Arachnodactyly refers to the elongated, thin "spider like" fingers pathognomic of Marfan's disease 1.
A metacarpal index has been suggested as a radiographic criteria for arachnodactyly. To obtain it, the length of the second, third, fourth and fifth metacarpals is divided by their width at the mid shaft. An index of greater than 8.4 is considered the upper limit of normal 2 .
- marfan's syndrome
- other hereditary diseases of connective tissue
History and Etymology
From the Greek "arachno" refers to spiders and "dactyly" means fingers
- 1. Rodney Grahame, Alan J. Hakim. Arachnodactyly—a key to diagnosing heritable disorders of connective tissue. (2013) Nature Reviews Rheumatology. 9 (6): 358. doi:10.1038/nrrheum.2013.24
- 2. Ha HI, Seo JB, Lee SH, Kang JW, Goo HW, Lim TH, Shin MJ. Imaging of Marfan syndrome: multisystemic manifestations. (2007) Radiographics : a review publication of the Radiological Society of North America, Inc. 27 (4): 989-1004. doi:10.1148/rg.274065171 - Pubmed