Plantar fasciitis

What it means

The plantar fascia is a thick, tough band of tissue that stretches like a bowstring along the sole of the foot, connecting the heel bone to the base of the toes and helping support the foot's arch with every step. Plantar fasciitis is irritation and small-scale, repetitive strain of that band, usually concentrated where it attaches to the heel bone. Despite the "-itis" ending suggesting active inflammation, imaging and tissue studies often show changes that look more like gradual wear and micro-tearing than classic inflammation, which is why some clinicians now prefer the term plantar fasciopathy.

Why it appears on a CT or MRI report

On MRI or ultrasound, the affected fascia typically looks thickened at its attachment to the heel, sometimes with surrounding fluid or signal changes suggesting irritation of the adjacent tissue. Reports describe the thickness in millimeters, note whether there is a small heel spur — a bony projection that often coexists with, but does not cause, the pain — and comment on whether the changes are limited to the fascia's origin or extend further along its length. Imaging is not usually needed to diagnose plantar fasciitis, since the history and a simple physical exam are often enough, but it may be ordered when symptoms are unusual or do not improve with standard treatment.

What it usually means

Plantar fasciitis is extremely common, especially in runners, people who stand for long hours at work, and people who have recently increased their activity level, gained weight, or changed footwear. The classic pattern is a sharp, stabbing pain in the bottom of the heel with the very first steps out of bed in the morning or after sitting for a while, which then eases somewhat with gentle movement but can return after prolonged standing or at the end of the day. It is a benign, self-limited condition for the great majority of people, and even without treatment, most cases substantially improve within about a year, though treatment can meaningfully speed that timeline.

When to follow up

Simple measures such as calf and foot stretching, supportive footwear, over-the-counter arch supports or heel cushions, and reducing high-impact activity for a few weeks resolve most cases and can be started without waiting to see a doctor. Check in with your doctor or a physical therapist if the pain has not improved after several weeks of these steps, if it is severe enough to change how you walk, or if you notice swelling, redness, warmth, numbness, or pain that is worse at night, since these can point to a different cause that needs its own evaluation.

A plain-language way to picture it

Think of the plantar fascia as the taut string of a bow, anchored at the heel and stretching forward to the base of the toes. Every step pulls on that string a little, and repeated overload — from too much running, unsupportive shoes, or simple overuse — causes small amounts of fraying right where the string is anchored, much like a rope wearing thin at the point where it is tied off. Given rest, support, and time to remodel, that fraying gradually settles and the string returns to handling everyday loads comfortably.