Assessment of Plantar Heel Pain - A Literature Review

Original Editor - User Name

Top Contributors - Merinda Rodseth, Jess Bell, Kim Jackson, Ewa Jaraczewska and Olajumoke Ogunleye  

Introduction

The diagnosis of plantar heel pain syndrome (PHPS) is predominantly based on the symptoms of the patient together with manual palpation of the painful heel . Validation of this diagnosis through the use of a reliable clinical test is however still elusive.  Assessment tools are essential for the optimal management of patients - not only as a way to assess the status of the patient, but also the efficacy of treatment interventions and as a guide to which treatment methods to use.

Assessment Tools for PHPS

A variety of tests have been proposed for the assessment and diagnosis of PHPS but none have been accepted as the “gold standard”. This necessitates an analysis of the available research to identify which of the proposed tests are reliable and valid for assessing PHPS (Figure 1).

Figure 1. Assessment tools for PHPS

Windlass Test

The “windlass mechanism” describes the way in which the plantar fascia supports the foot during weight-bearing activities while providing information about the biomechanical stresses placed on the plantar fascia. Hicks originally described the foot and its ligaments as an “arch-like triangular structure” with the plantar fascia forming the base/tie-rod that run from the calcaneus to the phalanges . With the propulsive phase of gait, the plantar fascia is wound around the head of the first metatarsal during ankle and hallux dorsiflexion, which shortens the distance between the calcaneus and the metatarsals. The shortening of the plantar fascia that results from dorsiflexion of the big toe simulates the “windlass” (tightening rope/cable) mechanism .

The Windlass Test, therefore, induces strain on the plantar fascia through forced dorsiflexion of the great toe which is associated with an increase of pain at the site of the insertion of the plantar fascia in patients with plantar fasciitis . De Garceau et al studied the association between the diagnosis of plantar fasciitis and the results of the Windlass test and found that even though the test is specific for PHPS, it had a low rate of sensitivity which limits its value in clinical evaluation (Figure 2).

Figure 2. The association between the diagnosis of plantar fasciitis and the Windlass test results

The strain induced with first metatarsal extension was also not limited to the plantar fascia alone, but included various structures in the foot, including the tibial nerve and the medial plantar nerve .

Palpation of the Painful Heel Area

Manual palpation of the heel by thumb pressure is a common tool used by clinicians to locate the exact site of pain, which is proposed to aid with the diagnosis and prescription of treatment in patients with PHPS . No study has however quantified the mechanical pressure needed to elicit pain in patients with PHPS and no clinical trials exist to support it as a valid assessment tool for PHPS .

Figure 3. Topographic distribution of pressure pain sensitivity of the heel

Saban & Masharawi used pain pressure threshold (PPT) to assess the area and extent of pain sensitivity in individuals with and without heel pain (Figure 3). They identified the anterior medial heel as the most sensitive location in the heel but no significant differences were found between those with and without heel pain (Figure 4), making the test not sensitive enough for PHPS and therefore not a diagnostic tool for heel pain .

Figure 4. Pressure pain threshold values

Imaging

Imaging is generally useful for acquiring accurate diagnoses, prompting appropriate treatment and determining prognosis . Various imaging methods, including conventional radiograph, ultrasound and magnetic resonance imaging (MRI), have been used to assess various structures implicated in plantar heel pain (Figure 5) .

Figure 5. Imaging modalities and tissues examined

Imaging of the plantar fascia

Individuals with PHPS were found to be 105 times more likely to present with a thickened plantar fascia measuring more than 4.0 mm compared to those without making it a reliable sign of PHPS .

Following this, Mahowald et al investigated the correlation between plantar fascia thickness and symptoms of plantar fasciitis as a way to gauge the efficacy of treatment modalities and found that a reduction in pain correlated strongly with a reduction in plantar fascia thickness. The thickness of the plantar fascia however remained above 4 mm, which would still be indicative of PHPS (Figure 6) .

Figure 6. Correlation between Plantar Facia Thickness and Symptoms of Plantar Fasciitis

Rathleff et al used thickness of the plantar fascia as an outcome measure to assess the efficacy of shoe inserts and plantar fascia specific stretching vs shoe inserts and high-load strength training in patients with plantar fasciitis. They also reported a reduction in plantar fascia thickness in both groups but similarly the plantar fascia thickness remained more than 4 mm (Figure 7) .

Figure 7. Changes in Plantar Fascia Thickness with a stretch and strengthening program

Additional imaging findings related to the plantar fascia can be found in Figure 8 .

Figure 8. Additional characteristics of the plantar fascia as evident with imaging

Imaging of other structures in the foot

Besides plantar fascia thickness, heel pads and calcaneal spurs are also evident on imaging, but, as previously discussed in the lecture about risk factors, are not significant in PHPS. The influence of electromyography will be discussed in more depth in the lecture on anatomy (Figure 9).

Figure 9. Imaging of other structures of the foot

Even though medical imaging studies can be useful in detecting abnormalities in the feet of individuals with heel pain, there is still controversy  about its ability to identify individuals with PHPS and to reflect meaningful changes in the condition of the patient. It is also not commonly available to many clinicians for the on-site assessment of patients .

Tinel’s Tarsal Tunnel Test

Figure 10. Structures in the tarsal tunnel

Tarsal tunnel syndrome has also been attributed as a cause of plantar heel pain following entrapment of the tibial nerve or its branches in the fibrous tarsal tunnel (Figure 10) . Tinel’s tarsal tunnel test, which involves tapping on the tibial nerve at the tarsal tunnel eliciting pain/tingling in the heel, has therefore been suggested as an assessment for PHPS (Figure 10) . There is however currently no evidence for the use of Tinel’s tarsal tunnel test in PHPS.

Patient Reported Outcomes

Following the lack of objective measures to assess PHPS, many studies have used patient reported outcomes (PRO’s) as a way to gauge the efficacy of treatment modalities in individuals with PHPS . Both Clinical Guidelines on heel pain by the American Physical Therapy Association recommended the use of four different PRO’s/questionnaires in the assessment of PHPS (Figure 11).

Figure 11. Patient reported outcomes recommended by the Clinical Guidelines of the American Physical Therapy Association

Martin et al proposed that in order to properly interpret their scores, outcome measures for the foot and ankle should possess four distinct qualities and that these should also be considered by clinicians when selecting and using an outcome measure (Figure 12).

Figure 12. Categories of evidence for PROs

Following this, Martin et al recommended the use of 5 instruments in individuals with foot and ankle-related pathology, four of which also coincided with those proposed by the Clinical Guidelines of the American Physical Therapy Association (Figure 13) .

Figure 13. Self-reported outcome measures for the foot and ankle

In a meta-analysis study of the foot and ankle literature from 2002-2011, Hunt et al identified 139 different questionnaires for foot pain. The  five most popular PRO’s used included the Foot Function Index (FFI), which was also included in the Clinical Guidelines (Figure 14) .

Figure 14. The five most popular PRO’s for ankle and foot pain

In conclusion on PRO’s it is worth mentioning a few final points that can be found in Figure 15 .

Figure 15. Conclusion on PRO’s

PRO’s might be ideal for determining the patient’s perception of their abilities but fail to fully capture the extent of the patient’s functioning . PRO’s is thereby also more useful for assessing a series of treatment rather than individual treatments .

What do Physiotherapists do?

Following the lack of objective measures for the assessment of PHPS, Grieve & Palmer conducted an online survey on the current practice of Physiotherapists in the UK for plantar fasciitis. A summary of their findings on the diagnostic tests/criteria used by physiotherapists to confirm a diagnosis of plantar fasciitis from the 257 completed questionnaires received, is displayed in Figure 16 .

Figure 16. Current Practice of Physiotherapists for diagnosing plantar fasciitis

Each of these factors can however be faulted based on a lack of supporting evidence, as has been discussed in the literature review lectures of this programme about PHPS. This reiterates the lack of evidence for physical examination tests to be used in the clinical assessment of patients with PHPS and brings us to the aim of this course series - the introduction of a new protocol for PHPS which will be discussed in detail further along the series. Saban & Masharawi have identified three clinical tests that can provoke the relevant heel pain in individuals with PHPS and can therefore be useful in the assessment of PHPS - single leg static stance, single leg half squat, and single leg heel raise. These will be further discussed in the lecture on the proposal of a new protocol.