I was seeing a woman who administered discipline for several years. She had to stop over-the-knee spanking because of a knee injury. It seems the weight of the spankee would irritate her knee so badly, that it was becoming a real problem for her. I always thought that a chair that supported the weight of the recipients legs and torso might have been a good solution for her. The appliance in this illustration, although being used for an altogether different purpose is a good example of what I had in mind.
Very interesting form of correction shown here though!