Syndactyly, the most common congenital hand anomaly, is an abnormal connection of fingers or toes to one another—the digits are “webbed,” and have failed to separate normally during development. It most commonly involves the middle and ring fingers. In about 50% of cases, both hands are involved. Syndactyly may occur alone, or with other anomalies as part of a syndrome.
Typically, syndactyly is not painful. However, in some very severe cases, in which the nails might dig into the joined fingertips, minor infections and wounds can cause some discomfort.
Syndactyly may occur in different forms. Complete syndactyly occurs when the digits are joined all the way to their tips, while in incomplete syndactyly, the digits are joined only for part of their length. Simple syndactyly means that the digits are joined by the skin and soft tissue only, while complex syndactyly means that the bones of the digits are fused together.
Syndactyly can occur in any newborn infant. Overall, syndactyly occurs in approximately one out of 2500 newborns. In up to approximately 40% of cases, there is a family history of syndactyly. If syndactyly occurs alone, it is inherited as an autosomal dominant condition; that is, the children of an affected individual will have a 50% chance of having syndactyly. However, syndactyly is not the same from one generation to the next, and can be more or less severe than in the affected parents. Syndactyly is more common in Caucasians than in other ethnicities, and affects boys twice as often as girls.
When the hands and feet are developing in the womb, they start out as flat “paddles” that then normally separate into five digits. Syndactyly occurs when there is a failure of this separation process. This may be caused by a genetic abnormality or by environmental influences.
The primary issue in syndactyly is function of the hand and digits. Syndactyly causes limitation of function, because the involved digits cannot move completely independently. In very severe cases, with multiple digits involved in complex syndactyly, there can be problems with infections and skin breakdown.
Some children with syndactyly will have other congenital abnormalities or syndromes. Syndactyly may occur as part of several different syndromes. For example, in the craniofacial dysostosis syndromes, such as Apert’s syndrome (see Craniofacial Syndromes), in addition to very severe, symmetric syndactyly of the hands and feet, there are also significant head and face abnormalities.
While every patient is treated individually, with treatment plans made specifically for him or her, some generalizations are possible. Syndactyly is treated surgically, with an operation that separates the digits using skin from the digits and, usually, skin grafts from the lower abdomen to cover the separated fingers. When the small finger or thumb is involved, this operation is done at about six months of age, to avoid distortion of the adjacent ring or index finger with growth, since the thumb and small finer are shorter than their neighboring digits. Otherwise, syndactyly release is usually done at about eighteen months of age. Before this age, the incidence of wound healing complications and skin graft failures is significantly higher. In special cases with very complex syndactyly—or complicated syndactyly–such as in Apert’s syndrome (see Craniofacial Syndromes), surgery may begin earlier, and multiple procedures may be required in a staged sequence to achieve separation of all the digits.
You will meet with your surgeon soon after your baby is born. In some cases, diagnosis is made prenatally by ultrasound exam, and you may have the opportunity to meet your surgeon before your baby is born. Your surgeon will examine your baby and take xrays of the affected hand. Your baby will be examined in the clinic periodically during the months before surgery. The treatment plan and the details of the surgical procedures will be carefully explained to you by your surgeon. Usually, no special treatment or therapy is required before surgery.
At the very least, your child will be treated by the hand surgeon and a certified hand therapist. In addition, a geneticist and developmental pediatrician are usually involved in the care of babies with syndactyly.
Ideally, you will meet your surgeon either prenatally or soon after your baby is born. You will meet with your surgeon several times before surgery, and will get to know him quite well.