Syndactyly

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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).

Epidemiology

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

Pathology

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

Associations

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

Aneuploidic syndromic

triploidy: tend to affect the 3^rd and 4^th digits of the hands

Non aneuploidic syndromic

acrocephalosyndactylies
- type I: Apert syndrome
- type II: Crouzon syndrome
- type III: Saethre-Chotzen syndrome
- type V: Pfeiffer syndrome
acrocephalopolysyndactylies
- type I: Noack syndrome
- type II: Carpenter syndrome: typically gives soft tissue syndactyly
- type III: Sakati-Nyhan syndrome
- type IV: Goodman syndrome
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 syndrome¹⁰

Non syndromic

isolated polydactyly, a.k.a. polysyndactyly
isolated brachydactyly, a.k.a. brachysyndactyly
isolated ectrodactyly

Distribution

As a whole the 2^nd and 3^rddigits tend to be most frequently associated ⁶. May involve the toes more than fingers.

Radiographic features

Plain radiograph

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

Antenatal ultrasound

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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