The presence of 2 phalanges in the 5th toe was first described by Leonardo da Vinci in 1492 (O’Malley & Saunders, 1952) and is recognised as a normal variant. It is probably a true anatomical variant resulting from incomplete segmentation rather than the result of phalangeal fusion (Venning, 1960; Le Minor, 1995) and has been noted to be present in fetuses from as early as 12 wk (Venning, 1960). This variant (and the much rarer 2 biphalangeal 2nd–4th toes) is an exclusively human phenomenon suggesting it is a response to bipedalism (Le Minor, 1995). Various investigators have reported the incidence of the 2 phalanged 5th toe of populations as between 35.5% and 80.4% with the lower values being seen in Europeans and the higher in Japanese (Venning, 1960; Thompson & Chang, 1995). Our study compared foot radiographs in the old and young to see if there was any difference in incidence.
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机译：莱昂纳多·达·芬奇（Leonardo da Vinci）于1492年首次描述了在第5个脚趾中有2个趾骨（O’Malley＆Saunders，1952年），并被认为是正常变体。它可能是真正的解剖变异，是由于不完全的分割而不是指骨融合的结果（Venning，1960； Le Minor，1995），并且已经注意到早在12周就存在于胎儿中（Venning，1960）。这种变体（以及罕见的2个第2到第2个第4脚趾）是一种人类独有的现象，表明它是对两足动物的一种反应（Le Minor，1995）。许多研究者报告说，第二趾趾五趾人群的发生率在35.5％至80.4％之间，在欧洲人中较低，日本人中较高（Venning，1960； Thompson＆Chang，1995）。我们的研究比较了老年人和年轻人的脚部X光片，以查看发病率是否存在差异。
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