syndactyly

Syndactyly is a congenital condition in which two or more digits are fused or joined. The fusion can involve only skin (cutaneous syndactyly) or also bone and other tissues (complex or osseous syndactyly). It can affect fingers or toes and may occur as an isolated finding or as part of a broader syndrome.

Classification distinguishes simple versus complex and complete versus partial syndactyly. Simple syndactyly involves only soft tissue without bone fusion, while complex syndactyly includes osseous fusion. Complete syndactyly spans the full length of the digits, whereas partial syndactyly affects only a portion. The condition may be unilateral or bilateral and can be non-syndromic or associated with other anomalies.

Causes and inheritance: Syndactyly develops during fetal growth when the normal process that separates digits fails, leading to persistent webbing or fusion. Genetic factors often play a role, and many cases are inherited in an autosomal dominant pattern. Several syndromic forms include Apert and Pfeiffer syndromes, Greig cephalopolysyndactyly syndrome, and other genetic conditions.

Presentation, diagnosis, and management: Syndactyly is usually evident at birth as webbing or fusion of digits. Evaluation includes physical examination and radiographs to assess bone involvement. Prenatal ultrasound can detect some cases. Mild isolated cutaneous syndactyly may not require treatment. Surgical release is commonly pursued when function or appearance is affected, typically in early childhood, with goals of improved digit separation and function and minimized scarring. Potential complications include infection, scar formation, recurrence, and stiffness.

Epidemiology and prognosis: It is the most common congenital limb malformation, occurring in about 1 in 2,000 to 3,000 live births. Prognosis after treatment is generally favorable, with good functional outcomes in many cases.