- Email: [email protected]
Clinical and Functional Characteristics of People With Chronic and Recent-Onset Plantar Heel Pain
Accepted Manuscript Clinical and functional characteristics of people with chronic and recent onset plantar heel pain Allegra Barnes, PT, B.App.Sc.(Physiotherapy)Hons, Justin Sullivan, PT, PhD, Evangelos Pappas, PT, PhD, Roger Adams, PhD, Joshua Burns, PhD PII:
S1934-1482(17)30540-3
DOI:
10.1016/j.pmrj.2017.04.009
Reference:
PMRJ 1893
To appear in:
PM&R
Received Date: 28 September 2016 Revised Date:
4 April 2017
Accepted Date: 8 April 2017
Please cite this article as: Barnes A, Sullivan J, Pappas E, Adams R, Burns J, Clinical and functional characteristics of people with chronic and recent onset plantar heel pain, PM&R (2017), doi: 10.1016/ j.pmrj.2017.04.009. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Clinical and functional characteristics of people with chronic and recent onset plantar heel pain Allegra Barnes PT, B.App.Sc.(Physiotherapy)Hons1 [email protected] Evangelos Pappas PT, PhD2,4 [email protected] Roger Adams PhD2 [email protected] Joshua Burns PhD3 [email protected]
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Justin Sullivan PT, PhD 2 [email protected]
Physiotherapy Department, Royal North Shore Hospital, New South Wales, Australia.
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Discipline of Physiotherapy, Faculty of Health Sciences, The University of Sydney, New South Wales, Australia.
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Sydney Children’s Hospitals Network (Randwick and Westmead), University of Sydney. New South Wales, Australia
Arthritis and Musculoskeletal Research Group, Faculty of Health Sciences, The University of Sydney, New South Wales, Australia
Correspondence: Justin Sullivan
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Faculty of Health Sciences, The University of Sydney
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P.O Box 170
Lidcombe, NSW, Australia 1825 Phone: 61(02) 9351 9156
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Fax: 61(02) 9351 9601
Email: [email protected]
Author Disclosures:
The authors declare that there are no competing interests or financial benefits to authors with respect to the research, authorship, and/or publication of this article. The study was funded by the Podiatry Council of New South Wales, Australia. The research, manuscript and abstract have not been presented elsewhere.
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ABSTRACT
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Background: Plantar heel pain is a common condition that reduces health-related quality
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of life. Recovery usually occurs within 12 months; however, up to 20 percent of people
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remain symptomatic beyond this time-frame. The level of pain and function in this chronic
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heel pain group is not well described.
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Objective: To identify clinical and functional characteristics associated with chronic
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plantar heel pain compared with heel pain of recent onset.
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Design: Cross-sectional study
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Setting: University research laboratory and private physiotherapy clinic
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Participants: A total of 71 people with plantar heel pain for longer than 12 months and 64
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people with plantar heel pain for less than 6 months were recruited from the general public.
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Methods: Functional characteristics of participants in both heel pain groups were assessed
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using a variety of clinical measures and the Foot Health Status Questionnaire. Clinical
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measures included; Body Mass Index, foot and ankle muscle strength using hand-held
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dynamometry, as well as ankle and first metatarsophalangeal joint range of motion. The
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Foot Health Status Questionnaire was used to collect self-reported measures of foot pain
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severity, foot function and physical activity.
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Main Outcome measurements: Univariate analyses of variance were performed to detect
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differences between the two groups for each of the variables measured.
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Results: The chronic heel pain group exhibited reduced ankle dorsiflexor and toe flexor
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strength, yet better self-reported foot function. There was no difference between groups for
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Body Mass Index, ankle and first metatarsophalangeal joint range of motion, inversion
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strength, eversion strength, calf endurance, self-reported foot pain and physical activity.
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Conclusions: Chronic plantar heel pain is associated with selective weakness of foot and
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ankle muscle groups, but less affected foot function when compared to heel pain of recent
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onset. Those with chronic symptoms may moderate or make adaptations to their daily
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activities, or simply accept their condition, enabling more effective coping. Strength
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deficits, although possibly a cause or consequence of chronic symptoms, suggest a need to
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include resistance exercise in the management of plantar heel pain.
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INTRODUCTION
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Plantar heel pain is the most common foot disorder treated by health care practitioners.[1]
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It occurs in people of both active and sedentary lifestyles,[2,3] with 83% of those with the
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condition being working age adults.[4] In the USA approximately two million people seek
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treatment for plantar heel pain every year,[4] at a cost of over $300 million,[3]
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representing a considerable economic burden on health services.
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Plantar heel pain is a mechanical disorder that is multifactorial in nature.[5] It is thought to
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occur due to excessive stress on the plantar fascia and its enthesis at the calcaneal
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tuberosity.[6] The term plantar fasciitis has been frequently used for this condition,
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however, it is now widely accepted that degeneration and thickening of the plantar fascia
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predominates over inflammatory changes, making this term inaccurate.[7] Current heel
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pain guidelines identify risk factors that include: limited ankle dorsiflexion range of
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motion (ROM), high body mass index (BMI) in nonathletic individuals, running and work
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related weight-bearing activities.[1] Foot and ankle strength deficits have also been
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demonstrated in people with plantar heel pain,[8,9] including a report involving
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participants in this study compared with asymptomatic controls.[8] A clinical
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examination is considered sufficient for the diagnosis of plantar heel pain,[5,10] with the
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major sign being point tenderness on the plantar aspect of the heel at the medial calcaneal
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tuberosity.[11] Commonly reported symptoms include; pain on first steps in the morning
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or following prolonged rest, as well as pain during prolonged standing or walking.[3,5,11]
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Although prevalent, the etiology of plantar heel pain is not well understood.[5] There is
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limited evidence supporting the efficacy of interventions used in clinical practice,[12]
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with a subsequent lack of consensus regarding the ideal management approach.[2,4,13] As
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a result, heel pain is often difficult to treat, and commonly progresses to a chronic
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condition. Up to 20% of people treated using conservative measures report symptoms
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beyond 12 months.[14,15] Furthermore, it is also common for people to present after 12
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months of symptoms.[1] In addition to this, those who experience symptoms for a
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prolonged period prior to seeking medical attention are placed at a higher risk for
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continued symptoms.[15] Once chronic, treatment can become costly, as symptoms are
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recurring, recovery is lengthy and the response to treatment is unpredictable.[3,15] It has
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also been demonstrated that plantar heel pain has detrimental effects on foot specific and
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general health-related quality of life.[16] Such detriments include limitations in
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performing physical tasks, reduced energy to participate in activities, as well as social
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isolation.[16] Thus, there is potential for longer-term health consequences relating to
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reduced mobility for people with chronic plantar heel pain; including weight-gain,
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hypertension, coronary artery disease and non-insulin dependent diabetes mellitus.[7]
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The aim of this study is to compare clinical and functional characteristics between adults
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with recent onset and chronic plantar heel pain. Differences found between the two groups
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could identify characteristics associated with chronic plantar heel pain, of which there is
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little known to date. Such findings may indicate the effect that prolonged symptoms have
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on foot function, as well as assist in uncovering potential risk factors for chronicity. This,
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in turn, could aid the development of specific strategies to manage or prevent chronic
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symptoms.
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METHODS
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Participants
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202 people with plantar heel pain volunteered to participate in the original study.[8]
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People were recruited from the general public between August 2008 and August 2012
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through local media advertisements and notices in medical, physiotherapy and university
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premises. For this analysis, 64 people were included in the recent onset group, and 71
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were included in the chronic group. Participants in the recent onset group were required to
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have experienced symptoms for at least 3 weeks, but less than 6 months. Those in the
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chronic group were required to have experienced symptoms for more than 12 months.
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These periods were selected because evidence demonstrates that the majority of people
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with heel pain experience resolution of symptoms within 12 months, leaving a chronic
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group of people with continuing symptoms past 12 months. Recent onset was determined
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as 6 months or less in order to provide a group for comparison that was well within the
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common recovery time and clearly separated from the chronic group. In accordance with
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current clinical guidelines[1] symptomatic participants were included if they reported
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tenderness on palpation of the medial calcaneal tuberosity and exhibited one of the
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following complaints; pain on the first step in the morning or after prolonged sitting, pain
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on prolonged standing,[1,4] or pain when running.[1] Participants were excluded if they
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had undergone surgery to the plantar fascia or had any of the following conditions:
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systemic arthritis, neurological conditions, lumbar radiculopathy, neurological or vascular
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compromise of the foot related to diabetes, or any coexisting painful musculoskeletal
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condition of the lower limb. Each participant attended data collection on a single occasion
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at either theXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX. In accordance
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with approval from the XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX, written
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consent was obtained, and all participants were screened for the presence of plantar heel
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pain.
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Procedures
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Foot and Ankle Range of Motion
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To measure first metatarsophalangeal joint (MTPJ) extension ROM, participants were
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positioned in long sitting, with the ankle in plantargrade. The assessor extended the first
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MTPJ to maximal range while plantarflexion of the first ray was prevented. The
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landmarks used for the measurement were the navicular, the MTPJ axis, and the middle of
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the interphalangeal joint. The angle formed by these landmarks was measured with a
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goniometer. Ankle dorsiflexion ROM was measured using the flexed knee lunge test [17]
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and the straight knee lunge test.[18] For the flexed knee lunge test, participants were
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instructed to stand, feet shoulder-width apart, with their hands against a wall, and the foot
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being tested one step behind the other. Participants flexed their back knee directly over the
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foot until the heel began to leave the ground. The ROM was measured with a digital
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inclinometer (Chattanooga Baseline; DJO Global, Vista, CA, USA) placed on the lowest
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part of the anterior tibia. The same procedure was used for the straight knee lunge test,
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however the ipsilateral knee was kept straight.
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Strength
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Foot and ankle muscle strength was assessed using handheld dynamometry (JTech
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Commander PowerTrack II; JTech Medical, Salt Lake City, UT). High intratester and
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intertester reliability has been demonstrated using this approach in the assessment of foot
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and ankle muscle strength.[19,20] For each strength test, progressive muscle force was
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developed to achieve a maximum isometric contraction. The maximum force achieved
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from 3 attempts was selected for data analysis.
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For the ankle strength tests, participants sat with their hips in 90 degrees of flexion, knees
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extended, and feet over the end of the examination table. The knees were positioned
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slightly flexed over a rolled towel or pillow and participants were instructed to hold the
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edge of the treatment table for stability. The ankle was then placed in a neutral position by
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the examiner. Flat, comfortable and easily reproducible contact points were chosen for
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dynamometer placement. For dorsiflexion strength testing, the handheld dynamometer
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was placed on the dorsum of the foot, just proximal to the metatarsal heads. For inversion
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strength testing, it was placed on the medial side of the foot, just proximal to the first
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metatarsal head. For eversion strength testing, the dynamometer was placed on the lateral
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side of the foot, just proximal to the fifth metatarsal head.
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For the toe flexor strength tests, participants sat with their knees and hips at approximately
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90 degrees, and their feet on a wooden block. The toes of the foot being tested were
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positioned over the edge of the block, with the MTPJs and interphalangeal joints in
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neutral. For great toe flexor strength testing, the dynamometer was placed longitudinally
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along the plantar aspect of the great toe. For lesser toe flexor strength testing, it was
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placed across the plantar surface of the second, third, and fourth toes. Hand-held
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dynamometry has been shown to be a reliable instrument to measure toe flexor strength,
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with excellent intrarater and interrater reliability.[21]
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Calf endurance was measured using a standardized unilateral heel raise test.[22]
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Participants stood at arm’s length from a wall with their feet underneath a wooden block.
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The participants performed unilateral heel raises on the affected side until fatigue. To
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ensure full range of motion was reached on each repetition, the test protocol required the
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top of the foot or anterior ankle to touch the underside of the block at full heel raise.
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Instructions were given to keep the knee straight, and a metronome was used to ensure
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identical frequency between participants. The number of heel raises was counted and
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recorded, not including attempts that failed to reach the required height or those involving
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knee flexion.
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Foot pain, function and physical activity
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Foot health related quality of life was measured using the Foot Health Status
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Questionnaire (FHSQ) Version 1.03.[23] Three domains of the questionnaire were used in
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the study to quantify foot pain, foot function and physical activity limitation. Each domain
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consists of a series of questions answered on a Likert scale. The foot pain domain consists
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of four questions that pertain to level, frequency and quality of foot pain. The foot
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function domain consists of four questions that examine the extent to which the
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participant’s feet interfere with regular daily activities, work, walking and climbing stairs.
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The physical activity limitation domain exposes if, and, how limited participants are in
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activities as a result of their general health. It asks 9 questions about various activities,
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which include but are not limited to; running, sports, cleaning, carrying shopping,
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climbing a flight of stairs, walking and self-care activities. The Foot Health Status
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Questionnaire Data Analysis Software (Version 1.03) was used to process the data.
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Individual domain scores were calculated and reported from 0 (poorest state of foot
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health) to 100 (optimal foot health). Higher scores reflect better foot health and quality of
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life.
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Toe deformity
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As hallux valgus has been shown to be associated with reduced toe strength [24] and
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poorer foot function, [25] the two groups were compared for the degree of this deformity
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prior to further statistical analyses. Each participant was assessed using the Manchester
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scale, which is a reliable method of grading Hallux valgus. [26] This tool is a four-point
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scale which requires matching an individual’s foot with one of four photographs that
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depict progressive stages of Hallux Valgus; namely, normal, mild, moderate and severe.
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Statistical Analyses
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Statistical analyses were carried out using SPSS, version 22 (SPSS, Inc, an IBM
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Company, Chicago, IL). The groups were compared for age, sex, hallux valgus, height
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and weight prior to further analyses. Age, height and weight differences were assessed
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using independent samples t-tests, hallux valgus by a Mann-Whitney U test, and sex was
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compared using a Chi-square test. The level of significance was set at α = .05. Following
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this, univariate analyses of variance were performed to compare each variable between the
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recent onset and chronic heel pain groups. The level of significance was set at α = .05.
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Partial η2 values were calculated to report an effect size for each variable found to differ
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between the 2 groups. Values greater than .01 were considered representative of a small
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difference, values greater than .06 representative of a medium-sized effect, and values
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greater than .14 representative of a large difference between groups.[27] Less than 1% of
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the complete data set was missing. This included some incomplete questionnaires, as well
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as 3 people unable to perform some strength tests for safety reasons. Table 2 denotes
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group numbers for statistical analyses that were performed with less than the full study
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cohort.
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RESULTS
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The characteristics of the participants in each group are summarized in Table 1. Both
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groups were equivalent for age, sex, height and weight. The groups were also equivalent
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regarding hallux valgus grade (U= 2358.5; p= .672). The results of the univariate
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analyses of variance are summarized in Table 2. Compared with the recent onset heel
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pain group, members of the chronic heel pain group had reduced dorsiflexion strength,
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reduced great toe flexor strength, reduced lesser toe flexor strength, and a higher FHSQ
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foot function domain score. Partial η2 values for dorsiflexor, great toe and lesser toe
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flexor strength were calculated to be .054, .052 and .044 respectively, indicating a small
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effect size. A partial η2 value of .076 was calculated for the FHSQ foot function domain
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score, indicating a medium effect size. There was no significant difference between
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groups for BMI, first MTPJ extension ROM, flexed lunge, extended lunge, inversion
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strength, eversion strength, calf endurance, foot pain domain score, and physical activity
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domain score.
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DISCUSSION
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The findings of this study indicate that, in the general population, people who have had
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plantar heel pain for more than 12 months have deficits in foot and ankle strength when
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compared to those who have had the condition for less than 6 months. An unexpected yet
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interesting outcome of the study was that the chronic group had better self-reported foot
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function compared to the recent onset group, despite these strength deficits. People with
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chronic symptoms, however, have similar BMI, foot and ankle flexibility, and report
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equivalent pain levels and physical activity limitations to those with recent onset
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symptoms.
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Strength deficits were apparent in the sagittal plane directions, including ankle
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dorsiflexion and flexion of the toes. Due to the cross sectional design of the study, it is
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uncertain whether these deficits are a cause or consequence of the condition becoming
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chronic. It may be that as a result of their condition, the gait patterns of those in the
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chronic group are less dynamic, and their functional activities adjusted. Evidence shows
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that people with heel pain have reduced walking velocity, and a less than normal vertical
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component of floor reaction force at heel strike and toe off.[28] It has been suggested that
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this may be an attempt to avoid high stresses on the painful heel throughout the gait
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cycle.[28] As a result of this, muscle recruitment and activation patterns may be altered,
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and therefore result in weakness of the suggested muscles. Gait is a sagittal plane
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dominant movement, which may account for strength reductions in muscle groups that
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have primarily a sagittal based function. Equally, it is possible that the strength deficits
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may have preceded chronicity, and therefore, may instead be a predisposing factor to the
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development of chronic heel pain. The plantar fascia is intricately attached to, and
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associated with, a number of contractile and non-contractile structures. Both intrinsic and
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extrinsic muscles support the longitudinal arch. Therefore, any weakness of these muscles
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could result in excessive stress on non-contractile structures, including the plantar fascia,
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and contribute to continuing heel pain. If this were the case, there would be important
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clinical implications, including the need to screen patients for foot and ankle weakness as
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a risk factor for chronic heel pain as well as implementing preventative strengthening
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programs. It is not known to what extent strengthening exercises were used by the
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participants in this study as part of any treatment that they may have received during the
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course of their condition. It is, therefore, not able to be determined whether this type of
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intervention had any effect on the foot strength of the individuals in either group. In
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general, these results do suggest that specific strength deficits appear to be associated with
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chronic plantar heel pain, however, longitudinal research is needed to determine whether
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this weakness is a cause or consequence of ongoing symptoms.
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Unlike the strength deficits described, the chronic heel pain group displayed equivalent
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foot and ankle range of motion to the recent onset participants. This suggests that, while
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reduced ankle dorsiflexion appears to be associated with plantar heel pain in general, [1,8]
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this impairment is not more prominent in those with symptoms beyond one year. Of note,
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stretching exercises for the plantar fascia and the ankle plantarflexors are commonly
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recommended for people with plantar heel pain. [1] Data investigating the use of,
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frequency, dose and type of stretching used amongst the participants, however, was not
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collected in this study. Therefore, it remains unclear as to whether the range of motion
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profile of these participants was affected by such interventions. Dorsiflexion restriction
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has also been reported as a predictor of reduced plantar heel pain following intervention
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with a combination of stretching, supportive footwear and orthoses. [29] Such a finding
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may indicate the possibility that reduced dorsiflexion range of motion may be a less likely
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feature of chronic plantar heel pain presentations, which does not appear consistent with
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the results of the current study. Dorsiflexion restriction on initial presentation may predict
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short-term pain-related outcomes following a combination of specific management
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strategies, however, the effect of these interventions on dorsiflexion range of motion, as
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well as long term outcomes, has not been established. [29] In addition, Wrobel et al [29]
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measured dorsiflexion range of motion with a non-weight-bearing measure incorporating
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slight rearfoot supination, whereas the current study used the weight-bearing lunge test. It
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is possible that the differences in these procedures could also explain varying results.
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The chronic heel pain group have similar levels of pain and physical limitation when
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compared to the recent onset group, despite having foot and ankle strength deficits.
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However, surprisingly, the chronic group had better self-reported foot function. The
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findings of similar pain levels and physical limitation are consistent with the existing
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literature in this area, however the latter finding of better foot function in the chronic
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group is not.[30] One previous study comparing people with chronic and more acute heel
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pain investigate chronic versus more recent onset heel pain reported no association
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between pain level and symptom duration, consistent with the findings of this study.
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However, in contrast to this study, they found acute and chronic heel pain patients did not
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differ in self-reported foot function. These different results regarding foot function might
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be explained by two distinct possibilities. Firstly, the inclusion criteria in the study by
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Klein et al [30] specified that participants in the chronic group must have experienced
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symptoms for 6 months or greater, and those in the acute group, for less than 6 months.
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Thus, the inclusion criteria for the two studies were quite different. Categorizing chronic
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heel pain as experiencing symptoms for more than 12 months, and recent onset as less
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than 6 months, as done in this study, creates a much greater distinction between the
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groups, potentially allowing for differences between groups to be better identified.
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Secondly, the Foot and Ankle Ability Measure (FAAM) used by Klein et al [30] is less
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individualized than the FHSQ and uses more specific activity ratings. The foot function
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domain of the FHSQ asks if whether during the last week, the participant’s feet have
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caused them to have difficulties in their work or activities. The use of the personal
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pronoun “your” in the question individualizes the question, requiring the participant to
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draw on their own particular work or activities, rather than suggesting more generic tasks
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or activities. It is possible that work-related and other daily activities of a person with
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chronic symptoms could have become more limited. If their usual work or activities are
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reduced compared to those without a chronic condition, then it is reasonable that their
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condition may not be interfering or causing as much difficulty in their daily life. This
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study did not include data that directly measured activity level, current exercise
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participation or physical work demands and is therefore unable to confirm whether
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activity withdrawal or reduction is a feature of chronic plantar heel pain. There is
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emerging evidence that body-worn activity sensors may be more sensitive than
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questionnaire-based measures for identifying changes or differences in activity levels. [31]
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Future studies could incorporate this technology to further assess activity levels in people
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with chronic plantar heel pain. Of interest, while Klein et al [30] found no difference in
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foot function between the chronic and recent onset groups overall, the chronic group
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reported a significantly higher level of function amongst the individual domains of
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walking down stairs, on curbs, or walking less than 5 minutes. These results are partially
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consistent with those found in this study.
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Another possible explanation for the chronic group reporting better foot function relates to
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the associated features of chronic pain. It is arguable that, as a result of having a chronic
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condition and associated characteristics such as hypervigilance to pain, participants have
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learned pain-reducing strategies and made adaptations to their gait and functional
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activities over time. Such adaptations may allow them to function more efficiently than
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those who have only experienced the condition for a shorter period. These adaptations
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may also help to explain the previously discussed strength deficits identified in the chronic
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pain group. There is evidence that people with chronic musculoskeletal pain, who have
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demonstrated acceptance of their condition, have better self-reported function regardless
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of pain level.[32,33] Furthermore, people with chronic musculoskeletal pain that continue
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activity despite pain, demonstrate improved function.[34]
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The similarity in physical activity limitation between groups is in fact a comparable
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finding to that of Klein et al.[30] Like the physical activity limitation domain of the
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FHSQ, the activity of daily living subscale that was used to measure activity limitation in
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the FAAM is also based on specific tasks. While the majority of people with heel pain
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demonstrate physical activity limitation compared to those without the condition,[16] this
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does not appear to worsen with ongoing pain beyond 12 months duration. This is an
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important finding considering the high prevalence of plantar heel pain and the deleterious
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repercussions that can occur with physical inactivity. In summary, the findings of this
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study suggest that people with chronic heel pain have similar pain levels and overall
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physical capacity, but may either moderate or make adaptations to their daily activities
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and therefore feel less affected or impacted by their foot condition.
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The findings of this study need to be considered in the context of some limitations. The
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cross-sectional nature is unable to differentiate whether the strength deficits present in the
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chronic heel pain participants preceded chronicity, or occur as a result of it. This limitation
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highlights the need for longitudinal research in patients with chronic plantar heel pain.
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Details of recent or current use of strengthening and stretching exercise by any of the
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participants is unknown; therefore, the effects of such interventions on the strength and
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flexibility measures taken in this study cannot be determined. Lastly, a single tester
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performed all of the measurements to enhance reliability, however was not necessarily
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blinded to each individual participant’s group, therefore examiner bias cannot be
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discounted entirely.
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CONCLUSION
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People with chronic plantar heel pain demonstrated weakness in particular foot and ankle
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muscle groups, but better self-reported foot function than those with pain of recent onset.
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Both groups experienced similar levels of pain, foot flexibility and activity limitation.
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These findings suggest that those with chronic symptoms may moderate or develop
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adaptations to their daily activities, or possibly accept their condition, which enables them
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to cope better and feel less affected by their foot. Longitudinal studies are needed to
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establish whether strength impairments are a result of the condition persisting, or rather a
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risk factor for chronicity. Regardless, there are potential clinical implications, including
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the need for strengthening programs to manage or possibly prevent chronic plantar heel
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pain.
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ACKNOWLEDGEMENTS
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The authors would like to acknowledge the
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XXXXXXXXXXXXXXXXXXXXXXXXXX who provided funding for this study. The
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Authors would also like to acknowledge XXXXXXXXXXXXXXXXXXXXcontribution
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to this research project.
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J Orthop Sport Phys 2014; 44:A1-33.
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10. Buchbinder R. Clinical practice. Plantar fasciitis. N Engl J Med 2004; 350:2159-2166.
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11. Pribut SM. Current Approaches to the Management of Plantar Heel Pain Syndrome,
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12. Landorf KB. Plantar heel pain and plantar fasciitis. BMJ Clin Evid 2015; 2015.
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13. League AC. Current concepts review: plantar fasciitis. Foot Ankle Int 2008; 29:358-366.
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14. Martin RL, Irrgang JJ, Conti SF. Outcome study of subjects with insertional plantar
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15. Wolgin M, Cook C, Graham C, Mauldin D. Conservative Treatment of Plantar Heel Pain:
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Long-Term Follow-Up. Foot Ankle Int 1994; 15:97-102.
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16. Irving DB, Cook JL, Young MA, Menz HB. Impact of chronic plantar heel pain on health-
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17. Bennell KL, Talbot RC, Wajswelner H, Techovanich W, Kelly DH, Hall AJ. Intra-rater and
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18. Munteanu SE, Strawhorn AB, Landorf KB, Bird AR, Murley GS. A weightbearing
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20. Wang CY, Olson SL, Protas EJ. Test-retest strength reliability: hand-held dynamometry
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21. Spink MJ, Fotoohabadi MR, Menz HB. Foot and ankle strength assessment using hand-
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22. Moller M, Lind K, Styf J, Karlsson J. The reliability of isokinetic testing of the ankle joint
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23. Bennett PJ, Patterson C, Wearing S, Baglioni T. Development and validation of a
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88:419-428.
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24. Hurn SE, Vicenzino B, Smith MD. Functional impairments characterizing mild,
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moderate, and severe hallux valgus. Arthritis Care Res (Hoboken) 2015; 67:80-88.
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25. Coskun G, Talu B, Bek N, Bayramlar KY. Effects of hallux valgus deformity on rear foot
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26. Garrow AP, Papageorgiou A, Silman AJ, Thomas E, Jayson MI, Macfarlane GJ. The
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grading of hallux valgus. The Manchester Scale. J Am Podiatr Med Assoc 2001; 91:74-78.
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27. Cohen J. Statistical power analysis for the behavioral sciences. Hillsdale, NJ: Erlbaum;
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28. Katoh Y, Chao EY, Laughman RK, Schneider E, Morrey BF. Biomechanical analysis of
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29. Wrobel JS, Fleischer AE, Matzkin-Bridger J, et al. Physical Examination Variables Predict
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30. Klein SE, Dale AM, Hayes MH, Johnson JE, McCormick JJ, Racette BA. Clinical
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presentation and self-reported patterns of pain and function in patients with plantar heel
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pain. Foot Ankle Int 2012; 33:693-698.
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31. Wrobel JS, Fleischer AE, Crews RT, Jarrett B, Najafi B. A randomized controlled trial of
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custom foot orthoses for the treatment of plantar heel pain. J Am Podiatr Med Assoc
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32. McCracken LM. Learning to live with the pain: acceptance of pain predicts adjustment
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33. McCracken LM, Eccleston C. Coping or acceptance: what to do about chronic pain?
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Pain 2003; 105:197-204.
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34. McCracken LM, Eccleston C. A prospective study of acceptance of pain and patient
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functioning with chronic pain. Pain 2005; 118:164-169.
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Table 1. Participant characteristics
55.3 (11.8) 48.0 (67.6%) 164.7 (8.6) 80.7 (18.9)
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Age, years 56.0 (14.3) Sex, female, (%) 39.0 (60.9%) Height, cm 166.2 (8.7) Weight, kg 79.9 (14.7) Values are mean (SD) unless otherwise stated
Chronic Heel Pain Group (n = 71)
P Value .76 .42 .30 .79
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Recent Onset Heel Pain Group (n = 64)
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Effect size
(Confidence Interval)
(Partial η2)
.41 (-2.47 to 1.00)
.005
61.8 (12.0)
63.1 (10.8)
.51 (-5.17 to 2.59)
.003
39.7 (6.3)
39.7 (7.7)
31.2 (7.0)
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29.6 (5.7)
.99 (-2.40 to 2.42)
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Flexed Knee Lunge (º) Straight Knee Lunge (º) Dorsiflexion Strength (N) Inversion Strength (N) Eversion Strength (N) Great Toe Flexor Strength (N)
P Value
28.8 (4.5)
31.0 (9.4)
217.2 (56.7) 191.9 (49.5) n=63 n=69 159.9 (40.5) 151.2 (42.0) n=69 166.7 (44.5) 160.4 (42.4) n=69 159.3 (34.5) 144.0 (31.4) n=70
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Body Mass Index (kg/m2) First MTPJ Extension ROM (º)
Chronic Heel Pain Group Mean (SD) (n=71)
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Recent Onset Heel Pain Group Mean (SD) (n=64)
.89 (-2.66 to 3.06)
<.001
.007 (6.98 to 43.57)
.054
.23 (-5.50 to 22.82)
.011
.40 (-8.60 to 21.21)
.005
.008 (4.07 to 26.57)
.052
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120.2 (24.9) 109.7 (24.4) .01 (2.13 to 19.00) Lesser Toe Flexor n=70 Strength (N) 22.1 (8.5) 21.1 (8.4) .52 (-1.96 to 3.89) Calf Endurance n=63 n=69 (repetitions) Foot Pain 42.5 (25.0) 49.4 (24.3) .11 (-15.40 to 1.47) n=70 (FHSQ) Foot Function 52.9 (27.1) 67.4 (23.9) .001 (-23.28 to -5.79) n=63 n=70 (FHSQ) Physical Activity 63.4 (25.8) 66.9 (25.3) .43 (-12.29 to 5.21) Limitation (FHSQ) n=70 MTPJ = metatarsophalangeal joint, ROM = range of motion, FHSQ = Foot Health Status Questionnaire
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.044 .003 .020 .076 .005
S1934-1482(17)30540-3
DOI:
10.1016/j.pmrj.2017.04.009
Reference:
PMRJ 1893
To appear in:
PM&R
Received Date: 28 September 2016 Revised Date:
4 April 2017
Accepted Date: 8 April 2017
Please cite this article as: Barnes A, Sullivan J, Pappas E, Adams R, Burns J, Clinical and functional characteristics of people with chronic and recent onset plantar heel pain, PM&R (2017), doi: 10.1016/ j.pmrj.2017.04.009. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Clinical and functional characteristics of people with chronic and recent onset plantar heel pain Allegra Barnes PT, B.App.Sc.(Physiotherapy)Hons1 [email protected] Evangelos Pappas PT, PhD2,4 [email protected] Roger Adams PhD2 [email protected] Joshua Burns PhD3 [email protected]
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Justin Sullivan PT, PhD 2 [email protected]
Physiotherapy Department, Royal North Shore Hospital, New South Wales, Australia.
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Discipline of Physiotherapy, Faculty of Health Sciences, The University of Sydney, New South Wales, Australia.
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Sydney Children’s Hospitals Network (Randwick and Westmead), University of Sydney. New South Wales, Australia
Arthritis and Musculoskeletal Research Group, Faculty of Health Sciences, The University of Sydney, New South Wales, Australia
Correspondence: Justin Sullivan
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Faculty of Health Sciences, The University of Sydney
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P.O Box 170
Lidcombe, NSW, Australia 1825 Phone: 61(02) 9351 9156
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Fax: 61(02) 9351 9601
Email: [email protected]
Author Disclosures:
The authors declare that there are no competing interests or financial benefits to authors with respect to the research, authorship, and/or publication of this article. The study was funded by the Podiatry Council of New South Wales, Australia. The research, manuscript and abstract have not been presented elsewhere.
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ABSTRACT
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Background: Plantar heel pain is a common condition that reduces health-related quality
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of life. Recovery usually occurs within 12 months; however, up to 20 percent of people
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remain symptomatic beyond this time-frame. The level of pain and function in this chronic
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heel pain group is not well described.
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Objective: To identify clinical and functional characteristics associated with chronic
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plantar heel pain compared with heel pain of recent onset.
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Design: Cross-sectional study
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Setting: University research laboratory and private physiotherapy clinic
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Participants: A total of 71 people with plantar heel pain for longer than 12 months and 64
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people with plantar heel pain for less than 6 months were recruited from the general public.
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Methods: Functional characteristics of participants in both heel pain groups were assessed
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using a variety of clinical measures and the Foot Health Status Questionnaire. Clinical
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measures included; Body Mass Index, foot and ankle muscle strength using hand-held
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dynamometry, as well as ankle and first metatarsophalangeal joint range of motion. The
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Foot Health Status Questionnaire was used to collect self-reported measures of foot pain
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severity, foot function and physical activity.
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Main Outcome measurements: Univariate analyses of variance were performed to detect
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differences between the two groups for each of the variables measured.
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Results: The chronic heel pain group exhibited reduced ankle dorsiflexor and toe flexor
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strength, yet better self-reported foot function. There was no difference between groups for
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Body Mass Index, ankle and first metatarsophalangeal joint range of motion, inversion
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strength, eversion strength, calf endurance, self-reported foot pain and physical activity.
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Conclusions: Chronic plantar heel pain is associated with selective weakness of foot and
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ankle muscle groups, but less affected foot function when compared to heel pain of recent
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onset. Those with chronic symptoms may moderate or make adaptations to their daily
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activities, or simply accept their condition, enabling more effective coping. Strength
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deficits, although possibly a cause or consequence of chronic symptoms, suggest a need to
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include resistance exercise in the management of plantar heel pain.
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INTRODUCTION
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Plantar heel pain is the most common foot disorder treated by health care practitioners.[1]
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It occurs in people of both active and sedentary lifestyles,[2,3] with 83% of those with the
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condition being working age adults.[4] In the USA approximately two million people seek
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treatment for plantar heel pain every year,[4] at a cost of over $300 million,[3]
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representing a considerable economic burden on health services.
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Plantar heel pain is a mechanical disorder that is multifactorial in nature.[5] It is thought to
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occur due to excessive stress on the plantar fascia and its enthesis at the calcaneal
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tuberosity.[6] The term plantar fasciitis has been frequently used for this condition,
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however, it is now widely accepted that degeneration and thickening of the plantar fascia
55
predominates over inflammatory changes, making this term inaccurate.[7] Current heel
56
pain guidelines identify risk factors that include: limited ankle dorsiflexion range of
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motion (ROM), high body mass index (BMI) in nonathletic individuals, running and work
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related weight-bearing activities.[1] Foot and ankle strength deficits have also been
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demonstrated in people with plantar heel pain,[8,9] including a report involving
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participants in this study compared with asymptomatic controls.[8] A clinical
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examination is considered sufficient for the diagnosis of plantar heel pain,[5,10] with the
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major sign being point tenderness on the plantar aspect of the heel at the medial calcaneal
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tuberosity.[11] Commonly reported symptoms include; pain on first steps in the morning
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or following prolonged rest, as well as pain during prolonged standing or walking.[3,5,11]
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Although prevalent, the etiology of plantar heel pain is not well understood.[5] There is
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limited evidence supporting the efficacy of interventions used in clinical practice,[12]
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with a subsequent lack of consensus regarding the ideal management approach.[2,4,13] As
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a result, heel pain is often difficult to treat, and commonly progresses to a chronic
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condition. Up to 20% of people treated using conservative measures report symptoms
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beyond 12 months.[14,15] Furthermore, it is also common for people to present after 12
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months of symptoms.[1] In addition to this, those who experience symptoms for a
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prolonged period prior to seeking medical attention are placed at a higher risk for
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continued symptoms.[15] Once chronic, treatment can become costly, as symptoms are
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recurring, recovery is lengthy and the response to treatment is unpredictable.[3,15] It has
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also been demonstrated that plantar heel pain has detrimental effects on foot specific and
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general health-related quality of life.[16] Such detriments include limitations in
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performing physical tasks, reduced energy to participate in activities, as well as social
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isolation.[16] Thus, there is potential for longer-term health consequences relating to
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reduced mobility for people with chronic plantar heel pain; including weight-gain,
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hypertension, coronary artery disease and non-insulin dependent diabetes mellitus.[7]
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The aim of this study is to compare clinical and functional characteristics between adults
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with recent onset and chronic plantar heel pain. Differences found between the two groups
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could identify characteristics associated with chronic plantar heel pain, of which there is
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little known to date. Such findings may indicate the effect that prolonged symptoms have
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on foot function, as well as assist in uncovering potential risk factors for chronicity. This,
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in turn, could aid the development of specific strategies to manage or prevent chronic
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symptoms.
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METHODS
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Participants
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202 people with plantar heel pain volunteered to participate in the original study.[8]
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People were recruited from the general public between August 2008 and August 2012
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through local media advertisements and notices in medical, physiotherapy and university
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premises. For this analysis, 64 people were included in the recent onset group, and 71
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were included in the chronic group. Participants in the recent onset group were required to
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have experienced symptoms for at least 3 weeks, but less than 6 months. Those in the
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chronic group were required to have experienced symptoms for more than 12 months.
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These periods were selected because evidence demonstrates that the majority of people
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with heel pain experience resolution of symptoms within 12 months, leaving a chronic
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group of people with continuing symptoms past 12 months. Recent onset was determined
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as 6 months or less in order to provide a group for comparison that was well within the
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common recovery time and clearly separated from the chronic group. In accordance with
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current clinical guidelines[1] symptomatic participants were included if they reported
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tenderness on palpation of the medial calcaneal tuberosity and exhibited one of the
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following complaints; pain on the first step in the morning or after prolonged sitting, pain
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on prolonged standing,[1,4] or pain when running.[1] Participants were excluded if they
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had undergone surgery to the plantar fascia or had any of the following conditions:
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systemic arthritis, neurological conditions, lumbar radiculopathy, neurological or vascular
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compromise of the foot related to diabetes, or any coexisting painful musculoskeletal
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condition of the lower limb. Each participant attended data collection on a single occasion
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at either theXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX. In accordance
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with approval from the XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX, written
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consent was obtained, and all participants were screened for the presence of plantar heel
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pain.
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Procedures
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Foot and Ankle Range of Motion
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To measure first metatarsophalangeal joint (MTPJ) extension ROM, participants were
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positioned in long sitting, with the ankle in plantargrade. The assessor extended the first
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MTPJ to maximal range while plantarflexion of the first ray was prevented. The
123
landmarks used for the measurement were the navicular, the MTPJ axis, and the middle of
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the interphalangeal joint. The angle formed by these landmarks was measured with a
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goniometer. Ankle dorsiflexion ROM was measured using the flexed knee lunge test [17]
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and the straight knee lunge test.[18] For the flexed knee lunge test, participants were
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instructed to stand, feet shoulder-width apart, with their hands against a wall, and the foot
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being tested one step behind the other. Participants flexed their back knee directly over the
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foot until the heel began to leave the ground. The ROM was measured with a digital
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inclinometer (Chattanooga Baseline; DJO Global, Vista, CA, USA) placed on the lowest
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part of the anterior tibia. The same procedure was used for the straight knee lunge test,
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however the ipsilateral knee was kept straight.
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Strength
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Foot and ankle muscle strength was assessed using handheld dynamometry (JTech
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Commander PowerTrack II; JTech Medical, Salt Lake City, UT). High intratester and
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intertester reliability has been demonstrated using this approach in the assessment of foot
138
and ankle muscle strength.[19,20] For each strength test, progressive muscle force was
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developed to achieve a maximum isometric contraction. The maximum force achieved
140
from 3 attempts was selected for data analysis.
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For the ankle strength tests, participants sat with their hips in 90 degrees of flexion, knees
143
extended, and feet over the end of the examination table. The knees were positioned
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slightly flexed over a rolled towel or pillow and participants were instructed to hold the
145
edge of the treatment table for stability. The ankle was then placed in a neutral position by
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the examiner. Flat, comfortable and easily reproducible contact points were chosen for
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dynamometer placement. For dorsiflexion strength testing, the handheld dynamometer
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was placed on the dorsum of the foot, just proximal to the metatarsal heads. For inversion
149
strength testing, it was placed on the medial side of the foot, just proximal to the first
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metatarsal head. For eversion strength testing, the dynamometer was placed on the lateral
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side of the foot, just proximal to the fifth metatarsal head.
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For the toe flexor strength tests, participants sat with their knees and hips at approximately
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90 degrees, and their feet on a wooden block. The toes of the foot being tested were
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positioned over the edge of the block, with the MTPJs and interphalangeal joints in
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neutral. For great toe flexor strength testing, the dynamometer was placed longitudinally
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along the plantar aspect of the great toe. For lesser toe flexor strength testing, it was
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placed across the plantar surface of the second, third, and fourth toes. Hand-held
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dynamometry has been shown to be a reliable instrument to measure toe flexor strength,
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with excellent intrarater and interrater reliability.[21]
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Calf endurance was measured using a standardized unilateral heel raise test.[22]
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Participants stood at arm’s length from a wall with their feet underneath a wooden block.
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The participants performed unilateral heel raises on the affected side until fatigue. To
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ensure full range of motion was reached on each repetition, the test protocol required the
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top of the foot or anterior ankle to touch the underside of the block at full heel raise.
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Instructions were given to keep the knee straight, and a metronome was used to ensure
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identical frequency between participants. The number of heel raises was counted and
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recorded, not including attempts that failed to reach the required height or those involving
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knee flexion.
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Foot pain, function and physical activity
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Foot health related quality of life was measured using the Foot Health Status
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Questionnaire (FHSQ) Version 1.03.[23] Three domains of the questionnaire were used in
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the study to quantify foot pain, foot function and physical activity limitation. Each domain
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consists of a series of questions answered on a Likert scale. The foot pain domain consists
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of four questions that pertain to level, frequency and quality of foot pain. The foot
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function domain consists of four questions that examine the extent to which the
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participant’s feet interfere with regular daily activities, work, walking and climbing stairs.
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The physical activity limitation domain exposes if, and, how limited participants are in
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activities as a result of their general health. It asks 9 questions about various activities,
182
which include but are not limited to; running, sports, cleaning, carrying shopping,
183
climbing a flight of stairs, walking and self-care activities. The Foot Health Status
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Questionnaire Data Analysis Software (Version 1.03) was used to process the data.
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Individual domain scores were calculated and reported from 0 (poorest state of foot
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health) to 100 (optimal foot health). Higher scores reflect better foot health and quality of
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life.
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Toe deformity
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As hallux valgus has been shown to be associated with reduced toe strength [24] and
191
poorer foot function, [25] the two groups were compared for the degree of this deformity
192
prior to further statistical analyses. Each participant was assessed using the Manchester
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scale, which is a reliable method of grading Hallux valgus. [26] This tool is a four-point
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scale which requires matching an individual’s foot with one of four photographs that
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depict progressive stages of Hallux Valgus; namely, normal, mild, moderate and severe.
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Statistical Analyses
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Statistical analyses were carried out using SPSS, version 22 (SPSS, Inc, an IBM
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Company, Chicago, IL). The groups were compared for age, sex, hallux valgus, height
200
and weight prior to further analyses. Age, height and weight differences were assessed
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using independent samples t-tests, hallux valgus by a Mann-Whitney U test, and sex was
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compared using a Chi-square test. The level of significance was set at α = .05. Following
203
this, univariate analyses of variance were performed to compare each variable between the
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recent onset and chronic heel pain groups. The level of significance was set at α = .05.
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Partial η2 values were calculated to report an effect size for each variable found to differ
206
between the 2 groups. Values greater than .01 were considered representative of a small
207
difference, values greater than .06 representative of a medium-sized effect, and values
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greater than .14 representative of a large difference between groups.[27] Less than 1% of
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the complete data set was missing. This included some incomplete questionnaires, as well
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as 3 people unable to perform some strength tests for safety reasons. Table 2 denotes
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group numbers for statistical analyses that were performed with less than the full study
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cohort.
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RESULTS
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The characteristics of the participants in each group are summarized in Table 1. Both
216
groups were equivalent for age, sex, height and weight. The groups were also equivalent
217
regarding hallux valgus grade (U= 2358.5; p= .672). The results of the univariate
218
analyses of variance are summarized in Table 2. Compared with the recent onset heel
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pain group, members of the chronic heel pain group had reduced dorsiflexion strength,
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reduced great toe flexor strength, reduced lesser toe flexor strength, and a higher FHSQ
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foot function domain score. Partial η2 values for dorsiflexor, great toe and lesser toe
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flexor strength were calculated to be .054, .052 and .044 respectively, indicating a small
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effect size. A partial η2 value of .076 was calculated for the FHSQ foot function domain
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score, indicating a medium effect size. There was no significant difference between
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groups for BMI, first MTPJ extension ROM, flexed lunge, extended lunge, inversion
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strength, eversion strength, calf endurance, foot pain domain score, and physical activity
227
domain score.
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DISCUSSION
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The findings of this study indicate that, in the general population, people who have had
231
plantar heel pain for more than 12 months have deficits in foot and ankle strength when
232
compared to those who have had the condition for less than 6 months. An unexpected yet
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interesting outcome of the study was that the chronic group had better self-reported foot
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function compared to the recent onset group, despite these strength deficits. People with
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chronic symptoms, however, have similar BMI, foot and ankle flexibility, and report
236
equivalent pain levels and physical activity limitations to those with recent onset
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symptoms.
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Strength deficits were apparent in the sagittal plane directions, including ankle
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dorsiflexion and flexion of the toes. Due to the cross sectional design of the study, it is
241
uncertain whether these deficits are a cause or consequence of the condition becoming
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chronic. It may be that as a result of their condition, the gait patterns of those in the
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chronic group are less dynamic, and their functional activities adjusted. Evidence shows
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that people with heel pain have reduced walking velocity, and a less than normal vertical
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component of floor reaction force at heel strike and toe off.[28] It has been suggested that
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this may be an attempt to avoid high stresses on the painful heel throughout the gait
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cycle.[28] As a result of this, muscle recruitment and activation patterns may be altered,
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and therefore result in weakness of the suggested muscles. Gait is a sagittal plane
249
dominant movement, which may account for strength reductions in muscle groups that
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have primarily a sagittal based function. Equally, it is possible that the strength deficits
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may have preceded chronicity, and therefore, may instead be a predisposing factor to the
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development of chronic heel pain. The plantar fascia is intricately attached to, and
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associated with, a number of contractile and non-contractile structures. Both intrinsic and
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extrinsic muscles support the longitudinal arch. Therefore, any weakness of these muscles
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could result in excessive stress on non-contractile structures, including the plantar fascia,
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and contribute to continuing heel pain. If this were the case, there would be important
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clinical implications, including the need to screen patients for foot and ankle weakness as
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a risk factor for chronic heel pain as well as implementing preventative strengthening
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programs. It is not known to what extent strengthening exercises were used by the
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participants in this study as part of any treatment that they may have received during the
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course of their condition. It is, therefore, not able to be determined whether this type of
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intervention had any effect on the foot strength of the individuals in either group. In
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general, these results do suggest that specific strength deficits appear to be associated with
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chronic plantar heel pain, however, longitudinal research is needed to determine whether
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this weakness is a cause or consequence of ongoing symptoms.
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Unlike the strength deficits described, the chronic heel pain group displayed equivalent
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foot and ankle range of motion to the recent onset participants. This suggests that, while
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reduced ankle dorsiflexion appears to be associated with plantar heel pain in general, [1,8]
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this impairment is not more prominent in those with symptoms beyond one year. Of note,
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stretching exercises for the plantar fascia and the ankle plantarflexors are commonly
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recommended for people with plantar heel pain. [1] Data investigating the use of,
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frequency, dose and type of stretching used amongst the participants, however, was not
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collected in this study. Therefore, it remains unclear as to whether the range of motion
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profile of these participants was affected by such interventions. Dorsiflexion restriction
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has also been reported as a predictor of reduced plantar heel pain following intervention
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with a combination of stretching, supportive footwear and orthoses. [29] Such a finding
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may indicate the possibility that reduced dorsiflexion range of motion may be a less likely
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feature of chronic plantar heel pain presentations, which does not appear consistent with
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the results of the current study. Dorsiflexion restriction on initial presentation may predict
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short-term pain-related outcomes following a combination of specific management
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strategies, however, the effect of these interventions on dorsiflexion range of motion, as
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well as long term outcomes, has not been established. [29] In addition, Wrobel et al [29]
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measured dorsiflexion range of motion with a non-weight-bearing measure incorporating
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slight rearfoot supination, whereas the current study used the weight-bearing lunge test. It
286
is possible that the differences in these procedures could also explain varying results.
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The chronic heel pain group have similar levels of pain and physical limitation when
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compared to the recent onset group, despite having foot and ankle strength deficits.
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However, surprisingly, the chronic group had better self-reported foot function. The
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findings of similar pain levels and physical limitation are consistent with the existing
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literature in this area, however the latter finding of better foot function in the chronic
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group is not.[30] One previous study comparing people with chronic and more acute heel
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pain investigate chronic versus more recent onset heel pain reported no association
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between pain level and symptom duration, consistent with the findings of this study.
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However, in contrast to this study, they found acute and chronic heel pain patients did not
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differ in self-reported foot function. These different results regarding foot function might
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be explained by two distinct possibilities. Firstly, the inclusion criteria in the study by
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Klein et al [30] specified that participants in the chronic group must have experienced
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symptoms for 6 months or greater, and those in the acute group, for less than 6 months.
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Thus, the inclusion criteria for the two studies were quite different. Categorizing chronic
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heel pain as experiencing symptoms for more than 12 months, and recent onset as less
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than 6 months, as done in this study, creates a much greater distinction between the
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groups, potentially allowing for differences between groups to be better identified.
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Secondly, the Foot and Ankle Ability Measure (FAAM) used by Klein et al [30] is less
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individualized than the FHSQ and uses more specific activity ratings. The foot function
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domain of the FHSQ asks if whether during the last week, the participant’s feet have
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caused them to have difficulties in their work or activities. The use of the personal
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pronoun “your” in the question individualizes the question, requiring the participant to
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draw on their own particular work or activities, rather than suggesting more generic tasks
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or activities. It is possible that work-related and other daily activities of a person with
312
chronic symptoms could have become more limited. If their usual work or activities are
313
reduced compared to those without a chronic condition, then it is reasonable that their
314
condition may not be interfering or causing as much difficulty in their daily life. This
315
study did not include data that directly measured activity level, current exercise
316
participation or physical work demands and is therefore unable to confirm whether
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activity withdrawal or reduction is a feature of chronic plantar heel pain. There is
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emerging evidence that body-worn activity sensors may be more sensitive than
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questionnaire-based measures for identifying changes or differences in activity levels. [31]
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Future studies could incorporate this technology to further assess activity levels in people
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with chronic plantar heel pain. Of interest, while Klein et al [30] found no difference in
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foot function between the chronic and recent onset groups overall, the chronic group
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reported a significantly higher level of function amongst the individual domains of
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walking down stairs, on curbs, or walking less than 5 minutes. These results are partially
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consistent with those found in this study.
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326 327
Another possible explanation for the chronic group reporting better foot function relates to
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the associated features of chronic pain. It is arguable that, as a result of having a chronic
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condition and associated characteristics such as hypervigilance to pain, participants have
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learned pain-reducing strategies and made adaptations to their gait and functional
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activities over time. Such adaptations may allow them to function more efficiently than
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those who have only experienced the condition for a shorter period. These adaptations
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may also help to explain the previously discussed strength deficits identified in the chronic
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pain group. There is evidence that people with chronic musculoskeletal pain, who have
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demonstrated acceptance of their condition, have better self-reported function regardless
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of pain level.[32,33] Furthermore, people with chronic musculoskeletal pain that continue
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activity despite pain, demonstrate improved function.[34]
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The similarity in physical activity limitation between groups is in fact a comparable
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finding to that of Klein et al.[30] Like the physical activity limitation domain of the
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FHSQ, the activity of daily living subscale that was used to measure activity limitation in
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the FAAM is also based on specific tasks. While the majority of people with heel pain
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demonstrate physical activity limitation compared to those without the condition,[16] this
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does not appear to worsen with ongoing pain beyond 12 months duration. This is an
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important finding considering the high prevalence of plantar heel pain and the deleterious
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repercussions that can occur with physical inactivity. In summary, the findings of this
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study suggest that people with chronic heel pain have similar pain levels and overall
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physical capacity, but may either moderate or make adaptations to their daily activities
349
and therefore feel less affected or impacted by their foot condition.
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350 351
The findings of this study need to be considered in the context of some limitations. The
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cross-sectional nature is unable to differentiate whether the strength deficits present in the
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chronic heel pain participants preceded chronicity, or occur as a result of it. This limitation
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highlights the need for longitudinal research in patients with chronic plantar heel pain.
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Details of recent or current use of strengthening and stretching exercise by any of the
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participants is unknown; therefore, the effects of such interventions on the strength and
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flexibility measures taken in this study cannot be determined. Lastly, a single tester
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performed all of the measurements to enhance reliability, however was not necessarily
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blinded to each individual participant’s group, therefore examiner bias cannot be
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discounted entirely.
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CONCLUSION
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People with chronic plantar heel pain demonstrated weakness in particular foot and ankle
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muscle groups, but better self-reported foot function than those with pain of recent onset.
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Both groups experienced similar levels of pain, foot flexibility and activity limitation.
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These findings suggest that those with chronic symptoms may moderate or develop
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adaptations to their daily activities, or possibly accept their condition, which enables them
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to cope better and feel less affected by their foot. Longitudinal studies are needed to
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establish whether strength impairments are a result of the condition persisting, or rather a
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risk factor for chronicity. Regardless, there are potential clinical implications, including
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the need for strengthening programs to manage or possibly prevent chronic plantar heel
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pain.
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ACKNOWLEDGEMENTS
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The authors would like to acknowledge the
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XXXXXXXXXXXXXXXXXXXXXXXXXX who provided funding for this study. The
377
Authors would also like to acknowledge XXXXXXXXXXXXXXXXXXXXcontribution
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to this research project.
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11. Pribut SM. Current Approaches to the Management of Plantar Heel Pain Syndrome,
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12. Landorf KB. Plantar heel pain and plantar fasciitis. BMJ Clin Evid 2015; 2015.
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13. League AC. Current concepts review: plantar fasciitis. Foot Ankle Int 2008; 29:358-366.
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14. Martin RL, Irrgang JJ, Conti SF. Outcome study of subjects with insertional plantar
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15. Wolgin M, Cook C, Graham C, Mauldin D. Conservative Treatment of Plantar Heel Pain:
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16. Irving DB, Cook JL, Young MA, Menz HB. Impact of chronic plantar heel pain on health-
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17. Bennell KL, Talbot RC, Wajswelner H, Techovanich W, Kelly DH, Hall AJ. Intra-rater and
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18. Munteanu SE, Strawhorn AB, Landorf KB, Bird AR, Murley GS. A weightbearing
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31. Wrobel JS, Fleischer AE, Crews RT, Jarrett B, Najafi B. A randomized controlled trial of
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33. McCracken LM, Eccleston C. Coping or acceptance: what to do about chronic pain?
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Table 1. Participant characteristics
55.3 (11.8) 48.0 (67.6%) 164.7 (8.6) 80.7 (18.9)
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Age, years 56.0 (14.3) Sex, female, (%) 39.0 (60.9%) Height, cm 166.2 (8.7) Weight, kg 79.9 (14.7) Values are mean (SD) unless otherwise stated
Chronic Heel Pain Group (n = 71)
P Value .76 .42 .30 .79
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Recent Onset Heel Pain Group (n = 64)
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Effect size
(Confidence Interval)
(Partial η2)
.41 (-2.47 to 1.00)
.005
61.8 (12.0)
63.1 (10.8)
.51 (-5.17 to 2.59)
.003
39.7 (6.3)
39.7 (7.7)
31.2 (7.0)
SC
29.6 (5.7)
.99 (-2.40 to 2.42)
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Flexed Knee Lunge (º) Straight Knee Lunge (º) Dorsiflexion Strength (N) Inversion Strength (N) Eversion Strength (N) Great Toe Flexor Strength (N)
P Value
28.8 (4.5)
31.0 (9.4)
217.2 (56.7) 191.9 (49.5) n=63 n=69 159.9 (40.5) 151.2 (42.0) n=69 166.7 (44.5) 160.4 (42.4) n=69 159.3 (34.5) 144.0 (31.4) n=70
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Body Mass Index (kg/m2) First MTPJ Extension ROM (º)
Chronic Heel Pain Group Mean (SD) (n=71)
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Recent Onset Heel Pain Group Mean (SD) (n=64)
.89 (-2.66 to 3.06)
<.001
.007 (6.98 to 43.57)
.054
.23 (-5.50 to 22.82)
.011
.40 (-8.60 to 21.21)
.005
.008 (4.07 to 26.57)
.052
EP
120.2 (24.9) 109.7 (24.4) .01 (2.13 to 19.00) Lesser Toe Flexor n=70 Strength (N) 22.1 (8.5) 21.1 (8.4) .52 (-1.96 to 3.89) Calf Endurance n=63 n=69 (repetitions) Foot Pain 42.5 (25.0) 49.4 (24.3) .11 (-15.40 to 1.47) n=70 (FHSQ) Foot Function 52.9 (27.1) 67.4 (23.9) .001 (-23.28 to -5.79) n=63 n=70 (FHSQ) Physical Activity 63.4 (25.8) 66.9 (25.3) .43 (-12.29 to 5.21) Limitation (FHSQ) n=70 MTPJ = metatarsophalangeal joint, ROM = range of motion, FHSQ = Foot Health Status Questionnaire
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<.001
.044 .003 .020 .076 .005