Congenital absence of the lateral metatarso-phalangeal sesamoid bone of the human hallux: a case report

A case of congenital absence of the lateral metatarsophalangeal sesamoid bo ne of the hallux is reported, in a 47-year-old woman. The lateral sesamoid bone was absent on the right hallux, and extremely reduced on the left hall ux. The normal intersesamoidean crest and both sesamoidean grooves of the m etatarsal head were absent. Physical examination was normal, and no functio nal disturbance resulted from,this variant. Only,two previous cases have be en found in the literature. It must be distinguished from a total resorptio n due to an infectious process, or from an absence due to surgical excision . This absence can be related to the general tendency of disappearance of t he sesamoid bones within hominoid primates.