The plantar fascia is a broad ligament structure that extends from the heel bone to the base of the toes. Its characterised by a thick rubber band on the bottom arch of the foot. It originates from the anteromedial border of the calcaneus. It inserts on the flexor mechanism of the toes at the metatarsal heads. The plantar fascia provides support for the medial longitudinal arch of the foot. Shortly after a heel strike, at the beginning of the stance phase of the gait cycle, the tibia rotates internally and the foot pronates, stretching the plantar fascia as the foot flattens. Since the fascia has no elastic properties, repetitive stretching results in micro tears at its origin. Over-pronation (flat feet) is the leading cause of plantar fasciitis. Over-pronation occurs in the walking process, when a person's arch collapses upon weight bearing, causing the plantar fascia to be stretched away from the heel bone. (Denlinger 2001).
Through over exercising, weight gain or injury, the plantar fascia can develop strain at its insertion into the heel bone, or anywhere along its length. This causes pain, which can be quite severe at times. Plantar fasciitis is considered a chronic inflammatory syndrome rather than a post-traumatic disorder and is common in runners and dancers who use a repetitive, maximal plantar flexion of the ankle or dorsiflexion of the MTP joints. It is cause by repetitive stretching of a tight plantar fascial band leading to micro tears at its origin on the heel.
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Plantar fasciitis is the most common cause of heel pain. It is common to all types of people and their activities. This includes runners and other athletes, people who have jobs that require a fair amount of walking or standing on a hard surface. Pregnancy and dietary changes have also known to trigger plantar fasciitis. Other causes could include no support in shoes, lack of flexibility in the calf muscles or dysfunction in the area.