Syndactyly, also known as “webbed fingers,” is the most common congenital malformation of the hand due to failure to separate the fingers during embryonic development, with an incidence of 1 in 2000. The majority of patients are disseminated, and Flatt found a family history of syndactyly in 40% of patients, suggesting a genetic component. Several family trees show autosomal dominant inheritance of central ring finger syndactyly, but with incomplete epistasis.
The syndactyly is divided into complete or incomplete syndactyly and simple or complex syndactyly. Complete syndactyly means that the two fingers are joined from the web to the tip of the finger; incomplete syndactyly means that the two fingers are joined from the web to a point proximal to the tip of the finger. Simple juxtaposition means that only the skin or other soft tissues are bridged together; in complex juxtaposition, the two fingers share bony structures. Gap-jointed fingers are joined distally with a gap proximally. Short syndactyly is the simultaneous presence of shortened fingers and syndactyly. In Poland’s syndrome, the thoracic rib portion of the ipsilateral pectoralis major muscle is absent, and hand deformities include unilateral shortening of the index, middle, and ring fingers, multiple simple incomplete syndactyly, and hand hypoplasia.
Optimal timing of treatment There is no rush to surgical treatment. While waiting for the right age for surgery, parents are encouraged to massage the finger webs to stretch the skin between the fingers to facilitate later surgery. Surgical reconstruction is best done before school age, and children after 18 months of age are better off with surgical correction, especially for the final shape of the joint. Premature surgery has a tendency for distal displacement and constriction of the web of the finger to occur. If there is only a syndactyly between the 2nd or 3rd finger webs and no other deformity, surgery should be delayed until at least 18 months of age. If fingers of different sizes are fully involved, whether simple or complex juxtaposition, early separation within 6-12 months is preferable because angulation, rotation and flexion deformities may occur. These deformities are difficult to correct and prevention of these deformities is preferable to the possibility of distal web movement and contracture. When multiple fingers are involved, the marginal finger should be released first, followed by release of the other juxtaposed fingers 6 months later. Simultaneous release of the radial and ulnar sides of one finger is contraindicated, as this can lead to finger necrosis.