Syndactyly 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.
There is a very wide spectrum of syndactyly ranging from partial to complete.
Syndactyly can occur as an isolated phenomenon or can be associated with numerous other entities. Isolated cases can be either either sporadic or familial.
- triploidy: tend to affect the 3rd and 4th digits of the hands
Non aneuploidic syndromic
- amniotic band syndrome 3
- Fraser syndrome / cryptophthalmos syndrome 4
- Gorlin syndrome
- Greig cephalopolysyndactyly syndrome 5
- Macrodystrophia lipomatosa
- Pallister-Hall syndrome
- Poland syndrome
- proximal radioulnar synostoses: Cenani Lenz syndactyly
- prune belly syndrome
- Roberts syndrome
- VACTERL association
- Down syndrome 10
- isolated polydactyly, a.k.a. polysyndactyly
- isolated brachydactyly, a.k.a. brachysyndactyly
- isolated ectrodactyly
As a whole the 2nd and 3rd digits tend to be most frequently associated 6. May involve the toes more than 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 suggest if the digits appear to contantly move together 7. The fingers may appear constantly deformed with complex syndactyly 6.
Treatment and prognosis
The overall prognosis can be extremely variable dependent on the presence of other associated anomalies.
History and etymology
The term syndactyly is derived from the Greek words syn meaning together and daktulos meaning fingers.
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