Polydactyly refers to extra digits - in the hand, extra fingers or thumbs. Polydactyly is one of the most common variations on the basic growth pattern of the hand. There are many different forms of polydactyly, ranging from:

• a small extra bump on the side of the hand,

• a finger which widens to end in two fingertips,

• an extra finger which dangles by a thin cord from the hand,

• a hand which looks normal except that it has a thumb and five fingers,

• an infinite number of other variations.

Right hand with exra digit and wide thumb

Usually, when a digit has duplicated, each half is somewhat smaller than usual, and it is common for the joints to angle to the sides, often in mirror image zig zag directions.

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Polydactyly occurs in the womb as a detour on the road to developing just one thumb and four fingers on the hand. In the womb, the new hand starts out in the shape of a paddle, then splits into separate fingers. Sometimes the fingers don't split apart enough, and webbed fingers result: syndactyly. Sometimes a extra split forms and extra fingers result: polydactyly. Syndactyly and polydactyly are about equally common disorders. Combinations of both can occur as well - webbed extra fingers.

It is not due to anything the mother did during pregnancy - it just happens. Sometimes these problems are in the genes and can be passed down generation to generation, but many times there is simply no known explanation.

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The main decision is to decide whether or not to do anything for the problem. Certain types of polydactyly are associated with other birth related problems elsewhere in the body, and it is a good idea to have an evaluation for this reason alone.

Surgery for polydactyly is usually best done in the first few years of life so that the look, feel and function of the corrected hand is the most natural for the child. A hand therapist can help with some problems before and after surgery, tailored to the individual problem and the temperament of the child, but some children proceed through their surgery and recovery without needing therapy.

Left foot with extra digit (2nd big toe)

The main treatment of polydactyly is surgery to remove the extra parts and more importantly to correct associated problems with what remains. This is sometimes fairly complicated surgery, because there may be variations in all of the structures of the digit which is kept - twisted bones, crooked joints, missing or extra tendons, nerves, and blood vessels. Abnormalities in the fingers which are kept may be more obvious after surgery than before, but with careful planning, a hand surgery specialist will attempt to anticipate and correct these problems at the time of surgery.

After surgery, it is usual to protect the hand in a large bandage for weeks to months, depending on what is done. Surgery done in childhood may need to be adjusted for growth with "touch up" surgery when the child is older. The goals of surgery are to improve the appearance of the hand and to prevent progressive deformity from developing as the child grows. Surgery is generally successful in both of these areas, largely correcting the appearance and social stigmata of congenitalism. In many cases, surgery results in a greatly improved but not perfectly normal appearance, and in some situations a normal appearance can not be expected.

Fortunately, unless there is something particularly eye-catching about the hand (like an extra finger or thumb), what people notice about another person's hand is not the appearance of an individual finger or thumb, but how the person uses their hand. Hiding one's hand actually draws attention to it, and if surgery allows the person to use their hand in a natural, unselfconscious way, many small details, such as a somewhat small thumb, will go unnoticed.

Polydactyly does not generally pose any health risk over time. Surgical treatment is more likely to result in a satisfactory outcome if surgery is done in the first few years of life to give the child the most ability to adapt and accommodate to the changes in their hand. People are less likely to be satisfied with surgery for polydactyly if surgery is delayed past early childhood.

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