What are Heel Spurs?

For a long time heel spurs were thought to be the cause of heel pain. The reason for this was that X-rays were the only diagnostic tool available to look at heels. As X-rays only clearly show boney pathology any bony abnormality would stand out as the cause of the heel pain. On a side view of the foot, people with heel pain often showed a spike of bone growing out of the medial process of the plantar tubercle of the calcaneaus (heel bone). This is the main attachment point of the plantar fascia.

Heel Spur Diagnosis Problems

For a long time this boney spike was thought to be the cause of the pain. However when the heel spur is looked at post mortem it appears to move as a flat extension on the heel bone when viewed from the bottom of the heel. The problem with X-rays is it is very difficult to view bone over bone, so the only view that could pick up the spur was from the side. The effect was the difference in perspective of viewing a table from the side, rather than from the top. A table from the side looks like a narrow beam, whereas from the top it looks like a broad board. So the spur was not a spike but a plateau.

Two things finally squashed the theory that heel spurs were the cause of heel pain. The first was that heel spurs turned up frequently in side x-rays of people with no history of heel pain. As new technologies were developed to assess soft tissues, more interesting pathological changes were found in the plantarfascia and surrounding structures such as thickening and fluid in the fascia seen on soft tissue ultrasound and fluid in the heel bone seen on MRI.

How do Heel Spurs form?

Heel spurs are thought to form in the following way. Bone is stimulated to grow under compression and the heel spur (or plateau) forms under the plantar muscles of the foot but above the plantarfascia.  It is acting as boney sandwich filler between two slices of the support structures of the proximal arch of the foot. With the plantar fascia under increased strain, and the muscles contracting hard to support the arch of the foot the far edge of the plantar tubercle is squeezed, and this compression forms the bone plateau. Mechanically this might help in that extending the attachment point of the fascia shortening the distance it has to support.