Plantar fasciitis is the most common cause of heel pain, and is one of the most common causes of foot pain in general. The plantar fascia is a thick band of tissue, technically a ligament, that runs from the front of the heel to the ball of the foot. The plantar fascia is separated into three different bands. One is positioned near the instep, the other in the center of the foot, and the final band runs near the outer side of the foot. The plantar fascia can be damaged in a number of different ways, and the inflammation from that injury is what is known as plantar fasciitis.

Plantar fasciitis almost always develops because of chronic strain or stress to the fascia, instead of an actual injury. The most common cause by far is flat feet or feet that tend to flatten during walking. When a person walks or stands with flat or flattening feet, the stretching of the bottom of the foot when it flattens will eventually cause microscopic injury to the plantar fascia near where it attaches to the heel. This process may take many years to develop, or a slight unnoticed injury can quickly hasten the damage. As the strain of walking flat footed continues, so does the microscopic damage, until one day the fascia become so irritated that it thickens, becomes painful to walk on, and remains like that for a long period of time. If one has high arches, they can also develop this condition, although for a slightly different reason. High arches do not absorb the shock generated by walking well, and subsequently the shock will go right through the heel, eventually irritating the plantar fascia. Not everyone with flat feet or high arches will suffer from plantar fasciitis, and even those with 'normal' arches have the potential to damage their plantar fascia with daily activities. However, those with flat feet and those with high arches do suffer the majority of plantar fascia cases for the above reasons.

Another less common cause of plantar fasciitis is due to an injury to the heel itself. Stepping on a rock, root, or other blunt object can cause bruising and damage to the fascia, leading to fasciitis. Excessive use of stairs, a stair stepper exercise machine, or ladders can lead to partial tearing of the fascia. Finally, an injury that forces the foot upward can cause an outright rupture or tear of the fascia.

Symptoms of plantar fasciitis are usually universal, although there can be some variations depending on if nearby nerves or other tissue is involved in the damage. For the most part, plantar fasciitis causes immediate pain in the arch and heel upon arising out of bed in the morning. This pain slowly fades as more steps are taken throughout the first part of the morning, as the fascia loosens up a little. After one participates in more activity, the strain to the fascia increases, and pain returns. The heel and arch pain will continue until one rests from walking or standing. Once one arises from this rest (such as getting out of a chair), the pain cycle begins anew. Some people have pain that is more constant and never fades with stretching of the fascia, and some people do not feel pain until the end of the day. The pain itself can be some combination of sharp, stabbing, achy, or throbbing. When burning and tingling are present, the nerve structure near the fascia may also be inflamed. This can sometimes lead to a sensation of shooting pain across the heel or up the leg.

Plantar fasciitis is treated with a combination of methods, and not everyone responds equally to every treatment technique. In general, treatment must reduce the inflammation so the fascia may heal, and stabilize the fascia so the condition does not return in the future. The inflammation is reduced by stretching the fascia, icing it, and taking anti-inflammatory medications. Cortisone-like injections also rapidly decrease the inflammation process. The damage is reversed and subsequently prevented by using high quality arch supports initially, followed long-term by prescription supports (orthotics). Orthotics are made form an impression of the foot while it is held in a corrected position, and will act to reduce foot flattening to the exact degree needed. In the case of high arches, the form fitting of the insert will help to carry shock away from the heel tissue. Some cases require more treatment, which can include physical therapy or immobilization. A small number of cases (less than 5% in this practice) have to have surgery to repair the damage.