Apparatus for the prevention of pressure sores, namely pads; apparatus for the treatment of pressure sores, namely pads; pads for preventing pressure sores on patient bodies; orthopaedic insoles for corrective treatment of conditions of the feet; medical apparatus for the prevention of ulcers and blisters on the feet; orthotic inserts for footwear; orthopaedic insoles for footwear; orthopaedic inserts for footwear