The Knuckle runs down the leg ending at the knee bone. It can be used for dicing, roasting and thin slicing but does generally work better being slow cooked.
The knuckle is an exceptionally lean, very affordable cut from the Round (between the Top Round & Bottom Round). It can be cut into roasts, pot roasts, cubes for kebab or stew, etc. It can also be cut into low cost steaks which are typically cut very thin and pinned (cubed) for tenderness.