syndactyly

description

syndactyly is a descriptive term denoting fusion of two or more digits. the degree of fusion is complete if it extends to the tips of the fingers, partial if short of that. it is defined as simple if the fingers are bound together only by skin and complicated if there is synostosis between adjacent bones or sharing of neurovascular structures. syndactyly may be associated with various syndromes, including apert syndrome. when encountered as an isolated malformation, five autosomal dominant types can be clearly delineated: type i (zygodactyly) has cutaneous syndactyly up to the nails of the long and ring fingers and toes 2 and 3. type ii (synpolydactyly) also involves the long and ring fingers, 4th and 5th toes, but there is an extra digit hidden in the web (central polydactyly). type iii involves the ring and little fingers with a rudimentary middle phalanx in the latter. the toes are not affected. in type iv (hass) all the fingers, including the thumb, are fused so that the hand is in a cup-like position; the feet also display postaxial polydactyly. type v (mc/mt synostosis) involves the long and ring fingers and 2nd and 3rd toes. there is fusion of 4th and 5th metacarpals and metatarsals.