The history and evolution of surgical instruments. VI. The surgical blade: from finger nail to ultrasound.

Elective surgery requires planned incisions and incisions require appropriate blades. In the prehistoric era, division of the umbilical cord and other minor procedures were probably undertaken with human teeth and nails, and later with plant, animal and mineral substitutes, as witnessed by studies of primitive societies still surviving or recently extinct. More efficient metallic blades appeared in historic times and ultimately generated five specific shapes which are analysed in detail. Today, as minimally invasive techniques, endoscopes, laser and ultrasound sources evolve, many hallowed incisions of surgical access diminish in length or disappear entirely. In historical terms, elective surgery of the twentieth century will be recalled as an interlude characterised by maximally invasive incisions.