What is "knee splitter"

n. A device of torture whereupon two spiked blocks facing each other, and held together by large screws, may be cranked to close in on a limb to destroy the surrounded limb.

The knee splitter was a form of torture used mainly during the inquisition. It’s said that this device was a uniquely German device, first recorded in 1530;also going by the names Kranz or Schneiden. It was created from two spiked wood blocks, placed in front of, and behind the knee. The blocks were connected with two large screws. When turned, the blocks would close towards each other, destroying the knee underneath them. This method was used to render the knees useless. The number of spikes on the blocks would range from three to twenty, depending on the captive. To make the pain more unbearable, the torture master would sometimes amuse himself by tapping on the metal cap with a small hammer.