George Ampat and Richu Philip ask, would the use of an iStep scanner to determine a specific prefabricated orthotic best suited for the patient be more beneficial than using a standard orthotic in the treatment of plantar fasciitis?
Aim
Orthotics are commonly used in the treatment of plantar fasciitis. This study aims to distinguish whether an orthotic selected based on a pedobarograph (plantar foot pressure measurement) offers better symptom relief in comparison to a standard orthotic.
Hypothesis
A specific prefabricated orthotic selected following a pedobarograph and recommendation of the iStep scanner will be a more effective treatment modality than a standard orthotic.
Background
Plantar fasciitis (PF) is the most common cause of inferior heel pain, estimated to occur in 10 per cent of the population during their life course [1,2]. Although the exact aetiology is not understood, PF tends to affect those who have a Body Mass Index (BMI) over 30, those involved in weight-bearing occupations, middle-aged women and in athletes [2]. Young male runners seem to be more affected than other athletes by plantar fasciitis [3]. Despite being at different ends of the spectrum, the overall evidence suggests that both a sedentary lifestyle and high intensity activities can lead to plantar fasciitis. This is due to the excess pressure exerted on the foot [4].
Pathogenesis:
In order to understand plantar fasciitis, it is crucial to consider the normal anatomy and structures of the foot. The skeletal structure of the foot is composed of seven tarsal bones, five metatarsals and phalanges. The seven tarsal bones include the talus, calcaneus, navicular, cuboid and three cuneiforms [5]. These bones are arranged in two arches, longitudinal and transverse, they are held in place by ligaments and tendons. These arches are fundamental to the biomechanics of the foot, they support the body weight and gives leverage for walking. Since the arches are not rigid, they yield when weight is imposed and spring back up when the weight is removed. This way energy is stored for the next step and any shock to the foot is absorbed [5]. Figure 1 illustrates the bones of the foot and the arches [5].
Figure 1: An illustration of the bones and arches of the foot.
Anatomically, the foot is divided into dorsal (top of the foot) and plantar (under surface of the foot) sides. Muscles, tendons and ligaments allow the movement of the foot as well as provide support. The plantar fascia is deep connective tissue that runs from the calcaneus bone and then splits into five branches, one going to each of the digits [6]. The function of the plantar fascia is to support the longitudinal arch of the foot and the tendons that allow the foot to flex [5]. Plantar fasciitis refers to the inflammation of the plantar fascia due to prolonged irritation causing pain or discomfort. The exact cause of the condition has not yet been pinpointed, however it is believed that excess tensile pressure on the fascia is the cause. Abnormal biomechanics of the foot such as pes planus (flatfoot), leg length discrepancy and calf muscle tightness have been attributed to cause increased loading of the fascia [7]. It is suggested that this extra pressure on the longitudinal arch and the plantar fascia leads to microscopic tears and inflammation in the fascia. Analysis of the histologic features of the condition has shown thickening and fibrosis, calcification and collagen necrosis of the plantar fascia [8].
Diagnosis:
The diagnosis is primarily clinical as it classically presents “first step pain”, referring to pain upon walking after waking up in the morning. The pain then slowly subsides throughout the day, but with acute exacerbations when rising after a period of inactivity [4]. Patients usually experience pain in the medial plantar part of the heel [8]. A “Windlass test” is performed during a musculoskeletal examination of both of the lower legs. The test is positive if pain is elicited on palpation of the medial plantar heel and during dorsiflexion (pointing the foot towards the ceiling/upwards) of the ankle and toes [8]. Imaging is not necessary, other than to eliminate the possibilities of other conditions.
Treatment:
Initially, patients are prescribed over-the-counter Non-Steroidal Anti-inflammatory Drugs (NSAIDs) for analgesic purposes. They are advised to implement lifestyle changes that reduce tensile loading of the foot such as weight-bearing and focused stretches that target the plantar fascia [8,9].
Orthoses are a non-invasive and cost-effective treatment currently available to patients with plantar fasciitis. Many studies have shown that orthoses can provide symptom relief for patients. An orthotic occupies the space between the foot and shoes, meaning there is an increased contact area, allowing the stress from the longitudinal arches to be distributed to the medial aspects of the foot [10]. One particular participant in a blinded randomised control study which compared the effectiveness between sham orthoses, prefabricated orthoses and customised orthoses found that both prefabricated and customised orthoses provided better pain relief than the sham orthoses. However, there was no significant differences between prefabricated and customised orthotics [11]. Having considered this result, it is important to consider that customised orthotics are significantly more expensive (£200-£275) than prefabricated orthoses (£40-£80), the difference in cost-effectiveness is staggering [11].
Another method of treatment available for plantar fasciitis is types of injections. One is corticosteroid injections, they have an anti-inflammatory effect on the body. Another treatment administered via injection is autologous blood injections, this is when the patient’s own blood is injected into an area which requires healing [12]. A study by the American Orthopaedic Foot & Ankle Society compared these two methods. They found that although corticosteroid injections provide faster relief in pain, its effectiveness plateaued over time and was similar to that of autologous blood injections. Despite the signs of improvements with injections, the study recommends that non-invasive treatments such as orthoses should be used as first line therapy, since they are very much less invasive. Side effects of injections can include potential rupture of the fascia [13].
External Shock Wave Therapy (ESWT) is a form of treatment where shock waves are applied onto the affected area through the skin. It is suggested that this dissolves deposits around the plantar fascia, allowing healing. It has been shown that ESWT can be effective in treating plantar fasciitis, it is recommended if conservative treatment has failed [14]. However, ESWT requires several clinic appointments and it is labour intensive as well as time consuming for the patient.
A recent study assessed the effectiveness of percutaneous plantar fasciitis release (needle procedure through the skin), it showed that results in 88.46 per cent of patients were excellent [15]. This could potentially be an effective method. Although less invasive than fully subcutaneous surgery, it is still more invasive in comparison to other treatment methods.
iStep pedobarograph:
The iStep is a static pedobarograph which measures the pressure exerted by the foot while standing and an image is produced. The measurements and image is then used by the iStep software by its algorithm to suggest three orthotics. The first suggestion is the most suitable for the participant. Effectively, the iStep scan matches a specific prefabricated orthotic to the particular patient depending on the mechanics of their foot. The iStep scanner is a product of Aetrex Incorporation. Aetrex® IStep® (Aetrex Worldwide, Inc. 414 Alfred Avenue, Teaneck, NJ 07666, USA).
Research design
The study aims to recruit 100 voluntary participants who have suffered from plantar fasciitis for three months or more. Participants would be recruited by sending out letters to General Practitioners, social media announcements and other advertisements.
The independent variable in this study is the type of orthotic the participants receive, it will either be a specific prefabricated orthotic as recommended by pedobarograph or a standard orthotic. The dependent variable of the study will be the effect of the orthotic as experienced by each participant. The dependent variable will be quantitatively measured using the “11 point Numerical Rating Scale” (NPRS) and a Self-reported Foot and Ankle Questionnaire (SEFAS). A “Global Rating of Change Scale” will also have to be completed.
In addition to the orthotics the participants are also taught specific stretching exercises, which they are advised to perform during the course of the study.
The study is longitudinal in nature, and aims to record the results over a six-month period. Data will be collected at one month, three months and six months to sustain close monitoring of symptom progression. This is a participant blinded study, so the volunteers will not be aware whether they have a specifically chosen orthotic or a standard orthotic. The table below explains the inclusion and exclusion criteria.
Table 1: Showing inclusive and exclusion criteria.
Methods
Following the inclusion and exclusion criteria 100 voluntary participants will be recruited. They will be required to complete the 11-point NPRS and SEFAS. This will provide the baseline measurement for each participant prior to intervention.
Each participant will have an iStep pedobarograph taken and be taught stretching exercises for the plantar fascia and Achilles tendon which they should adhere to through the course of the study.
Participants will then be randomly divided into groups A and B. This will be achieved by the use of opaque sealed envelopes, assigning each participant to group A or group B.
Group A will be provided with orthotic recommended by iStep scan, first, second or third recommendation is chosen depending on participant’s size and fit. The choice of orthotic is documented by the researchers.
Group B will be provided with the standard Aetrex L400 orthotic.
Participants are asked to complete the 11-point NPRS, SEFAS and Global Rating of Change at one, three and six months.
Discussion
Strengths:
This study fills in a current gap in literature, as there are several studies, which have explored the use of orthoses in the treatment of PF. A handful of studies have also compared the effectiveness of fully customised orthoses in comparison to standard orthoses. However, despite the use of pedobarograph and foot measurements being in clinical use for some time, not many studies have tested its use to determine a specific prefabricated orthotic for the treatment of PF, to the best of researcher’s knowledge. Therefore, this study will be a valuable contribution to the field.
This study could potentially provide a middle-ground solution between a standard orthotic and a customised orthotic. As aforementioned, customised orthoses are extremely expensive and so might not be accessible to all.
The fact that the study is longitudinal allows sufficient time for the actions of orthoses to occur, if any. This is in concurrence with previous literature, which has suggested that the best outcome from treatment for plantar fasciitis is present, on average, six months after commencement [8]. The longitudinal nature allows for a follow-up of progress rather than a single snapshot.
Participant blinding enables the results to be more valid, as it can potentially decrease bias or effects of pre-conceptions that participants may hold.
The fact that the participants are advised to perform stretching exercises alongside the use of orthoses is concurrent with current evidence from literature, which suggests that orthoses show optimum benefit when used with stretching exercises that target the plantar fascia and Achilles tendon [16].
Limitations:
The study aims to recruit 100 participants, this is not a very representative sample, so it might not be representative of the population. In addition, since the study is over a six-month period, there is a chance that participants may drop out or not complete the questionnaires as requested. This will be tried to be minimised by giving patients sufficient warning before surveys are due, through their preferred route of contact.
The measurement tools used, although quantitative in nature, it could be argued that they are not entirely objective. Each participant may perceive the phenomenon of pain differently, therefore pain scores can be subjective and vary. However, this is possibly the least invasive and efficient way by which symptoms can be monitored.
Future scopes:
This study allows for the exploration of orthoses in the treatment of PF, which still remain to be a primary first line mode of treatment. This study can encourage future interest into the field.
References
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Authors
Richu Philip, Medical Student, Liverpool Medical School
George Ampat, Consultant Orthopaedic Surgeon, Royal Liverpool Hospital
Conflict of interest
George Ampat has a commercial interest in Feet and Spine, which distributes Aetrex (Lynco) orthotics in the UK.
