Heel spurs are a common musculoskeletal issue affecting the foot, defined as abnormal bony growths that develop over time. They are often discovered incidentally during imaging for other foot complaints. Understanding their composition and location is the first step toward addressing the discomfort they can sometimes cause.
What Is a Calcaneal Spur?
A heel spur is medically termed a calcaneal spur or a heel osteophyte, describing a bony outgrowth projecting from the heel bone. This formation consists of calcium deposits that accumulate slowly over many months or years in response to long-term physical stress. On an X-ray, the spur typically appears as a small, hook-like projection extending forward from the heel bone. Although they can grow up to half an inch in length, the presence of a calcaneal spur does not automatically mean a person will experience pain. Many individuals have these bony formations without ever knowing they exist.
Anatomical Placement in the Foot
The heel spur is specifically located on the calcaneus, the largest bone in the foot. The vast majority of heel spurs form on the underside, or plantar aspect, of this bone. They develop at the calcaneal tuberosity, near the medial tubercle of the heel. This location is the primary attachment site for the plantar fascia, a thick band of connective tissue running along the sole of the foot. The bony projection often extends forward, toward the arch.
This inferior placement is the most common presentation, referred to as a plantar calcaneal spur. A less frequent type, the posterior calcaneal spur, forms on the back of the heel where the Achilles tendon inserts. The spur commonly associated with foot pain occurs underneath the foot. The development of the spur is a localized response by the bone tissue to chronic pulling and tension exerted by the soft tissues.
Factors Leading to Spur Development
The formation of a heel spur results from chronic, repetitive strain on the heel bone and its attached soft tissues. When tissues connecting to the calcaneus, particularly the plantar fascia, are subjected to excessive tension, micro-tears occur at the insertion point. The body attempts to stabilize and repair this area by initiating reactive bone proliferation. This leads to the gradual deposition of calcium and subsequent bone growth, forming the characteristic spur.
Several biomechanical and lifestyle factors contribute to this chronic stress. Repetitive impact activities, such as running or prolonged standing, increase the pulling force on the fascia. Structural issues like flat feet or high arches alter the foot’s gait, leading to uneven weight distribution. Other contributing factors include obesity and wearing improper footwear that lacks adequate arch support or cushioning.
Distinguishing Heel Spurs from Heel Pain
A widespread misconception is that the bony heel spur itself causes the sharp pain experienced in the heel. In reality, the pain is rarely due to the spur piercing the soft tissue, as the growth lies within the tissue fibers. The actual source of discomfort is typically the inflammation of the soft tissues surrounding the spur, a condition most often identified as plantar fasciitis. This inflammatory state arises from the same chronic strain and micro-trauma that prompted the spur to form.
This distinction is supported by the fact that many people with visible heel spurs on an X-ray report no pain whatsoever. When pain does occur, it is associated with the irritation of the plantar fascia and the periosteum, the membrane covering the bone. The pain is often described as a sharp, stabbing sensation with the first steps after waking or following a period of rest. Effective treatment focuses on reducing the inflammation and strain on the soft tissues, rather than attempting to remove the bony projection.