The instep borer was a medieval German

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 instrument of torture

Torture

Torture is the act of inflicting severe pain as a means of punishment, revenge, forcing information or a confession, or simply as an act of cruelty. Throughout history, torture has often been used as a method of political re-education, interrogation, punishment, and coercion...

 that externally resembled an iron boot. It was hinged to permit the free insertion and removal of the bare foot. A crank projected from a housing over the instep, which concealed a long, thick, serrated iron

Iron

Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...

 blade, grooved so as to inflict maximum damage and promote liberal blood flow.

Turning the crank slowly advanced the blade into the boot, punching a hole through the center of the instep. The resultant wound was so large that it was not unusual for the prisoner to die of toxaemia soon after.

It seems that the instep borer was used only in Nuremberg

Nuremberg

Nuremberg[p] is a city in the German state of Bavaria, in the administrative region of Middle Franconia. Situated on the Pegnitz river and the Rhine–Main–Danube Canal, it is located about north of Munich and is Franconia's largest city. The population is 505,664...

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