Introduction

Plantar fasciitis is inflammation of the thick tissue on the bottom (plantar surface) of the foot. The tissue that is inflamed is known as the plantar fascia.  Often times people mistake pain in this area to be a symptom associated with the formation of a heel spur.  Although this may sometimes be the case, many people with heel spurs have absolutely no complaint of pain.  The formation of a spur is a sign that too much tension has developed within the plantar fascia, partially tearing from its origin at the calcaneus (heel bone). The result is new bone formation at the site of the injury. The presence of new bone is an attempt by the body to stabilize and reinforce this area in response to the stresses and strains placed upon it. 

Anatomy:

The plantar fascia is a large band of dense connective tissue, also known as the plantar aponeurosis, which assists in maintaining the stability of the foot and secures or braces the longitudinal arch.  Its attachment begins at the medial surface of the calcaneus and fans out as it attaches to the metatarsophalangeal (beginning of the toes) articulations.  In younger people the plantar fascia is also intimately related to the Achilles tendon.  However, the continuity of this connection decreases with age to a point where there are few, if any, connecting fibers. There are also distinct attachments of the plantar fascia and the Achilles tendon to the calcaneus so the two do not directly contact each other. Nevertheless, there is an indirect relationship whereby if the toes are extended, the plantar fascia becomes tightened. If a force is generated in the Achilles tendon, it will increase the strain in the plantar fascia. Clinically, this relationship has been used as a basis of treatment for plantar fasciitis.

Discussion:

The most frequent cause of plantar fasciitis is an abnormal motion of the foot called excessive pronation. Normally, while walking or during long distance running, your foot will strike the ground on the heel, then roll forward toward your big toe and inward to the arch. Your arch should only dip slightly during this motion. If it lowers too much, you have what is known as excessive pronation, which can cause the arch of your foot to stretch excessively with each step. Poor biomechanics at the feet and much higher up at the hip can cause improper bone alignment that will adversely affect muscles, ligaments, and tendons, and can create a variety of aches and pains. Proper muscle function at the hip is a very common mechanism that plays a large role in limiting excessive pronation.

Other factors which may contribute to plantar fasciitis include a sudden increase in daily activities, increase in weight, or a change of shoe type. Runners who dramatically increase their training intensity or duration may be more prone to plantar fasciitis. Shoes that are too flexible in the middle of the arch or shoes that bend before the toe joints will cause an increase in tension in the plantar fascia. A change in running style or parameters, such as starting speed work, running on the ball of your foot or a sudden increase in hill workouts may lead to problems. Any and all changes made to your choice of running gait (altering your foot strike position), running shoe (or lack thereof) or running intensity should be made gradually to allow your muscles, bones, and other body structures to adapt to the alterations you are attempting.