Syndactyly

Syndactyly is a common congenital anomaly of the extremities characterized by the fusion of adjacent digits involving soft tissue and/or bone. This condition can occur in both the upper and lower extremities, creating the appearance of "webbed" or "super" digits, depending on the degree of fusion. Syndactyly is classified as simple or complex, with complex cases involving bony fusion, while simple cases involve only soft tissue. Complete syndactyly extends to the tips of the digits, including the nail folds, whereas incomplete syndactyly does not. Complicated syndactyly involves additional abnormalities, such as accessory phalanges or abnormal bones.  The most prevalent location is between the second and third toe in the feet and between the long and ring fingers in the hand. Syndactyly is most likely to present as an isolated phenomenon following autosomal dominant inheritance with incomplete penetrance but is also associated with multiple genetic syndromes such as Apert and Poland syndrome. Syndactyly is better tolerated in the feet than the hand, where independent digital motion is needed. Except for mild cases, surgical separation of the digits is often indicated to optimize hand function (See Syndactyly, a Common Congenital Anomaly of the Extremities).