- Email: [email protected]
Role of mechanical factors in the clinical presentation of plantar heel pain: Implications for management
Journal Pre-proof Role of mechanical factors in the clinical presentation of plantar heel pain: implications for management Justin Sullivan, Evangelos Pappas, Joshua Burns
PII:
S0958-2592(19)30083-5
DOI:
https://doi.org/10.1016/j.foot.2019.08.007
Reference:
YFOOT 1636
To appear in:
The Foot
Received Date:
23 May 2019
Revised Date:
6 August 2019
Accepted Date:
30 August 2019
Please cite this article as: Sullivan J, Pappas E, Burns J, Role of mechanical factors in the clinical presentation of plantar heel pain: implications for management, The Foot (2019), doi: https://doi.org/10.1016/j.foot.2019.08.007
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 Published by Elsevier.
Role of mechanical factors in the clinical presentation of plantar heel pain: implications for management.
Justin Sullivan PT, PhD 1,3 [email protected] Evangelos Pappas PT, PhD1,3 [email protected]
ro
1
of
Joshua Burns PhD2,3 [email protected]
Discipline of Physiotherapy, Faculty of Health Sciences, The University of Sydney, New South
2
-p
Wales, Australia.
Sydney Children’s Hospitals Network (Randwick and Westmead), University of Sydney, New
Musculoskeletal Health, Faculty of Health Sciences, The University of Sydney, New South Wales, Australia
ur na
Correspondence:
lP
3
re
South Wales, Australia
Justin Sullivan
Faculty of Health Sciences, The University of Sydney P.O Box 170
Jo
Lidcombe, NSW, Australia 1825 Phone: 61(02) 9351 9156 Fax: 61(02) 9351 9601
Email: [email protected]
1
Highlights:
Plantar heel pain is associated with high Body Mass Index in non-athletic groups. Plantar heel pain is associated with specific foot and ankle strength deficits, as well as reduced ankle dorsiflexion range of motion. The association between foot alignment and heel pain is unclear. There is limited evidence that plantar heel pain is associated with loading factors such as running mileage and occupational weight-bearing demands.
of
ro
Abstract
Plantar heel pain is a common musculoskeletal foot disorder that can have a negative impact on
-p
activities of daily living and it is of multifactorial etiology. A variety of mechanical factors,
re
which result in excessive load at the plantar fascia insertion, are thought to contribute to the onset of the condition. This review presents the evidence for associations between commonly
lP
assessed mechanical factors and plantar heel pain, which could guide management. Plantar heel pain is associated with a higher BMI in non-athletic groups, reduced dorsiflexion range of
ur na
motion, as well as reduced strength in specific foot and ankle muscle groups. There is conflicting, or insufficient evidence regarding the importance of foot alignment and first metatarsophalangeal joint range of motion. Plantar heel pain appears to be common in runners, with limited evidence for greater risk being associated with higher mileage or previous injuries.
Jo
Conflicting evidence exists regarding the relationship between work-related standing and plantar heel pain, however, longer standing duration may be associated with plantar heel pain in specific worker groups. The evidence presented has been generated through studies with cross-sectional designs, therefore it is not known whether any of these associated factors have a causative relationship with plantar heel pain. Longitudinal studies are needed to ascertain whether the strength and flexibility impairments associated with plantar heel pain are a cause or consequence 2
of the condition, as well as to establish activity thresholds that increase risk. Intervention approaches should consider strategies that improve strength and flexibility, as well as those that influence plantar fascia loading such as body weight reduction, orthoses and management of
of
athletic and occupational workload.
Key words:
-p
ro
Plantar Fasciitis, fasciopathy, activity, loading, flexibility, alignment, strength, body mass
re
Introduction
Plantar heel pain is a condition that affects adults across all ages [1] of both active and sedentary
lP
lifestyles.[1, 2] In the USA approximately two million people seek treatment for plantar heel pain every year,[3] with an estimated cost of between US$192-376 million in 2007.[2] Plantar
ur na
heel pain is the most common foot condition treated by physical therapists. [4] In addition to its prevalence, plantar heel pain results in limitations in performing physical tasks, [5] including both work and leisure activities.[6] Foot pain and function in people with plantar heel pain appears comparable to those awaiting surgery for interdigital neuroma, but worse than those
Jo
awaiting surgery for forefoot deformities.[5, 7]
Plantar heel pain is a musculoskeletal disorder primarily affecting the enthesis of the plantar fascia, and is synonymous with terms such as plantar fasciitis, painful heel syndrome, heel spur syndrome, runners’ heel and plantar fasciopathy. [8],[9] Plantar fasciitis has been the most
3
commonly used term for this condition, most likely due to initial beliefs that pain results from an inflammatory reaction at the fascial enthesis.[10] It is now clearer that the condition is more commonly due to a degenerative process, [11-13] thus, rendering the term ‘fasciitis’ less suitable for broader use. The pathogenesis of plantar heel pain is considered to be excessive cumulative strain at the enthesis of the plantar fascia.[8] Continuing biomechanical stresses result in microfailure of the plantar fascia, inhibition of normative repair process and abnormal
of
histological responses.[14] Histological investigations involving people with chronic plantar heel
ro
pain commonly describe degeneration and fiber disorientation, increased mucoid ground
substance, angiofibroblastic hyperplasia, and calcification, [8, 13] with minimal or no evidence
-p
of inflammation.[14] Hence, inflammation does not appear to be a predominant feature in plantar
re
heel pain, with the mechanism more likely to be one of advanced fascial degeneration, potentially the end result of a series of acute and chronic inflammatory phases. Inflammation and
lP
degeneration may not be different phases of the condition, but could be independent processes
ur na
with the potential to co-exist.[8]
Despite the magnitude of its prevalence and the impact on those who experience it, the etiology of plantar heel pain is not well understood[15] which leads to uncertainty regarding the most effective intervention strategy.[1, 16, 17] This, in essence, renders the condition somewhat
Jo
enigmatic and often difficult to effectively treat, with estimates between 5-19% of people continuing to have symptoms beyond one year.[18-20] Plantar heel pain is considered to be a multifactorial condition, with numerous causative or associated mechanical factors.[21, 22] The aim of this review is to present the evidence regarding associations between commonly collected clinical measures and plantar heel pain, in an attempt to provide a clearer description of the
4
mechanical factors related to the condition. This, in turn, will assist with the development of more targeted prevention and intervention strategies, as well as highlight priorities for further research.
Contributing and associated factors Many factors are thought to be associated with plantar heel pain. These include both intrinsic and
of
extrinsic factors. Intrinsic factors relate directly to the anatomy or biomechanics of an individual,
ro
including; foot and lower limb alignment, foot and ankle range of motion, muscle strength and endurance, as well as body mass. Extrinsic factors relate to outside influences acting on the foot,
-p
including; the length of time spent standing or exercising, footwear and floor surfaces. Numerous
re
studies have explored the musculoskeletal and lifestyle factors associated with plantar heel pain
Foot alignment
lP
and provide evidence which can assist in guiding clinical practice and future research.
ur na
Foot posture, in particular longitudinal arch height, has long been considered important in the etiology of plantar heel pain. A planus, or low-arched foot, that flattens excessively through the stance phase of gait is thought to increase tensile loading of the plantar fascia, leading to excessive stress at the attachment to the calcaneus.[14] A cavus, or high-arched foot, known to
Jo
produce higher ground reaction forces and peak pressure beneath the heel during walking [23],[24], has also been suggested as being associated with heel pain.[25] Numerous studies investigating foot posture and arch height in relation to plantar heel pain are discussed below, with key findings summarized in Table 1.
5
Static measures of foot and arch alignment in standing include measures of calcaneal angle, arch height, as well as global foot posture. Arch height measures have been performed using radiology, footprint analysis, longitudinal arch angle and foot height to truncated length measures. Two studies involving general population samples have reported a lower arch to be associated with the presence of plantar heel pain. One of these studies used the radiological measurement of calcaneal pitch as an indicator of arch height[26] and the other calculated the
of
arch index from weight-bearing footprints [27]. Only 12 of the 46 participants in this second
ro
study had plantar heel pain, leaving the sample size of symptomatic participants small. In
contrast, longitudinal arch angle, measured as 368the angle created from lines connecting the
-p
center of the medial malleolus, the navicular tuberosity and the first metatarsal head, did not
re
differ in a study comparing 20 participants with plantar heel pain and 20 age- and sex-matched controls.[22] In studies including athletic people with plantar heel pain, a range of different
lP
findings regarding arch height measures are reported. Studies have reported athletes with heel pain to have arch height equivalent to asymptomatic athletes using navicular height measures,
ur na
[28] a flatter arch when compared using the height of the foot at 50% of foot length divided by truncated foot length as an arch height measure, [29] and a higher arch than non-injured runners when compared using the arch index measure.[30] In this study, arch index was calculated from footprints generated using a podoscope and was equal to the area of the midfoot divided by the
Jo
area of the entire foot. The varying results of these studies involving athletic people with heel pain may reflect the differences in the measurement procedures used, or be related to the small size and characteristics of the samples included. In addition, differing reports of arch height in people with plantar heel pain in the studies using an arch index may reflect the variations in technique used, as well as the validity of the measurement. Although arch index is considered to
6
represent arch height as it correlates with truncated navicular height,[31] it only represents about half the variation in navicular height [31] and can be affected by body composition.[32] Ultimately, arch index and other footprint based measures may only represent angles and indices of the plantar surface of the foot, rather than assessing the overall alignment of the foot and ankle.[33]
of
A simpler way to assess foot posture is by examining calcaneal alignment. Cross-sectional
ro
studies measuring the angle formed by the calcaneus with respect to vertical or the lower limb report no differences between people with heel pain and asymptomatic controls. [22, 29, 30]
-p
Collectively, these studies suggest a lack of association between rearfoot angle in standing and
re
plantar heel pain, however, some caution with this interpretation is needed as the studies included small samples and two contained only athletic participants. The Foot Posture Index
lP
(FPI) is a more global measure of foot alignment and is a reliable 25-point tool rating foot posture from more supinated to more pronated, based on observation and palpation of the
ur na
alignment of six different sections of the foot.[34] Alignment observations making up part of the FPI include calcaneal angle and arch congruency. Two studies have reported higher FPI scores in people with heel pain compared to age- and sex-matched controls, suggesting a potential link between a more pronated foot posture and plantar heel pain.[35, 36] Of note, average FPI scores
Jo
were lower (indicating less pronation), than published normative data [37] in both controls and symptomatic patients in one of these studies, [35] as well as in the controls of the second study. [36] In contrast to these findings, a larger study reported no difference in FPI scores between groups with and without plantar heel pain,[38] with both groups exhibiting FPI scores similar to published normative data.[37]
7
Several studies have investigated the association between dynamic foot and ankle motion and plantar heel pain, with no differences evident between people with plantar heel pain and asymptomatic controls. Two small studies that used digital fluoroscopy to compare 10 people with plantar heel pain and 10 age-, sex- and body mass-matched controls, did not find any differences in arch movement or maximum arch angle during walking.[39, 40] In a study of 25
of
female runners with a history of plantar heel pain, three dimensional kinematic analysis of
ro
running revealed no differences in rearfoot eversion occurring during stance phase in runners
-p
with heel pain compared to age- and mileage-matched controls.[29]
re
These studies, due to their variable results in both general and athletic samples, as well as in matched and unmatched groups, along with different measurement procedures and often small
lP
sample sizes, are unable to clearly determine if there is an association between static or dynamic foot and arch alignment and plantar heel pain. Therefore, current evidence linking arch height
ur na
and foot alignment to plantar heel pain is equivocal. Future investigations of larger samples of people with heel pain, using accurate and valid measures of foot alignment and dynamic motion, are needed to clarify any potential association. The uncertainty of any link between foot posture and plantar heel pain may have some impact on management strategies that influence mechanical
Jo
function of the foot, such as orthoses. Pre-fabricated and custom orthoses have been demonstrated to be equally effective in reducing plantar heel pain, with the mechanism possibly one of offloading via support of the arch, or a reduction in pressure beneath the painful heel. Whilst these strategies may be useful in offloading the heel and reducing pain in the short term,
8
usage of orthoses to prevent recurring heel pain based on presenting foot posture does not appear to be supported by evidence.
Foot and Ankle Range of motion Impairments in range of motion at particular foot and ankle joints have been suggested as being associated with plantar heel pain. Table 2 summarizes the research that has investigated the
of
relationship between foot and ankle range of motion and heel pain. Reduced ankle joint motion,
ro
specifically dorsiflexion, is often proposed as a risk factor for plantar heel pain. Lack of ankle dorsiflexion during the stance phase of the gait cycle could potentially lead to a compensatory
-p
increase in midfoot dorsiflexion motion,[41] essentially lowering the arch further and increasing
re
tensile load on the plantar fascia. In addition, anatomical studies have described a contiguous connection between the plantar fascia and the Achilles tendon, which appears less evident with
lP
increasing age.[42, 43] In individuals where this anatomical link exists, it is feasible that increased tensile load on the gastrocnemius-soleus complex due to inflexibility could transmit
ur na
directly to the plantar fascia. Conversely, given the association between these anatomical structures, reducing dorsiflexion during gait and other activities may serve to offload tension in the plantar fascia and ultimately reduce pain in people with plantar heel pain. Continuation of such as strategy could result in tissue adaptations and a reduction in dorsiflexion range as a
Jo
consequence of plantar heel pain.
Three studies have reported reduced ankle dorsiflexion in general population samples of people with heel pain. Two of these studies measured dorsiflexion using goniometry, in non-weightbearing with the knee extended and subtalar joint in neutral,[3] [44] whilst the other used both
9
the bent-knee and straight-knee lunge tests.[38] In contrast, ankle dorsiflexion, using the bentknee lunge test, was found not to be associated with plantar heel pain in a study comparing 80 symptomatic participants and 80 age- and sex-matched controls.[35]
Three studies have investigated dorsiflexion range of motion in people with plantar heel pain specifically from athletic populations. Sport related tasks are likely to require greater joint
of
flexibility than many daily activities, hence, restrictions in foot and ankle range of motion could
ro
be more problematic for athletes. Significantly reduced ankle dorsiflexion range has been
reported in the affected feet of runners with plantar heel pain, when compared to reference
-p
norms, the uninvolved foot, or to a group of active controls who ran as a part of their sport.[45]
re
A detailed description of the measurement procedure in this study, however, was not available. In contrast, two studies have reported no difference in ankle dorsiflexion between runners with
lP
heel pain and asymptomatic control participants. One of these studies, however, used a measure which involved the participants actively dorsiflexing the ankle, which may not necessarily reflect
ur na
true available joint range, as the capacity of the dorsiflexors to generate force may be the limiting factor.[28] The other study included female runners with a history of plantar heel pain, meaning that they no longer had heel pain and their ankle range of motion at the time of data collection may not reflect what it was prior to, or during the time they were symptomatic.[29] It is
Jo
possible, therefore, that the differences in the results of these studies involving athletic participants may be related to the measurement procedures used or participant inclusion criteria.
Whilst there are some conflicting results in the research investigating the relationship between plantar heel pain and dorsiflexion restriction, the weight of evidence from studies using valid,
10
reliable measures supports an association being likely, particularly in general population samples. Importantly, only case-control studies of level III-3 evidence have investigated this to date, leaving the need for future prospective cohort studies to evaluate whether this association is causative or consequential. Regardless, clinicians should consider the use of strategies aimed at improving dorsiflexion flexibility, or accommodating for restricted motion, when managing
of
people with heel pain.
ro
Reduced extension of the 1st MTPJ is also considered to be a potential contributing factor to
plantar heel pain. The plantar fascia is placed under tension by extending the digits, thus reduced
-p
digit extension could be related to plantar fascia inflexibility. Loss of extension of the 1st MTPJ
re
may therefore be associated with increased tensile load within the plantar fascia during toe-off in walking and running, and hence contribute to plantar heel pain.[22] A very small study reported
lP
reduced 1st MTPJ extension in runners with heel pain,[46] however, further investigation with larger sample sizes is required to support these findings. Studies containing samples of
ur na
participants from the general population have reported differing results. 2 studies have found no difference in 1st MTPJ extension range between groups of participants with and without plantar heel pain, suggesting that the extensibility of soft tissues influencing 1st MTPJ range is not related to the condition.[22] [38] In contrast, however, a recent study with 50 people attending a
Jo
clinic with plantar heel pain and 50 matched controls attending for hyperkeratosis or nail disorders, reported reduced 1st MTPJ extension in the heel pain group.[36]
These results are unable to clearly establish whether an association exists between plantar heel pain and 1st MTPJ extension range of motion. Variations exist in the measurement procedures
11
described in each of these studies, which could possibly explain the different results. These differences include whether the first ray is in a relaxed, flexed position or not, as well as the landmarks chosen to represent the joint angle measured. Of interest, tissue-specific stretching of the plantar fascia utilizing toe extension has been demonstrated to be effective in reducing plantar heel pain. The mechanism behind the effectiveness of this intervention, however, is not understood and remains speculative. [47] With the relationship between toe range of motion and
of
heel pain unclear, the mechanism may not necessarily be one of simply improving flexibility, but
ro
could potentially involve other factors such as reducing fascia microtrauma when done prior to
-p
initial weight-bearing [48] or tissue desensitization and improved tolerance to stretch.
re
Muscle strength and endurance
Deficits in muscle function are considered possible contributing factors to plantar heel pain.
lP
Intrinsic foot muscles have a role in supporting the longitudinal arch,[49-51] as do extrinsic muscles such as the tibialis posterior and peroneus longus.[52-54] Weakness in any of these
ur na
muscle groups could result in excessive stress on non-contractile structures including the plantar fascia and contribute to heel pain. Alternatively, as plantar heel pain negatively impacts work and leisure activities,[6] reductions in or modifications to daily activity could result in strength
Jo
loss due to muscle atrophy.
Deficits in peak ankle plantar flexor torque have been found in runners with unilateral plantar heel pain. The symptomatic feet of runners displayed significant strength deficits on isokinetic testing when compared to normative data or to the uninvolved foot, indicating that plantar heel pain was associated with decreased calf strength.[45] Plantar flexor endurance, however, has
12
been found to be unrelated to plantar heel pain in participants recruited from the general population, as two studies have reported no significant difference in plantar flexor endurance between symptomatic and asymptomatic participants using the standing heel raise test.[35, 38] Interestingly, one smaller study used a rocker board device to isolate weightbearing plantar flexor testing to motion at the ankle by removing motion at the toes. This study reported reduced endurance in 27 people with plantar heel pain, compared with age, sex and BMI matched control
of
participants.[55] Whilst this result suggests the potential for plantar flexor endurance to be
ro
affected in people with heel pain, as this particular procedure could be more sensitive in
detecting muscle performance deficits at the ankle, further research is needed to support this.
-p
[55] The larger studies, using a more functional test, suggest that reduced plantar flexor
re
endurance is not likely to be a feature of plantar heel pain.
lP
Toe flexor strength deficits appear to be associated with plantar heel pain. Three studies, using different measurement procedures have consistently demonstrated reductions in flexor muscle
ur na
strength in groups with heel pain compared to asymptomatic controls. Toe flexor strength has been measured by having participants press their toes into a metal bar attached to an electronic strain gauge, [22] hand-held dynamometry targeting the great toe and lesser toes separately, [38] or a modified paper grip test to assess toe flexor force. This paper grip test modification
Jo
incorporated a pinch gauge to assess plantar flexion force of both the great toe and lesser toes separately. [55] These studies suggest that toe flexor weakness could be either a cause of, or a result of, plantar heel pain. However, as these studies all involved participants recruited from the general population, it is not clear as to whether toe flexor strength deficits are associated with heel pain in athletic groups. As the intrinsic and extrinsic muscles that contribute to toe flexion
13
are capable of providing support to the longitudinal arch, decreased capacity of these muscles to generate force could result in passive structures, including the plantar fascia, experiencing greater load. Alternatively, reductions in toe flexor strength could occur as result of plantar heel pain. The intrinsic muscles and long toe flexors are most active in the second half of stance phase.[56] This phase of the gait cycle is also where the greatest strain on the plantar fascia occurs.[57] Modification to the push off phase of gait, in order to lessen plantar fascia tensile
ro
of
load, could result in a reduced toe flexor contribution and subsequent loss of strength.
To date, only one study has assessed ankle invertor and evertor strength in people with plantar
-p
heel pain. Using hand-held dynamometry, eversion strength was found to be reduced in people
re
with heel pain when compared to control participants. Inversion strength did not differ between groups, resulting in an altered inversion/eversion ratio in those with heel pain.[38] These
lP
findings could be potentially explained by an alteration in loading of the foot during walking. People with heel pain have been shown to reduce loading at the heel, as well as reduce maximum
ur na
force beneath the medial forefoot and increase the force-time integral beneath the lateral forefoot.[58] This offloading type strategy may reduce peroneus longus activity in stabilizing the first ray, leading to weakness. Conversely, peroneus longus weakness could theoretically precede the onset of plantar heel pain. Reduced first ray plantarflexion force due to weakness could result
Jo
in less arch stability and lead to excessive stress on the plantar fascia.
The available evidence suggests that people with heel pain are likely to demonstrate deficits in foot and ankle muscle strength, but not in plantar flexor endurance. The cross-sectional nature of these studies does not allow conclusions to be drawn regarding causation. Given these findings,
14
however, resistance exercises should be considered when developing intervention strategies for people with plantar heel pain as they may be useful in addressing associated impairments. To date, there has been limited investigation into the effectiveness of resistance exercise for plantar heel pain, with differing findings.[59, 60] Further research is needed to support and guide the use of resistance exercise as an intervention for plantar heel pain generally, as well as investigate
of
the association between muscle strength and plantar heel pain in specific athletic groups.
ro
Body Mass Index
A number of studies have measured Body Mass Index (BMI) in people with plantar heel pain.
-p
Excessive body mass results in greater forces loading the foot during weightbearing and could
re
potentially increase stresses at the heel. A higher BMI has been shown to be associated with foot pain in general.[61] A BMI of > 30 kg/m2 is associated with an increased risk of plantar heel
lP
pain, [3] and a number of studies have reported higher BMI scores in people with plantar heel pain compared to asymptomatic control participants.[27, 35, 38, 62, 63] These findings strongly
ur na
suggest an association between a high BMI and the presence of plantar heel pain. In addition, some evidence suggests a high BMI may also be associated with greater self-reported disability in people with heel pain, [6] as well as a poorer prognosis following surgical intervention.[64] In
Jo
contrast, BMI does not appear to influence outcomes after conservative management.[65, 66]
In a study involving runners with plantar heel pain, there was no significant difference in BMI between a group of 36 symptomatic runners and a control group of asymptomatic runners.[28] This suggests that increased BMI does not seem to be a significant factor in the development of plantar heel pain in athletic populations. Therefore the evidence to date suggests that plantar heel
15
pain is associated with a higher BMI in non-athletic populations, but not in athletic groups.
Activity-related factors Factors such as work-related standing and the amount of weight-bearing exercise undertaken are considered possible contributors to plantar heel pain. It has been reported that plantar heel pain is more likely to occur in people who are on their feet for most of the day.[3] This study, however,
of
simply asked both control and plantar heel pain participants whether they spent most of the day
ro
on their feet, with the answer being “yes” or “no”. No specific data on actual length of time
standing or walking were recorded. In contrast, plantar heel pain has been demonstrated to have
-p
no association with occupational ‘lower limb stress’.[35] Lower limb stress was measured using
re
the Occupational Rating Scale, with no difference apparent between people with plantar heel pain and asymptomatic controls for the scale’s standing component. The authors conceded that
lP
data were representative of each individual’s occupation at the time of data collection, and may not necessarily reflect the occupational lower limb stress at the time of onset of plantar heel pain.
ur na
Similarly, people with heel pain reported equivalent work-related standing time to a group with no history of the condition.[38] This study gathered data using patient recall of their occupational standing requirements at the time of symptom onset. As the median time of symptom duration was 10 months, data collected on work-related standing requirements may have been affected by
Jo
recall bias. More recently, longer work-related standing duration on hard surfaces was related to the presence of plantar heel pain in a specific sample of assembly workers.[67] Whether this relationship exists across the wider population of people with heel pain is unknown. Given the scant research to date, and the limitations of these existing studies, the influence of occupationbased standing on plantar heel pain is not well understood.
16
With regard to exercise, regular running is reported to be a risk factor for plantar heel pain.[68] Plantar heel pain is reported to have a prevalence of 5.2 -17.5% among runners,[69] and is among the three most common injuries in this population.[69, 70] Training mileage has been linked to running injury risk in general,[71] and some evidence exists associating higher mileage with plantar heel pain.[72] Younger age and previous injury may also be risk factors for heel
of
pain in runners.[28] While samples of runners have been the focus of a number of individual
ro
research studies, the association between heel pain and weight-bearing exercise more broadly has been the focus of only limited investigation. One study has reported people with heel pain to
-p
participate in equal amounts of weight-bearing exercise to asymptomatic controls.[38] Although
re
data collected in this study reflected exercise levels at the time of onset of heel pain, many of the symptomatic participants had chronic symptoms (median 10 months), leaving recall bias as a
lP
significant study limitation. Future studies should incorporate the use of wearable technology to more accurately measure physical activity in people with plantar heel pain. This may be
ur na
particularly useful in identifying risky levels of exercise in more active people with heel pain in longitudinal studies.
The evidence regarding BMI, exercise and occupational standing suggests that higher external
Jo
loading may play a role in plantar heel pain through excessive body mass, training loads or occupational weight-bearing requirements. While further investigation is needed to better determine risky levels of loading, intervention strategies for plantar heel pain should include an element of load management, which may include but not be limited to; weight-loss, activity modification, and relative rest from exercise or occupational weight-bearing loads followed by a graduated reloading of tissues. Similar strategies have been implemented in tendon disorders 17
[73] and could be investigated for efficacy in future plantar heel pain trials.
Conclusion Plantar heel pain is associated with a high BMI in non-athletic people, reduced ankle dorsiflexion range, as well as specific foot and ankle strength deficits. Foot and ankle plantar
of
flexor endurance does not appear to be associated with heel pain and the importance of foot
ro
alignment and great toe flexibility remains unclear. Limited evidence supports running mileage and work-related standing duration as potential risk factors for plantar heel pain. Importantly,
-p
investigations into the relationships between these mechanical factors and heel pain are limited to cross-sectional studies, which are unable to determine if these factors have a role in the
re
etiology of the condition. Studies with higher levels of evidence, particularly prospective cohort
lP
studies, would assist in determining whether these associated factors are causative or consequential, as well as determine the occupational and athletic activity thresholds that increase
ur na
risk. Management strategies for plantar heel pain should include evidence-based interventions such as orthoses and tissue-specific plantar fascia stretching, as well as targeting specific strength and flexibility deficits and load management. Along with strategies to reduce body weight, load management strategies could include reductions in training or occupational load, followed by
Jo
graduated return to necessary activity levels. Further studies are needed to investigate the effectiveness of resistance exercise and load management strategies as intervention strategies for plantar heel pain.
18
Declarations of interests: None
Justin Sullivan contributed to the concept and design of the article, drafting the manuscript and approved the final version Evangelos Pappas contributed to the concept and design of the article, drafting the manuscript and approved the final version
ro
of
Joshua Burns contributed to the concept and design of the article, drafting the manuscript and approved the final version
Jo
ur na
lP
re
-p
This work has not been submitted to any other publisher and is only currently submitted to ‘The Foot’
19
References [1] Cole C, Seto C, Gazewood J. Plantar fasciitis: evidence-based review of diagnosis and therapy. Am Fam Physician. 2005;72:2237-42. [2] Tong KB, Furia J. Economic burden of plantar fasciitis treatment in the United States. Am J Orthop (Belle Mead NJ). 2010;39:227-31.
of
[3] Riddle DL, Pulisic M, Pidcoe P, Johnson RE. Risk factors for Plantar fasciitis: a matched case-control study. J Bone Joint Surg Am. 2003;85-A:872-7.
ro
[4] Reischl S. Physical therapist foot care survey. Orthop Pract. 2001;13:548.
-p
[5] Irving DB, Cook JL, Young MA, Menz HB. Impact of chronic plantar heel pain on healthrelated quality of life. J Am Podiatr Med Assoc. 2008;98:283-9.
re
[6] Riddle DL, Pulisic M, Sparrow K. Impact of demographic and impairment-related variables on disability associated with plantar fasciitis. Foot Ankle Int. 2004;25:311-7.
lP
[7] Bennett PJ, Patterson C, Dunne MP. Health-Related Quality of Life Following Podiatric Surgery. J Am Podiatr Med Assoc. 2001;91:164-73. doi:10.7547/87507315-91-4-164
ur na
[8] Wearing SC, Smeathers JE, Urry SR, Hennig EM, Hills AP. The pathomechanics of plantar fasciitis. Sports Med. 2006;36:585-611.
[9] Rompe JD, Furia J, Weil L, Maffulli N. Shock wave therapy for chronic plantar fasciopathy.
Jo
Br Med Bull. 2007;81-82:183-208. 10.1093/bmb/ldm005 [10] Furey JG. Plantar fasciitis. The painful heel syndrome. J Bone Joint Surg Am. 1975;57:6723.
[11] Puttaswamaiah R, Chandran P. Degenerative plantar fasciitis: A review of current concepts. Foot. 2007;17:3-9. http://dx.doi.org/10.1016/j.foot.2006.07.005
20
[12] Hossain M, Makwana N. “Not Plantar Fasciitis”: the differential diagnosis and management of heel pain syndrome. Orthop Trauma. 2011;25:198-206. http://dx.doi.org/10.1016/j.mporth.2011.02.003 [13] Lemont H, Ammirati KM, Usen N. Plantar Fasciitis. J Am Podiatr Med Assoc. 2003;93:234-7. 10.7547/87507315-93-3-234 [14] Hunt GC, Sneed T, Hamann H, Chisam S. Biomechanical and histiological considerations
of
for development of plantar fasciitis and evaluation of arch taping as a treatment option to control
ro
associated plantar heel pain: a single-subject design. Foot. 2004;14:147-53.
[15] Beeson P. Plantar fasciopathy: revisiting the risk factors. Foot Ankle Surg. 2014;20:160-5.
-p
10.1016/j.fas.2014.03.003
re
[16] League AC. Current concepts review: plantar fasciitis. Foot Ankle Int. 2008;29:358-66. 10.3113/FAI.2008.0358
lP
[17] Landorf KB. Plantar heel pain and plantar fasciitis. BMJ Clin Evid. 2015;2015. [18] Wolgin M, Cook C, Graham C, Mauldin D. Conservative Treatment of Plantar Heel Pain:
ur na
Long-Term Follow-Up. Foot Ankle Int. 1994;15:97-102. 10.1177/107110079401500303 [19] Davis PF, Severud E, Baxter DE. Painful Heel Syndrome: Results of Nonoperative Treatment. Foot Ankle Int. 1994;15:531-5. 10.1177/107110079401501002 [20] Thomas JL, Christensen JC, Kravitz SR, Mendicino RW, Schuberth JM, Vanore JV, et al.
Jo
The diagnosis and treatment of heel pain: a clinical practice guideline-revision 2010. J Foot Ankle Surg. 2010;49:S1-19. 10.1053/j.jfas.2010.01.001 [21] McPoil TG, Martin RL, Cornwall MW, Wukich DK, Irrgang JJ, Godges JJ. Heel pain-plantar fasciitis: clinical practice guildelines linked to the international classification of function,
21
disability, and health from the orthopaedic section of the American Physical Therapy Association. J Orthop Sports Phys Ther. 2008;38:A1-a18. 10.2519/jospt.2008.0302 [22] Allen RH, Gross MT. Toe flexors strength and passive extension range of motion of the first metatarsophalangeal joint in individuals with plantar fasciitis. J Orthop Sports Phys Ther. 2003;33:468-78. 10.2519/jospt.2003.33.8.468 [23] Bolgla LA, Malone TR. Plantar fasciitis and the windlass mechanism: a biomechanical link
of
to clinical practice. J Athl Train. 2004;39:77-82.
ro
[24] Burns J, Crosbie J, Hunt A, Ouvrier R. The effect of pes cavus on foot pain and plantar
pressure. Clin Biomech (Bristol, Avon). 2005;20:877-82. 10.1016/j.clinbiomech.2005.03.006
-p
[25] Gill LH. Plantar Fasciitis: Diagnosis and Conservative Management. Journal Am Acad
re
Orthop Surg. 1997;5:109-17.
[26] Huang Y-C, Wang L-Y, Wang H-C, Chang K-L, Leong C-P. The relationship between the
2004;27:443-8.
lP
flexible flatfoot and plantar fasciitis: ultrasonographic evaluation. Chang Gung Med J.
ur na
[27] Prichasuk S, Subhadrabandhu T. The relationship of pes planus and calcaneal spur to plantar heel pain. Clin Orthop Relat Res. 1994;306:192 - 6. [28] Rome K, Howe T, Haslock I. Risk factors associated with the development of plantar heel pain in athletes. Foot. 2001;11:119-25. http://dx.doi.org/10.1054/foot.2001.0698
Jo
[29] Pohl MB, Hamill J, Davis IS. Biomechanical and anatomic factors associated with a history of plantar fasciitis in female runners. Clin J Sport Med. 2009;19:372-6. 10.1097/JSM.0b013e3181b8c270
22
[30] Ribeiro AP, Trombini-Souza F, Tessutti V, Rodrigues Lima F, Sacco Ide C, Joao SM. Rearfoot alignment and medial longitudinal arch configurations of runners with symptoms and histories of plantar fasciitis. Clinics. 2011;66:1027-33. [31] McCrory JL, Young MJ, Boulton AJM, Cavanagh PR. Arch index as a predictor of arch height. Foot. 1997;7:79-81. http://dx.doi.org/10.1016/S0958-2592(97)90052-3 [32] Wearing SC, Hills AP, Byrne NM, Hennig EM, McDonald M. The Arch Index: A Measure
of
of Flat or Fat Feet? Foot Ankle Int. 2004;25:575-81. 10.1177/107110070402500811
ro
[33] Hawes MR, Nachbauer W, Sovak D, Nigg BM. Footprint Parameters as a Measure of Arch Height. Foot Ankle Int. 1992;13:22-6. 10.1177/107110079201300104
-p
[34] Redmond AC, Crosbie J, Ouvrier RA. Development and validation of a novel rating system
re
for scoring standing foot posture: the Foot Posture Index. Clin Biomech (Bristol, Avon). 2006;21:89-98. 10.1016/j.clinbiomech.2005.08.002
lP
[35] Irving DB, Cook JL, Young MA, Menz HB. Obesity and pronated foot type may increase the risk of chronic plantar heel pain: a matched case-control study. BMC Musculoskelet Disord.
ur na
2007;8:41. 10.1186/1471-2474-8-41
[36] Aranda Y, Munuera PV. Plantar Fasciitis and Its Relationship with Hallux Limitus. J Am Podiatr Med Assoc. 2014;104:263-8. 10.7547/0003-0538-104.3.263 [37] Redmond AC, Crane YZ, Menz HB. Normative values for the Foot Posture Index. J Foot
Jo
Ankle Res. 2008;1:6. 10.1186/1757-1146-1-6 [38] Sullivan J, Burns J, Adams R, Pappas E, Crosbie J. Musculoskeletal and Activity-Related Factors Associated With Plantar Heel Pain. Foot Ankle Int. 2015;36:37-45. 10.1177/1071100714551021
23
[39] Wearing SC, Smeathers JE, Yates B, Sullivan PM, Urry SR, Dubois P. Sagittal movement of the medial longitudinal arch is unchanged in plantar fasciitis. Med Sci Sports Exerc. 2004;36:1761-7. [40] Wearing SC, Smeathers JE, Sullivan PM, Yates B, Urry SR, Dubois P. Plantar fasciitis: are pain and fascial thickness associated with arch shape and loading? Phys Ther. 2007;87:1002-8. [41] Karas MA, Hoy DJ. Compensatory Midfoot Dorsiflexion in the Individual with Heelcord
of
Tightness: Implications for Orthotic Device Designs. JPO: J Prosthet Orthot. 2002;14:82-93.
ro
[42] Snow SW, Bohne WH, DiCarlo E, Chang VK. Anatomy of the Achilles tendon and plantar fascia in relation to the calcaneus in various age groups. Foot Ankle Int. 1995;16:418-21.
-p
[43] Kim PJ, Richey JM, Wissman LR, Steinberg JS. The variability of the Achilles tendon
re
insertion: a cadaveric examination. J Foot Ankle Surg. 2010;49:417-20. S1067-2516(10)00189-4 [pii]10.1053/j.jfas.2010.05.002
lP
[44] Bolivar YA, Munuera PV, Padillo JP. Relationship between tightness of the posterior muscles of the lower limb and plantar fasciitis. Foot Ankle Int. 2013;34:42-8.
ur na
10.1177/1071100712459173
[45] Kibler WB, Goldberg C, Chandler TJ. Functional biomechanical deficits in running athletes with plantar fasciitis. Am J Sports Med. 1991;19:66-71. [46] Creighton D, Olson VL. Evaluation of range of motion of the first metatarsophalangeal joint
Jo
in runners with plantar faciitis*. J Orthop Sports Phys Ther. 1987;8:357-61. 1953 [pii] [47] Rompe JD, Cacchio A, Weil L, Furia JP, Haist J, Reiners V, et al. Plantar fascia-specific stretching versus radial shock-wave therapy as initial treatment of plantar fasciopathy. J Bone Joint Surg Am. 2010;92:2514-22. 10.2106/jbjs.i.01651
24
[48] DiGiovanni BF, Nawoczenski DA, Lintal ME, Moore EA, Murray JC, Wilding GE, et al. Tissue-specific plantar fascia-stretching exercise enhances outcomes in patients with chronic heel pain. A prospective, randomized study. J Bone Joint Surg Am. 2003;85-a:1270-7. [49] Fiolkowski P, Brunt D, Bishop M, Woo R, Horodyski M. Intrinsic pedal musculature support of the medial longitudinal arch: an electromyography study. J Foot Ankle Surg.
of
2003;42:327-33. 10.1053/j.jfas.2003.10.003S1067251603003910 [pii] [50] Mann R, Inman VT. Phasic Activity of Intrinsic Muscles of the Foot. J Bone Joint Surg Am.
ro
1964;46:469-81.
-p
[51] Headlee DL, Leonard JL, Hart JM, Ingersoll CD, Hertel J. Fatigue of the plantar intrinsic foot muscles increases navicular drop. J Electromyogr Kinesiol. 2008;18:420-5. S1050-
re
6411(06)00170-2 [pii]10.1016/j.jelekin.2006.11.004
lP
[52] Kaye RA, Jahss MH. Tibialis posterior: a review of anatomy and biomechanics in relation to support of the medial longitudinal arch. Foot Ankle. 1991;11:244-7. [53] Kitaoka HB, Luo ZP, An KN. Effect of the posterior tibial tendon on the arch of the foot
ur na
during simulated weightbearing: biomechanical analysis. Foot Ankle Int. 1997;18:43-6. [54] Johnson CH, Christensen JC. Biomechanics of the first ray. Part I. The effects of peroneus longus function: a three-dimensional kinematic study on a cadaver model. J Foot Ankle Surg.
Jo
1999;38:313-21.
[55] McClinton S, Collazo C, Vincent E, Vardaxis V. Impaired Foot Plantar Flexor Muscle Performance in Individuals With Plantar Heel Pain and Association With Foot Orthosis Use. J Orthop Sports Phys Ther. 2016;46:681-8. 10.2519/jospt.2016.6482 [56] Gray EG, Basmajian JV. Electromyography and cinematography of leg and foot ("normal" and flat) during walking. Anat Rec. 1968;161:1-15. 10.1002/ar.1091610101 25
[57] Erdemir A, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA. Dynamic loading of the plantar aponeurosis in walking. J Bone Joint Surg Am. 2004;86-A:546-52. [58] Sullivan J, Burns J, Adams R, Pappas E, Crosbie J. Plantar heel pain and foot loading during normal walking. Gait Posture.41:688-93. 10.1016/j.gaitpost.2015.01.025 [59] Rathleff MS, Molgaard CM, Fredberg U, Kaalund S, Andersen KB, Jensen TT, et al. Highload strength training improves outcome in patients with plantar fasciitis: A randomized
of
controlled trial with 12-month follow-up. Scand J Med Sci Sports. 2015;25:e292-300.
ro
10.1111/sms.12313
[60] Kamonseki DH, Goncalves GA, Yi LC, Junior IL. Effect of stretching with and without
-p
muscle strengthening exercises for the foot and hip in patients with plantar fasciitis: A
re
randomized controlled single-blind clinical trial. Man Ther. 2016;23:76-82. 10.1016/j.math.2015.10.006
lP
[61] Hill CL, Gill TK, Menz HB, Taylor AW. Prevalence and correlates of foot pain in a population-based study: the North West Adelaide health study. J Foot Ankle Res. 2008;1:2.
ur na
10.1186/1757-1146-1-2
[62] Rano JA, Fallat LM, Savoy-Moore RT. Correlation of heel pain with body mass index and other characteristics of heel pain. J Foot Ankle Surg. 2001;40:351-6. http://dx.doi.org/10.1016/S1067-2516(01)80002-8
Jo
[63] Ozdemir H, Yilmaz E, Murat A, Karakurt L, Poyraz AK, Ogur E. Sonographic evaluation of plantar fasciitis and relation to body mass index. Eur J Radiol. 2005;54:443-7. http://dx.doi.org/10.1016/j.ejrad.2004.09.004 [64] Saxena A. Uniportal endoscopic plantar fasciotomy: a prospective study on athletic patients. Foot Ankle Int. 2004;25:882-9. 10.1177/107110070402501207
26
[65] Pfeffer G, Bacchetti P, Deland J, Lewis A, Anderson R, Davis W, et al. Comparison of custom and prefabricated orthoses in the initial treatment of proximal plantar fasciitis. Foot Ankle Int. 1999;20:214-21. 10.1177/107110079902000402 [66] McClinton SM, Cleland JA, Flynn TW. Predictors of response to physical therapy intervention for plantar heel pain. Foot Ankle Int. 2015;36:408-16. 10.1177/1071100714558508 [67] Werner RA, Gell N, Hartigan A, Wiggerman N, Keyserling WM. Risk factors for plantar
of
fasciitis among assembly plant workers. PM R. 2010;2:110-6. 10.1016/j.pmrj.2009.11.012
ro
[68] Martin RL, Davenport TE, Reischl SF, McPoil TG, Matheson JW, Wukich DK, et al. Heel pain-plantar fasciitis: revision 2014. J Orthop Sports Phys Ther. 2014;44:A1-33.
-p
10.2519/jospt.2014.0303
re
[69] Lopes A, Hespanhol L, Jr., Yeung S, Costa L. What are the Main Running-Related Musculoskeletal Injuries? Sports Med. 2012;42:891-905. 10.1007/BF03262301
lP
[70] Taunton JE, Ryan MB, Clement DB, McKenzie DC, Lloyd-Smith DR, Zumbo BD. A retrospective case-control analysis of 2002 running injuries. Br J Sports Med. 2002;36:95-101.
ur na
10.1136/bjsm.36.2.95
[71] van Gent BRN, Siem DD, van Middelkoop M, van Os TAG, Bierma-Zeinstra SSMA, Koes BBW. Incidence and determinants of lower extremity running injuries in long distance runners: A systematic review. Br J Sports Med. 2007. 10.1136/bjsm.2006.033548
Jo
[72] Warren BL. Anatomical factors associated with predicting plantar fasciitis in long-distance runners. Med Sci Sports Exerc. 1984;16:60-3. [73] Malliaras P, Cook J, Purdam C, Rio E. Patellar Tendinopathy: Clinical Diagnosis, Load Management, and Advice for Challenging Case Presentations. J Orthop Sports Phys Ther. 2015;45:887-98. 10.2519/jospt.2015.5987
27
Table 1. Studies investigating foot alignment and plantar heel pain. Study
Sample
Prichasuk & Subhadrabandhu 1994
Size: 82 with PHP and 400 controls
Foot alignment measure Radiological: Calcaneal pitch
Result
Level of Evidence
Footprint-based Arch index
Greater incidence of PHP in flexible flatfoot group (10/23 vs 2/23)
PHP group were found to have a flatter arch
III-3
Type: General population
of
Type: General population
Clinical Navicular height
No difference between PHP and controls
III-3
Three-dimensional kinematic analysis Peak rearfoot eversion
No difference between PHP and controls
III-3
Clinical rearfoot alignment
No differences between groups for rearfoot alignment
III-3
Podoscope Medial longitudinal arch angle
Higher arch reported in the PHP group
re
Matched: No Size: 166 particpants recruited – 36 with PHP and 130 Controls
lP
Rome et al. 2001
IV
ro
Matched: No Size: 23 people with a low arch and 23 people with a normal arch. (12 of the total 26 participants had PHP)
-p
Huang et al. 2004
ur na
Type: Athletic – sports involving running
Pohl et al. 2009
Matched: No Size: 25 with PHP and 25 controls
Jo
Type: Female runners
Ribeiro et al. 2011
Matched: matched for age and mileage Size: 45 with PHP (30 symptomatic and 15 with previous history) and 60 controls.
28
Type: Experienced runners
Clinical Longitudinal arch angle
Type: General population
Rearfoot to leg angle
Matched: matched for age and sex Size: 80 with PHP and 80 controls
Clinical Foot Posture Index
No differences between PHP and controls
PHP group more pronated foot posture
III-3
Dynamic radiological Calcaneal-first metatarsal angle
No difference between PHP and controls
III-3
Clinical Foot Posture Index
PHP group more pronated foot posture
III-3
Clinical Foot Posture Index
No difference between PHP and controls
III-3
re
Wearing et al. 2004
-p
Type: General population Matched: matched for age and sex Size: 10 with PHP and 10 controls
III-3
of
Irving et al. 2007
Matched: No Size: 20 with PHP and 20 controls
ro
Allen & Gross 2003
lP
Type: General population
ur na
Matched: Matched for age, sex and body mass Size: 50 with PHP and 50 controls
Jo
Aranda & Munuera 2014
Sullivan et al. 2015
Type: Clinic attendees. Control group were attending for hyperkeratosis or nail disorders. Matched: Matched for age, sex and Body Mass Index Size: 202 with PHP and 70 controls
29
Type: General population Matched: No
Jo
ur na
lP
re
-p
ro
of
PHP= plantar heel pain
30
Table 2. Studies investigating foot and ankle range of motion and plantar heel pain
Irving et al. 2007
Matched: Matched for age and sex Size: 80 with PHP and 80 controls Type: General population
Kibler et al. 1991
Matched: matched for age and sex Size: 43 with PHP (mostly runners) and 45 controls (other sports)
Result Ankle dorsiflexion reduced in the PHP group
Level of Evidence III-3
Ankle dorsiflexion Bent knee lunge. Rearfoot pronation not controlled.
Ankle dorsiflexion greater in the PHP group
III-3
Ankle dorsiflexion Method not described
People with PHP had reduced dorsiflexion compared to the unaffected limb, controls and normative data.
III-3
No difference in dorsiflexion between groups.
III-3
Ankle dorsiflexion Goniometry, tested passively
People with a history of heel pain had greater dorsiflexion than controls.
III-3
Great toe extension Goniometry
No difference between groups for passive great toe extension
III-3
lP
Ankle dorsiflexion Goniometry, tested actively. Rearfoot pronation controlled.
ur na
Rome et al. 2001
re
Type: Athletes Matched: matched for age and sex Size: 166 participants recruited – 36 with PHP and 130 Controls
of
Type: General population
Measure Ankle dorsiflexion Goniometry, tested passively. Rearfoot pronation controlled
ro
Sample Size: 50 with PHP and 50 controls
-p
Study Riddle et al. 2003
Type: Athletic – sports involving running
Jo
Pohl et al. 2009
Allen & Gross 2003
Matched: No Size: 25 with PHP previously and 25 controls
Type: Female runners with a history of heel pain Matched: matched for age and mileage Size: 20 with PHP and 20 controls Type: General population
31
People with PHP had reduced active and passive great toe extension
III-3
Ankle Dorsiflexion Goniometry, tested both with knee extended and flexed
People with PHP had reduced ankle dorsiflexion in both tests.
III-3
Ankle dorsiflexion Bent knee lunge and straight knee lunge
People with PHP had reduced ankle dorsiflexion on both tests
Type: General population
Sullivan et al. 2015
Matched: Yes Size: 202 with PHP and 70 controls Type: General population Matched: No
Aranda & Munuera 2014
Size: 50 with PHP and 50 controls
Great toe extension Goniometry Great toe extension Goniometry
ur na
lP
Type: Clinic attendees. Control group were attending for hyperkeratosis or nail disorders.
No differences between groups for passive toe extension People with PHP had reduced passive toe extension
re
Bolivar et al. 2013
Matched: Not stated Size:50 with PHP and 50 controls
-p
Type: Runners
of
Great toe extension Goniometry
Matched: Matched for age, sex and Body Mass Index
Jo
PHP= plantar heel pain
32
III-3
ro
Creighton & Olsen 1987
Matched: matched for age and sex Size: 6 with PHP and 6 controls
III-3
PII:
S0958-2592(19)30083-5
DOI:
https://doi.org/10.1016/j.foot.2019.08.007
Reference:
YFOOT 1636
To appear in:
The Foot
Received Date:
23 May 2019
Revised Date:
6 August 2019
Accepted Date:
30 August 2019
Please cite this article as: Sullivan J, Pappas E, Burns J, Role of mechanical factors in the clinical presentation of plantar heel pain: implications for management, The Foot (2019), doi: https://doi.org/10.1016/j.foot.2019.08.007
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. 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. © 2019 Published by Elsevier.
Role of mechanical factors in the clinical presentation of plantar heel pain: implications for management.
Justin Sullivan PT, PhD 1,3 [email protected] Evangelos Pappas PT, PhD1,3 [email protected]
ro
1
of
Joshua Burns PhD2,3 [email protected]
Discipline of Physiotherapy, Faculty of Health Sciences, The University of Sydney, New South
2
-p
Wales, Australia.
Sydney Children’s Hospitals Network (Randwick and Westmead), University of Sydney, New
Musculoskeletal Health, Faculty of Health Sciences, The University of Sydney, New South Wales, Australia
ur na
Correspondence:
lP
3
re
South Wales, Australia
Justin Sullivan
Faculty of Health Sciences, The University of Sydney P.O Box 170
Jo
Lidcombe, NSW, Australia 1825 Phone: 61(02) 9351 9156 Fax: 61(02) 9351 9601
Email: [email protected]
1
Highlights:
Plantar heel pain is associated with high Body Mass Index in non-athletic groups. Plantar heel pain is associated with specific foot and ankle strength deficits, as well as reduced ankle dorsiflexion range of motion. The association between foot alignment and heel pain is unclear. There is limited evidence that plantar heel pain is associated with loading factors such as running mileage and occupational weight-bearing demands.
of
ro
Abstract
Plantar heel pain is a common musculoskeletal foot disorder that can have a negative impact on
-p
activities of daily living and it is of multifactorial etiology. A variety of mechanical factors,
re
which result in excessive load at the plantar fascia insertion, are thought to contribute to the onset of the condition. This review presents the evidence for associations between commonly
lP
assessed mechanical factors and plantar heel pain, which could guide management. Plantar heel pain is associated with a higher BMI in non-athletic groups, reduced dorsiflexion range of
ur na
motion, as well as reduced strength in specific foot and ankle muscle groups. There is conflicting, or insufficient evidence regarding the importance of foot alignment and first metatarsophalangeal joint range of motion. Plantar heel pain appears to be common in runners, with limited evidence for greater risk being associated with higher mileage or previous injuries.
Jo
Conflicting evidence exists regarding the relationship between work-related standing and plantar heel pain, however, longer standing duration may be associated with plantar heel pain in specific worker groups. The evidence presented has been generated through studies with cross-sectional designs, therefore it is not known whether any of these associated factors have a causative relationship with plantar heel pain. Longitudinal studies are needed to ascertain whether the strength and flexibility impairments associated with plantar heel pain are a cause or consequence 2
of the condition, as well as to establish activity thresholds that increase risk. Intervention approaches should consider strategies that improve strength and flexibility, as well as those that influence plantar fascia loading such as body weight reduction, orthoses and management of
of
athletic and occupational workload.
Key words:
-p
ro
Plantar Fasciitis, fasciopathy, activity, loading, flexibility, alignment, strength, body mass
re
Introduction
Plantar heel pain is a condition that affects adults across all ages [1] of both active and sedentary
lP
lifestyles.[1, 2] In the USA approximately two million people seek treatment for plantar heel pain every year,[3] with an estimated cost of between US$192-376 million in 2007.[2] Plantar
ur na
heel pain is the most common foot condition treated by physical therapists. [4] In addition to its prevalence, plantar heel pain results in limitations in performing physical tasks, [5] including both work and leisure activities.[6] Foot pain and function in people with plantar heel pain appears comparable to those awaiting surgery for interdigital neuroma, but worse than those
Jo
awaiting surgery for forefoot deformities.[5, 7]
Plantar heel pain is a musculoskeletal disorder primarily affecting the enthesis of the plantar fascia, and is synonymous with terms such as plantar fasciitis, painful heel syndrome, heel spur syndrome, runners’ heel and plantar fasciopathy. [8],[9] Plantar fasciitis has been the most
3
commonly used term for this condition, most likely due to initial beliefs that pain results from an inflammatory reaction at the fascial enthesis.[10] It is now clearer that the condition is more commonly due to a degenerative process, [11-13] thus, rendering the term ‘fasciitis’ less suitable for broader use. The pathogenesis of plantar heel pain is considered to be excessive cumulative strain at the enthesis of the plantar fascia.[8] Continuing biomechanical stresses result in microfailure of the plantar fascia, inhibition of normative repair process and abnormal
of
histological responses.[14] Histological investigations involving people with chronic plantar heel
ro
pain commonly describe degeneration and fiber disorientation, increased mucoid ground
substance, angiofibroblastic hyperplasia, and calcification, [8, 13] with minimal or no evidence
-p
of inflammation.[14] Hence, inflammation does not appear to be a predominant feature in plantar
re
heel pain, with the mechanism more likely to be one of advanced fascial degeneration, potentially the end result of a series of acute and chronic inflammatory phases. Inflammation and
lP
degeneration may not be different phases of the condition, but could be independent processes
ur na
with the potential to co-exist.[8]
Despite the magnitude of its prevalence and the impact on those who experience it, the etiology of plantar heel pain is not well understood[15] which leads to uncertainty regarding the most effective intervention strategy.[1, 16, 17] This, in essence, renders the condition somewhat
Jo
enigmatic and often difficult to effectively treat, with estimates between 5-19% of people continuing to have symptoms beyond one year.[18-20] Plantar heel pain is considered to be a multifactorial condition, with numerous causative or associated mechanical factors.[21, 22] The aim of this review is to present the evidence regarding associations between commonly collected clinical measures and plantar heel pain, in an attempt to provide a clearer description of the
4
mechanical factors related to the condition. This, in turn, will assist with the development of more targeted prevention and intervention strategies, as well as highlight priorities for further research.
Contributing and associated factors Many factors are thought to be associated with plantar heel pain. These include both intrinsic and
of
extrinsic factors. Intrinsic factors relate directly to the anatomy or biomechanics of an individual,
ro
including; foot and lower limb alignment, foot and ankle range of motion, muscle strength and endurance, as well as body mass. Extrinsic factors relate to outside influences acting on the foot,
-p
including; the length of time spent standing or exercising, footwear and floor surfaces. Numerous
re
studies have explored the musculoskeletal and lifestyle factors associated with plantar heel pain
Foot alignment
lP
and provide evidence which can assist in guiding clinical practice and future research.
ur na
Foot posture, in particular longitudinal arch height, has long been considered important in the etiology of plantar heel pain. A planus, or low-arched foot, that flattens excessively through the stance phase of gait is thought to increase tensile loading of the plantar fascia, leading to excessive stress at the attachment to the calcaneus.[14] A cavus, or high-arched foot, known to
Jo
produce higher ground reaction forces and peak pressure beneath the heel during walking [23],[24], has also been suggested as being associated with heel pain.[25] Numerous studies investigating foot posture and arch height in relation to plantar heel pain are discussed below, with key findings summarized in Table 1.
5
Static measures of foot and arch alignment in standing include measures of calcaneal angle, arch height, as well as global foot posture. Arch height measures have been performed using radiology, footprint analysis, longitudinal arch angle and foot height to truncated length measures. Two studies involving general population samples have reported a lower arch to be associated with the presence of plantar heel pain. One of these studies used the radiological measurement of calcaneal pitch as an indicator of arch height[26] and the other calculated the
of
arch index from weight-bearing footprints [27]. Only 12 of the 46 participants in this second
ro
study had plantar heel pain, leaving the sample size of symptomatic participants small. In
contrast, longitudinal arch angle, measured as 368the angle created from lines connecting the
-p
center of the medial malleolus, the navicular tuberosity and the first metatarsal head, did not
re
differ in a study comparing 20 participants with plantar heel pain and 20 age- and sex-matched controls.[22] In studies including athletic people with plantar heel pain, a range of different
lP
findings regarding arch height measures are reported. Studies have reported athletes with heel pain to have arch height equivalent to asymptomatic athletes using navicular height measures,
ur na
[28] a flatter arch when compared using the height of the foot at 50% of foot length divided by truncated foot length as an arch height measure, [29] and a higher arch than non-injured runners when compared using the arch index measure.[30] In this study, arch index was calculated from footprints generated using a podoscope and was equal to the area of the midfoot divided by the
Jo
area of the entire foot. The varying results of these studies involving athletic people with heel pain may reflect the differences in the measurement procedures used, or be related to the small size and characteristics of the samples included. In addition, differing reports of arch height in people with plantar heel pain in the studies using an arch index may reflect the variations in technique used, as well as the validity of the measurement. Although arch index is considered to
6
represent arch height as it correlates with truncated navicular height,[31] it only represents about half the variation in navicular height [31] and can be affected by body composition.[32] Ultimately, arch index and other footprint based measures may only represent angles and indices of the plantar surface of the foot, rather than assessing the overall alignment of the foot and ankle.[33]
of
A simpler way to assess foot posture is by examining calcaneal alignment. Cross-sectional
ro
studies measuring the angle formed by the calcaneus with respect to vertical or the lower limb report no differences between people with heel pain and asymptomatic controls. [22, 29, 30]
-p
Collectively, these studies suggest a lack of association between rearfoot angle in standing and
re
plantar heel pain, however, some caution with this interpretation is needed as the studies included small samples and two contained only athletic participants. The Foot Posture Index
lP
(FPI) is a more global measure of foot alignment and is a reliable 25-point tool rating foot posture from more supinated to more pronated, based on observation and palpation of the
ur na
alignment of six different sections of the foot.[34] Alignment observations making up part of the FPI include calcaneal angle and arch congruency. Two studies have reported higher FPI scores in people with heel pain compared to age- and sex-matched controls, suggesting a potential link between a more pronated foot posture and plantar heel pain.[35, 36] Of note, average FPI scores
Jo
were lower (indicating less pronation), than published normative data [37] in both controls and symptomatic patients in one of these studies, [35] as well as in the controls of the second study. [36] In contrast to these findings, a larger study reported no difference in FPI scores between groups with and without plantar heel pain,[38] with both groups exhibiting FPI scores similar to published normative data.[37]
7
Several studies have investigated the association between dynamic foot and ankle motion and plantar heel pain, with no differences evident between people with plantar heel pain and asymptomatic controls. Two small studies that used digital fluoroscopy to compare 10 people with plantar heel pain and 10 age-, sex- and body mass-matched controls, did not find any differences in arch movement or maximum arch angle during walking.[39, 40] In a study of 25
of
female runners with a history of plantar heel pain, three dimensional kinematic analysis of
ro
running revealed no differences in rearfoot eversion occurring during stance phase in runners
-p
with heel pain compared to age- and mileage-matched controls.[29]
re
These studies, due to their variable results in both general and athletic samples, as well as in matched and unmatched groups, along with different measurement procedures and often small
lP
sample sizes, are unable to clearly determine if there is an association between static or dynamic foot and arch alignment and plantar heel pain. Therefore, current evidence linking arch height
ur na
and foot alignment to plantar heel pain is equivocal. Future investigations of larger samples of people with heel pain, using accurate and valid measures of foot alignment and dynamic motion, are needed to clarify any potential association. The uncertainty of any link between foot posture and plantar heel pain may have some impact on management strategies that influence mechanical
Jo
function of the foot, such as orthoses. Pre-fabricated and custom orthoses have been demonstrated to be equally effective in reducing plantar heel pain, with the mechanism possibly one of offloading via support of the arch, or a reduction in pressure beneath the painful heel. Whilst these strategies may be useful in offloading the heel and reducing pain in the short term,
8
usage of orthoses to prevent recurring heel pain based on presenting foot posture does not appear to be supported by evidence.
Foot and Ankle Range of motion Impairments in range of motion at particular foot and ankle joints have been suggested as being associated with plantar heel pain. Table 2 summarizes the research that has investigated the
of
relationship between foot and ankle range of motion and heel pain. Reduced ankle joint motion,
ro
specifically dorsiflexion, is often proposed as a risk factor for plantar heel pain. Lack of ankle dorsiflexion during the stance phase of the gait cycle could potentially lead to a compensatory
-p
increase in midfoot dorsiflexion motion,[41] essentially lowering the arch further and increasing
re
tensile load on the plantar fascia. In addition, anatomical studies have described a contiguous connection between the plantar fascia and the Achilles tendon, which appears less evident with
lP
increasing age.[42, 43] In individuals where this anatomical link exists, it is feasible that increased tensile load on the gastrocnemius-soleus complex due to inflexibility could transmit
ur na
directly to the plantar fascia. Conversely, given the association between these anatomical structures, reducing dorsiflexion during gait and other activities may serve to offload tension in the plantar fascia and ultimately reduce pain in people with plantar heel pain. Continuation of such as strategy could result in tissue adaptations and a reduction in dorsiflexion range as a
Jo
consequence of plantar heel pain.
Three studies have reported reduced ankle dorsiflexion in general population samples of people with heel pain. Two of these studies measured dorsiflexion using goniometry, in non-weightbearing with the knee extended and subtalar joint in neutral,[3] [44] whilst the other used both
9
the bent-knee and straight-knee lunge tests.[38] In contrast, ankle dorsiflexion, using the bentknee lunge test, was found not to be associated with plantar heel pain in a study comparing 80 symptomatic participants and 80 age- and sex-matched controls.[35]
Three studies have investigated dorsiflexion range of motion in people with plantar heel pain specifically from athletic populations. Sport related tasks are likely to require greater joint
of
flexibility than many daily activities, hence, restrictions in foot and ankle range of motion could
ro
be more problematic for athletes. Significantly reduced ankle dorsiflexion range has been
reported in the affected feet of runners with plantar heel pain, when compared to reference
-p
norms, the uninvolved foot, or to a group of active controls who ran as a part of their sport.[45]
re
A detailed description of the measurement procedure in this study, however, was not available. In contrast, two studies have reported no difference in ankle dorsiflexion between runners with
lP
heel pain and asymptomatic control participants. One of these studies, however, used a measure which involved the participants actively dorsiflexing the ankle, which may not necessarily reflect
ur na
true available joint range, as the capacity of the dorsiflexors to generate force may be the limiting factor.[28] The other study included female runners with a history of plantar heel pain, meaning that they no longer had heel pain and their ankle range of motion at the time of data collection may not reflect what it was prior to, or during the time they were symptomatic.[29] It is
Jo
possible, therefore, that the differences in the results of these studies involving athletic participants may be related to the measurement procedures used or participant inclusion criteria.
Whilst there are some conflicting results in the research investigating the relationship between plantar heel pain and dorsiflexion restriction, the weight of evidence from studies using valid,
10
reliable measures supports an association being likely, particularly in general population samples. Importantly, only case-control studies of level III-3 evidence have investigated this to date, leaving the need for future prospective cohort studies to evaluate whether this association is causative or consequential. Regardless, clinicians should consider the use of strategies aimed at improving dorsiflexion flexibility, or accommodating for restricted motion, when managing
of
people with heel pain.
ro
Reduced extension of the 1st MTPJ is also considered to be a potential contributing factor to
plantar heel pain. The plantar fascia is placed under tension by extending the digits, thus reduced
-p
digit extension could be related to plantar fascia inflexibility. Loss of extension of the 1st MTPJ
re
may therefore be associated with increased tensile load within the plantar fascia during toe-off in walking and running, and hence contribute to plantar heel pain.[22] A very small study reported
lP
reduced 1st MTPJ extension in runners with heel pain,[46] however, further investigation with larger sample sizes is required to support these findings. Studies containing samples of
ur na
participants from the general population have reported differing results. 2 studies have found no difference in 1st MTPJ extension range between groups of participants with and without plantar heel pain, suggesting that the extensibility of soft tissues influencing 1st MTPJ range is not related to the condition.[22] [38] In contrast, however, a recent study with 50 people attending a
Jo
clinic with plantar heel pain and 50 matched controls attending for hyperkeratosis or nail disorders, reported reduced 1st MTPJ extension in the heel pain group.[36]
These results are unable to clearly establish whether an association exists between plantar heel pain and 1st MTPJ extension range of motion. Variations exist in the measurement procedures
11
described in each of these studies, which could possibly explain the different results. These differences include whether the first ray is in a relaxed, flexed position or not, as well as the landmarks chosen to represent the joint angle measured. Of interest, tissue-specific stretching of the plantar fascia utilizing toe extension has been demonstrated to be effective in reducing plantar heel pain. The mechanism behind the effectiveness of this intervention, however, is not understood and remains speculative. [47] With the relationship between toe range of motion and
of
heel pain unclear, the mechanism may not necessarily be one of simply improving flexibility, but
ro
could potentially involve other factors such as reducing fascia microtrauma when done prior to
-p
initial weight-bearing [48] or tissue desensitization and improved tolerance to stretch.
re
Muscle strength and endurance
Deficits in muscle function are considered possible contributing factors to plantar heel pain.
lP
Intrinsic foot muscles have a role in supporting the longitudinal arch,[49-51] as do extrinsic muscles such as the tibialis posterior and peroneus longus.[52-54] Weakness in any of these
ur na
muscle groups could result in excessive stress on non-contractile structures including the plantar fascia and contribute to heel pain. Alternatively, as plantar heel pain negatively impacts work and leisure activities,[6] reductions in or modifications to daily activity could result in strength
Jo
loss due to muscle atrophy.
Deficits in peak ankle plantar flexor torque have been found in runners with unilateral plantar heel pain. The symptomatic feet of runners displayed significant strength deficits on isokinetic testing when compared to normative data or to the uninvolved foot, indicating that plantar heel pain was associated with decreased calf strength.[45] Plantar flexor endurance, however, has
12
been found to be unrelated to plantar heel pain in participants recruited from the general population, as two studies have reported no significant difference in plantar flexor endurance between symptomatic and asymptomatic participants using the standing heel raise test.[35, 38] Interestingly, one smaller study used a rocker board device to isolate weightbearing plantar flexor testing to motion at the ankle by removing motion at the toes. This study reported reduced endurance in 27 people with plantar heel pain, compared with age, sex and BMI matched control
of
participants.[55] Whilst this result suggests the potential for plantar flexor endurance to be
ro
affected in people with heel pain, as this particular procedure could be more sensitive in
detecting muscle performance deficits at the ankle, further research is needed to support this.
-p
[55] The larger studies, using a more functional test, suggest that reduced plantar flexor
re
endurance is not likely to be a feature of plantar heel pain.
lP
Toe flexor strength deficits appear to be associated with plantar heel pain. Three studies, using different measurement procedures have consistently demonstrated reductions in flexor muscle
ur na
strength in groups with heel pain compared to asymptomatic controls. Toe flexor strength has been measured by having participants press their toes into a metal bar attached to an electronic strain gauge, [22] hand-held dynamometry targeting the great toe and lesser toes separately, [38] or a modified paper grip test to assess toe flexor force. This paper grip test modification
Jo
incorporated a pinch gauge to assess plantar flexion force of both the great toe and lesser toes separately. [55] These studies suggest that toe flexor weakness could be either a cause of, or a result of, plantar heel pain. However, as these studies all involved participants recruited from the general population, it is not clear as to whether toe flexor strength deficits are associated with heel pain in athletic groups. As the intrinsic and extrinsic muscles that contribute to toe flexion
13
are capable of providing support to the longitudinal arch, decreased capacity of these muscles to generate force could result in passive structures, including the plantar fascia, experiencing greater load. Alternatively, reductions in toe flexor strength could occur as result of plantar heel pain. The intrinsic muscles and long toe flexors are most active in the second half of stance phase.[56] This phase of the gait cycle is also where the greatest strain on the plantar fascia occurs.[57] Modification to the push off phase of gait, in order to lessen plantar fascia tensile
ro
of
load, could result in a reduced toe flexor contribution and subsequent loss of strength.
To date, only one study has assessed ankle invertor and evertor strength in people with plantar
-p
heel pain. Using hand-held dynamometry, eversion strength was found to be reduced in people
re
with heel pain when compared to control participants. Inversion strength did not differ between groups, resulting in an altered inversion/eversion ratio in those with heel pain.[38] These
lP
findings could be potentially explained by an alteration in loading of the foot during walking. People with heel pain have been shown to reduce loading at the heel, as well as reduce maximum
ur na
force beneath the medial forefoot and increase the force-time integral beneath the lateral forefoot.[58] This offloading type strategy may reduce peroneus longus activity in stabilizing the first ray, leading to weakness. Conversely, peroneus longus weakness could theoretically precede the onset of plantar heel pain. Reduced first ray plantarflexion force due to weakness could result
Jo
in less arch stability and lead to excessive stress on the plantar fascia.
The available evidence suggests that people with heel pain are likely to demonstrate deficits in foot and ankle muscle strength, but not in plantar flexor endurance. The cross-sectional nature of these studies does not allow conclusions to be drawn regarding causation. Given these findings,
14
however, resistance exercises should be considered when developing intervention strategies for people with plantar heel pain as they may be useful in addressing associated impairments. To date, there has been limited investigation into the effectiveness of resistance exercise for plantar heel pain, with differing findings.[59, 60] Further research is needed to support and guide the use of resistance exercise as an intervention for plantar heel pain generally, as well as investigate
of
the association between muscle strength and plantar heel pain in specific athletic groups.
ro
Body Mass Index
A number of studies have measured Body Mass Index (BMI) in people with plantar heel pain.
-p
Excessive body mass results in greater forces loading the foot during weightbearing and could
re
potentially increase stresses at the heel. A higher BMI has been shown to be associated with foot pain in general.[61] A BMI of > 30 kg/m2 is associated with an increased risk of plantar heel
lP
pain, [3] and a number of studies have reported higher BMI scores in people with plantar heel pain compared to asymptomatic control participants.[27, 35, 38, 62, 63] These findings strongly
ur na
suggest an association between a high BMI and the presence of plantar heel pain. In addition, some evidence suggests a high BMI may also be associated with greater self-reported disability in people with heel pain, [6] as well as a poorer prognosis following surgical intervention.[64] In
Jo
contrast, BMI does not appear to influence outcomes after conservative management.[65, 66]
In a study involving runners with plantar heel pain, there was no significant difference in BMI between a group of 36 symptomatic runners and a control group of asymptomatic runners.[28] This suggests that increased BMI does not seem to be a significant factor in the development of plantar heel pain in athletic populations. Therefore the evidence to date suggests that plantar heel
15
pain is associated with a higher BMI in non-athletic populations, but not in athletic groups.
Activity-related factors Factors such as work-related standing and the amount of weight-bearing exercise undertaken are considered possible contributors to plantar heel pain. It has been reported that plantar heel pain is more likely to occur in people who are on their feet for most of the day.[3] This study, however,
of
simply asked both control and plantar heel pain participants whether they spent most of the day
ro
on their feet, with the answer being “yes” or “no”. No specific data on actual length of time
standing or walking were recorded. In contrast, plantar heel pain has been demonstrated to have
-p
no association with occupational ‘lower limb stress’.[35] Lower limb stress was measured using
re
the Occupational Rating Scale, with no difference apparent between people with plantar heel pain and asymptomatic controls for the scale’s standing component. The authors conceded that
lP
data were representative of each individual’s occupation at the time of data collection, and may not necessarily reflect the occupational lower limb stress at the time of onset of plantar heel pain.
ur na
Similarly, people with heel pain reported equivalent work-related standing time to a group with no history of the condition.[38] This study gathered data using patient recall of their occupational standing requirements at the time of symptom onset. As the median time of symptom duration was 10 months, data collected on work-related standing requirements may have been affected by
Jo
recall bias. More recently, longer work-related standing duration on hard surfaces was related to the presence of plantar heel pain in a specific sample of assembly workers.[67] Whether this relationship exists across the wider population of people with heel pain is unknown. Given the scant research to date, and the limitations of these existing studies, the influence of occupationbased standing on plantar heel pain is not well understood.
16
With regard to exercise, regular running is reported to be a risk factor for plantar heel pain.[68] Plantar heel pain is reported to have a prevalence of 5.2 -17.5% among runners,[69] and is among the three most common injuries in this population.[69, 70] Training mileage has been linked to running injury risk in general,[71] and some evidence exists associating higher mileage with plantar heel pain.[72] Younger age and previous injury may also be risk factors for heel
of
pain in runners.[28] While samples of runners have been the focus of a number of individual
ro
research studies, the association between heel pain and weight-bearing exercise more broadly has been the focus of only limited investigation. One study has reported people with heel pain to
-p
participate in equal amounts of weight-bearing exercise to asymptomatic controls.[38] Although
re
data collected in this study reflected exercise levels at the time of onset of heel pain, many of the symptomatic participants had chronic symptoms (median 10 months), leaving recall bias as a
lP
significant study limitation. Future studies should incorporate the use of wearable technology to more accurately measure physical activity in people with plantar heel pain. This may be
ur na
particularly useful in identifying risky levels of exercise in more active people with heel pain in longitudinal studies.
The evidence regarding BMI, exercise and occupational standing suggests that higher external
Jo
loading may play a role in plantar heel pain through excessive body mass, training loads or occupational weight-bearing requirements. While further investigation is needed to better determine risky levels of loading, intervention strategies for plantar heel pain should include an element of load management, which may include but not be limited to; weight-loss, activity modification, and relative rest from exercise or occupational weight-bearing loads followed by a graduated reloading of tissues. Similar strategies have been implemented in tendon disorders 17
[73] and could be investigated for efficacy in future plantar heel pain trials.
Conclusion Plantar heel pain is associated with a high BMI in non-athletic people, reduced ankle dorsiflexion range, as well as specific foot and ankle strength deficits. Foot and ankle plantar
of
flexor endurance does not appear to be associated with heel pain and the importance of foot
ro
alignment and great toe flexibility remains unclear. Limited evidence supports running mileage and work-related standing duration as potential risk factors for plantar heel pain. Importantly,
-p
investigations into the relationships between these mechanical factors and heel pain are limited to cross-sectional studies, which are unable to determine if these factors have a role in the
re
etiology of the condition. Studies with higher levels of evidence, particularly prospective cohort
lP
studies, would assist in determining whether these associated factors are causative or consequential, as well as determine the occupational and athletic activity thresholds that increase
ur na
risk. Management strategies for plantar heel pain should include evidence-based interventions such as orthoses and tissue-specific plantar fascia stretching, as well as targeting specific strength and flexibility deficits and load management. Along with strategies to reduce body weight, load management strategies could include reductions in training or occupational load, followed by
Jo
graduated return to necessary activity levels. Further studies are needed to investigate the effectiveness of resistance exercise and load management strategies as intervention strategies for plantar heel pain.
18
Declarations of interests: None
Justin Sullivan contributed to the concept and design of the article, drafting the manuscript and approved the final version Evangelos Pappas contributed to the concept and design of the article, drafting the manuscript and approved the final version
ro
of
Joshua Burns contributed to the concept and design of the article, drafting the manuscript and approved the final version
Jo
ur na
lP
re
-p
This work has not been submitted to any other publisher and is only currently submitted to ‘The Foot’
19
References [1] Cole C, Seto C, Gazewood J. Plantar fasciitis: evidence-based review of diagnosis and therapy. Am Fam Physician. 2005;72:2237-42. [2] Tong KB, Furia J. Economic burden of plantar fasciitis treatment in the United States. Am J Orthop (Belle Mead NJ). 2010;39:227-31.
of
[3] Riddle DL, Pulisic M, Pidcoe P, Johnson RE. Risk factors for Plantar fasciitis: a matched case-control study. J Bone Joint Surg Am. 2003;85-A:872-7.
ro
[4] Reischl S. Physical therapist foot care survey. Orthop Pract. 2001;13:548.
-p
[5] Irving DB, Cook JL, Young MA, Menz HB. Impact of chronic plantar heel pain on healthrelated quality of life. J Am Podiatr Med Assoc. 2008;98:283-9.
re
[6] Riddle DL, Pulisic M, Sparrow K. Impact of demographic and impairment-related variables on disability associated with plantar fasciitis. Foot Ankle Int. 2004;25:311-7.
lP
[7] Bennett PJ, Patterson C, Dunne MP. Health-Related Quality of Life Following Podiatric Surgery. J Am Podiatr Med Assoc. 2001;91:164-73. doi:10.7547/87507315-91-4-164
ur na
[8] Wearing SC, Smeathers JE, Urry SR, Hennig EM, Hills AP. The pathomechanics of plantar fasciitis. Sports Med. 2006;36:585-611.
[9] Rompe JD, Furia J, Weil L, Maffulli N. Shock wave therapy for chronic plantar fasciopathy.
Jo
Br Med Bull. 2007;81-82:183-208. 10.1093/bmb/ldm005 [10] Furey JG. Plantar fasciitis. The painful heel syndrome. J Bone Joint Surg Am. 1975;57:6723.
[11] Puttaswamaiah R, Chandran P. Degenerative plantar fasciitis: A review of current concepts. Foot. 2007;17:3-9. http://dx.doi.org/10.1016/j.foot.2006.07.005
20
[12] Hossain M, Makwana N. “Not Plantar Fasciitis”: the differential diagnosis and management of heel pain syndrome. Orthop Trauma. 2011;25:198-206. http://dx.doi.org/10.1016/j.mporth.2011.02.003 [13] Lemont H, Ammirati KM, Usen N. Plantar Fasciitis. J Am Podiatr Med Assoc. 2003;93:234-7. 10.7547/87507315-93-3-234 [14] Hunt GC, Sneed T, Hamann H, Chisam S. Biomechanical and histiological considerations
of
for development of plantar fasciitis and evaluation of arch taping as a treatment option to control
ro
associated plantar heel pain: a single-subject design. Foot. 2004;14:147-53.
[15] Beeson P. Plantar fasciopathy: revisiting the risk factors. Foot Ankle Surg. 2014;20:160-5.
-p
10.1016/j.fas.2014.03.003
re
[16] League AC. Current concepts review: plantar fasciitis. Foot Ankle Int. 2008;29:358-66. 10.3113/FAI.2008.0358
lP
[17] Landorf KB. Plantar heel pain and plantar fasciitis. BMJ Clin Evid. 2015;2015. [18] Wolgin M, Cook C, Graham C, Mauldin D. Conservative Treatment of Plantar Heel Pain:
ur na
Long-Term Follow-Up. Foot Ankle Int. 1994;15:97-102. 10.1177/107110079401500303 [19] Davis PF, Severud E, Baxter DE. Painful Heel Syndrome: Results of Nonoperative Treatment. Foot Ankle Int. 1994;15:531-5. 10.1177/107110079401501002 [20] Thomas JL, Christensen JC, Kravitz SR, Mendicino RW, Schuberth JM, Vanore JV, et al.
Jo
The diagnosis and treatment of heel pain: a clinical practice guideline-revision 2010. J Foot Ankle Surg. 2010;49:S1-19. 10.1053/j.jfas.2010.01.001 [21] McPoil TG, Martin RL, Cornwall MW, Wukich DK, Irrgang JJ, Godges JJ. Heel pain-plantar fasciitis: clinical practice guildelines linked to the international classification of function,
21
disability, and health from the orthopaedic section of the American Physical Therapy Association. J Orthop Sports Phys Ther. 2008;38:A1-a18. 10.2519/jospt.2008.0302 [22] Allen RH, Gross MT. Toe flexors strength and passive extension range of motion of the first metatarsophalangeal joint in individuals with plantar fasciitis. J Orthop Sports Phys Ther. 2003;33:468-78. 10.2519/jospt.2003.33.8.468 [23] Bolgla LA, Malone TR. Plantar fasciitis and the windlass mechanism: a biomechanical link
of
to clinical practice. J Athl Train. 2004;39:77-82.
ro
[24] Burns J, Crosbie J, Hunt A, Ouvrier R. The effect of pes cavus on foot pain and plantar
pressure. Clin Biomech (Bristol, Avon). 2005;20:877-82. 10.1016/j.clinbiomech.2005.03.006
-p
[25] Gill LH. Plantar Fasciitis: Diagnosis and Conservative Management. Journal Am Acad
re
Orthop Surg. 1997;5:109-17.
[26] Huang Y-C, Wang L-Y, Wang H-C, Chang K-L, Leong C-P. The relationship between the
2004;27:443-8.
lP
flexible flatfoot and plantar fasciitis: ultrasonographic evaluation. Chang Gung Med J.
ur na
[27] Prichasuk S, Subhadrabandhu T. The relationship of pes planus and calcaneal spur to plantar heel pain. Clin Orthop Relat Res. 1994;306:192 - 6. [28] Rome K, Howe T, Haslock I. Risk factors associated with the development of plantar heel pain in athletes. Foot. 2001;11:119-25. http://dx.doi.org/10.1054/foot.2001.0698
Jo
[29] Pohl MB, Hamill J, Davis IS. Biomechanical and anatomic factors associated with a history of plantar fasciitis in female runners. Clin J Sport Med. 2009;19:372-6. 10.1097/JSM.0b013e3181b8c270
22
[30] Ribeiro AP, Trombini-Souza F, Tessutti V, Rodrigues Lima F, Sacco Ide C, Joao SM. Rearfoot alignment and medial longitudinal arch configurations of runners with symptoms and histories of plantar fasciitis. Clinics. 2011;66:1027-33. [31] McCrory JL, Young MJ, Boulton AJM, Cavanagh PR. Arch index as a predictor of arch height. Foot. 1997;7:79-81. http://dx.doi.org/10.1016/S0958-2592(97)90052-3 [32] Wearing SC, Hills AP, Byrne NM, Hennig EM, McDonald M. The Arch Index: A Measure
of
of Flat or Fat Feet? Foot Ankle Int. 2004;25:575-81. 10.1177/107110070402500811
ro
[33] Hawes MR, Nachbauer W, Sovak D, Nigg BM. Footprint Parameters as a Measure of Arch Height. Foot Ankle Int. 1992;13:22-6. 10.1177/107110079201300104
-p
[34] Redmond AC, Crosbie J, Ouvrier RA. Development and validation of a novel rating system
re
for scoring standing foot posture: the Foot Posture Index. Clin Biomech (Bristol, Avon). 2006;21:89-98. 10.1016/j.clinbiomech.2005.08.002
lP
[35] Irving DB, Cook JL, Young MA, Menz HB. Obesity and pronated foot type may increase the risk of chronic plantar heel pain: a matched case-control study. BMC Musculoskelet Disord.
ur na
2007;8:41. 10.1186/1471-2474-8-41
[36] Aranda Y, Munuera PV. Plantar Fasciitis and Its Relationship with Hallux Limitus. J Am Podiatr Med Assoc. 2014;104:263-8. 10.7547/0003-0538-104.3.263 [37] Redmond AC, Crane YZ, Menz HB. Normative values for the Foot Posture Index. J Foot
Jo
Ankle Res. 2008;1:6. 10.1186/1757-1146-1-6 [38] Sullivan J, Burns J, Adams R, Pappas E, Crosbie J. Musculoskeletal and Activity-Related Factors Associated With Plantar Heel Pain. Foot Ankle Int. 2015;36:37-45. 10.1177/1071100714551021
23
[39] Wearing SC, Smeathers JE, Yates B, Sullivan PM, Urry SR, Dubois P. Sagittal movement of the medial longitudinal arch is unchanged in plantar fasciitis. Med Sci Sports Exerc. 2004;36:1761-7. [40] Wearing SC, Smeathers JE, Sullivan PM, Yates B, Urry SR, Dubois P. Plantar fasciitis: are pain and fascial thickness associated with arch shape and loading? Phys Ther. 2007;87:1002-8. [41] Karas MA, Hoy DJ. Compensatory Midfoot Dorsiflexion in the Individual with Heelcord
of
Tightness: Implications for Orthotic Device Designs. JPO: J Prosthet Orthot. 2002;14:82-93.
ro
[42] Snow SW, Bohne WH, DiCarlo E, Chang VK. Anatomy of the Achilles tendon and plantar fascia in relation to the calcaneus in various age groups. Foot Ankle Int. 1995;16:418-21.
-p
[43] Kim PJ, Richey JM, Wissman LR, Steinberg JS. The variability of the Achilles tendon
re
insertion: a cadaveric examination. J Foot Ankle Surg. 2010;49:417-20. S1067-2516(10)00189-4 [pii]10.1053/j.jfas.2010.05.002
lP
[44] Bolivar YA, Munuera PV, Padillo JP. Relationship between tightness of the posterior muscles of the lower limb and plantar fasciitis. Foot Ankle Int. 2013;34:42-8.
ur na
10.1177/1071100712459173
[45] Kibler WB, Goldberg C, Chandler TJ. Functional biomechanical deficits in running athletes with plantar fasciitis. Am J Sports Med. 1991;19:66-71. [46] Creighton D, Olson VL. Evaluation of range of motion of the first metatarsophalangeal joint
Jo
in runners with plantar faciitis*. J Orthop Sports Phys Ther. 1987;8:357-61. 1953 [pii] [47] Rompe JD, Cacchio A, Weil L, Furia JP, Haist J, Reiners V, et al. Plantar fascia-specific stretching versus radial shock-wave therapy as initial treatment of plantar fasciopathy. J Bone Joint Surg Am. 2010;92:2514-22. 10.2106/jbjs.i.01651
24
[48] DiGiovanni BF, Nawoczenski DA, Lintal ME, Moore EA, Murray JC, Wilding GE, et al. Tissue-specific plantar fascia-stretching exercise enhances outcomes in patients with chronic heel pain. A prospective, randomized study. J Bone Joint Surg Am. 2003;85-a:1270-7. [49] Fiolkowski P, Brunt D, Bishop M, Woo R, Horodyski M. Intrinsic pedal musculature support of the medial longitudinal arch: an electromyography study. J Foot Ankle Surg.
of
2003;42:327-33. 10.1053/j.jfas.2003.10.003S1067251603003910 [pii] [50] Mann R, Inman VT. Phasic Activity of Intrinsic Muscles of the Foot. J Bone Joint Surg Am.
ro
1964;46:469-81.
-p
[51] Headlee DL, Leonard JL, Hart JM, Ingersoll CD, Hertel J. Fatigue of the plantar intrinsic foot muscles increases navicular drop. J Electromyogr Kinesiol. 2008;18:420-5. S1050-
re
6411(06)00170-2 [pii]10.1016/j.jelekin.2006.11.004
lP
[52] Kaye RA, Jahss MH. Tibialis posterior: a review of anatomy and biomechanics in relation to support of the medial longitudinal arch. Foot Ankle. 1991;11:244-7. [53] Kitaoka HB, Luo ZP, An KN. Effect of the posterior tibial tendon on the arch of the foot
ur na
during simulated weightbearing: biomechanical analysis. Foot Ankle Int. 1997;18:43-6. [54] Johnson CH, Christensen JC. Biomechanics of the first ray. Part I. The effects of peroneus longus function: a three-dimensional kinematic study on a cadaver model. J Foot Ankle Surg.
Jo
1999;38:313-21.
[55] McClinton S, Collazo C, Vincent E, Vardaxis V. Impaired Foot Plantar Flexor Muscle Performance in Individuals With Plantar Heel Pain and Association With Foot Orthosis Use. J Orthop Sports Phys Ther. 2016;46:681-8. 10.2519/jospt.2016.6482 [56] Gray EG, Basmajian JV. Electromyography and cinematography of leg and foot ("normal" and flat) during walking. Anat Rec. 1968;161:1-15. 10.1002/ar.1091610101 25
[57] Erdemir A, Hamel AJ, Fauth AR, Piazza SJ, Sharkey NA. Dynamic loading of the plantar aponeurosis in walking. J Bone Joint Surg Am. 2004;86-A:546-52. [58] Sullivan J, Burns J, Adams R, Pappas E, Crosbie J. Plantar heel pain and foot loading during normal walking. Gait Posture.41:688-93. 10.1016/j.gaitpost.2015.01.025 [59] Rathleff MS, Molgaard CM, Fredberg U, Kaalund S, Andersen KB, Jensen TT, et al. Highload strength training improves outcome in patients with plantar fasciitis: A randomized
of
controlled trial with 12-month follow-up. Scand J Med Sci Sports. 2015;25:e292-300.
ro
10.1111/sms.12313
[60] Kamonseki DH, Goncalves GA, Yi LC, Junior IL. Effect of stretching with and without
-p
muscle strengthening exercises for the foot and hip in patients with plantar fasciitis: A
re
randomized controlled single-blind clinical trial. Man Ther. 2016;23:76-82. 10.1016/j.math.2015.10.006
lP
[61] Hill CL, Gill TK, Menz HB, Taylor AW. Prevalence and correlates of foot pain in a population-based study: the North West Adelaide health study. J Foot Ankle Res. 2008;1:2.
ur na
10.1186/1757-1146-1-2
[62] Rano JA, Fallat LM, Savoy-Moore RT. Correlation of heel pain with body mass index and other characteristics of heel pain. J Foot Ankle Surg. 2001;40:351-6. http://dx.doi.org/10.1016/S1067-2516(01)80002-8
Jo
[63] Ozdemir H, Yilmaz E, Murat A, Karakurt L, Poyraz AK, Ogur E. Sonographic evaluation of plantar fasciitis and relation to body mass index. Eur J Radiol. 2005;54:443-7. http://dx.doi.org/10.1016/j.ejrad.2004.09.004 [64] Saxena A. Uniportal endoscopic plantar fasciotomy: a prospective study on athletic patients. Foot Ankle Int. 2004;25:882-9. 10.1177/107110070402501207
26
[65] Pfeffer G, Bacchetti P, Deland J, Lewis A, Anderson R, Davis W, et al. Comparison of custom and prefabricated orthoses in the initial treatment of proximal plantar fasciitis. Foot Ankle Int. 1999;20:214-21. 10.1177/107110079902000402 [66] McClinton SM, Cleland JA, Flynn TW. Predictors of response to physical therapy intervention for plantar heel pain. Foot Ankle Int. 2015;36:408-16. 10.1177/1071100714558508 [67] Werner RA, Gell N, Hartigan A, Wiggerman N, Keyserling WM. Risk factors for plantar
of
fasciitis among assembly plant workers. PM R. 2010;2:110-6. 10.1016/j.pmrj.2009.11.012
ro
[68] Martin RL, Davenport TE, Reischl SF, McPoil TG, Matheson JW, Wukich DK, et al. Heel pain-plantar fasciitis: revision 2014. J Orthop Sports Phys Ther. 2014;44:A1-33.
-p
10.2519/jospt.2014.0303
re
[69] Lopes A, Hespanhol L, Jr., Yeung S, Costa L. What are the Main Running-Related Musculoskeletal Injuries? Sports Med. 2012;42:891-905. 10.1007/BF03262301
lP
[70] Taunton JE, Ryan MB, Clement DB, McKenzie DC, Lloyd-Smith DR, Zumbo BD. A retrospective case-control analysis of 2002 running injuries. Br J Sports Med. 2002;36:95-101.
ur na
10.1136/bjsm.36.2.95
[71] van Gent BRN, Siem DD, van Middelkoop M, van Os TAG, Bierma-Zeinstra SSMA, Koes BBW. Incidence and determinants of lower extremity running injuries in long distance runners: A systematic review. Br J Sports Med. 2007. 10.1136/bjsm.2006.033548
Jo
[72] Warren BL. Anatomical factors associated with predicting plantar fasciitis in long-distance runners. Med Sci Sports Exerc. 1984;16:60-3. [73] Malliaras P, Cook J, Purdam C, Rio E. Patellar Tendinopathy: Clinical Diagnosis, Load Management, and Advice for Challenging Case Presentations. J Orthop Sports Phys Ther. 2015;45:887-98. 10.2519/jospt.2015.5987
27
Table 1. Studies investigating foot alignment and plantar heel pain. Study
Sample
Prichasuk & Subhadrabandhu 1994
Size: 82 with PHP and 400 controls
Foot alignment measure Radiological: Calcaneal pitch
Result
Level of Evidence
Footprint-based Arch index
Greater incidence of PHP in flexible flatfoot group (10/23 vs 2/23)
PHP group were found to have a flatter arch
III-3
Type: General population
of
Type: General population
Clinical Navicular height
No difference between PHP and controls
III-3
Three-dimensional kinematic analysis Peak rearfoot eversion
No difference between PHP and controls
III-3
Clinical rearfoot alignment
No differences between groups for rearfoot alignment
III-3
Podoscope Medial longitudinal arch angle
Higher arch reported in the PHP group
re
Matched: No Size: 166 particpants recruited – 36 with PHP and 130 Controls
lP
Rome et al. 2001
IV
ro
Matched: No Size: 23 people with a low arch and 23 people with a normal arch. (12 of the total 26 participants had PHP)
-p
Huang et al. 2004
ur na
Type: Athletic – sports involving running
Pohl et al. 2009
Matched: No Size: 25 with PHP and 25 controls
Jo
Type: Female runners
Ribeiro et al. 2011
Matched: matched for age and mileage Size: 45 with PHP (30 symptomatic and 15 with previous history) and 60 controls.
28
Type: Experienced runners
Clinical Longitudinal arch angle
Type: General population
Rearfoot to leg angle
Matched: matched for age and sex Size: 80 with PHP and 80 controls
Clinical Foot Posture Index
No differences between PHP and controls
PHP group more pronated foot posture
III-3
Dynamic radiological Calcaneal-first metatarsal angle
No difference between PHP and controls
III-3
Clinical Foot Posture Index
PHP group more pronated foot posture
III-3
Clinical Foot Posture Index
No difference between PHP and controls
III-3
re
Wearing et al. 2004
-p
Type: General population Matched: matched for age and sex Size: 10 with PHP and 10 controls
III-3
of
Irving et al. 2007
Matched: No Size: 20 with PHP and 20 controls
ro
Allen & Gross 2003
lP
Type: General population
ur na
Matched: Matched for age, sex and body mass Size: 50 with PHP and 50 controls
Jo
Aranda & Munuera 2014
Sullivan et al. 2015
Type: Clinic attendees. Control group were attending for hyperkeratosis or nail disorders. Matched: Matched for age, sex and Body Mass Index Size: 202 with PHP and 70 controls
29
Type: General population Matched: No
Jo
ur na
lP
re
-p
ro
of
PHP= plantar heel pain
30
Table 2. Studies investigating foot and ankle range of motion and plantar heel pain
Irving et al. 2007
Matched: Matched for age and sex Size: 80 with PHP and 80 controls Type: General population
Kibler et al. 1991
Matched: matched for age and sex Size: 43 with PHP (mostly runners) and 45 controls (other sports)
Result Ankle dorsiflexion reduced in the PHP group
Level of Evidence III-3
Ankle dorsiflexion Bent knee lunge. Rearfoot pronation not controlled.
Ankle dorsiflexion greater in the PHP group
III-3
Ankle dorsiflexion Method not described
People with PHP had reduced dorsiflexion compared to the unaffected limb, controls and normative data.
III-3
No difference in dorsiflexion between groups.
III-3
Ankle dorsiflexion Goniometry, tested passively
People with a history of heel pain had greater dorsiflexion than controls.
III-3
Great toe extension Goniometry
No difference between groups for passive great toe extension
III-3
lP
Ankle dorsiflexion Goniometry, tested actively. Rearfoot pronation controlled.
ur na
Rome et al. 2001
re
Type: Athletes Matched: matched for age and sex Size: 166 participants recruited – 36 with PHP and 130 Controls
of
Type: General population
Measure Ankle dorsiflexion Goniometry, tested passively. Rearfoot pronation controlled
ro
Sample Size: 50 with PHP and 50 controls
-p
Study Riddle et al. 2003
Type: Athletic – sports involving running
Jo
Pohl et al. 2009
Allen & Gross 2003
Matched: No Size: 25 with PHP previously and 25 controls
Type: Female runners with a history of heel pain Matched: matched for age and mileage Size: 20 with PHP and 20 controls Type: General population
31
People with PHP had reduced active and passive great toe extension
III-3
Ankle Dorsiflexion Goniometry, tested both with knee extended and flexed
People with PHP had reduced ankle dorsiflexion in both tests.
III-3
Ankle dorsiflexion Bent knee lunge and straight knee lunge
People with PHP had reduced ankle dorsiflexion on both tests
Type: General population
Sullivan et al. 2015
Matched: Yes Size: 202 with PHP and 70 controls Type: General population Matched: No
Aranda & Munuera 2014
Size: 50 with PHP and 50 controls
Great toe extension Goniometry Great toe extension Goniometry
ur na
lP
Type: Clinic attendees. Control group were attending for hyperkeratosis or nail disorders.
No differences between groups for passive toe extension People with PHP had reduced passive toe extension
re
Bolivar et al. 2013
Matched: Not stated Size:50 with PHP and 50 controls
-p
Type: Runners
of
Great toe extension Goniometry
Matched: Matched for age, sex and Body Mass Index
Jo
PHP= plantar heel pain
32
III-3
ro
Creighton & Olsen 1987
Matched: matched for age and sex Size: 6 with PHP and 6 controls
III-3