I’ve just used the familiar terms “tendinitis” and “inflammation” to introduce plantar fasciitis in the most familiar and conventional way. However, these are misleading terms and the truth is more complicated. The plantar fascia is not really a tendon: it’s a sheet of connective tissue (“fascia”), more like a ligament than a tendon. It stretches from the heel to toes, spanning the arch of the foot, from bones at the back to bones at the front (whereas tendons connect muscles to bones).
The “itis” suffixes in tendinitis and fasciitis mean “inflammation,” Many people are afraid of running because between 30 to 70 percent of runners get injured every year.but the tissue is rarely inflamed the way we usually understand it (maybe at first, not for long). Instead, the plantar fascia shows signs of collagen degeneration and disorganization. In 2003, Lemont et allooked at 50 cases and found so little inflammation that they declared that plantar fasciitis “is a degenerative fasciosis without inflammation, not a fasciitis.”6 So it would be better to use a more generic suffix — like opathy(diseased) or osis (condition).
In fact, this is true of all so-called “tendinitis” — inflamed tendons are not so very inflamed. “Recent basic science research suggests little or no inflammation is present in these conditions.”7 And Khan et al wrote that “numerous investigators worldwide have shown that the pathology underlying these conditions is tendonosis or collagen degeneration. This applies equally in the Achilles, patellar, medial and lateral elbow, and rotator cuff tendons.”8
And in the plantar fascia, where the degeneration is “similar to the chronic necrosis of tendonosis.”9 Necrosis is bad. It’s Latin for “tissue death.” In plantar “fasciitis,” the plantar fascia is not just hurting, it’s dying — eroding like a rotten plank.10 And this isn’t just to make you squeamish: inflammation and “necrosis” are not the same medical situation, and understanding the difference is essential for effective treatment.
If the arch of your foot is like a bow, think of the plantar fascia as the bow’s string. The plantar fascia, along with several muscles both in the foot and in the leg, supports the arch and makes it springy.11 Too springy, and the foot flattens out, overstretching the plantar fascia. Not springy enough, and the plantar fascia absorbs too much weight too suddenly.
Either way, it starts to burn with the strain.
Other than the fact that it’s on the bottom of your foot and you step on it a lot, why is the plantar fascia vulnerable to strain? Why exactly? What happens?