Classification

Symbrachydactyly has been classified by Yamauchi (1) into seven types:

1. triphalangia; hands have normal number of bones but some phalanges may be short
2. diphalangia; one phalanx is absent in at least one digit. Middle finger most affected
3. monophalangia type; a hand in which one or more fingers has only one phalanx
4. aphalangia type; one or more digits has all three phalanges missing
5. ametacarpia; hand in which at least one digit has all three phalanges and one metacarpal missing
6. acarpia; hand in which there is absence of all digits and partial or complete absence of carpal bones
7. forearm amputation; absence of distal portion of forearm with hypoplastic digits - 'nubbins' - on the stump

Ref: (1) Yamauchi Y. In Buck-Gramcko D (ed): Congenital Malformations of the Hand and Forearm. London, Churchill-Livingstone, 1998. P. 149-157.