Last revised by Joshua Yap on 8 May 2023

Syndactyly (plural: syndactylies) refers to a congenital fusion of two or more digits. It may be confined to soft tissue (soft tissue syndactyly / simple syndactyly) or may involve bone (bony syndactyly / complex syndactyly).

The overall estimated incidence is at ~1 per 2500 to 5000 live births 6,8. There may be a greater male predilection.

Syndactyly can occur as an isolated phenomenon or can be associated with numerous other entities. Isolated cases can be either sporadic or familial.

There is a very wide spectrum of syndactyly ranging from partial to complete.

Overall, the 2nd and 3rd digits tend to be most frequently associated 6. May involve the toes more than the fingers.

Postnatally the type and degree of bony syndactyly can be easily diagnosed on plain film.

Often difficult to diagnose on ultrasound (especially with soft tissue syndactyly). The diagnosis may be suggested if the digits appear to constantly move together 7. The fingers may appear constantly deformed with complex syndactyly 6.

The overall prognosis can be extremely variable depending on the presence of other associated anomalies.

The term syndactyly is derived from the Greek words "syn" meaning together and "daktulos" meaning fingers.

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