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Plantar fasciitis

Description

Plantar fasciitis is a common source of pain along the sole, or plantar surface, of the foot.  The etiology of the condition is thought to be overuse, with traction and shear forces applied to the plantar fascia; it is not an inflammatory condition as the “itis” suffix would suggest.   Typical findings of the condition include pain and tenderness at the junction of the plantar fascia and the medial calcaneal tuberosity,  usually worse with the first few steps in the morning (so-called “start up pain” ). Helpful treatments include stretching of the calf muscles and the plantar fascia itself and the use of orthotics with a medial arch support.

Structure and function  

The plantar fascia is a sheet of fibrous tissue  (technically termed an aponeurosis) running along the sole of the foot from the calcaneus to the base of the proximal phalanges, with fibers merging with the dermis, transverse metatarsal ligaments, and flexor tendon sheaths as well.  The plantar fascia is mostly inelastic, with minimal elongation. Although the terminal insertion of the fascia is on the toes, the functional insertion point is at the of the metatarsal, as the phalanges are dorsiflexed relative to the metatarsals, forcing the tissue to curve around the joint. (This relationship is similar to the semitendinosus tendon, which technically inserts on the anterior aspect of the tibia, but flexes the knee as if it attached on the posterior surface.

Weight-bearing forces tend to flatten the medial longitudinal arch as forces are applied to the foot; the plantar fascia prevents this collapse, by maintaining the distance between the calcaneus and the metatarsals.  Note that the insertion of the plantar fascia is on the toes; hence dorsiflexion of the toes pulls on the plantar fascia, winding it under the metatarsals and thereby elevating the arch, a so-called “windlass” effect.

Plantar fasciitis is thought to be produced by overuse, creating a chronic microscopic injury to the plantar-medial origin of the plantar fascia.  A heel spur is not uncommonly found, but is neither a sensitive nor specific finding. Only 50% of patients with heel pain will have heel spurs and about 15% of people with asymptomatic feet will have them: accordingly, it is likely that the spur is not causing the condition.  Further, cadaveric dissections have demonstrated that the spur from the calcaneus is within the flexor tendons, rather than the plantar fascia itself.

Histologic evidence includes  tears in the fascia, myxoid degeneration, angiofibroblastic hyperplasia, and collagen necrosis and not inflammation per se. Inflammation could be part of the healing process, however.   

Patient presentation 

Healing of micro-trauma is thought to cause tightening of the plantar fascia  when the patient is at rest, especially as the foot and ankle assume a plantarflexed position at night.  Upon ambulation, when the foot and ankle forced into a neutral and dorsiflexed position, the healing tissue is strained.  Thus, the classic presentation of plantar fasciitis is an especially sharp  pain with the first few steps in the morning or after prolonged rest.  This pain is localized to the plantar medial aspect of the calcaneal tuberosity (Figure 1). It will often improve after some movement or stretching. However, it will tend to recur and worsen as the day progresses, particularly if the patient has had prolonged periods of significant weight-bearing activities such as walking or standing.

 

The foot and ankle physical exam should include inspection of the patient’s stance, foot shape, and gait; full neurologic evaluation; and identification of any areas of tenderness, especially at the medial plantar aspect of the heel. Confidence of the diagnosis is increased if dorsiflexion of the toes exacerbates the pain via the windlass effect.

 

Figure 1. Common location of plantar fascia pain

 

Figure 2. Plantar Fascia Specific Stretch

Objective Evidence

Plantar fasciitis is diagnosed by history and physical examination but imaging studies can help rule out other diagnoses.  A lateral weight-bearing view of the foot will often demonstrate a calcaneal heel spur, though this should be considered an incidental finding ; as noted, the presence of a heel spur does not directly correlate with symptoms.  

A triple-phase bone scan or MRI can plantar fasciitis from calcaneal stress fracture. An MRI may be used also to rule out other causes of heel pain such as tumors and infection.  Ultrasound is less expensive than an MRI and provides no radiation exposure but requires specific expertise that many physicians lack. Typical ultrasound findings include a thickened, hypoechoic plantar fascia with soft-tissue edema.

Laboratory studies are usually normal in the patient with plantar heel pain, but serum hematologic and immunologic testing can detect other systemic causes. HLA-B27, complete blood count, erythrocyte sedimentation rate, rheumatoid factor, antinuclear antibodies, and uric acid can be considered in patients with bilateral or atypical heel pain. EMG/NCV studies are effective in identifying a spinal radiculopathy, peripheral neuropathy, as well as local nerve entrapment.

 

Epidemiology

Plantar fasciitis is the most common cause of heel pain. Patients are usually  about 50 years of age. Plantar fasciitis  is bilateral heel in about 30% of primary conditions.

Differential diagnosis

Plantar fasciitis is the most likely cause of heel pain but other entities such as heel pad atrophy, entrapment of the first branch of the lateral plantar nerve (Baxter’s nerve), tarsal tunnel syndrome, calcaneal stress fracture and seronegative inflammatory disease might be responsible.

Pain after a sudden increase in the patient’s level of activity or training should prompt a work-up to rule out a calcaneal stress fracture. Infection or neoplasm are more likely when the plantar heel pain is present at night, especially when accompanied by unplanned weight loss, fevers or chills. These are, in general, unlikely diagnoses.

Burning pain is not typical of plantar fasciitis and may suggest nerve irritation as a source of the pain: Baxter’s neurtitis (compression of the inferior calcaneal nerve); peripheral neuropathy or radiculopathy.

 

Red flags

Any deviation from the classic history for plantar fasciitis  (eg pain that is worse with the first steps, then better, and then maybe worse as the day goes on if there is a lot of standing) should be a red flag to consider other diagnoses. 

Treatment options and Outcomes

The vast majority of patients , will have their symptoms resolve with or without treatment over a period of 6 months. Recovery can be accelerated with a program of calf and plantar fascia stretching, activity modification to avoid precipitating activities, and comfort shoe wear.  Formal physical therapy, immobilization via cast or boot, steroid injections, and rarely extracorporeal shock wave therapy may also be employed.

Calf stretching should be performed  with the knee straight so that the gastrocnemius (which originates on the femur) is stretched. Six sets of 30 seconds per side done daily is recommended.  Equally good results can be obtained with a plantar fascia stretch.   This is done in a seated position with the heel on the ground. The patient then places an object (eg, a sock, the contralateral foot) under the metatarsals and steps on it. This produces tension in the plantar fascia.  The stretch position should be held for 10 seconds and repeated 10 times. The timing of when this is performed is important. It should be done prior to the first step in the morning and during the day before standing after prolonged inactivity.

With resolution of the heel pain symptoms, it is important to continue calf stretching and plantar fascia stretching on a semi-regular basis so as to minimize the risk of recurrence.

Any activity that has recently been started, such as a new running routine or a new exercise at the gym that may have increased loading through the heel area, should be stopped on a temporary basis until the symptoms have resolved. At that point, these activities can be gradually started again.  

A soft, over-the-counter orthotic with an accommodating arch support might be helpful. Evidence supporting the need for a custom orthotic is lacking. Shoes with a stiff sole and rocker-bottom contour off-load the plantar fascia at its origin and likewise may be effective

Anti-inflammatory medication may ameliorate symptoms, but does not address the pathology (as again, despite the “itis” suffix, inflammation is not the cause).

Corticosteroid Injection can give temporary relief but may lead to atrophy of the fat pad. Data on the salubrious effects of  plasma-rich protein injections are  limited.

A splint (Figure 5) that keeps the ankle in a neutral position, perpendicular to the foot,  while the patient sleeps, can be helpful in alleviating the significant morning symptoms.  Avoiding the position of plantar flexion can prevent some of the shortening of the fascia that occurs at night.

 Surgery is rarely required to treat plantar fasciitis.  Only patients who have persistent symptoms despite religiously adhering to the non-operative treatment for a minimum of 6 months should be considered for surgery.  Endoscopic or open partial plantar fasciectomy involves removal of the injured area of the plantar fascia.  Although this procedure has produced good results in some cases, complete release of the plantar fascia leads to flat foot and even worse problems. Therefore, it is recommended that less than 40% of the plantar fascia be released (though an appropriately conservative release may limit the effectiveness of the procedures. A recession of the gastrocnemius theoretically should help resolve the symptoms associated with plantar fasciitis,  as gastrocnemius contracture is a known risk factor for the development plantar fasciitis. There are only limited studies assessing the long-term effectiveness of this procedure.

Figure 3. Gastrocnemius stretch of the right leg. Note that the back knee is straight and the back foot is internally rotated.

Figure 5. Plantar fasciitis night splint

 

 

Risk factors and prevention

Risk factors for plantar fasciitis include excessive standing,  greater body weight, increasing age, a change in activity level, Achilles tightness, and a stiff calf muscle (gastrocnemius).  A flat foot or a high arch deformity (pes planus and pes cavus, respectively) can increase loading  of the plantar fascia and increase the risk of developing plantar fasciitis.  However, any foot type can develop this condition. 

Miscellany

Fascia and political Fascism are related words. A fascia is of course connective tissue, typically that wraps around muscle fibers.  Fascism comes from the Italian word fasci, political groups or guild, itself derived from the Latin word fascis, meaning "bundle"

Key terms 

plantar fascia, plantar fasciitis, calcaneous, Achilles tendon

Skills  

Learn how to instruct patients on stretching the plantar fascia and gastrocnemius.

References

  1. Crawford F, Atkins D, Young P, et al: Steroid injections for heel pain: Evidence of short-term effectiveness. A randomized controlled trial. Rheumatology 1999; 38:974-977.
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  12. Wolgin M, Cook C, Graham C, et al: Conservative treatment of plantar heel pain: Long-term follow-up. Foot Ankle Int 1994;15:97-102.
  13. Mizel MS, Marymont JV, Trepman E: Treatment of plantar fasciitis with a night splint and shoe modification consisting of a steel shank and anterior rocker bottom. Foot Ankle Int
  14. Chen HS, Chen LM, Huang TW: Treatment of painful heel syndrome with shock waves. Clin Orthop Relat Res 2001; 387:41-46.
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  1. Jul 18, 2016

    Edited July 18th 2016