A bone spur is a bump or corner of bone that causes either direct or indirect pain. Bone spurs develop along the edge of the bones, usually where the bones meet at the joint. Because the foot has 30 joints, it is one of the most common areas for bone spurs to develop. More specifically, bone spurs typically develop on the bottom of the heel, on top of the foot, outside of the foot, inside of the foot, and on the toes.