Plantar fasciitis

What is plantar fasciitis?

Plantar fasciitis continues to be widely used for the clinical syndrome of undersurface heel pain. However, the use of 'itis' denotes an inflammatory disorder. This is a misnomer as plantar fasciitis is a degenerative rather than an inflammatory condition.¹

The plantar fascia is a thick, fibrous band of connective tissue. Its origin is the medial plantar tubercle of the calcaneum. It runs along the sole of the foot like a fan, being attached at its other end to the base of each of the toes. It is a tough, resilient structure that has a number of critical functions during running and walking:

• It stabilises the metatarsal joints during impact with the ground.

• It acts as a shock absorber for the entire leg.

• It forms the longitudinal arch of the foot and helps to lift the arch to prepare it for the 'take-off' phase of the gait cycle.

Plantar fasciitis pathophysiology²¹

Plantar fascia and Achilles tendon

© By Ryxi10, via Wikimedia Commons

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• The plantar fascia is a sturdy structure but the degree of stress that it takes makes it susceptible to injury. A force equal to almost three times the body's weight passes through the foot with each step. On running, this typically happens about 90 times a minute.

• Plantar fasciitis is thought to be a traction and overuse injury. Damage to the plantar fascia is usually in the form of micro-tears. Plantar fasciitis is a degenerative rather than an inflammatory process.

• Damage tends to occur near the heel, where stress on the fibres is greatest and where the fascia is the thinnest. The fascia broadens as it extends toward the toes.

• Plantar fasciitis is often associated with calcaneal (heel) spurs. These are depositions of calcium where the fascia suffers most damage. Spurs are most commonly on the medial side at the origin of the fascia from the calcaneum. Spurs are the result of the process of plantar fasciitis and not the cause of the pain.

• Plantar fasciitis can present bilaterally.¹

Epidemiology

Plantar fasciitis is common in runners but can also affect sedentary people.³

Plantar fasciitis risk factors⁴

• Intrinsic:

  • Pes planus.

  • Pes cavus.

  • Over-pronation or limited dorsiflexion of the ankle.

  • Leg-length discrepancy.

  • Excessive lateral tibial torsion.

  • Excessive femoral anteversion.

  • Being overweight.

  • Gastrocnemius and soleus muscles tightness.

  • Achilles tendon tightness.

  • Gastrocnemius, soleus and intrinsic foot muscles weakness.

  • Ageing of the heel fat pad.

  • Atrophy of the heel fat pad.

  • Plantar fascia stiffness.

• Extrinsic:

  • Overuse eg, prolonged standing or jumping.

  • Mechanical stresses and micro-tearing.

  • Incorrect training: a too-fast increase in the distance, intensity, duration, or frequency of activities that involve repetitive impact loading of the feet.

  • Inadequate or inappropriate footwear.

History

• The principal complaint is heel/plantar pain. Most often this is 1 or 2 cm distal to the medial calcaneal tuberosity.

• Ask about the onset of the symptoms and any precipitating, aggravating, or relieving factors. What brings it on? What makes it worse?

  • Plantar fasciitis is often at its most severe during the first few steps after prolonged inactivity, such as sleeping or sitting.

  • Sitting with the foot elevated usually relieves the pain.

  • For those who are on their feet all day, pain is worst at the end of the day.

  • Walking barefoot, on toes, or up stairs can precipitate pain.

• Ask about running or jogging and other sports.

• Ask about footwear and when it was last replaced.

• Ask about previous trauma to the foot.

Examination

• Look at the foot. Note any obvious deformities, skin changes, or congenital conditions. Look for pes planus or pes cavus.

• There is often tightness of the Achilles tendon and ankle dorsiflexion may be limited.

• Palpate the plantar surface over the medial calcaneal tuberosity and along the course of the plantar fascia, pressing quite hard. The reproduction of the pain is the most important physical sign to confirm the diagnosis.

• Pain may be reproduced by asking the patient to stand on their toes or by passive dorsiflexion of the toes.

• Palpate the back of the heel and ankle to exclude Achilles tendonitis.

• Subcalcaneal bursitis produces a tender swelling underneath the calcaneum. It is not aggravated by dorsiflexing the toes. There is usually little or no swelling in plantar fasciitis.

• Referred pain from an S1/S2 lesion should be excluded. Perform the straight leg raising test as for examination of the back. Check the ankle tendon reflex (S1) and calf strength. This is easily performed by asking the patient to walk on toes or stand on one leg and raise the heel off the floor. These tests should be normal.

• Exclude tarsal tunnel syndrome: the posterior tibial nerve passes under the flexor retinaculum which runs between the medial malleolus and the calcaneum. Percuss over the nerve below and posterior to the medial malleolus. This can reproduce pain, numbness and burning on the medial side of the foot, ankle, or calf if there is tarsal tunnel syndrome.

• Press together the heads of the 2nd and 3rd metatarsals and then the 3rd and 4th. Reproduction of the pain suggests Morton's neuroma, with entrapment of the common digital nerve between the metatarsal heads.

• A stress fracture of the calcaneum will cause tenderness over the calcaneum rather than anterior to it.

Differential diagnosis

See also the separate Painful foot and Foot fractures and dislocations articles.

• Achilles tendonitis.

• Subcalcaneal bursitis.

• S1 radiculopathy or referred pain.

• Tarsal tunnel syndrome.

• Morton's neuroma.

• Sever's disease (children and adolescents).

• Stress fracture of calcaneum.

Very rarely:

• Fibrosarcoma.

• Metastases.

• Foreign body.

• Paget's disease of bone.

• Osteomyelitis.

• Tuberculosis.

• Gout.

Investigations¹⁵

The diagnosis is essentially clinical. However, imaging may be required to exclude other possible underlying conditions.

• Blood tests are not helpful.

• X-ray: should not be performed as a matter of routine but may be indicated if you suspect another diagnosis. A lateral view may show soft tissue calcifications or a calcified spur on the anterior aspect of the calcaneus. X-ray may also help to exclude stress fracture, although stress fractures may not always be evident.

• Ultrasound: this may show a thicker heel aponeurosis or plantar fascia in plantar fasciitis.

• MRI is occasionally used in patients who are not responding to standard management; it may detect a stress fracture, tear of the plantar fascia or osteochondral defect in the cartilage and bone of the foot or ankle.

Plantar fasciitis treatment and management

Treatments include stretching and physiotherapy, orthotics, extracorporeal shock wave therapy (ESWT) and corticosteroid injections (CSI), given either with lidocaine or protein rich plasma (PRP). General advice would include rest when pain is severe and weight loss in the case of overweight or obesity. Non-steroidal anti-inflammatory drugs and ice may be useful. Runners should run on a soft surface where possible and wear laced shoes which are replaced regularly, as well as considering the use of orthotics. During severe symptoms, a temporary shift to swimming, cycling, a step machine in a gym, or other low-impact exercise may be helpful.

Physiotherapy and stretching exercises

• Treatment with physio (which may include deep massage of the plantar fascia) and exercises alone will take at least 6-8 weeks to see an improvement and recent systematic reviews suggest that the trend towards improvement with physiotherapy alone is non-significant, with most benefit being in the short-term. The addition of kinesiology taping or ESWT (discussed later) improve prognosis. ²⁶

Orthotics, splinting and casting

• There is some evidence that full-length orthotics relieve symptoms to a greater extent than those which just cover the heels.

• Combining these with night splints (which keep the ankle dorsiflexed and the toes extended) or rocker shoes can show a greater improvement compared with either of the three interventions alone. ⁷

Corticosteroid injection (CSI)

• CSI can be given in combination with lidocaine or PRP and there is some evidence that a CSI with PRP is more beneficial than one given with lidocaine, particularly when it comes to long-term improvement in pain and function. ⁸⁹⁸¹

• Ultrasound guidance is often used to facilitate accurate injection. ¹⁰

• Such injections are not part of routine primary care and would be done by a GP with an extended role in musculoskeletal medicine, as part of a separately commissioned service, or in secondary care.

• Adverse effects include fat pad necrosis, skin atrophy, rupture of the plantar fascia and (very rarely) infection such as osteomyelitis. ¹¹CSI are usually limited to 2-3 injections per year, to reduce the risk of adverse effect.

Extracorporeal shock-wave therapy (ESWT)

• There is evidence for ESWT causing a reduction in pain intensity as well as improvement in functional outcomes, with some studies showing that it is more beneficial than CSI. It is generally a safe treatment. ¹²¹³

• The most recent National Institute for Health and Care Excellence (NICE) guidance (which has not been updated since 2009) says that evidence is inconsistent and that it should only be used with special arrangements for clinical governance, consent and audit, or research.¹⁴ It is however offered by the NHS and private sector in many areas.

Botulinum toxin A injections

• This may produce some benefit in the short term and would generally be used when first-line therapies have not helped. ¹⁵

• More evidence is probably needed before this becomes more widely used. ¹⁶

Radiotherapy

• Low-dose radiotherapy has been shown to provide effective pain relief.^{17 18}

Surgery

• Endoscopic fasciotomy may be required in patients who continue to have pain that limits activity and function despite exhausting non-operative treatment options.³

• Further research is needed to fully establish long-term outcomes. ¹⁹

Plantar fasciitis prognosis

• Pain may be long-standing and can last for some years, but 75% show spontaneous response within 12 months.¹

• It is important to avoid the vicious cycle whereby walking is painful and therefore the patient becomes progressively more inactive and potentially gains weight, thus worsening the pain. ²⁰

Plantar fasciitis prevention

• Regularly changing footwear used for running and walking.

• Wearing shoes with good cushioning in the heels and good arch support.

• Losing weight if overweight.

• Avoiding exercising on a hard surface.

• Regular stretching exercises for the plantar fascia and Achilles tendon.