A heel spur develops as an abnormal growth of the heel bone. Calcium deposits form when the plantar fascia pulls away from the heel area, causing a bony protrusion, or heel spur to develop. The plantar fascia is a broad band of fibrous tissue located along the bottom surface of the foot that runs from the heel to the forefoot. Heel spurs can cause extreme pain in the rear foot, especially while standing or walking. This stretching of the plantar fascia is usually the result of over-pronation (flat feet), but people with unusually high arches (pes cavus) can also develop heel spurs. The cause is usually over-pronation (flat feet), a custom orthotic with rearfoot posting and longitudinal arch support is an effective device to reduce the over-pronation, and allow the condition to heal. Other common treatments include stretching exercises, losing weight and wearing shoes that have good cushioning for heel spur relief.