What is Plantar Fasciitis?

Plantar fasciitis is an inflammation of the plantar fascia-a band of dense fibrous tissue (i.e., fascia) located along the bottom of the foot (i.e., plantar surface) extending from the heel bone (i.e., calcaneus) to the ball of the foot (figure 1 below). It is the most important structure in maintaining the longitudinal arch of the foot [4]. With every step forward, bodyweight follows-starting at the heel, progressing through the midfoot (arch area), ending with the toes pushing off the ground. When bodyweight is shifted to the midfoot, the arch normally flattens, and in doing so, acts as a shock absorber to the body by dissipating forces from the ground. The extent to which the arch flattens is limited by the degree at which the plantar fascia can hold it. Herein lies the problem. Unlike tendon, the plantar fascia is not elastic and therefore cannot stretch when forces on the foot to flatten the arch become too great. If it was elastic, the arch would collapse and rebound excessively with every step-imagine bouncing down the street without need of a pogo stick. Because of its inelasticity, the plantar fascia begins to separate from its weakest point of attachment, often the heel bone, resulting in pain and inflammation that is distinct and treatable.

Think of the foot as an archer's bow where the bowstring is your plantar fascia and the bow is your arch. If the tips of the bow were brought closer together, the bowstring would be limp. In the case of plantar fasciitis, the tips of the bow are brought further apart, thus increasing the tension on the bowstring to a point where it will snap, tearing the plantar fascia from its heel bone insertion resulting in heel pain.