Plantar fasciosis is the degeneration (deterioration) of the plantar fascia as a result of repetitive stress. The plantar fascia is a broad, thick, fibrous band that extends from the base of the calcaneus (heel bone) to the base of the toes. The fascia is composed of a dense network of highly organized collagen fibers, which gives it the strength necessary to support the tremendous force placed through the arch when walking. During the push off or propulsive phase of walking, the plantar fascia tightens like a cable, increasing the arch height, shortening the foot and helping to create a rigid lever which increases the efficiency of motion as the body is propelled forward.
During this process, the section of the plantar fascia at the inside base of the heel is placed under the most tension. When excess force loads exceed the strength of the fascia, tearing occurs most commonly at this area. Small tears occur each time the fascia is placed under excess stress and the tearing resembles fraying of a rope. Microtears within the plantar fascia weaken the structural integrity of the tissue and increase the chance of further injury. The condition generally takes weeks to develop, but acute injuries and full fascial ruptures are possible under the right conditions.
As soon as the injury occurs, the body responds by increasing blood flow to the injured area, sending inflammatory cells and starting the healing process. The inflammatory process continues for about one week, but it can last much longer. The inflammatory process is overlapped by the reparative process. During the reparative phase, cells produce more collagen and the collagen is laid down in an unorganized fashion. The random configuration of collagen allows for bridging of the gap caused by the tear, but does not give the fascia it’s full strength. This phase generally lasts for 2-3 weeks, but can be prolonged and last for many more weeks. The last phase of the healing process is the remodeling phase. This phase can last for weeks to months and involves organization of the collagen fibers. The organization and alignment of the collagen fibers increase the strength and improves function of the plantar fascia.
When the injury occurs and the inflammatory process begins, plantar fasciitis is the most appropriate term for the condition. When the condition is diagnosed and treated immediately, the phases of healing progress and the condition heals within a few weeks. When the condition goes untreated and the plantar fascia is subject to repetitive injury, the inflammatory phase is prolonged and the reparative process is interrupted. This is a more common scenario as the initial microtears within the fascia may not cause much pain. Even when the condition becomes painful, it is difficult to minimize the stress on the plantar fascia because walking is a part of everyday life. Unless steps are taken to remove the aggravating factors which have contributed to the excess stress on the plantar fascia, the condition quickly worsens. The plantar fascia begins to deteriorate, which is represented by a disorganization and fragmentation of the collagen fibers and death of surrounding cellular tissue. The collagen fibers are separated by a myxoid substance, a semi-solid gel intermixed with waste products, which thickens the fascia, decreases cohesion between the fibers and further decreases it’s strength. The initial increase of oxygen, nutrients and cells to the injured area during the inflammatory process is replaced by a decrease in small blood vessels and a lack of oxygen, nutrients and growth factors.
As most cases of plantar fasciitis tend to progress in this fashion, plantar fasciosis has become a more appropriate term for this condition. Unfortunately, plantar fasciosis is much more difficult to treat when individuals fail to recognize the problem and seek treatment early.
More information on diagnosis and treatment of plantar fasciitis/fasciosis.
View our five part series on plantar fasciitis, plantar fasciosis and plantar fascia structure.
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