Footballers and other sports players wreck their knee joints by twisting. Many designs of boots attempt to lessen the stresses which cause this.
Today’s invention is one such consisting of a cylindrical ‘cookie cutter’ blade moulded into the base of a boot. This would be edgy enough to provide good grip on the surface but not so sharp as to allow injury to people coming in contact with it.
The foot could be well planted on the turf and then the player could spin around the centre of the cutter, without causing any internal damage.