Heel spurs occur when calcium deposits build up on the underside of the heel bone, a process that usually occurs over a period of many months.
Heel spurs are often caused by strains on foot muscles and ligaments, stretching of the plantar fascia, and repeated tearing of the membrane that covers the heel bone.
Heel spurs are especially common among athletes whose activities include large amounts of running and jumping.
Although heel spurs are often painless, they can cause heel pain. They are frequently associated with plantar fasciitis, a painful inflammation of the fibrous band of connective tissue (plantar fascia) that runs along the bottom of the foot and connects the heel bone to the ball of the foot.