Plantar Fasciitis

The plantar fascia is a dense, fibrous band serving as a biomechanical stabilizer, as well as a protector to the vulnerable neurovascular structures on the plantar aspect of the foot.  The diagnosis “plantar fasciitis” encompasses disorders ranging from acute inflammation to chronic fibrotic degeneration, usually involving the calcaneal attachment.  (1,2) Plantar fasciitis most commonly affects the medial portion of the band.  (2) 

The band’s proximal origin is the medial calcaneal tubercle, and its distal attachments are all five toes.  The band functions, via the “windlass mechanism” to stabilize the foot during gait; i.e., at heel strike, the plantar fascia is slack to allow the foot to accommodate uneven surfaces.  As the heel lifts and forefoot dorsiflexes toward toe off, the distal plantar fascia “winds” up and around the first MTP joint, pulling the plantar fascia taut, shortening the distance between the heel and forefoot, raising the arch and creating a stiffer lever for propulsion.  (3)

Plantar Fasciitis

Although the term, “plantar fasciitis” implies inflammation, more recent studies suggest that plantar fascia pain results from a non-inflammatory, degenerative process.  (4-12) Initial insults may generate an acute inflammatory reaction, but repetitive chronic overload results in a breakdown of the inflammatory process and a disorganized healing process that fails to regenerate “normal” tissue.

Plantar fasciitis is the most common cause of plantar heel pain, affecting approximately 10% of the population.  (14-18) The condition is present bilaterally in 20-30% of those affected.  (19)  The condition is common in young runners and middle-aged women, but the majority of plantar fascia patients are over the age of 40.  (16-18) 

Causes

Like most cumulative trauma disorders, the etiology of plantar fasciitis is multi-factoral.  (21) Problems typically arise when repetitive eccentric strain exceeds the tissue’s threshold for injury. Certain factors may increase the likelihood of developing the disorder.  The leading biomechanical cause for plantar fasciitis is pes planus (fallen arch) which increases tension on the plantar fascia, leading to repetitive micro-trauma at the band’s vulnerable attachment on the medial calcaneus.  (22) Patients with pes cavus are likewise predisposed since a cavus foot is relatively immobile, and forces that would generally be dissipated by bony structures are now absorbed by the plantar fascia.  (16,25)

Tightness or weakness in the gastroc and soleus directly contribute to plantar fasciitis by increasing tensile strain on the plantar fascia.  (25-27)  Gastroc and soleus hypertonicity limits dorsiflexion, meaning the plantar fascia must accommodate for this lost motion.  (28)  Gastroc and soleus weakness limits propulsion and increases loads on the plantar fascia and the intrinsic muscles of the foot.  (28)

Hamstring

Patients with plantar fasciitis are almost 9 times more likely to demonstrate hamstring hypertonicity.  (29) Hamstring tightness may induce prolonged forefoot loading and increase strain to the plantar fascia. (30) Rapid weight gain and obesity are also recognized as contributors to plantar fasciitis.  (17,25) Patients with BMIs greater than 35 are approximately 2.5 times more likely to experience plantar fasciitis, as compared to those with BMIs less than 35.  (29)

Patients may be predisposed by occupations or activities that involve prolonged ambulation, including teachers, construction workers, cooks, nurses, distance runners, etc. Runners average 1200 steps per mile at a 6-minute per mile pace, and walkers average 2300 steps at a 20-minute/mile pace.  The plantar fascia must absorb up to seven times body weight during the push-off phase of running and biomechanical deficits are quickly amplified. Patients often present following an increase in training demand or change in running surface, such as concrete.  (25)

Complaints

The most common presenting complaint of plantar fasciitis is a sharp pain with the first couple of steps in the morning or following any period of prolonged inactivity.  (16,25) Symptoms are often noted during the push-off phase when the band is at peak tension.  (32) Symptoms are amplified by prolonged weight bearing, especially when compounded by inadequate foot support or walking barefoot.  (25) Walking upstairs and sprinting or forefoot running tends to exacerbate symptoms by increasing plantar fascia strain. Patients report relief when unloading the foot by sitting or lying down. Symptomatic episodes are more frequent following periods of inactivity late in the day. 

Testing

Palpation will likely reveal tenderness at the medial calcaneal tubercle. (33) Some patients note tenderness to palpation in the mid portion of the plantar arch.  (33) Palpation may demonstrate plantar fascia tightness with palpable bands of tenderness or adhesion. Tenderness to palpation is often exacerbated by simultaneously dorsiflexing the great toe to 65 degrees.  (34) The Windlass test for plantar fasciitis is the reproduction of heel pain during passive dorsiflexion of the toes.  Performing this test while the patient is standing/weight bearing more than doubles sensitivity to almost 33%.  (35)

Clinicians should palpate the posterior aspect of the calcaneus to assess for alternate sources of pain (i.e. Sever’s disease, retrocalcaneal bursitis, Achilles tendinopathy, stress fracture, etc.) The heel squeeze test may help identify a stress fracture. Asking the patient to walk on his or her toes may provide additional information, as patients with plantar fasciitis report discomfort when shifting weight onto their toes, while patients with stress fractures or heel spurs find relief in that position.  (36) Patients with stress fractures of symptomatic heel spurs may note pain at heel strike.  (32)

Range of motion may demonstrate limited ankle dorsiflexion due to Achilles or gastroc hypertonicity.  Clinicians should assess for hamstring tightness, as well as the strength of the posterior tibialis and flexor digitorum brevis.  The flexor digitorum brevis works in concert with the plantar fascia by contracting to divert strain away from the overworked fascia.  (37) The flexor digitorum brevis may be assessed via the “Paper grip test” (the seated patient stands with the second through fifth digits on a business card, while the clinician attempts to pull the card from beneath the patient’s toes.)  (38)

Clinicians should assess for biomechanical deficiencies, including leg length discrepancy, pes cavus, hyperpronation, or pes planus.  (33)  Clinicians may assess the patient’s arch with hyperpronation cluster tests. Evaluation of shoe insoles may help to determine flexor digitorum brevis strength.  Runners with strong flexor digitorum brevis muscles will demonstrate indents beneath their middle toes.  (36)

Red Flags

Peripheral neuropathies, including tarsal tunnel syndrome and Baxter’s neuritis, sometimes masquerade as plantar fasciitis. Baxter’s neuritis is an often-overlooked cause of heel pain and may account for up to 20% of all heel pain.  Baxter’s neuritis is compression of the inferior calcaneal nerve, resulting in weakness of the abductor digiti minimi. (39)  Entrapment may result in pain that is indistinguishable from plantar fasciitis and a subtle loss of fifth digit abduction.  (40-46) The pain of Baxter’s neuritis may be provoked by abducting and dorsiflexing the forefoot for 30-60 seconds. (2,96) Tarsal tunnel syndrome is compression of the posterior tibial nerve, as it passes through the tarsal tunnel, resulting in pain and/or paresthesia radiating into the plantar arch and heel.  Tarsal tunnel syndrome may be identified by a positive Tinel sign and a Dorsiflexion-eversion test.

Any patient with bilateral plantar fasciitis should be carefully screened for the presence of inflammatory arthropathy.  (48)  Some reports indicate that 16% of subcalcaneal heel pain patients will later be diagnosed with a systemic disease, such as RA, Beckets, AS, SLR, Reiters, psoriatic arthritis, diabetes, or gout.  (49)  Early signs of inflammatory arthropathy are similar to those of plantar fasciitis with the exception of symptoms that tend to occur bilaterally with more pronounced swelling.  (2) 

Additional differential considerations for plantar fasciitis include contusion, Sever’s disease, stress fracture, peripheral neuropathy, fat pad syndrome, infection, neoplasm, inflammatory arthropathy, neuropathic pain, Padgett’s disease, S1 radiculopathy, and tendinitis/tendinopathy. 

Radiology

Radiographs are typically not required for the diagnosis of plantar fasciitis.  (51)  Radiographs may, however, be useful in differentiating plantar fasciitis from other diagnoses, including neoplasm or fracture.  A calcaneal stress fracture may appear on standard radiography as a radiopaque band traversing the trabecular pattern in the posterior calcaneus. Plain film radiographs commonly expose plantar calcaneal enthesopathy (heel spurs). Studies demonstrate no correlation between spur size and the patient’s subjective complaints.  (52) Calcaneal enthesophytes are considered coincidental and irrelevant radiographic findings.  (53) They are a sequela rather than a cause of the process.  (54,55) Spurs are thought to develop when long-standing tension creates a traction apophysitis, via Wolf’s Law.  The presence of a heel spur suggests abnormal stress in the region for at least six months.  (56) Heel spurs are present in approximately 50% of symptomatic patients and 15-20% of asymptomatic patients.  (54,57) Studies now suggest that heel spurs develop at the origin of the flexor digitorum brevis muscle, as opposed to the plantar fascia attachment.  (58)  

Bone scans may be useful to rule out calcaneal stress fracture or neoplasm, although they will not differentiate between the two.  Advanced imaging, including MRI, may be appropriate for recalcitrant cases or to rule out differential diagnostic considerations, including Baxter’s neuritis. Sonographic studies demonstrate that while the average plantar fascia is approximately 2 mm thick, patients with plantar fasciitis symptoms demonstrate a degenerative thickening of 4 mm or greater.  (59) Diagnostic ultrasound evidence of decreasing plantar fascia thickness is associated with improvement.  (60)

Treatment

Eighty to ninety percent of plantar fasciitis patients who forego treatment will report the resolution of their complaints within 18 months. Conservative treatment, including manual therapy, stretching, myofascial release, exercise, orthotics, physical therapy modalities, and night splints may improve results.  (61-63) The best treatment outcomes are achieved by combining multiple techniques- particularly mobilization and exercise.  (63,97)

Patients may need to temporarily limit activities that exacerbate symptoms, including jumping, running, and sprinting.  Once patients find a tolerable level of activity, they should not increase their training intensity by more than 10% per week.  (64) Runners should avoid running hills, and toe or forefoot runners may need to temporarily alter their running form.  Runners may benefit by reducing stride length and increasing cadence.  (36) Running shoes lose half of their shock absorption capacity after 300-500 miles and should be replaced within that range.  (65,88,89) Safer alternatives to running include swimming, bicycling, and elliptical machines.  (66) 

Patients who hyperpronate and those with fallen arches will benefit from arch supports or orthotics.  (67) The use of a Tensoplast wrap or commercial elastic wrap (PSC fabrifoam) will help support fallen arches.  Low dye taping is effective in limiting pronation.  (68) A medial heel wedge forces the foot into a varus posture and significantly reduces plantar fascia strain.  (69) Patients with true hypersensitivity to pressure may benefit from a viscoelastic heel cup or small cushion donut over the medial calcaneal tubercle.  (70)    The use of elastic therapeutic tape has been proposed for the treatment of plantar fasciitis. 

Immobilization

Immobilizing tissue in a lengthened state speeds recovery.  (71) Chronic plantar fasciitis patients may benefit from using a boot or night splint (Strassburg sock), which limits passive plantar flexion and allows the plantar fascia to “heal” in a lengthened state. (92,93)  Patients should be counseled on proper shoe wear.  Patients with low arches may benefit from “motion control” shoes.  Runners with average arches should choose “neutral” or “stability” shoes.  (72) Patients with high arches may benefit from a “cushioned” shoe.  (73)

Since most chronic cases of plantar fasciitis do not show histologic evidence of inflammation, the benefit of “anti-inflammatory” modalities is questionable.  (74) Some patients report at least palliative relief by using NSAIDs, ice, and modalities. Low-level laser therapy may be useful for the treatment of chronic plantar fasciitis.  (75)

Ankle joint mobilization and manipulation can help restore normal motion, particularly dorsiflexion.  (76,77,90) The addition of gastroc/ soleus and plantar fascia trigger point massage and soft tissue manipulation to traditional treatment programs produces superior short-term outcomes.  (62)  Myofascial release procedures, including transverse friction massage and IASTM, are effective tools that may stimulate fibroblast proliferation and plantar fascia regeneration.  (79,80,95) IASTM may be performed in a fanning fashion over the length of the plantar fascia in a strumming fashion near the medial calcaneal origin.

Stretching Exercises

Stretching exercises are appropriate for the gastroc, soleus, hamstring, and plantar fascia.  (81,91)  The plantar fascia may be effectively stretched by sitting in a Figure 4 position, and fully dorsiflexing the great toe for 10 seconds repetitively throughout the day.  Routinely stretching the plantar fascia in this fashion is associated with significantly improved outcomes.  (81) Plantar fascia mobilization may be performed at home by rolling a golf ball or frozen water bottle beneath the plantar fascia. The use of a Prostretch may assist in stretching and mobilizing the plantar flexors.

Strengthening exercises are appropriate for the gastroc, soleus, posterior tibialis, and intrinsic muscles of the foot. (82) Examples include marble and towel gripping exercises. Strengthening exercises for the posterior tibialis should be implemented to help arch support.  Strengthening of the flexor digitorum brevis is an important component of treatment and may be accomplished by performing toe flexion with an exercise band.  (36) Eccentric heel raises with the great toe positioned in passive dorsiflexion (i.e. great toe propped up with a towel) have shown benefit for plantar fasciitis patients. (98) 

Nearly two-thirds of foot and ankle orthopedic specialists prefer stretching and manual therapy over anti-inflammatories or corticoid steroid injections for chronic plantar fasciitis patients.  (83) Medical management of recalcitrant plantar fasciitis includes extracorporeal shock-wave therapy (ESWT), cortisone injections, and surgery.  ESWT has shown to help some patients.  (63,85) ESWT (originally developed as lithotripsy) is thought to break up calcific deposits and stimulate fibroblast activity to encourage healing.  Corticoid steroids may provide an anti-inflammatory effect in cases where inflammation is present, but carry the risk of spontaneous plantar fascia rupture or damage to the heel pad.  (62,87)  Surgical management includes fasciotomy.

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