Plantar fasciitis, which may cause the heel to hurt, feel hot or swell, is inflammation of the plantar fascia, a thin layer of tough tissue supporting the arch of the foot. Repeated microscopic tears of the plantar fascia cause pain. Sometimes plantar fasciitis is called "heel spurs", but this is not always accurate, since bony growths on the heel may or may not be a factor.
Diagnostic testing, such as X-rays, usually is not necessary to diagnose plantar fasciitis, although it may be useful to rule out other potential causes of heel pain. Typically with plantar fasciitis, the pain is worse when first getting out of bed, or is noticeable at the beginning of an activity and gets better as the body warms up. Prolonged standing may cause pain, as well. In more severe cases, the pain may worsen toward the end of the day.
There are a number of possible causes for plantar fasciitis and they often work in combination. Tightness of the foot and calf, improper athletic training, stress on the arch or weakness of the foot are potential causes. Shoes that don't fit, certain play or work actions or overuse (running too fast, too far, too soon) may hurt the plantar fascia. People with low arches, flat feet or high arches are at increased risk of developing plantar fasciitis.