Heel bone spur. Lateral X-ray of the ankle and upper part of the left foot of a 30-year-old patient with a bony spur on the heel bone (calcaneus). The heel bone is the large bone at lower left. The bony spur is the projection on the lower right edge of this bone. The appearance of such spurs are often due to osteoarthritis, the degeneration of the body's joints due to wear and tear.