Here’s a summary of the various definitions of plantar fasciitis given by online sources that I believe are reputable. (Along with About.com and Wikipedia, which can be good but are not always correct.)
You’ll find a lot of differences in the definitions, but together they help build a useful view of our condition.
Plantar fasciitis (PLAN-tur fas-e-I-tis) involves pain and inflammation of a thick band of tissue, called the plantar fascia, that runs across the bottom of your foot and connects your heel bone to your toes. Plantar fasciitis is one of the most common causes of heel pain.
Plantar fasciitis (say “PLAN-ter fash-ee-EYE-tus”) is the most common cause of heel pain. The plantar fascia is the flat band of tissue (ligament) that connects your heel bone to your toes. It supports the arch of your foot. If you strain your plantar fascia, it gets weak, swollen, and irritated (inflamed). Then your heel or the bottom of your foot hurts when you stand or walk.
The Plantar Fascia is a broad, thick band of tissue that runs from under the heel to the front of the foot.
Plantar fasciitis can also be known as a heel spur although they are not strictly the same. A heel spur is a bony growth that occurs at the attachment of the plantar fascia to the heel bone (calcaneus). A heel spur can be present (through repetitive pulling of the plantar fascia) on a foot with no symptoms at all and a painful heel does not always have a heel spur present.
Plantar fasciitis is traditionally thought to be an inflammatory condition. This is now believed to be incorrect due to the absence of inflammatory cells within the fascia. The cause of pain and dysfunction is now thought to be degeneration of the collagen fibres close to the attachment to the calcaneus (heel bone).
From the NY Times Health Guide
Plantar fasciitis is inflammation of the thick tissue on the bottom of the foot. This tissue is called the plantar fascia. It connects the heel bone to the toes and creates the arch of the foot.
Plantar fasciitis is a common, painful foot condition. Patients, and sometimes doctors often confuse the terms plantar fasciitis and heel spurs. Plantar fasciitis refers to the syndrome of inflammation of the band of tissue that runs from the heel along the arch of the foot; a heel spur is a hook of bone that can form on the heel bone (calcaneus). About 70% of patients with plantar fasciitis have been noted to have a heel spur that can be seen on X-Ray.
The fibrous tissue that surrounds muscle and separates various tissues of the body is referred to as the fascia. The bottom, or plantar, surface of the foot has a strip of this tough tissue, referred to as the plantar fascia, stretching from the heel to the front of the bottom of the foot. This “bowstring-like” plantar fascia that stretches underneath the sole that attaches at the heel can become inflamed by disease or injury. Inflammation of the plantar fascia is referred to as plantar fasciitis.
Plantar fasciitis is that pain in the bottom of your foot usually felt around your heel. That pain is especially strong with the first few steps in the morning as you are getting out of bed and standing on your feet, or after sitting and resting for awhile.
The name Plantar fasciitis comes from: “Plantar” which means something that belongs to the foot, “fascia” which is a band or ligament or a connective tissue, and “itis” which means inflammation…. The band connects the heel bone to the bones of the toes. The pain is caused by injuring this tough band on the bottom of the foot.
The plantar fascia is a strong, relatively inflexible, fibrous ligament band that runs through the bottom of the foot. That band helps to keep the complex arch system of the foot, absorb shock, plays a role in body balance and in the various phases of gait. The band transmits your weight across the bottom of the foot with each step you take. When the heel of the trailing leg starts to get off the ground, the band bears tension that is approximately twice the body weight. The tension on the band at this moment is even greater if the calf muscles are not flexible enough.
… Plantar fasciitis will usually be close to the heel but it can happen anywhere along the band. If the band gets bruised or stretched, the inflammation causes the pain. In more severe cases the band can also get a little detached from the heel bone or a bony growth can form a heel spur.
Plantar fasciitis is sometimes mixed up with a heel spur although they are not the same. A heel spur is a calcium deposit that occurs where the plantar fascia is attached to the heel bone (calcaneus). In many cases a heel spur is found on a foot with no pain or other symptoms at all. And in many painful heels there is no sign for a heel spur. Heel spur and painful heal does not necessarily go together.
For many years plantar fasciitis was believed to be an inflammatory condition. It is thought now to be inaccurate because there were many cases of the disorder with no inflammatory signs observed within the fascia. The heel pain cause is now believed to be damage to the collagen fibers of the fascia. This damage, caused by stress injury, sometimes may include inflammatory cells.
Plantar fasciitis (PF) is a painful inflammatory process of the plantar fascia, the connective tissue on the sole (bottom surface) of the foot. It is often caused by overuse of the plantar fascia or arch tendon of the foot. It is a very common condition and can be difficult to treat if not looked after properly. Another common term for the affliction is “policeman’s heel”.
Longstanding cases of plantar fasciitis often demonstrate more degenerative changes than inflammatory changes, in which case they are termed plantar fasciosis. The suffix “osis” implies a pathology of chronic degeneration without inflammation. Since tendons and ligaments do not contain blood vessels, they do not actually become inflamed. Instead, injury to the tendon is usually the result of an accumulation over time of microscopic tears at the cellular level.
The plantar fascia is a thick fibrous band of connective tissue originating on the bottom surface of the calcaneus (heel bone) and extending along the sole of the foot towards the toes. It has been reported that plantar fasciitis occurs in two million Americans a year and in 10% of the U.S. population over a lifetime. It is commonly associated with long periods of weight bearing. Among non-athletic populations, it is associated with a high body mass index. The pain is usually felt on the underside of the heel and is often most intense with the first steps of the day. Another symptom is that the sufferer has difficulty bending the foot so that the toes are brought toward the shin (decreased dorsiflexion of the ankle). A symptom commonly recognized among sufferers of plantar fasciitis is an increased probability of knee pains, especially among runners.
Now that you have some idea what plantar fasciitis is, you may want to check out: