Kayakfisher;
I would go with the leg bone, you can make it a diamond cross section, and like Mullet said, make little serrations, and alternate the sharp angles of the bone. (bevels) Cooking doesn't affect it. I have used raw bone that I have gotten off an old dairy, that came from dead cows, and I have used cooked bones, from soup bones, and bones from pet stores. I have yet to see any difference in strength or working ability. Like it was said, they won't be as sharp as stone, but you should be able to get a decent cutting edge, by serration, with the down, up type of angles on the serration edges. IN other words, one edge will be angled down, the next will be angled up, etc. You can vary the angles, from the front to back, and on the back edges, you can vary the angles from back to front, like those little rectangular pink erasers, that have one end beveled up, and the end beveled down. That way, it will cut on entrance, and exit, and when being moved by the animal, and arrow hitting objects.
It is like copper vs. steel. The copper is just too soft, to be as good a cutting instrument, as steel, and stone is harder than steel, and will give a superior edge. But in a survival situation, I would use whatever I could. Don't bother using pork bones. They are brittle, and crumbly. Beef, deer, elk, antelope, buffalo, giraffe, etc. Just about any animal with a thick bone will work, except for porkers. Antelope are supposed to have the strongest leg bones going.
Wayne