Plantar fasciitis and other causes of heel and sole pain

INTRODUCTION — Disorders of the ankle and foot, including ankle sprains, tendinitis, plantar fasciitis, and bursitis, usually occur in association with movement and result from trauma. In some cases, subtle skeletal structural faults (such as limb length discrepancy) predispose to these cumulative movement disorders or repetitive strain injuries. It is therefore important to conduct a careful examination to detect these defects. (See "Evaluation for subtle structural defects of the lower limb").

Other factors can contribute to recurrent or perplexing lower limb distress. These include stress fractures that occur due to osteoporosis, inflammatory arthritis due to rheumatoid arthritis, and the spondyloarthropathies which may also present with an enthesitis (inflammation at tendon insertions into bone), painful peripheral neuropathies (eg, associated with diabetes) that may also predispose to Charcot's joints, improper footwear, moving from a building with wood flooring to one with a concrete slab, prolonged standing, weakness and unsteadiness associated with the problems of ageing, and structural disorders such as joint laxity or malalignment of the lower limbs.

This topic review will discuss painful disorders of the foot. Tendinitis of the ankle and ankle sprains are discussed separately. (See "Posterior ankle tendinopathies" and see "Ankle sprain").

PLANTAR FASCIITIS — The predominant symptom of plantar fasciitis is pain in the plantar region of the foot that is worse when initiating walking. Plantar fasciitis is one of the most common causes of foot pain in adults estimated to be responsible for about one million patient visits to the doctor per year [1]. The peak incidence occurs between ages 40 and 60 years in the general population with a younger peak in runners [2,3]. It may be bilateral in up to a third of cases [2,4,5].

Heel spurs often coexist [6,7]; whether they have a causal role is unknown. They may represent a secondary response to an inflammatory reaction [2].

Anatomy — The deep plantar fascia (plantar aponeurosis) is a thick, pearly white tissue with longitudinal fibers intimately attached to the skin (show figure 1). The central portion is thickest and attaches to the medial process of the tuberosity of the calcaneus; distally it divides into five slips, one for each toe. The plantar fascia provides support; as the toes extend during the stance phase of gait, it is tightened by a windlass mechanism, resulting in elevation of the longitudinal arch, inversion of the hindfoot, and a resultant external rotation of the leg [8].

Etiology — The etiology is poorly understood and is probably multifactorial. Possible risk factors for the development of plantar fasciitis include obesity, prolonged standing or jumping, flat feet, reduced ankle dorsiflexion, and heel spurs [3,5,7,9-11]. There is a high incidence in runners, suggesting that plantar fasciitis, at least in this population, is due to an injury caused by repetitive microtrauma [12]. In this group, the following have been proposed as risk factors [13-16]: Excessive training (particularly a sudden increase in the distance run) Faulty running shoes Running on unyielding surfaces Flat feet (pes planus or pronated ankles) Limited ankle dorsiflexion (eg due to a shortened Achilles tendon) Pes cavus (high-arched) foot

However, evidence of an association for most of these factors is limited or absent [14].

Plantar fasciitis is common among ballet dancers [17] and those performing dance aerobic exercise. Stress applied to the Achilles tendon, either due to muscle contraction or passive stretching, results in increased tension in the plantar fascia [18]. Decreased knee extension, as may occur with tight hamstring muscles, causes an increase in loading of the forefoot when walking [19]; this could in turn increase the stress on the plantar fascia.

Plantar fasciitis usually occurs as an isolated problem but may be associated with systemic rheumatic diseases particularly reactive arthritis and the spondyloarthritites. Plantar fasciitis has been reported in association with fibromyalgia [20], fluoride used for the treatment of osteoporosis [21], and may be the presenting symptom in patients with nutritional osteomalacia [22].

Pathology — The site of abnormality is typically near the origin of the plantar fascia at the medial tuberosity of the calcaneum. Specimens of plantar fascia obtained during surgery for plantar fasciitis reveal a spectrum of changes, ranging from degeneration of the fibrous tissue, to fibroblastic proliferation, with or without evidence of chronic inflammation [23-25].

Diagnosis — A hallmark for diagnosis of plantar fasciitis is local point tenderness. This is best elicited by the examiner dorsiflexing the patient's toes with one hand in order to pull the plantar fascia taut, and then palpating with the thumb or index finger of the other hand along the fascia from the heel to the forefoot (show picture 1). Points of discrete tenderness can be found and marked for possible later injection.

Laboratory testing is not helpful in the diagnosis of plantar fasciitis. Tests for inflammation (eg, erythrocyte sedimentation rate and C-reactive protein) will be normal unless there is coexistent inflammatory disease.

Radiographic studies may be required to establish the diagnosis when this is in doubt in patients with persistent plantar pain. The primary goal of radiography is to rule out other disorders, especially calcaneal stress fractures. Lateral and axial radiographs are the appropriate views due to the myriad of diagnostic possibilities. The presence of heel spurs is of no diagnostic value in either ruling in or ruling out plantar fasciitis. In one study, 85 percent of 27 patients with plantar fasciitis and 46 percent of 79 controls had calcaneal spurs detected on plain non-weight bearing lateral X-Rays read by a radiologist blinded to the clinical diagnosis [26]. On the other hand, increased plantar fascia thickness and fat pad abnormalities detected in the same X-Rays had a sensitivity of 85 percent and specificity of 95 percent for plantar fasciitis.

The soft tissue may be evaluated with magnetic resonance imaging (MRI) in cases resistant to treatment [27]. Features suggestive of plantar fasciitis are thickening of the plantar fascia and increased signal on delayed (T2) and short tau inversion recovery (STIR) images [28]. Technetium scintigraphy has also been successful in localizing the inflammatory focus and ruling out stress fracture [29].

Ultrasonography of the foot may also be useful in detecting plantar fascial thickening, hypoechogenicity at the insertion upon the calcaneus, blurring of the boundary between fascia and surrounding tissues, and decreased echogenicity suggestive of edema [30,31]. The sensitivity and specificity of ultrasonography for the diagnosis of plantar fasciitis was 80 percent and 88.5 percent respectively in a study of 77 patients and a similar number of asymptomatic controls [32]. Doppler ultrasound may improve the value of this technique and provide additional information on local hyperemia [33].

Differential diagnosis — Plantar heel pain and pain in the sole of the foot may be induced by a number of other disorders. These include the following [34-36]: Rupture of the plantar fascia — Rupture of the plantar fascia generally follows physical activity and has a sudden onset, unlike the more gradual appearance of the pain of plantar fasciitis. Examination of the affected foot may reveal a loss of height of the arch and there may be visible swelling or ecchymosis present. Nerve pain due to entrapment — Entrapment of the posterior tibial nerve as it courses beneath the medial malleolus can cause pain, paresthesia, and numbness on the sole of the foot. Percussion tenderness over the posterior tibial nerve in the tarsal tunnel is characteristically found. (See "Overview of lower extremity peripheral nerve syndromes", section on Tarsal tunnel syndrome). Compression or trauma to branches of the posterior tibial nerve, particularly the medial calcaneal branch or to the nerve supplying the abductor digiti quinti can also cause pain in the heel. Bone pain — Pain arising from the calcaneus may also be associated with exacerbation during weight bearing. Pain caused by a neoplasm or infection is typically constant or characterized by nocturnal worsening. Stress fractures should be considered if there has been an increase in physical activity. While plain radiographs may be diagnostic, early changes with infection, tumor, and stress fracture are better differentiated by MRI. (See "Cancer pain syndromes", and see "Diagnosis of osteomyelitis in adults", and see "Overview of stress fractures").

Other causes of calcaneal bone pain are Paget's disease, which is generally apparent on plain radiographs with coarsened trabecular bone and may be accompanied by an elevated serum alkaline phosphatase. (See "Clinical manifestations and diagnosis of Paget's disease of bone"). Tendinitis of the posterior tibialis or flexor digitorum longus tendons — These typically have an insidious onset with pain and tenderness along the course of the tendons and tendon sheaths. Subtle changes in the position of bones of the midfoot may be indicative of tendon rupture. (See "Posterior ankle tendinopathies"). Reactive arthritis and other spondyloarthritides — Asymmetric involvement and a propensity for the joints and entheses of the lower extremities are frequently seen in the spondyloarthritides. Back pain with inflammatory features (eg, night pain, prolonged morning stiffness) is frequently present in patients with ankylosing spondylitis, while a prior history of enterocolitis or genitourinary infection is suggestive of reactive arthritis. (See "Reactive arthritis: Definition; diagnosis; and management" and see "Calcaneal periostitis" below). Painful heel pad syndrome — The painful heel pad syndrome most often occurs in marathon runners. It is thought to result from disruption of the fibrous septae that compartmentalize the fat in the heel pad. Pain is localized to the heel pad; the plantar fascia is not tender and pain is not accentuated as the examiner dorsiflexes the toes. Insertion of heel cups [37] and "plastizote" that is individually molded to the patient's heel may be useful [38]. Atrophy of the heel pad — Atrophy of the heel pad occurs in the elderly. Palpation reveals bony prominence without the padding usually afforded by subcutaneous fat. Unlike pain due to plantar fasciitis, pain due to atrophy of the heel pad is absent in the morning and develops and worsens during weight bearing throughout the day. Piezogenic papules — Piezogenic papules are herniations of fat that occur as painful papules at the medial inferior border of the heel. They may be noted only upon weightbearing and are an uncommon cause of painful heels. Weight reduction, use of felt padding, and cushion-soled or crepe-soled shoes may provide relief [39]. Sarcoidosis — Heel pain has been reported to occur in sarcoidosis [40]. The combination of erythema nodosum, hilar adenopathy, migratory polyarthralgias, and fever is referred to as Lofgren's syndrome, and is typically seen in patients with sarcoidosis. (See "Erythema nodosum").

Treatment

Conservative therapy — Treatment of obesity, symptomatic flat feet, and systemic inflammation should be undertaken when these conditions are present. Others should begin with conservative therapy including measures to relieve pain, alterations in their shoes or habits, and exercise therapy. It should be noted there are limited data for the effectiveness of most of these modalities in the treatment of plantar fasciitis [34,41]. Rest and icing may give initial pain relief. Nonsteroidal antiinflammatory drugs (NSAIDs) are often used. A well-designed but small trial that randomly assigned 29 patients to NSAID or placebo reported a non-significant trend toward improved pain and disability in the NSAID group [42]. Use for longer than two or three weeks should be reserved for patients with systemic inflammation. There are conflicting reports on the benefit of resting padded foot splints [43-46]; these splints can usually be purchased in pharmacies that feature orthopedic supplies (show picture 2). The splints are worn at night to keep the ankle in the neutral position with or without dorsiflexion of the metatartophalangeal joints during sleep. A clinical trial reported they were of similar effectiveness to custom-fitted orthotics (see below) although there was better compliance and fewer side effects reported with orthoses use [47]. Prefabricated silicone heel inserts combined with stretching exercises (see below) may be of value [48]. Felt pads or rubber heel cups appear to be less effective than silicone inserts and magnetic insoles have not been found to provide additional benefit compared with nonmagnetic insoles [49,50]. Wearing slippers or going barefoot may aggravate symptoms or result in a recurrence of symptoms. Thus, the first step out of bed should be made with a supportive shoe or sandal on. Patients who work or reside in buildings with concrete floors should use cushion-soled or crepe-soled shoes. Excessive heel impact from jumping, excessive heel impact during walking, or use of a trampoline should be avoided. Athletic shoes, arch supporting shoes (particularly those with an extra-long counter, which is the firm part of the shoe that surrounds the heel), or shoes with rigid shanks (usually a metal insert into the sole of the shoe) may be helpful. Shoes with these features can be found in stores featuring work shoes or "orthopedic shoes". Exercises may be beneficial although evidence is limited. (See "Joint protection program for the lower limb" and see "Rehabilitation program for the lower limb"). Home exercises include the calf-plantar fascia stretch (show picture 3), foot/ankle circles (show picture 4), toe curls (show picture 5), and toe towel curls (show picture 6). One unblinded trial noted that non-weight bearing stretching exercises specific to the plantar fascia were more beneficial in the short term than weight-bearing Achilles tendon-stretching exercises [51], although the method of analysis may have biased towards this result. At two-year follow up there were no differences between groups [52]. Another placebo-controlled trial found no significant differences in pain and function in those who undertook a two-week calf muscle stretching program compared to those who did not [53]. Ultrasound therapy, ice massage, and deep friction massage may be used prior to exercise although their effectiveness is unknown. Tape support of the affected plantar surface, a technique referred to as low-Dye taping may be beneficial to some patients particularly for first-step pain [54,55]. Four strips of tape are applied as illustrated in the figure (show figure 2). The tape should not be applied too tightly and use of hypoallergenic tape is recommended to avoid allergic reactions [55].

If these inexpensive and noninvasive measures fail to bring about improvement within two to three weeks, the following may be considered: The points of tenderness along the plantar fascia may be injected with a corticosteroid/local anesthetic mixture (show picture 7). Injections may provide short-term, temporary pain relief. In a randomized placebo-controlled study, significantly less pain was noted in patients who received a single corticosteroid injection, a difference that was significant at one month, but not at three or six months [56]. An alternative, possibly less painful approach, a medial injection, may also provide significant benefit [57]. One of the authors (RS) injects into a minimum of three tender locations along the fascia while the other author (RB) uses a single injection directed to the site of maximal tenderness. The utility of using ultrasound to guide placement of the injection remains uncertain. Two randomised trials have found pain relief from ultrasound-guided injection was no different to blind injection [58,59] although one trial reported a lower recurrence rate [59].

Corticosteroid injection should be used judiciously since repeated injection may cause heel pad atrophy [60]. It may also predispose to plantar fascia rupture [61,62] although evidence for this is limited and non-conclusive. One study reported a series of 37 patients with a presumptive diagnosis of plantar fascia rupture, all of whom had had a prior episode of plantar fasciitis treated with corticosteroid injection into the calcaneal origin of the fascia [61]. In another study of 765 patients with plantar fasciitis, 43 of 51 patients with plantar fascia rupture had received one or more corticosteroid injections although the number of patients without plantar fascial rupture who received one or more corticosteroid injections was not reported [62].

A randomised trial of corticosteroid injection compared to extracorporeal shock wave therapy (see "Shock wave therapy" below) in 132 patients found that after three months there was significantly less pain in those who received the injection (mean differences in visual analog pain of 1.48 versus 3.69, respectively) [63]. Custom-fabricated inserts, usually provided by podiatrists, include inserted orthoses with foam rubber raised arches and rubber or tub heels, and molded ankle-foot orthoses. The efficacy of foot orthoses remains controversial, and there are considerable variations in the prescribing habits of podiatrists, orthopedists, and prosthetists [64-66]. Any advantage of customized orthotics over prefabricated ones must be weighed against a substantial difference in cost, estimated to be approximately two to six-fold more for the customized version [65]. A short walking cast is used by some orthopedists although again there are no published trials of this treatment approach. Iontophoresis with 0.4 percent dexamethasone (six sessions over two weeks) provided moderate initial relief of plantar pain in a small, randomized placebo-controlled trial in runners with plantar fasciitis although this effect was not maintained at 4 weeks [67]. In another small study, low-Dye taping combined with iontophoresis with a 5 percent solution of acetic acid was superior to taping and iontophoresis with 0.4 percent dexamethasone but no different to taping and iontophoresis with placebo [68].

Shock wave therapy — The effectiveness of extracorporeal shock wave therapy for plantar fasciitis has been more extensively studied than any other single treatment modality. As of April 2007, at least 14 randomised controlled trials that have compared shock wave therapy with either placebo or sub-therapeutic doses of shock waves have been published in English language journals [69-71]. These trials have been of variable methodological quality and have reported conflicting results. A systematic review published in 2005 included 11 trials and performed a pooled analysis of data from 6 trials involving 897 patients [69]. The authors concluded there was no clinically important benefit of shock wave therapy despite a small statistically significant benefit in morning pain of less than 0.5 cm on a 10 cm visual analogue scale. No statistically significant benefit was observed in a sensitivity analysis that only included high-quality trials.

There is ongoing clinical uncertainty about the effectiveness of shock wave therapy; opinions are highly polarized, fuelled by the lack of convergence of findings from randomised evaluations. Explanations that have been put forward to explain the differing results include variation in methodological quality, the different types of equipment that have been used to generate the shock waves, different delivery methods and different doses. Duration of symptoms has not been found to influence response to treatment [72,73]. An association between therapeutic response and the amount of the shock wave energy applied was noted in one study [71]. The major reported adverse effect is transient pain at the time of treatment.

Botulinum toxin injection — A single small double-blind placebo-controlled trial in 27 patients with unilateral or bilateral plantar fasciitis assessed the effect of two injections of botulinum toxin (40 units); one into the foot near the calcaneal tuberosity and the other in the arch (30 units) [74]. Feet injected with botulinum toxin had more improvement in pain and tenderness at 3 and 8 weeks than those injected with saline solution (placebo) although effect sizes were not reported. Further trials are needed before considering this treatment approach for usual care. (See "Botulinum toxins for chronic pain and headache").

Complementary therapies — Topical application of wheatgrass cream twice daily for 6 weeks was ineffective in a recent randomised double-blind placebo-controlled trial involving 80 participants [75]. Other trials of complementary therapies are expected.

Radiotherapy — Radiation therapy is sometimes used in Europe to treat chronic plantar fasciitis that is unresponsive to more conservative approaches [76]. Its effectiveness has not been assessed in randomised controlled trials and whether there is a long term increased risk of carcinogenesis is unknown. Because of concern about the possibility of late onset hematopoietic malignancy, radiation therapy is seldom used to treat plantar fasciitis in other parts of the world.

A survey of German radiation treatment institutions found that 81 percent provided radiation therapy for heel pain associated with calcaneal spurs [76]. There was wide variation in the amount of radiation delivered per session (median 1 Gy) and the total amount of radiation (median 6 Gy). Retrospective review of the outcomes of a single course of therapy in 7947 patients at 76 centers found that complete pain relief lasting at least 3 months occurred in 25 to 100 percent of patients (median 70 percent) and was not related to the dose of radiation delivered. Approximately 15 percent of treatment courses resulted in no pain relief.

Surgical therapy — It is estimated that 2 to 5 percent of patients with plantar fasciitis undergo surgical procedures [2,4,12,77] although the rate may be much lower. As an example, a report of the surgical experience at the Mayo Clinic found that only 16 operations had been performed during a twelve year study period [78].

While numerous surgical procedures have been described, none have been assessed in controlled trials. Favorable outcomes are reported in more than 75 percent of published case series although recovery time may be prolonged and persistent pain is not uncommon. Variations of open or closed partial of complete plantar fascia release with or without calcaneal spur resection, excision of abnormal tissue and nerve decompression have been described. Exostoses (bony projections) in runners and dancers may also improve with surgery [79].

In comparison to open release, closed procedures may allow more rapid recovery and resumption of usual activities [80,81]. In an uncontrolled series of 16 runners and 10 walkers with refractory plantar fasciitis, uniportal plantar fasciotomy gave good or excellent results provided the patient's body mass index was less than 27 [82]. Runners in this series required a mean of 2.6 months before returning to jogging.

Potential complications of surgery include transient heel pad swelling, calcaneal fracture injury to the posterior tibial nerve or its branches and flattening of the longitudinal arch with resultant midtarsal pain.

Cryosurgery — Promising results have recently been observed in a single study that used percutaneous cryosurgery, a minimally invasive technique for freezing tissue, to treat plantar fasciitis in 59 patients [83]. The effectiveness of this technique needs to be assessed in controlled trials.

Prevention — The efficacy of preventive strategies such as stretching exercises and controlling the intensity of running (eg distance, frequency and duration) in specifically preventing plantar fasciitis is unknown [84]. Footwear designed to maximize shock absorption may also be of value [85].

Prognosis — The outcome for patients with plantar fasciitis is generally favorable; approximately 80 percent of patients have complete resolution of pain within one year [4,77,86,87]. The favorable natural history of this benign condition should be borne in mind when weighing the potential benefits and risks of unproven and sometimes costly treatments.

Summary and recommendations — Plantar fasciitis is a painful disorder that is associated with degenerative and sometimes chronic inflammatory changes in the affected tissue. It has a good prognosis and patients can be informed that with conservative treatment 80 percent have complete resolution within a year. Although many types of treatments have been used for this disorder, few have been rigorously validated in clinical trials. Based upon the data presented earlier in this review, the following initial conservative interventions are recommended (see "Conservative therapy" above): Stretching exercises for the calf muscles and the plantar fascia, which the patient can perform at home Avoiding the use of flat shoes and bare-foot walking Using prefabricated, over-the-counter, silicone heel shoe inserts (arch supports and/or heel cups) Decreasing physical activities that are suggested by the medical history to be causative or aggravating (eg, excessive running, dancing, or jumping) Prescribing or recommending a short-term (two to three weeks) trial of NSAIDs is reasonable, but long-term use should be reserved for patients with known systemic rheumatic disease Injecting the tender areas of the plantar region with glucocorticoids and a local anesthetic.

If the treatments above have not produced sufficient improvement, more costly therapies can be considered although these remain unproven: Molded shoe inserts (orthotics) Night splints Immobilization with a cast Extracorporeal shock wave therapy

Surgery is generally reserved for those patients who do not respond to at least six to 12 months of conservative therapy.

OTHER CAUSES OF HEEL PAIN — A variety of other disorders may cause heel pain.

Haglund's syndrome — A prominent enlarged bony posterior superior calcaneal tubercle sometimes causes compression of soft tissue and foot pain (which may be due in part to a retrocalcaneal bursitis) in the posterior area of the heel over the bony prominence, above the site of attachment of the Achilles tendon [88]. The cause is usually a combination of developmental problems and altered foot dynamics including a more vertical pitch of the posterior portion of the calcaneus.

Patients with this disorder come to the physician due to an inability to wear shoes comfortably. A 2 to 3 mm bony extrusion is visible and palpable. The overlying skin may contain an area of erythema and swelling.

Nonoperative treatment of Haglund's syndrome includes a well-fitted heel cup, a laced or strapped shoe that reduces heel counter friction, and heel padding to raise the heel. A "V" cutout heel counter to decompress the bursa may be used if bursitis is present and persistent; incising the heel counter with a deep "V" will provide less friction. Surgical excision should be considered if the exostosis is large and symptoms persist [89]. Although calcaneal ostectomy provided good to excellent results in a series of 39 feet that were operated upon, six of 36 patients said they would not recommend the surgery to others, mainly due to the prolonged time to recover from the operation [90].

Calcaneal periostitis — Calcaneal periostitis may result from trauma, reactive arthritis, ankylosing spondylitis, psoriatic arthritis, or rheumatoid arthritis [91]. Pain is usually bilateral, along the lateral and plantar aspect of the heels, worse in the morning upon arising, and often accompanied by morning stiffness. Tenderness is diffusely present along the plantar aspect of the heel and midfoot, and along the lateral border of the heels.

Bilateral involvement should alert to the possibility of a coexistent systemic rheumatic disease. Fluffy calcific deposition of the plantar aspect of the heel on a lateral radiograph is suggestive of reactive arthritis.

Management includes use of NSAIDs for pain and inflammation; the resulting painful heel may have to be raised one to two cm with a heel lift for relief. Treatment of the underlying disease process will often be helpful.

Calcaneal spurs — Calcaneal spurs can develop on the plantar tuberosity and extend across the entire width of the calcaneus. The apex of the spur is embedded in the plantar fascia. Heel spurs are typically asymptomatic (show radiograph 1); pain occurs when the apex is angled downward by depression of the long arch. An acutely painful heel spur may also be seen in certain systemic diseases, such as ankylosing spondylitis, reactive arthritis, or rheumatoid arthritis.

Conservative treatment includes a cutout heel pad or a custom-made orthotic. Surgery usually is needed if the prominence is palpable with only a thin amount of natural heel pad intervening between the spur and skin. MRI may be useful if surgery is being considered; it may delineate other factors responsible for the pain, particularly if the spur is not palpable and the diagnosis is in doubt.


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