A heel spur is caused by the displacement of calcium on the bone that forms on the underside of the heel; it may be one small bony protrusion or a collection of tiny, irregularly shaped growths on the bone of the heel, which is called the calcaneum. Heel spurs are sometimes painful — described as a knife digging into the heel — and other times, a heel spur goes unnoticed and is only detected by an X-ray.
Because knowledge about the symptoms of heel spurs is somewhat limited, it’s common that it’s mistakenly assumed to be plantar fasciitis. A heel spur is simply the presence of an extra protrusion on the bony surface of the heel, while plantar fasciitis is the inflammation of the plantar fascia — a thick connective tissue band that extends from the heel bone to the heads of the metatarsal bones, which are five long bones in the foot located between the heel and the toes.