Plantar fasciitis is an inflammation of a thick band of tissue called the plantar fascia that runs across the bottom of the foot, connecting the heel bone to the toes. This causes pain in the heel area, but an ultrasound may be necessary to diagnosis the condition and rule out other possibilities, such as a stress fracture
This condition should not be confused with a heel spur, which is a bone spur on the bottom of the calcaneus (heelbone). Although the two conditions can be present and interrelated, they can also arise independently. One person may have plantar fasciitis despite having no heel spur, while another may have a heel spur but have no inflammation of the fascia or any heel pain.