Plantar heel pain

By Helen Branthwaite MSc Sports Biomechanics and Injuries

Anatomy of the Heel

The plantar fascia has been described as a ligament, band of fascia and an aponeurosis. It is believed in some text to be an extension of the Achilles tendon which diminishes its connection with age. (1) The nature of the tissue is agreed to be fibrous made primarily from white collangeous fibres and is approximately 4mm thick at the calcaneus.(2) From here the fibres are arranged in a longitudinal nature and run the length of the sole of the foot inserting into the 5 metatarsals as vertical and transverse bands and tracts. They form a texture which ties the skin to the skeleton and allows the passage way of vessels, nerves and tendons. (3)

Figure 1 - Anatomy of the Plantar Fascia, indicating the structure and position of the three bands.

Presentation

Plantar fasciitis is by direct definition, inflammation of the plantar fascia. However it is reported to exist with no inflammatory markers, particularly in chronic cases, and therefore should be considered as a fasciosis or deterioration of the fascia (4,5) More often there are multiple tissues that are affected with changes to the fat pad, calcaneal periosteum and flexor digitoruim brevis muscle and tendon. Plantar heel pain which encompasses all pathological processes is more frequently being used in place of plantar fasciitis. (6) As the clinical diagnosis of a single pathology is difficult this umbrella terminology allows for heel pain to be diagnosed and managed effectively.

The most common presentation of plantar heel pain is localized tenderness overlying the calcaneal tuberosity where the central and thickest portion of the plantar fascia is attached to the medial process of the calcaneal tuberosity. (7) Plantar heel pain is characterised by a sharp pain upon initial standing and primarily first thing in a morning, rising from bed. Acute pain is reported to improve after a few steps, but then after prolonged standing this changes to a dull aching pain. (8, 9)

Aetiology

Trauma and increased tensile stress on the fascia cause micro tears at the insertion of the central band on the calcaneus. This can be repetitive trauma over a long period of time causing changes in structure to the fascia and thickening. (2) Yet it can also be torn from an injury where the fascia is put under excessive stress. Plantar facial pain can be due to an enthesopathy, which are a common presentation in inflammatory arthritis. Bilateral presentation of plantar heel pain is an indicator of an underlying spondylarthopathy.

(10) Mechanical overloading of the plantar fascia is thought to be the primary cause of chronic plantar heel pain. As the heel lifts from the floor during late midstance the plantar fascia becomes taught, assisting the foot in becoming a rigid lever to allow for effective propulsion. If the heel lifts early due to a tight and ineffective posterior group muscle, then the plantar fascia is put under strain sooner in the gait cycle. This increases the length of time the fascia is under load and there is an increased amount of tensile stress applied to the fascia. (11) This positive correlation between Achilles tendon loading and plantar fascia tension has been indicated as a primary cause to plantar heel pain (12)

Relationships between plantar heel pain and arch dimensions have been scrutinised, giving many hypothesised theories as to the role of the plantar fascia in foot geometry. Pronation of the subtalar joint and midfoot along with dorsiflexion and eversion of the forefoot lowers the height of the inner longitudinal arch.(13) This complicated mechanism of foot motion is thought to elongate the fascia by over 6mm and therefore alter the collangeous structure and function leading to weakness and potential for injury to occur.(14) In contrast a supinated or pes cavus foot classification have shorter plantar structures which are tight and do not bear load as well, therefore when loaded repeatedly these structures become torn and weakened. Both foot types are known to have altered posterior group function during gait with an increased amount of force being directed through the Achilles tendon in both foot types. This increases the relevance of posterior group function and the correlation to plantar heel pain.

The windlass mechanism has been used to describe the tightening affect seen in the plantar structures during gait. This winding of the plantar fascia around the metatarsals assists in the elevation of the foot. (15) Altered forefoot propulsion from 1st metatarsal phalangeal joint pathologies can change this normal mechanism again leading to increase stress on the plantar fascia and an elongation of the fibres at the insertion. A truss structure can be used to describe the effect this has on the plantar fascia. (Fig 2)This coupled again with increased stress at the Achilles tendon can contribute to tears in the fibres at the insertion.

  1. Navicular – height lowers, loading the fascia
  2. Achilles load and pull increases
  3. tensile stress Windlass around 1st
  4. Metatarsal loads
  5. fascia
  6. Micro tears at insertion
  7. Plantar fascia increased tensile stress

Fig 2 Truss like structure of the plantar fascia and how the load can increase.

The intrinsic muscles of the foot have been shown to become more active when plantar heel pain is present. (14) This increased activity could be related to reduced stability at the forefoot during propulsion. The combination of all the above mechanisms provides a stressed environment for the fascia and surrounding tissues to work in. Increased loads, alterations in mechanics and excessive muscular activity have been observed in patients who present with plantar heel pain.

Other factors to consider in the aetiology are the alteration in fat pad properties, which have been suggested as an influential factor in the development of heel pain.(6) If the shock attenuation properties have become diminished then underlying structures become subjected to further pressure. This coupled with irritation to the calcaneal periosteum are contributing factors in plantar heel pain cases. A combination of the above mechanisms must be considered when trying to describe the aetiology of plantar heel pain.

Diagnosis

Clinical diagnosis is made from a patient history, tenderness overlying the insertion of the fascia, changes in thickness of the fascia, alteration in flexibility and function of the fascia. Ultrasound examination has proven effective in assessing thickness of the fascia and also identifying changes in the enthesis. (2) Standard lateral weight bearing radiographs may show a calcaneal spur, however this is not indicative of pathology and supports the fact of increased tension on the plantar fascia. (16)

Differential Diagnosis

Ineffective first line treatment and negative pain around the fascia may lead to an altered diagnosis. Table 1 lists some common alternative diagnoses and there presentation.

Pathology

Clinical Presentation

Tarsal Tunnel

Pain more medial, around the malleolus and

described as a burning sensation. Positive Tinnels sign on compressing tibia nerve. Symptoms persist after rest

Fat Pad Atrophy

Visible reduction in thickness of fat pad,

alteration in elasticity. Elderly or inflammatory arthritis.

Calcaneal Apophysitis

Pain at insertion of Achilles tendon, 8-15 years

old, pain on activity, irregularity in apophysis.

Sciatica

Referred pain from the sciatic nerve due to

compression on L5- S1- Usually accompanied

with pain down back of leg. Pain on elevation of thigh in prone.

Calcaneal Stress Fracture

Increased pain on medial lateral compression of

calcaneus. High level of activity

Table 1 Differential Diagnosis of Plantar Fasciitis

Treatment

There is an extensive choice of conservative and invasive treatments available for plantar heel pain with varying reports as to the effectiveness. The different therapies are highlighted in figure 3.

Orthotic intervention is commonly used to alter foot function and mechanics associated with elongation and stress on the plantar fascia. When dysfunction of the posterior group coupled with pes cavus or reduced inner longitudinal arch are present altering these parameters is thought to contribute to recovery from plantar heel pain. However, the exact role an orthoses plays is not truly understood but the effectiveness of introducing a device, be it custom or perform, has been shown to reduce symptoms in the short term. (19,20,21) With this in mind it is also an essential part of treatment to assess and advise patients about the footwear they wear. A low heel height will irritate the plantar structures when a tight posterior group is present. Footwear advice plays a key role in successful management.

(22) Invasive therapies do play a role in management in chronic and complicated cases. Corticosteroid injections have been shown effective in pain management. (17, 18) The long term effects of such treatment are not full reported on and care should be present on administration due to the destructive nature of the drug. In severe cases that have not responded to any of the conservative and injection therapies a fasciectomy may be required. Surgical resection of the fascia immediately reduces strain and pain experienced. However the implications of removing such a structure should be seriously considered. (18)

Considering the discussed aetiology of plantar heel pain, altered posterior muscle group function contributes significantly to strain on the fascia associated with both low and high arch profiles. The influence of this and altered foot mechanics are felt to be the most significant causes of plantar heel pain therefore the 3 therapies that are to be focused on are.

  1. Stretching and exercise of the posterior group.
  2. Taping of the foot to change function.
  3. Intrinsic foot stretching and exercise.

By stretching and strengthening the posterior group muscles there will be an altered heel lift reducing the incident of the heel being lifted earlier than required. The connection between the plantar fascia and Achilles tendon will also be effected by the stretches and the tension wil l be reduced. See figures 4, 5 & 6.

 

Fig 4                                                               Fig 5                                             Fig 6

Figure 4 demonstrates a method of stretching the Achilles tendon and posterior group muscles. Figure 5 can be referred to as a neutral or resting position and figure 6 eccentrically strengthens the muscle.

Altering the position of the arch by increasing support will also reduce the tensile stress applied to the fascia. Taping is an external reinforcement of internal structures. It can used to influence joint position, increase proprioceptive feedback, improve stability and reduce function. Low dye taping is traditionally utilised for plantar heel pain,(16) however the effectiveness of tape has been shown to be as little as 2-3 hours (17) The application of ‘Dyes’ technique is skilled and repeat application by the patient proves to be ineffective. Modified techniques are more user friendly and can still address functional issues. See figures 7&8 for a modified Dye tape and Fig 9 for a basic heel lock.


Fig 7 medial view                          Fig 8 plantar view.               Fig 9 Alternative approach

The modified dye is applied with patient in prone, with the foot relaxed over the couch. From the medial border of the 1st metatarsal phalangeal joint pull a strip of tape along the arch and around the calcaneus finish on the lateral border of the foot around the styloid process. Repeat this slightly above and below the original tape. Anchor the 1st meatatarsal with a strap from the dorsum to plantar, increasing the plantarflexion of this joint. Finish with a stirrup from the lateral border pulling up to the navicular. This can be repeated and will increase the shock attenuation of the plantar fat pad.

Exercise and stretching of the intrinsic muscles have been shown to be effective in recov ery from plantar heel pain (14) By stretching the insertion of the plantar fascia and the central band then the tensile load capabilities of the fascia are improved. Figure 10, 11, 12.

        Fig10                                                                Fig11                                              Fig12

Improving the function of the flexor and intrinsic foot muscles is thought to improve forefoot stability at the end stage of midstance. Figure 13&14.


                               Fig 13                                                                         Fig 14

Prognosis

It has been reported that most heel pain sufferers have a resolution in symptoms, with self rectification occurring in 6-12months. (16) Advancing to surgical fascietomy is a last resort and is known to cause complications on the lateral border of the foot (25)

Figure 2 Summary of available treatments for plantar heel pain (17-24)

References

1) Shaw, H.M. et, al. Development of the human Achilles tendon enthesis organ. 2008. J Anat. 213(6):718-24

2) Wearing ,S.C. et, al. Plantar Fasciitis: Are Pain and Fascial Thickness Associated With Arch Shape and Loading? 2007 Physical Therapy 87(8);1002-1008.

3) Snow,S.W. et, al. Anatomy of the Achilles tendon and plantar fascia in relation to the calcaneus in various age groups. 1995 Foot Ankle Int.16(7):418-21

4) Lemont, H. Ammirati, K. usen, N. Plantar Fasciitis – A degenerative Process( Fasciosis) without inflammation. 2003 J.Am.Podiatr Med Assoc 93(3):234-237.

5) Chang et al. Kinematics and anti-phase coordination of the rearfoot – forefoot couple in chronic plantar fasciitis. 2007 Society of Biomechanics.

6) Wearing, S.C.et , al. Bulk Compressive properties of the heel fat pad during walking: A pilot investigation in plantar heel pain 2009 Clinical Biomechancis 24(5): 397-402.

7) Draves.D. Anatomy of the lower extremity . Williams and Wilkins 1986.

8) Martin, J. et al Mechanical Treatment of Plantar Fasciitis 2001 J.Am.Podiatr Med Assoc 91 (2) 55-62.

9) Kalaci, A. et al. Treatment of plantar fasciitis using four different local injection modalities 2009 J.Am.Podiatr Med Assoc 99(2)108-113

10) Gladman, D.D. et, al. International spondyloarthritis – INSPIRE study. Assessment of peripheral joints, enthesitis and dactylitis. 2007 J.Rheumatol 34(8): 1740-5

11) Wearing, S.C. et, al. The Pathomechanics of Plantar Fasciitis. Sports Med 2006; 36(7):585-611.

12) Cheung JT, Zhang M, An KN. Effect of Achilles tendon loading on plantar fascia tendon in the standing foot 2006 Clinical Biomechancis 21(2).

13) Chang et, al. Kinematics and Antiphase co-ordination of the rearfoot:forefoot coupling in chronic plantar fasciitis 2007 J. Biomechanics 40 S179

14) Chang et, al. Energetics of the intrinsic foot muscles in plantar fasciitis. Journal of foot and ankle research 2008 1(Suppl).

15) Bogola . L. A. Plantar fasciitis and the windlass mechanicsm: a biomechanical link in clinical practice 2004 Athl Train.; 39(1): 77–82.

16) Tudor, G.R. et, al. The role of bone scintigraphy and plain radiography in intractable plantar fasciitis. Nuclear Medicine. 1997 18(9)

17) Kalaci, A. et, al. Treatment of Plantar Fasciitis Using Four Different Local Injection Modalities.2009 J. Am. Podiatr Med Assoc 99(20)

18) Pribut S. Current Approaches to the Management of Plantar Heel Pain Syndrome, Including the Role of Injectable Corticosteroids 2007. J. Am. Podiatr Med Assoc 97(1)

19) Landorf, K. et al. Effectiveness of Foot Orthoses to Treat Plantar Fasciitis A Randomized Trial. 2006 Arch Intern Med;166:1305-1310

20) Landorf, K. et, al. Effectiveness of Different Types of Foot Orthoses for the Treatment of Plantar Fasciitis 2004 J.Am.Podiatr Med Assoc 94(6)

21) Martin, J. E. et, al. Mechanical treatment of plantar fasciitis 2001 J.Am.Podiatr Med Assoc 91(2)

22) Kogler, G.F. et al. The effect of heel elevation on strain within the plantar aponeurosis: in vitro study 2001,The Foot international, 22 (5).

23) Maier, M. et, al. Extracorporeal shock wave application for chronic plantar fasciitis associated with heel spurs: prediction of outcome by MRI 2000 J Rheumatol 27(10)

24) Rompe, J.D. et, al. Evaluation of low-energy extracorporeal shock wave application for treatment of chronic plantat fasciitis. 2003 Clin J Sport Med. Jan;13(1):64.

25) Crawford, F. & Thomson, C. Interventions of treating plantar heel pain. 2000 Cochrane Database Syst Rev. ;(3):CD000416.