Biphalangeal fifth toe: an increasingly common variant?

Abstract

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.