Heel Spur

A heel spur is a calcium deposit causing a bony protrusion on the underside of the heel bone. On an X-ray, a heel spur can extend forward by as much as a half-inch. Without visible X-ray evidence, the condition is sometimes known as "heel spur syndrome.
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.
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. 
Treatments for heel spurs and associated conditions include exercise, orthotics, anti-inflammatory medications, and cortisone injections. If conservative treatments fail, surgery may be necessary.