Plantar heel pain is a common problem in adults. The most common cause of heel pain is inflammation to the dense tissue extending from the calcaneus to the metatarsal region, thus the descriptive term plantar fasciitis. Though not all cases of plantar heel pain are due to plantar fasciitis, an inflamed or damaged fascia may contribute to painful conditions caused by nerve injury or soft-tissue inflammation in local muscle and the fat pad. With the Internet and an increasing public awareness of plantar fasciitis comes greater demand for treatment when time and home remedies do not alleviate pain. The nature of upright human activity is repetitive tensile and compressive stress of the fascia that has a cumulative ability to damage or transform the tissue. Longer lifespans and greater recreational expectations of working adults also are contributing to the volume of patients seeking attention for plantar fasciitis.
The functional role of the plantar fascia still is being defined through basic research. One role is the so-called windlass mechanism, which is a vital connection between the hindfoot and forefoot, important in stance and gait. Cadaver studies indicate that cutting the plantar fascia weakens the medial longitudinal support of the arch and increases tensile force in other ligaments and the posterior tibial tendon. The plantar fascia contributes more mechanical support to the arch than does the spring ligament, plantar ligaments, or intrinsic muscles. Changes within the fascia substance may initiate dysfunction, or the histologic changes may be secondary to a damage or disease process. Current evidence indicates that normal cells and extracellular matrix are not associated with pain.
The origin of the plantar fascia on the calcaneus is an area that has fibrocartilage at the site of attachment to bone. This specialized zone of tissue has longitudinal fibers of collagen to resist tension but is metabolically active in the formation of cartilage. Therefore, the healing response may lead to calcified cartilage and eventual bone formation. There is a rich pattern of sensory innervation within the plantar fascia that includes the tissue near the attachment to the calcaneus. This may explain why repair processes beneath the heel are so painful.
Plantar fascia pain may be due to long-term damage with incomplete repair leading to an endless cycle of reparative attempts by the local tissue. The chemical mediators of inflammation most likely are the proximate cause of pain, thus the pain-relieving effects of anti-inflammatory medication reported in clinical experience. The actual repair of torn collagen fibers may be impaired by the mechanical demands of the plantar fascia with repetitive high loading in both tension and compression.
Another process affecting the fascia from within is myxoid degeneration and replacement of normal matrix with abnormal substances that are mechanically inefficient. Spontaneous rupture of all or part of the fascia may occur in extremely high-load situations, and the natural healing of torn fascia often is complicated by painful scar formation.
The prevalence of heel pain, particularly plantar fasciitis, has not been reported, and the incidence cannot be determined at present. No epidemiologic surveys have been taken for this condition. The general consensus from the orthopedic, podiatric, and general medicine literature is that plantar fasciitis is a common condition in adults older than 40 years.
Morbidity associated with plantar fasciitis primarily is the pain of weightbearing activity. Patients who rupture the fascia acquire a characteristic foot deformity that is similar to pes planus: collapse of the longitudinal arch, valgus of the calcaneus, and abduction of the forefoot. The collapsed foot may require custom insole orthotics and accommodative shoes or corrective surgery to realign and fuse the hindfoot.
The morbidity of surgery includes the same collapse of the foot due to the intentional disruption of the plantar fascia. Surgical morbidity may add considerable impairment if a calcaneal nerve branch is injured. Work activity and many daily living activities may be limited by the degree of plantar heel pain.
Mortality data from this condition are not available, though of itself, plantar fasciitis is not a lethal condition. The notable exception is the rare soft-tissue sarcoma in the foot, as when fibrosarcoma of the plantar fascia is the pathological condition. An estimated 30 such sarcomas of the foot are reported annually in the United States. Due to the delay in diagnosis of most soft-tissue sarcomas of the foot, the 5-year survival rate is less than 10%.
Differences based on race have not been reported, but risk factors have been identified.
Differences based on sex have not been reported, but risk factors have been identified.
As mentioned, plantar fasciitis is a common condition in adults who are middle aged and older. This may be the result of decreased elasticity and subsequent tearing or a diminished healing response.
Clinically diagnosing plantar fasciitis is easier than determining the various possible causes. Patients complain of pain underneath the heel that is most pronounced on first arising in the morning or after a period of nonweightbearing activity. The pain often is described as a searing or tearing of the tissues under the heel and often improves with further activity, only to recur following continued or prolonged weightbearing activity. Delays in symptoms are common. Therefore, when pain occurs the morning following physically stressful activity, the patient and physician may overlook strenuous or prolonged weightbearing as a source of the symptoms. Another characteristic of plantar fasciitis is the location of the pain, which usually is at the origin of the plantar fascia from the medial portion of the posterior calcaneus.
The following specific questions should be asked about the patient’s pain:
Where is the pain?
Is it always in the same place?
Is it worse with the first few steps in the morning?
Does it go away with rest?
Pain that is in the same location under the heel that is particularly exquisite with the first steps, that is relieved by rest, and that does not radiate into the leg and forefoot is very likely to be caused by plantar fasciitis.
Diagnosis of plantar fasciitis is confirmed by focal tenderness near the origin of the plantar fascia that often is aggravated by stretching the fascia. On physical examination, heel pain may be reproduced through simultaneous passive dorsiflexion of the toes and ankle. Occasionally, pain radiates along the plantar fascia toward the toes when a tender area is squeezed, and pain may expand to the lateral side of the foot when pressure is applied on the plantar surface of the calcaneus.
Clinical risk factors include obesity, repetitive stress activities, and age older than 40 years. Foot biomechanics are implicated, but no proven risk factors exist. Particularly, the cavus foot with the rigid high medial arch and limited heel pronation imparts increased stress within the substance of the plantar fascia. Also at risk is the flexible pes planus with abduction of the forefoot and pronation of the hindfoot causing large tensile strain in the plantar fascia. The Achilles tendon and triceps surae, when contracted, are a source of excessive stress with the plantar fascia.
Other possible relationships may exist with hard walking surfaces, the presence of a heel spur (osteophyte), height of heel and other shoe properties, and type of employment. To date, plantar fasciitis is not considered a work-related disorder for purposes of compensation.
Considerable disagreement exists regarding the role of heel spurs and plantar fasciitis. Heel spurs are increasingly prevalent with age. Spurs usually are within the muscles superior to the fascia and are not ossification of the fascia origin. The possibility of spurs causing heel pain indirectly through compression of the nerve to the abductor digiti quinti muscle or through stretching the plantar fascia has implications for surgical treatment of this condition.