Literature Review – Heel Pain

Plantar heel pain is a very common and painful condition.  One United States study estimates that one million patient visits each year are for the diagnosis and treatment of plantar heel pain. (1 in Radford, 07)  This disorder appears in the sedentary and geriatric population (2-4 in Radford), it makes up one quarter of all foot injuries in runners (5 in Radford), and is the reason for 8% of all injuries to people participating in sports. (6-8 in Radford, 07)  The exact nature of the disorder as well as the most appropriate treatment, however, remains unclear. (Martin 98, Radford 07, Wolgin 94, Crawford 02, Gill 97, Gill 96, Davis 94, Lynch 98)  A study of 364 painful heels could find no causal relationship. (Lapidus in Wolgin 94)  Few random, controlled studies document the efficacy of conservative care, (Barrett 11/06, Atkins in Barrett article, Radford 07, Crawford 02, Davis 94) ,yet success rates for conservative treatment of plantar heel pain vary from 46% to 100% in the literature. (Wolgin 94, Martin 98, Lynch 98,)   It becomes clear from a review of the literature that the etiology of plantar heel pain is multi-factorial i.e. “multiple etiology heel pain syndrome”.  There is not one specific cause, nor is there a panacea for conservative treatment.  In 1972, Snook and Chrisman (36 in Wolgin) wrote “ it is reasonably certain that a condition which has so many different theories of etiology and treatment does not have valid proof of any one cause”.  Are we any better off today?

The management of plantar heel pain begins with the correct differential diagnosis. (Gill 97, Shapiro 97, Meyer 02)  Plantar fasciitis is the most common diagnosis for plantar heel pain. (1-Aldredge in Barrett 06)  Clinical findings include medial heel pain which is often worse in the morning, worse after periods of rest, worse after prolonged weight bearing activity, and pain to palpation at the medial/plantar heel. (Perelman 95, 10-Scherer in Richie, Gill 97)  Most researchers agree that the pain is caused by microtrauma to the origin of the plantar fascia at the medial tubercle of the calcaneus. (Perelman 95, Richie 05, 7-Grasel in Richie 05, 10-Scherer in Richie, 7-Schon in Gill 97).  Subsequently, this microtrauma causes marked thickening and fibrosis at the origin of the plantar fascia. (Grasel in Richie, Schepsis, Martin 98) Many practitioners believe that the pain of plantar fasciitis is caused by inflammation. (Barrett, Khan’s work, Almekinder)  However, researchers have shown through histological examination that there is an absence of inflammatory cells in chronic overuse tendinopathies. (Khan’s, Almekinder, Huijregts 99, Puddu 76)  Animal studies conclusively demonstrate that, within 2-3 wks of insult to tendon tissue, inflammatory cells are not present. (Khan BMJ 02)  Histologic findings from plantar fasciotomies have been presented to support the thesis that plantar fasciitis is a degenerative fasciosis without inflammation, not a fasciitis. (Lemont, Schepsis 91).  In addition to the absence of inflammatory cells, tendinosis is characterized by a degeneration of tenocytes and collagen fibers with a subsequent increase in non-collagenous matrix. (Khan)   The collagen tissue of tendons, for example, have only 13% of the oxygen uptake of muscle and require >100 days to synthesize collagen. (Khan, 94-95 in Khan)  Thus, tissue repair in tendinosis may take 3 to 6 months. (Khan)  With this increasing body of evidence suggesting fasciosis, not fasciitis, the practitioner needs to shift his/her treatment perspective.

As payers demand practitioners to maximize outcomes and minimize costs, the need for evidence-based interventions becomes clear.  As stated above, however, there are few studies that have tested the efficacy of treatment protocols. (Khan, plus above)  The first treatment goal for plantar fasciosis should be to protect the healing tissue. (Khan, Chandler 93, Cornwall 99, McPoil 95, Ross 02, Crosby 01))  How can damaged tissue heal if environmental stresses are not controlled? (McPoil 95)  The second goal should be to restore the normal mechanical behavior of the tissue and to positively influence the structural reorientation of damaged collagen fibers. (Graston)  Physical therapists have proposed that the treatment of plantar heel pain should be impairment based. (Young 04)  A detailed examination would identify these impairments and an appropriate plan of care would utilize manual therapy, exercise, and modalitites. (Young 04)  There is no standard physical therapy protocol for plantar fasciosis, however, upon review of the literature by this author, a framework of evidence is available to establish an appropriate protocol.

Iontophoresis and corticosteroid injections have been used to treat the proposed presence of inflammation at the origin of the plantar fascia.  Iontophoresis is a process that uses bipolar electric fields to propel molecules of a drug such as dexamethasone across intact skin and into underlying tissue. (Anderson 03)  The depth of drug penetration averages 8-12 mm with deeper penetration occurring through a slower process of passive diffusion. (Anderson 03, Li 95, Costello 95)  Two articles have documented an improvement of plantar heel pain using iontophoresis with dexamethasone, yet long term relief was questionable. (Gudeman 97, Page 99)  Steroids have been shown to inhibit the early stages as well as the later manifestations of the inflammatory process. (Fredberg 96)  Corticosteroid injections for relief of plantar heel pain have had mixed results. (Martin 98, Wolgin 94, Crawford 02, Acevedo 98, Davis, Gill)  However, ultrasound guided peritendinous injections of achilles and patella tendonitis have shown a significant reduction in the average diameter of the affected tendons (Fredberg 04) as well as a disappearance of neovascularization. (Koenig in response)  Improper injection technique may be the reason for unfavorable results. (Wolgin 94)

Tissue protection can occur through rest, activity modification, taping techniques, and foot orthoses.  Low-dye taping and various plantar strapping techniques have been shown to be effective in relieving plantar heel pain as well as altering foot kinematics and plantar pressures. (Lange 04, Hyland 06, Keenan 01, Holmes 02, Vicenzino 00)  Although limited evidence exists  (Gross 02, Kogler 99, Kogler 96, Scherer&Waters 07, Mundermann 03,Razeghi 00, Pfefer, Lynch), no conclusive evidence has been found to demonstrate the effectiveness of foot orthoses on plantar heel pain. ( Young 04, Lynch, Gill, Davis, Gross 02, Brown 95, Landorf in Pod Tod)

Manual therapy procedures used by medical practitioners can include soft tissue mobilization, massage, manual traction, joint mobilization, and joint manipulation. (DiFabio 92)  Clinical interventions involving joint mobilizations and manipulations have been developed or refined by many authors. (Difabio 92, In DiFabio Maitland Periph/Spine, Grieve, Kaltenborn Periph/Spine, Cyriax, McKenzie)  Although there is clear evidence to justify the use of manual therapy on spinal disorders, there is an absence of controlled trials in peripheral joints. (DiFabio 92)  We can only speculate that a relationship exists between the identified joint impairment and the patient’s plantar heel pain. (Young)  There is, however, a body of work that attempts to demonstrate the effect of mobilizations and/or manipulations of the talus and fibula on ankle dorsiflexion range of motion, yet with varied results. (Dananberg 00, Pellow 01, Denegar 02, Soavi 00, Nield 93, Dimou 04, Green 01)

Dorsiflexion range of motion restrictions have been identified as a significant impairment associated with plantar heel pain. (Young 04)  One study reported a 5 degree or more dorsiflexion restriction in 78% of his patient population with unilateral plantar fasciitis. (Amis 88)  Numerous studies have shown that heel cord stretching is one of the most effective treatments for resolving plantar heel pain. (Richie, Wolgin, Gill, Davis, Pfeffer)  Plantar fascia-specific stretches have been shown to be even more effective than calf stretches in alleviating plantar heel pain (DiGiovanni 03,06)   Due to the viscoelastic properties of muscle-tendon units, the duration of the stretch, active warm-up, and the concept of reciprocal inhibition can influence the outcome of stretching. ( Shrier 00, Taylor 90)  Dorsiflexor and plantarflexor muscle weakness via isokinetic testing has  also been identified as impairments in chronic plantar fasciitis. (Chandler 93, Kibler 91)

Collagen production is probably the key cellular phenomenon that determines recovery from tendinosis. (Khan 00)  Animal experiments have revealed that loading the tissue improves collagen alignment and stimulates cross-linkage formation, both of which improve tensile strength. (Khan 00, Villarta #34 in Khan 00)  Interventions such as friction massage (DeLuccio, Loghmani 05, Davidson, Gehlsen 98, Chamberlain 82),  ultrasound (Enwemeka 89, Ramirez 97, Young 89, Crawford/Snaith 96,Gum 97,Speed 01, DeDeyne 95,Dyson 68, Noble 06,Cunha 01,Draper 95,Doan 99Jackson 90,Ng 03,Harvey 75), and eccentric exercise (Stanish 85,Cannell 00,Ohberg 02,Alfredson 98, Khan 99,00,00 have been shown to stimulate collagen production and, thus, help to reverse the tendinosis cycle.

The purpose of this outcome study is to determine the effect of a standardized treatment protocol on a group of subjects that present with the diagnosis of plantar fasciosis or fasciitis.  The subjects are required to have at least 3 of the 4 criteria listed above for the diagnosis of plantar fasciitis and to have a >4 week history of plantar heel pain.  The specific goals of this outcome study are the following: 1) to evaluate how the subject population responds to the treatment protocol in terms of pain reduction and functional outcome measures, 2) to determine improvements in ankle dorsiflexion range of motion utilizing the protocol, 3) to assess changes of thickness at the origin of the plantar fascia via diagnostic ultrasound after utilizing the protocol, 4) to investigate the duration of time between start of treatment and maximal improvement in symptoms,  5) to investigate the time relationship between onset of symptoms and start of treatment to clinical outcome, 6)  to investigate and document any reoccurrences of symptoms while performing a maintenance home program over a 6 month period, and 7) to assess patient compliance with the home program.