Syndactyly is the common congenital anomaly of the hand.Syn – means together and dactyls – means digits, i.e. the fusion of digit or failure of separation of the digits.
Approximate incidence is 1 in 2000 live birth; bilateral affection is seen in 50% of cases.
Male predominance is present (2:1).
Syndactyly is described as complete if the web space extends to include the fingertips and incomplete when the web space occurs anywhere between the normal commissure and fingertips.
Simple syndactyly has only skin or soft tissue connections whereas complex syndactyly is marked by skeletal anomalies.
The specific cause is unknown.
It is caused by the failure of fingers to separate during embryological development.
10 to 40% of cases demonstrate a positive family history and it is inherited as an autosomal dominant trait.
Syndactyly is associated with Poland and Apert syndrome.
Syndactyly most often affects the third webspace of hand, sequentially less common in the fourth, second, and first web space.
Syndactyly between the ring and little finger, or index finger and thumb results in gradual flexion contracture, lateral deviation, and rotational deformity with in the first year.
Syndactyly of the first web space hampers grasp and the development of pinch.
Syndactyly of the second, third, and fourth web space inhibits independent digital motion.
The most important aspect of hand evaluation is the determination of the quality of the affected digits.
Plain radiographs will reveal osseous union and marked joints and bony mal-alignment. However, in infancy, the area of chondral abnormalities in the joints, physis and between the digits exhibiting syndactyly will not be visible on the plain radiographs.
Magnetic Resonance Imaging and arteriography are used only in very complex situations, to define digital anatomy.
Children with incomplete syndactyly, especially where syndactyly won’t extend beyond the proximal interphalangeal joint, may choose not to undergo surgical separation.
Most parents and children with complete syndactyly desire separation of the digit for functional and cosmetic reasons.
Surgical intervention is not an urgent emergency procedure. While waiting for the child to reach the appropriate age for reconstruction, parents are encouraged to massage the web space in an attempt to stretch the intervening skin to facilitate the surgery at the later date.
Surgical reconstruction is best done before the child is of school age. Syndactylies involving the second and third web space are operated at around 18 months of age. Syndactylies involving the first and fourth web space are operated between the age of 6 and 12 months.
Untreated syndactylies will hamper the functions of the hand. Especially the first and fourth web space syndactylies will result in angular and rotational deformities.