Congenital Hand Differences Fundamentals

Congenital means "present at birth." A congenital hand difference is a variation in the normal formation of the hand that occurs when the fetus is in the uterus.

Differences in a child’s physical appearance — such as hand differences — are noticeable at birth, which can be distressing to the parents. In some cases, feelings of anger and guilt develop, especially in the mother, who may blame herself for some "failure" during the pregnancy. Parents may also become angry with healthcare providers for not detecting the problem during routine prenatal care. In fact, no one is at fault. Most hand differences are not hereditary (do not run in families) or preventable, and many cannot be detected before birth.

Although congenital hand differences are generally noticeable at birth, the doctor may take X-rays to determine the extent of bone/tissue involvement; for example, to see if the difference is simple or complex.

Hand differences can be grouped based on the type of difference present. These general categories include:

  • Problems with the formation of the entire arm or hand.
  • Failure of parts of the hand to separate.
  • Extra fingers or thumb.
  • Undergrowth or overgrowth of hand, fingers and/or thumb.

Specific congenital hand differences include the following:


Syndactyly is the most common congenital hand difference. The word syndactyly is derived from the Greek syn, which means together, and daktylos, which means digit (finger or toe). Syndactyly is a condition in which the fingers are fused together or the webbing between the fingers extends farther up the fingers than normal. The condition can be simple, with only skin shared by the fingers, or complex, with shared bone, nerves, blood vessels and/or other tissues. Syndactyly is usually treated by surgically separating the fingers. Often skin grafts are necessary, as there may be deficient skin to provide coverage for two fingers. Casting or splinting, as well as physical therapy, also may be recommended – especially in complex cases – to help maximize hand function postoperatively.


Polydactyly is the presence of more than five digits (poly means many). The extra finger or thumb may be attached only by skin or nerves, or it may have normal parts and be attached to a joint or an extra bone in the hand.

Ulnar polydactyly, the most common type, refers to an extra finger or part of a finger that develops on or near the little finger of the hand. (Ulnar refers to the ulna, the larger of the two bones of the forearm. The ulna is on the same side of the arm as the little finger.) Polydactyly can be treated by surgically removing the extra digit and reconstructing the remaining digit.

Thumb (Radial) Polydactyly

Thumb (Radial) Polydactyly refers to the presence of multiple thumbs on one hand. This condition can be treated by removal of the additional digit and surgical reconstruction of the remaining thumb.

Radial Club Hand

Radial club hand refers to a condition in which the radial (referring to the radius, the smaller bone of the forearm) or thumb-side of the arm is malformed, causing a shortening and curving of the forearm and giving the appearance of a J-shaped club. The thumb may be small or completely absent.

With a shortened forearm, people with radial club hand may have difficulty performing tasks that require two hands. This difference can occur in one (unilateral) or both (bilateral) arms.

Treatment depends on the functional abilities and needs of the child, and may include limb manipulation and stretching, splinting or casting, and/or surgery.

Cleft Hand

The term cleft hand actually refers to a group of congenital hand differences in which the fingers or parts of fingers in the center of the hand are missing, leaving a V-shaped space or indentation (called a cleft). Other differences, particularly syndactyly and polydactyly, often occur at the same time. There are many variations of cleft hand.

Typical cleft hand is characterized by a gap in the palm and the absence of the middle finger or fingers. Cleft hand can be unilateral or bilateral. (There are patients with a family history of clefting in both hands and feet.) In typical cleft hand, the hand is almost normal in size, and the arm bones are usually normal.

What causes congenital hand differences?

A fetus’ arms and hands form between the fourth and sixth week of pregnancy. Any disruption of this process can lead to a congenital hand difference. There are many factors that can affect the development of the human hand. These factors are generally divided into genetic and environmental.

Genetic factors involve changes to the information contained within the genes responsible for hand and arm formation. Genes are the basic biological unit of heredity and are passed on to children from their parents. They contain instructions for the growth and function of each cell in the body. In the case of hand differences, the genetic changes generally occur for no apparent reason (spontaneous). Less common are changes that run in families.

Environmental factors include infections and certain drugs, such as thalidomide (a drug used to treat nausea) and some drugs used for chemotherapy. These factors may cause a breakdown in otherwise healthy tissue, altering the developmental process and leading to a difference in hand formation.

Some hand differences can be explained by these factors, while others have no known cause. In some cases, the hand difference is an isolated event. In other cases, the difference is part of a syndrome that affects multiple parts of the body.

What are the benefits of treatment for congenital hand differences?

Each child with a hand difference is unique, and the approach to treatment is based on the child’s individual needs. The main goal and benefit of treatment is to improve the child’s ability to function with the difference. Another aim is to improve the appearance of the hand and support the child’s self-esteem.

Options for treating hand differences include:

  • Stretching
  • Splinting or casting
  • Physical therapy (to help increase strength and function)
  • Prosthetics (in the case of missing parts or bones)
  • Surgery

The outlook for treatment varies with the type and complexity of the difference. When the hand difference is an isolated occurrence, the outlook is generally good. Most children can learn to adapt to their differences. If the difference is part of a syndrome, the outlook depends on the type and extent of the condition.

Keep in mind that treatment cannot "cure" a hand difference, but it can help to improve function and appearance of the hand. A positive attitude and acceptance of the difference – by the child and the parents – are important to treatment success, as well as to the child’s healthy development.

What are the risks of treatment for congenital hand differences?

Risks include nerve injury, infection, bleeding and stiffness. There is also a risk that treatment will not restore or create a normal digit or hand.

Reviewed by a Cleveland Clinic medical professional.

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