What causes heel spurs?

Plantar fasciitis: In my experience, heel spurs are most commonly seen in patients who have plantar fasciitis. The area of the heel which develops the spur is the insertion point of the plantar fascia. When you walk, the plantar fascia excessivelly pulls at the site of its insertion which causes a spur over time. There's another condition which causes bone spurs all over the body but this is rare.

TENSION/INFLAMMATION: Heel spurs usually develop when tension and inflammation are both present. The heel is pulled upon by two strong soft tissue structures. The achilles tendon pulls on the back of the heel, and the plantar fascia on the bottom. After time, these opposing forces causes irritation/inflammation around the attachments on the bone, and these spurs develop. The spur itself usually isn't the source of pain.

Wolff's Law...: Paraphrased, bone grows in relation to stress. When an abnormal "pull" is placed on the bone, it will grow in that direction over time. After enough time, a "heel spur" can be visualized. It's more the sign of a chronic condition that the source of the pain.

Tightness: When the achilles tendon or plantar fascia pulls on the heel, the heel responds by putting more bone down to protect itself from the pulling. Stretching the calf muscle and rolling stretch underneath the heel and arch should loosen the tightness.

Mechanical stress: Excessive motion or collapse of the foot causes tension where the plantar fascia or achilles' tendon meet the heel bone. The bone reacts by "growing more bone". The spur itself, is seldom painful and pain resolves when the stress is relieved and inflammation controlled.

Excess pull: Heel spurs are extra bone formed by pull of a ligament or tendon insertion at the calcaneus. Plantar heel spurs are due to a pull from the plantar fascial ligament and are sometimes, but not necessarily, associated with plantar fasciitis. Posterior calcaneal heel spurs are due to a pull from the Achilles tendon. Plantar fasciitis or equinus can cause heel spurs.