Congenital third foot deformity: a case report.

A congenital accessory limb is a rare condition that may be associated with predisposing factors such as drug or alcohol or toxin exposure, trauma, and deformities such as spina bifida. This article describes a case involving an accessory foot in an otherwise healthy 33-year-old male. It is likely that the etiology of this case was an early embryologic exposure to amniotic constriction bands that affected the development of the distal limb.