital, neuromuscular, sports-related oncologic and traumatic upper limb conditions.

    Hand and Reconstructive Microsurgery Program

    The specialists in the Hand and Reconstructive Microsurgery Program at Boston Children's are experts in the management of congenital and acquired hand deformities. We recognize the social elements involved in pediatric hand surgery, so an essential part of these operations has been making the child's hand as symmetrical as possible with his unaffected hand.

    Thumb Duplication (Pre-axial Polydactyly): Reviewed by Amir Taghinia, MDBrian I. Labow, MDDonald S. Bae, MD © Boston Children's Hospital; posted in 2012

  • At Boston Children’s Hospital, our orthopedic and plastic surgery teams know that you’re concerned about your baby’s hand difference. It might ease your mind to know that we’ve developed innovative surgical treatments for children with all variations of thumb duplication. Learning more about this condition may help you feel more confident and informed as we work towards healing your child.

    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.

    Are there different variations and degrees of severity?

    Yes, although almost all forms of thumb duplication require complex surgical correction and hand reconstruction.

    • The extra thumb can occur at the joint of the outermost bone (distal phalanx).
    • The closer to the hand that the extra thumb occurs, the more complex the congenital difference is—such as bent or angular deformities, stiffness, limited range of motion and underdevelopment.

    Are certain ethnic groups predisposed to have a certain type of polydactyly?

    Yes, Asians, Caucasians and Native Americans are more likely to have an extra thumb, while African-American children are more likely to have an extra little (pinkie) finger.

    What causes thumb duplication and other forms of polydactyly?

    During normal development while the baby is still in the womb, the hand initially forms in the shape of a paddle. At about the sixth or seventh week of pregnancy, this “paddle” splits into separate fingers. Various forms of polydactyly—including thumb duplication—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. But some may be due to a genetic defect or an underlying hereditary syndrome, especially if your child’s thumb has three bones instead of two. Caucasians, Asians and Native-Americans are more likely to inherit the condition than African-Americans.

    How common is thumb duplication?

    Thumb duplication is one of the more common congenital hand conditions, affecting about one out of every 1,000 babies. Usually, only one of a child’s thumbs is affected.

    Does thumb duplication cause my baby pain?

    No, an extra thumb isn’t usually painful.

    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.

    How is thumb duplication treated, and at what age?

    Children’s orthopedic surgeons and plastic surgeons usually treat children with thumb duplication by surgically removing the extra thumb and reconstructing the hand. Typically, we do this surgery when a child is between 1 and 2 years old—young enough that he won’t miss developmental milestones such as pinch and grasp (prehension), but old enough that he can tolerate anesthesia very well.

    What’s the prognosis for my child after surgery for thumb duplication?

    The outlook for your child after reconstruction of his extra thumb is excellent if it occurs in isolation. Our orthopedic and plastic surgeons have vast experience treating children with thumb duplication. If the condition occurs in association with a genetic syndrome, your child’s outlook depends largely on the nature and severity of that syndrome.

    Can there be complications after surgery for thumb duplication?

    Complications after surgery are uncommon and often minor. Most cosmetic or functional deformities can be addressed later in additional surgery.

    Will my child be OK?

    If needed, your child’s team will work with you and your child to learn home exercises that are important to his recovery. He may need to wear a cast in some circumstances.

    The good news is that after surgery, most of our young patients have highly functional pinch and grasp (prehension) and an improved appearance of the thumb and hand. It is possible that in a severe case, your child may need additional reconstructive surgery to gain full function and/or improve his hand’s appearance.

    Causes

    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. Caucasians, Asians and Native-Americans are more likely to inherit the condition than African-Americans.

    Signs and symptoms

    Thumb duplication can be seen at birth. It’s also sometimes visible on a fetal ultrasound when a baby is still in utero.

    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.

    Questions to ask your doctor

    If your child is diagnosed with thumb duplication, you may feel stressed and lose track of the questions that occur to you. Lots of parents find it helpful to jot down questions as they arise—that way, when you talk to your child’s doctors, you can be sure that all of your concerns are addressed.

    Some of the questions you may want to ask include:

    • What is happening to my child, and why?
    • What will x-rays reveal?
    • What actions might you take after you review my child’s x-rays?
    • Is surgery necessary? Are there alternative therapies?
    • Will my child be OK after surgery?
    • Will there be restrictions on his activities or capabilities?
    • What will be the long-term effects?
    • What can we do at home?

    Complications

    Complications after surgery are uncommon and often minor. Most remaining cosmetic or functional problems can be addressed in later corrective surgery.

    Long-term outlook

    If needed, your child’s team will work with you and your child to learn home exercises that are important to his recovery. He may need to wear a cast or splint in some circumstances.

    Most of our young patients recover with good grasp function and an improved appearance of their thumb and hand. It is possible that in a severe case, your child may need additional reconstructive surgery to recover full function and improve the hand’s appearance.

    Your child may need to be followed for a number of months or years to:

    • ensure healing
    • check that your child’s thumb and hand have acceptable function
    • determine whether additional surgery is needed

    For parents

    It’s natural for parents whose babies are born with an extra thumb to feel concern. Depending on the extent of your child’s condition, his treatment and recovery may be fairly straightforward, or may require more than one surgery.

    Even though you understand the importance of surgery and therapy for your child, you still might experience his treatment and recovery as a stressful time. If you feel frustrated or depressed, speak to your doctor or counselor to get help. Professionals in Boston Children’s Center for Families can provide you with important resources and referrals.

    Thumb duplication glossary

    • The Center for Families at Boston Children’s: dedicated to helping families find the information, services and resources they need to understand their child’s medical condition and take part in their care
    • congenital: present at birth
    • embryonic development: development of the fetus in the womb
    • in utero: in the womb (uterus)
    • occupational and physical therapy: services offered by trained professionals to help restore function or (re)teach basic life skills, like walking or grasping objects
    • orthopedics: the medical specialty concerned with diagnosing, treating, rehabilitating and preventing disorders and injuries to the spine, skeletal system and associated muscles, joints and ligaments
    • orthopedic surgeon, orthopedist: a physician specializing in surgical and non-surgical treatment of the spine, skeletal system and associated muscles, joins and ligaments
    • prenatal (fetal) ultrasound: ultrasound performed at several stages of pregnancy; can detect polydactyly in the fetus
    • polydactyly: a condition in which the hand has one or more extra fingers
    • post-operative (post-op): occurring after surgery
    • prehension: grasp, an important function of the thumb; surgery for thumb duplication aims to ensure good grasping function
    • pre-operative (pre-op): occurring before surgery
    • range of motion (ROM) exercises:physical therapy exercises designed to improve or restore flexion and extension of joints
      radial (pre-axial) polydactyly: another term for thumb duplication (an extra thumb)
    • reconstructive surgery: surgery performed to repair and/or restore a body part to normal or as near normal as possible
    • sporadic: occurring without an apparent genetic cause
    • thumb duplication: an extra thumb on the hand; polydactyly of the thumb
    • x-rays: a diagnostic test that uses invisible ionizing radiation to produce images of internal tissues, bones, and organs onto film; usually the diagnostic tool of choice for thumb duplication

    Our plastic surgery programs and services include....

    Our complete orthopedic team

    Boston Children's is the primary pediatric teaching hospital of Harvard Medical School, where our physicians hold faculty appointments. We’re the largest pediatric orthopedic center in the nation, with 13 specialty clinics; an onsite brace shop; a plaster room; and a clinical team of orthopedic surgeons, orthopedic residents and fellows, certified physician assistants, nurse practitioners, registered nurses, physical/occupational therapists, brace technicians and cast technicians. 

  • At Boston Children's Hospital, we understand that the first step to treating your child is obtaining an accurate, timely and thorough diagnosis.

    A baby’s thumb duplication can sometimes be seen prenatally in ultrasound, and it’s apparent at the baby’s birth. Your doctor will:

    • take a thorough medical and family history
    • conduct a careful physical exam
    • use x-rays to assess the underlying structure of your baby’s thumb and hand and determine a course of treatment

    Our Orthopedic Clinical Effectiveness Research Center (CERC)

    Boston Children’s Orthopedic Clinical Effectiveness Research Center (CERC) was established by our Orthopedic Center to improve the quality of life for children with musculoskeletal disorders. This collaborative clinical research program is unique in the nation and is playing an instrumental role in establishing, for the first time, evidence-based standards of care for pediatric orthopedic patients throughout the world.

    If you come from far away, we can help

    As an international pediatric orthopedics center, Boston Children’s cares for young patients from all over the world. Our International Center assists families residing outside the United States: facilitating the medical review of patient records; coordinating appointment scheduling; and helping families with customs and immigration, transportation, hotel and housing accommodations.

    Boston Children's Hand and Reconstructive Microsurgery Program

    The doctors and staff in the Hand and Microsurgery Reconstructive Program at Boston Children's are recognized experts in the management of congenital and acquired hand deformities.

  • At Boston Children's Hospital, experts in our Orthopedic Center's Hand and Orthopedic Upper Extremity Program and our Plastic Surgery Department's Hand and Microsurgery Reconstructive Program provide comprehensive care—including evaluation, diagnosis, consultation, surgery and follow-up care.

    Our orthopedic surgeons and plastic surgeons treat children with thumb duplication by surgically removing the extra digit and reconstructing the hand—typically, when the child is between 1 and 2 years old—young enough that he won't miss milestones such as grasping (prehension) and fine motor development, but old enough to be able to tolerate anesthesia and surgery very well.

    Removing your child's extra thumb (radial polydactyly, thumb duplication) can be complex. A thumb is of primary importance in a child's hand function, and radial polydactyly can negatively impact the thumb's position (angle), shape and function.

    • Just removing the extra thumb is not usually enough.
    • Each of the split thumbs has elements (shared function) that need to be combined to recreate one fully functional thumb.
    • The procedure usually involves remodeling the remaining thumb, with special attention to its soft tissues, tendons, joints, ligaments and fingernails.
    • Even after treatment, the reconstructed thumb may be smaller than a normal thumb.

    Complications after surgery

    Complications after surgery are uncommon and often minor, and include scarring, stiffness, instability and late deformity. Most remaining cosmetic or functional issues can be addressed in later corrective surgery.

    Caring for your child after surgery

    If the surgery to remove the extra thumb is fairly complex, it can also involve your child's bone, ligaments and tendons. If that's the case, your child may need to wear a cast for a few weeks.

    Your doctor may recommend occupational or physical therapy to help reduce scarring, stiffness and swelling and improve function. If needed, your child's team will work with you and your child to learn home exercises that are important to his recovery. He may need to wear a cast or splint in some circumstances.

    What's my child's long-term outlook?

    After surgery, your child should have a very functional thumb and an improved appearance of his thumb and hand. His treated thumb may be a bit smaller than the other thumb, but it should have normal or near-normal function.

    Your child may need to be followed for a number of months or years to:

    • ensure that he is healing
    • check that your child's thumb and hand have full or acceptable function
    • determine whether additional surgery is needed to improve the function or appearance of your child's thumb and hand

    It's possible that in a severe case, your child may need additional reconstructive surgery to recover or retain full function and improve the hand's appearance. Also, it's rare but possible that the condition can come back, so your child may need an additional operation later in life.

    Coping and support

    At Boston Children's Hospital, we understand that a hospital visit can be difficult, and sometimes overwhelming. So, we offer many amenities to make your child's—and your own—hospital experience as pleasant as possible. Visit The Center for Families for all you need to know about:

    • getting to Boston Children's
    • accommodations
    • navigating the hospital experience
    • resources that are available for your family

    In particular, we understand that you may have a lot of questions when your child is diagnosed with thumb duplication. Will this affect my child long term? Will he be able to play sports and do regular activities? Boston Children's can connect you with extensive resources to help you and your family through this stressful time, including:

    • patient education: From doctor's appointments to physical therapy and recovery, our nurses and physical therapists will be on hand to walk you through your child's treatment and help answer any questions you may have—Why will my child need surgery? Are there non-surgical options? How long will his recovery take? How should we manage home exercises and physical therapy? We'll help you coordinate and continue the care and support your child received while at Children's.
    • parent-to-parent: Want to talk with someone whose child has been treated for radial polydactyly? We can often put you in touch with other families who've been through the same process that you and your child are facing, and who will share their experiences.
    • faith-based support: If you're in need of spiritual support, we'll connect you with the Boston Children's chaplaincy. Our program includes nearly a dozen clergy— representing Protestant, Jewish, Muslim, Roman Catholic and other faith traditions—who will listen to you, pray with you and help you observe your own faith practices during your hospital experience.
    • social work: Our social workers and mental health clinicians have helped many families in your situation. We can offer counseling and assistance with issues such as coping with your child's diagnosis, stresses relating to coping with illness and dealing with financial difficulties.
  • Research & Innovation

    Improving outcomes for upper extremity disorders

    Children’s Hospital Boston’s Orthopedic Center's Hand and Orthopedic Upper Extremity Program is dedicated to the comprehensive care of all upper limb conditions in infants, children and adolescents. Under the direction of Peter M. Waters, MD and Donald S. Bae, MD, patients with congenital, neuromuscular, sports-related, oncologic and traumatic or post-traumatic conditions of the upper extremity receive multi-disciplinary care that includes occupational and physical therapy, splinting/casting and reconstructive surgery.

    Our Hand and Orthopedic Upper Extremity Program is committed to improving clinical care through continued clinical and basic science research. The program is studying the treatment of a wide variety of upper limb conditions, including:

    • reconstruction of the congenitally deficient hand
    • the use of microsurgical techniques in reconstructive surgery for congenital upper extremity differences
    • instability of the sternoclavicular and glenohumeral joints of the shoulder
    • post-traumatic stiffness and deformity of the elbow
    • surgical correction of forearm deformity following previous fracture
    • ligament and/or cartilage injuries of the wrist
    • the use of microsurgical techniques in reconstructive surgery following limb salvage for bone and soft-tissue tumors

    Many of these investigations have resulted in national and international presentations or peer-reviewed medical publications—and all have increased our ability to provide the highest standard of patient care.

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