Skip to main content
Top
Gepubliceerd in: Journal of Foot and Ankle Research 1/2009

Open Access 01-12-2009 | Review

Understanding the nature and mechanism of foot pain

Auteurs: Fiona Hawke, Joshua Burns

Gepubliceerd in: Journal of Foot and Ankle Research | Uitgave 1/2009

Abstract

Approximately one-quarter of the population are affected by foot pain at any given time. It is often disabling and can impair mood, behaviour, self-care ability and overall quality of life. Currently, the nature and mechanism underlying many types of foot pain is not clearly understood. Here we comprehensively review the literature on foot pain, with specific reference to its definition, prevalence, aetiology and predictors, classification, measurement and impact. We also discuss the complexities of foot pain as a sensory, emotional and psychosocial experience in the context of clinical practice, therapeutic trials and the placebo effect. A deeper understanding of foot pain is needed to identify causal pathways, classify diagnoses, quantify severity, evaluate long term implications and better target clinical intervention.
Opmerkingen

Authors' contributions

FH searched the literature, retrieved articles and drafted the review. JB conceived the review, provided comments on content and made changes to the final document.

Background

Foot pain is experienced by 17 to 42% of the adult population [14]. It is disabling in nearly half of these cases [4] and can impair mood, behaviour, risk of falls, self-care ability and quality of life [3, 511]. Foot pain is complex, and difficulties in accurately diagnosing the source of pain and cause of tissue damage can impair clinical management of the pain [12, 13]. However, most people with foot pain do not seek professional treatment, even when the pain is disabling [4]. There is clearly a need to improve the provision of foot care to people suffering such pain.
Currently, the aetiological mechanisms underlying some types of tissue injury within the foot are not clearly understood. As a result, interventions targeting foot pain in clinical trials often lack specific targets (e.g. plantar heel pain) [14]. Perhaps as a result of this limitation, evidence from randomised controlled trials of some common interventions that are highly regarded in clinical practice (e.g. custom foot orthoses) have detected only small, if any, beneficial effects [15].
A deeper understanding of pain is needed to identify the nature and mechanism of foot pain, its diagnosis and how best to target clinical intervention. It has been two decades since a review on foot pain has been published [1619]. Given that almost all prevalence studies for foot pain have been performed since then, in addition to the recent advances in our understanding of the nature and mechanism of pain in general, a review of this type is warranted. The aim of this paper was to comprehensively review the literature on foot pain, with specific reference to its definition, prevalence, aetiology and predictors, classification, measurement and impact. We conclude by discussing the complexities of foot pain as a sensory, emotional and psychosocial experience in the context of clinical practice, therapeutic trials and the placebo effect.

Defining foot pain

Foot pain is an unpleasant sensory and emotional experience following perceived damage to any tissue distal to the tibia or fibula; including bones, joints, ligaments, muscles, tendons, apophyses, retinacula, fascia, bursae, nerves, skin, nails and vascular structures [20]. Foot pain is a general term, inferring neither pain class, injury mechanism nor histological pathology. As further discussed in later sections, it is important to recognise that foot pain is not the noxious-stimuli-induced activity in the nociceptive pathways [20, 21], but rather the perception of these processes and the consequent effects on suffering and pain-related behaviour [22].

Prevalence of foot pain

Few studies have investigated the prevalence of foot pain in large, randomly selected samples. Instead, attention is typically given to specific pathology (e.g. heel pain) or population groups (e.g. people over 65 years of age). A summary of studies reporting the prevalence of general foot pain in randomly selected samples is presented in Table 1. Overall, it is thought that foot pain affects 14 to 42% of people at any given time depending on definition and measurement of pain, sample characteristics (age, gender) and study location. Garrow et al. [4] found that the most commonly reported foot pain sites among people reporting symptoms of disabling foot pain (defined in Table 1) were the mid-foot/arch area (25.6%), first metatarsal head (20.2%), great toe (15.9%) and plantar surface of the heel (15.5%). Further research is required to characterise the exact types of foot pain in the general community.
Table 1
Prevalence of foot pain in randomly selected populations
Study
Sample source and description
Foot pain prevalence
Pain outcome measure and notes
Hill 2008
4,060 people aged ≥20 yrs (51% female) recruited by telephone interview (49% response rate) from north-western Adelaide, South Australia
17%
Foot pain defined as affirmative response to 'On most days do you have pain, aching or stiffness in either of your feet?'
Menz 2006
301 community-dwelling older adults (representing 31% response rate) aged 70–95 yrs (61% female) from Sydney, NSW, Australia
36% disabling
Disabling foot pain defined as: current foot pain, foot pain in the past month, plus at least one item marked on the Manchester Foot Pain and Disability Index [4].
Badlissi 2005
784 community-dwelling older adults (representing 85% response rate) aged 65–101 yrs (57% female) from Springfield, Massachusetts, USA
42%
Foot pain defined as: at least 'fairly often' foot pain in the previous week, or foot pain or discomfort 'most days' within the previous month [1].
Garrow 2004
3,417 community-dwelling adults (representing 84% response rate) aged 18–80 yrs (55% female) from North Cheshire and Manchester, England:
22% (9.5% disabling)
Foot pain defined as: foot pain during the past month lasting at least one day. 'Disabling' foot pain defined using the Manchester Foot Pain and Disability Index (defined above) [5].
Menz 2001
135 community-dwelling older adults, all members of one private health insurance company (response rate of 28%)aged 75–93 yrs (59% female) Sydney, NSW, Australia.
21%
Foot pain defined as: affirmative answer when asked whether they suffered from painful feet [7].
Leveille 1998
990 community-dwelling women (70% response rate) with a disability; aged 65 to ≥85 yrs from Baltimore, Maryland, USA
18% moderate (14% chronic and severe)
Chronic and severe foot pain defined as: 7–10 on 10-point VAS for ≥1 month within the last year and present in the previous month. Moderate foot pain defined as: 4–6 on VAS for ≥1 month within the last year, or pain rated as 7–10 on VAS lasting ≥1 month and not present within the previous month [10].

Aetiology of foot pain

Tissue damage in the foot may occur via chemical, mechanical or thermal stimulation [23] associated with direct trauma, musculoskeletal overload, infection, or systemic or proximal pathology (e.g. nerve entrapment, diabetic neuropathy). Many common types of foot pain such as tendonitis, stress fracture, corns and callus are routinely attributed, in part or full, to mechanical stress [24]. While mechanical stress (broadly defined as force applied to tissue) is a normal component of foot function, tissue damage occurs when the maximum stress threshold of the tissue is exceeded [25]. This may occur with: (1) short duration, high magnitude stress; (2) long duration, low magnitude stress; or (3) repetitive moderate-magnitude stress [26].

Associations and predictors of foot pain

Identifying factors that predict foot pain enables the clinician to modify or prevent contributing factors and even target at-risk groups with preventative strategies and more appropriate treatments. Demographically, advancing age and female gender are associated with foot pain [4]. However, while the prevalence of disabling foot pain has been shown to increase with age in both genders peaking at 55 to 64 years of age (15% for females and 12% for males), it has been reported to then steadily reduce with older age [4]. In contrast, studies specifically focussing on foot pain in older adults suggest otherwise, with prevalence as high as 42% (Table 1).
Disabling foot pain appears to occur typically in association with other pain regions, including hip/leg pain, axial skeletal pain and/or shoulder pain; and is more likely to occur in patients previously diagnosed with arthritides, diabetes and/or stroke [4, 5, 10]. In the largest study to date, Garrow et al. [4] reported people with rheumatoid arthritis were three times more likely to report disabling foot pain, although this did not reach statistical significance due to the very small number of people included in this part of the analysis.
Garrow et al. [4] also reported that people in Northwest England aged 18 to 80 years with disabling foot pain were significantly more likely than people without disabling foot pain to self-diagnose nail problems (42% vs. 22%), corns and callosities (41% vs. 30%), bunions (19.5% vs. 7%), swollen feet (34% vs. 10%), flat/planus feet (9% vs. 6%), high arch/cavus feet (18% vs. 13%) and toe deformity (33% vs. 13%) (p < 0.05). Menz et al. [5] also reported associations between disabling foot pain and pes planus as well as limited ankle joint range of motion in older Australians. In the study be Garrow et al [4], however, podiatrist-diagnosed foot problems using established criteria [2729] revealed only swollen feet as a correlate of disabling foot pain (43.7% vs 18.0%; OR: 3.8; 95% CI: 1.7 to 8.2). This unexpected result is supported by Badlissi et al. [1], who reported that people over 65 years of age with foot pain were no more likely than people without foot pain to have hallux valgus, pes planus or lesser toe deformity (including hammer, mallet, claw or overlapping toes and bunionette). Badlissi [1] did note, however, an association between foot pain and pes cavus. Discrepancies between these studies are possibly due to differences in sample characteristics and diagnostic/classification criteria.
Extrinsic factors commonly associated with foot pain include inappropriate footwear [30, 31] and occupational activities [32], although these areas have received little empirical investigation in the past. For both intrinsic and extrinsic factors, further research is needed to develop predictive models of foot pain causation in large prospective random samples of children, adolescents and adults.

Classification of foot pain

The difficulties in clearly defining pain have impeded the development of clinically relevant pain models capable of guiding foot pain classification and communication among and between practitioners and patients [3335]. Currently, emerging evidence of the neurological differences between physiological and pathophysiological pain is prompting the redevelopment of existing pain classification models, particularly for chronic pain, which will have implications on our understanding of foot pain [3638]. The following section clarifies the underlying neurological differences between the many clinical presentations of foot pain, although it is important to point out that many aspects of foot pain are not mutually exclusive.

Physiological foot pain

Physiological foot pain is experienced as an acute response to injury (or potential injury) following healthy functioning of both the peripheral and central nervous systems [37, 39]. It provides a feedback system to encourage the removal of potential tissue-damaging stimuli (as per defense-response theory) [35, 37, 40]. There are three essential criteria for classification as physiological foot pain [23, 35, 3739]: (1) noxious (potentially tissue damaging) stimuli are extrinsic to the nervous system; (2) pain perception is proportionate to the magnitude of noxious stimulation; (3) pain diminishes when the stimuli are removed. An example of physiological foot pain would be the response to a stone trapped in one's shoe or a blister from a new pair of shoes. The activity within the nervous system producing the experience of pain is termed nociception. Nociception in physiological foot pain comprises three distinct processes: transduction; transmission; and modulation.

Transduction

Foot pain is the end result of a cascade of impulses originating in the stimulation of structurally unspecialised free nerve endings within foot tissue [23, 41]. These free nerve endings are called nociceptors. In response to potentially harmful mechanical, thermal and chemical stimuli, nociceptor cell membranes depolarise. If the stimulation is strong enough, ion channels within the membrane are activated; creating a self-propagating change in membrane potential that sweeps along the electrically excitable membrane cells [23, 38].

Transmission

Nociceptors within the feet are capable of both efferent and afferent transmission [35]. Efferent transmission of the action potential (back to the site of stimulation) causes the release of neurotransmitters and neuropeptides from peripheral fibre terminals, producing the classic 'axon reflex': neurogenic inflammation at the site of tissue damage [23, 37]. Afferent transmission (away from the foot) occurs via two types of primary afferent nociceptive neurons: A-delta fibres and C fibres [22, 36]. The roles of these fibres in nociception from the foot are outlined briefly in Table 2[23, 35, 38]. A-delta fibres and C fibres of the primary afferent nociceptive neurons travel from the foot to synapse with second-order neurons in the superficial layers of the spinal dorsal horn [22, 23]. Second order neurons contralaterally ascend the spinal cord via several pathways [37], of which the spinothalamic pathway is regarded as the most important for nociception [38]. At this level, second order neurons activate lower motor neurons in the spinal ventral horn, provoking a reflex withdrawal from the noxious stimulus (e.g. jerking the foot away from splintered wood) [23]. Clinically, disruption of this protective reflex can be observed in some sensory and lower motor neuropathies including Diabetes Mellitus and Charcot-Marie-Tooth disease. Second order neurons ascending the spinothalamic pathway synapse with third order neurons in the thalamus. From the thalamus, impulses are propagated to the primary somatosensory cortex, where the discriminative components of pain are perceived, and to limbic cortical areas, where the affective and emotional aspects of the pain experience are perceived [23, 35, 38]. While these pathways are complex, it is important to maintain a clinical appreciation of the various levels at which dysfunction can occur and therapy can target.
Table 2
Roles of A-delta and C fibres in nociception
Role
A-delta fibres
C fibres
Myelination
Thinly myelinated
Unmyelinated
Neuronal diameter
1 to 5 microns
< 1.5 microns
Conduction speed
5–20 metres per second
0.5–2 metres per second
Stimuli
Mechanical and sometimes thermal
High intensity mechanical, thermal and chemical
Pain sensation
Fast
Dull, throbbing, aching

Modulation

Mechanisms capable of modifying the propagation of nociceptive impulses from the foot to the brain have been proposed to exist at all levels of the nervous system and to influence both sensory and emotional components of pain [35, 38, 42]. This selective projection and inhibition of impulses has been attributed in part to neural plasticity (the ability of neural tissue to regulate its own activity) [35]. The foundations of neural plasticity were first introduced in the Melzack-Wall gate control theory of pain in 1965 [43]. Melzack and Wall hypothesised that afferent impulses (ascending toward the brain) could be inhibited by efferent impulses (descending from the brain) in the dorsal spinal horn. Recent research has supported Melzack and Wall's hypothesis and highlighted the influence of psychosocial factors (e.g. pain beliefs) on the descending inhibition and consequent reduced experience of pain [22, 23, 36]. Modulation of nociception might account for some of the foot pain reduction experienced with the placebo effect.

Pathological foot pain

Pathological foot pain is experienced following nociceptive pathology; involving dysfunction of either or both of the peripheral or central nervous systems [37, 39]. While there is debate as to which classes of pain deserve categorisation as pathological foot pain, common suggestions include neuropathic, inflammatory and chronic pain [36, 37]. These pain classes are categorised as pathological foot pain since at least one of the three criteria for physiological foot pain is not met [23, 35, 3739]. That is, in pathological foot pain: (1) noxious stimuli are intrinsic to the nervous system; (2) foot pain perception is disproportionate to the magnitude of noxious stimulation; and/or (3) foot pain does not diminish when the stimuli are removed. Due to such dysfunction, pathological foot pain extends far beyond the mechanistic defense response role attributed to physiological foot pain [37].

Neuropathic foot pain

Neuropathic foot pain is pain instigated by a primary dysfunction, lesion or transitory perturbation in the peripheral or central nervous systems [20]. Neuropathic foot pain encompasses a heterogenous group of symptoms that share similar clinical characteristics, including spontaneous stimulus-dependent and stimulus-independent pain. Spontaneous foot pain typically appears incompatible with the initial cause and affected anatomical site, and often has unpredictable treatment responses [39, 4446]. A summary of the characteristics of neuropathic foot pain is presented in Table 3[20, 44], however the mechanisms underlying these clinical characteristics are not fully understood [39]. Symptoms have been proposed to reflect reactive hyperexcitability and sensitisation of peripheral and central neural elements, and relative suppression of central inhibitory pathways following central nervous system damage [39, 44, 47]. Changes include abnormal ion channel expression due to disruption of normal neuronal input and pathological activation of injured nerve fibres by inflammatory mediators and sympathetic excitation [44, 48]. These changes reduce depolarisation threshold, resulting in spontaneous, ectopic discharges [41]. The ensuing hectic and persistent neural activity can cause ephaptic conductions (electrical connections between injured and adjacent uninjured nerve fibres) [39]. The anatomical site of these changes may be at any level within the nervous system, from peripheral receptor within the foot to the highest cortical centres [44]. Ephaptic conductions might account for some clinically confusing presentations of foot pain and might underlie the spreading of pain experienced by some people. It is not clear from the literature whether ephaptic conductions form between afferent (sensory) and efferent (motor) fibres. If interfibre-type connections do occur, these might account for some motor disturbance in cases of neuropathic pain, e.g. autonomic dysfunction in complex regional pain syndrome type I [49, 50].
Table 3
Clinical characteristics of neuropathic foot pain [20, 44]
Characteristic
Definition
Allodynia
Evocation of pain by a stimulus that does not normally evoke pain.
Dysthesia
A spontaneous or evoked unpleasant, abnormal sensation, e.g. hyperalgesia and allodynia.
Hyperalgesia
Increased pain response to a stimulus that is normally painful. Might be static, punctate or dynamic, and might occur with thermal stimuli. Suggested to be a consequence of peripheral and/or central sensitisation.
Hyperesthesia
Increased sensitivity to stimulation, including diminished threshold and increased response. Excludes the special senses.
Hyperpathia
Increased threshold and abnormally painful reactions to stimuli, especially repetitive stimuli. Might occur with dysthesia, hyperalgesia, allodynia or hyperesthesia. Occurs in the presence of fibre loss.
Paraesthesia
A spontaneous or evoked, abnormal but not unpleasant sensation. Proposed to reflect spontaneous bursts of A-β fibre activity.
Paroxysms
Spontaneous or stimuli-associated shooting, electric-shock like or stabbing pains. Might be elicited by an innocuous tactile stimulus or by a blunt pressure.
Referred pain
Abnormal spread of pain from a peripheral or central lesion. Typically referred from deep to cutaneous structures.
Sensory deficit
Partial or complete loss of afferent sensory function. Might not involve all sensory pathways.
Neuropathic pain is routinely sub-categorised according to the causative factor, e.g. mechanical injury, neurotropic viral disease, neurotoxicity, metabolic disease, inflammatory and/or immunologic mechanisms, focal ischaemia or neurotransmitter dysfunction [47]. It is expected that continued advances in molecular neurobiology will expose links between sub-categories and allow for the development of a comprehensive and coherent classification system for neuropathic foot pain [39, 44].

Inflammatory foot pain

'Inflammation' describes a wide range of primarily vascular responses to tissue injury [51]. Pain (dolor) is one of the five classic, clinical features of acute inflammation, along with redness (rubor), heat (calor), swelling (tumor) and limitation of function (functio laesa) [52]. Inflammation produces characteristic changes within the nervous system [53]. In early stages, inflammatory mediators activate second-messenger systems, thereby sensitising polymodal nociceptors and reducing the activation thresholds of conducting ion channels [36, 41, 54]. Within the foot, cutaneous nociceptors are sensitised to thermal stimuli and deep somatic nociceptors are sensitised to mechanical stimuli [41]. Clinically, this can be observed as abnormally painful responses to surface temperature changes (e.g. application of ice) and/or palpation and physical movement of affected joints. During this process, 'silent' or 'sleeping' nociceptors within the foot may be activated [36, 37, 55]. Once activated, these nociceptors fire persistently to produce uninterrupted pain [23]. Longer term, cytokine and growth factor mediated transcription is accelerated, increasing the rate of receptor production [22]. As a result, primary hyperalgesia occurs at the site of tissue damage [36]. These changes are frequently accompanied by sensitisation of the central nervous system and nerve damage, which may provoke neuropathic foot pain [36].

Chronic foot pain

Proposed definitions of chronic pain are inconsistent and difficult to use in clinical practice [34, 37]. Despite its widespread use, the term 'chronic' has been criticised for its potential to be confusingly used as a descriptor of pain history and as a prognostic statement for pain [34]. The International Association for the Study of Pain (IASP) defines chronic pain as any pain persisting past the normal time of healing and suggests three months to be the most suitable point of division between acute and chronic pain for nonmalignant pain [20]. Variations to this definition are common, particularly with regards to time framing [20, 37, 56].
Despite semantic disagreement, there is apparent consensus regarding clinical and underlying physiological distinctions between acute and chronic pain [21]. Chronic foot pain does not typically share the sharp spatial localisation typical of acute foot pain. Chronic foot pain is characteristically diffuse, spreads beyond the original site of injury, exhibits a non-linear relationship between nociception and pain intensity, and involves adaptive changes at various levels of the nervous system, e.g. activation of propriospinal reflexes, which play a role in coordination, posture and locomotion [21, 35, 41].
Clinically, it is important to recognise that chronic foot pain is pain persisting past the normal time of healing following the removal of the noxious stimulus [20]. Chronic foot pain is not simply pain persisting past an arbitrary time point (e.g. three months). If the stimulus has not been removed, the pain should not be termed chronic.

Changes in foot pain perception with age

In recent years, several comprehensive reviews have discussed age-related changes in pain perception [57, 58]. Whilst there is some contradiction between empirical findings, most studies demonstrate age-related increases in pain threshold (the least amount of stimulation required for a person to experience pain) using heat or mechanical stimulation, but not from electrical stimulation [59]. The decline in heat pain sensitivity is most noticeable after 70 years of age and may be more pronounced in the distal extremities [60]. Pressure pain threshold increases by about 15% and is more noticeable in females than males [61]. Heat pain threshold increases by about 20% for radiant pain and 50% to 100% for CO2 laser pain [59, 62].
Whilst there appears to be a modest age-related increase in pain threshold and diminished sensitivity to low levels of noxious stimulation, response to higher intensity stimuli is increased and tolerance of strong pain is reduced [59]. Recent experimental studies suggest this may stem from alterations in peripheral A delta and C fibre nociception and central nervous system changes, including reduced central nervous system plasticity following injury and reduced efficacy of endogenous analgesic mechanisms [59].

Quantifying foot pain

There is currently no universally accepted standard for the measurement of pain [63]. As a result, numerous quantitative and qualitative pain measurement tools have been developed. Since pain is a subjective sensory and emotional experience, the participant's own reporting of pain is widely regarded as the most valid representation of their pain [63]. As such, self-reported pain intensity is the most frequently used research tool to measure pain [44, 64]. Popular tools include visual analogue scales (VAS), numerical rating scales and verbal category/Likert scales [44, 64, 65]. Tools used to measure foot pain include the: Foot Function Index [66]; Foot Health Status Questionnaire [67], physical health domains of the Diabetes Foot Ulcer Scale [68]; Manchester Foot Pain and Disability Index [69]; Rowan Foot Pain Assessment Questionnaire [70]; American Academy of Orthopaedic Surgeons Foot and Ankle Questionnaire [71]. Across all these tools, the individual's subjective reporting of pain is regarded as a valid representation of their pain [63]. However, criticism of pain intensity outcome measures have concluded that: people preferentially use the beginning, middle and end of continuous pain scales (e.g. VAS) [63]; there are specific clinical attributes of pain class not always captured in generic tools (e.g. chronic/inflammatory/neuropathic) [44]; the fluctuating nature of many pain conditions are often inappropriately disregarded [44]; the results of intervention trials are often difficult to interpret due to unknown or unspecified clinically important differences detected by the pain measurement tool used [63].
Despite these limitations, foot pain as an outcome measure has much to offer clinical practice and research [65]. It is important, however, to ensure that pain reduction does not dominate health outcome assessment in clinical practice. Jensen et al. [44] suggest that pain reduction has dangerously been equated with therapeutic success, leaving many other clinically relevant health outcomes overlooked, e.g. functional ability.

Impact of foot pain

Considering the combined sensory and emotional components of pain, pain has the potential to produce effects far surpassing the auto-protective role depicted by the defense response mechanism [9, 64, 7293]. A summary of the impacts of pain in general is presented in Table 4. Foot pain specifically has been associated with reduced functional ability, including self-care [3, 811], increased risk of falls [6], depression [5] and reduced physical and mental aspects of quality of life [94]. While these effects are much less extensive than those associated with pain in general (Table 4), relatively few studies have evaluated the impact of foot pain and the outcomes assessed have been limited in scope.
Table 4
The broader impact of pain in the community
Domain
Impact
Social life
Inability to pursue hobbies among children and adolescents [72]
Reduces social functioning among children, their families and older adults [7375]
School absenteeism among children and adolescents [72]
Physical function
Fear of movement and re-injury in chronic musculoskeletal pain [76]
Reduced physical functioning among children, adolescents, adults and older people [9, 64, 7781]
Mental function
Sleep disturbances among children, adolescents and older people [7274, 77]
Mood disturbances among adolescents and older people [73, 77]
Interpersonal strain due to behavioural changes among children and their families [75]
Increases depressive symptoms, particularly if accompanied by self-blame [8284]
Increases severity of depressive symptoms [85]
Overall impact
Reduces quality of life [73, 74, 77, 83, 86, 88, 89]
Health care
Increases prescription/consumption of analgesic drugs [80, 87, 90]
Impairs recognition of depression [91]
Impairs adherence to medication if coinciding with depression [93]
To gauge the full impact of foot pain on one's life, it can be useful to measure health-related quality of life. Health-related quality of life is an individual's health status encompassing any aspect of life affected by mental and physical well being [95]. In recent years, health-related quality of life has been increasingly promoted as one of the most important outcomes for the evaluation of therapeutic interventions for pain [88, 96, 97]. Pain has a detrimental effect on all aspects of health-related quality of life, spanning all age groups, pain types and pain sources [97]. Of clinical importance is that health-related quality of life is reduced most when pain is of long duration and high intensity [98]. From a study of 81 chronic pain sufferers, Dysvik et al. [88] identified five predictors of poor health-related quality of life in chronic pain sufferers: (1) female gender; (2) longer pain duration; (3) greater pain intensity; (4) a view of pain as mysterious; and (5) less social support. Clinically, it might be beneficial to address the modifiable predictors: pain intensity (e.g. by therapy); view of pain as mysterious (e.g. by education); and less social support (e.g. by providing contacts for local support networks).
Some specific tools used to measure health-related quality of life in foot pain research include: four domains of the 36-Item Short-Form Health Survey (physical functioning, general health, vitality, and social functioning) [99]; the Quality of Life subscale of Foot & Ankle Outcome Score [100]; and the Health-Related Quality of Life Index [101]. Evidence from randomised controlled trials demonstrates that effective treatment of foot pain can lead to clinically important improvements in health related quality of life [15].

Foot pain as a sensory, emotional and psychosocial experience

The biopsychosocial framework depicts foot pain as a result of interaction between biological, psychological and social factors [102]. These include somatic nociceptive input, pain beliefs, coping strategies, mood, social context, cultural context and personal expectations [103, 104]. The cognitive behaviour model similarly promotes the influence of psychological and emotional experiences on pain, linking pain beliefs to culturally shared values and powerful emotions [88, 105].
While the suggestion that psychological and social factors influence pain experience and treatment outcomes is not new [106], it is only recently that the biopsychosocial and cognitive behavior models have been supported by empirical research. Psychosocial environment and pain beliefs have been shown to affect: how pain is reported [107, 108]; the intensity of the pain experienced [84, 109]; physiological symptoms [84, 109111]; the development, maintenance and exacerbation of disability [76, 88, 110]; risk for future musculoskeletal pain [112, 113]; and treatment outcomes [84, 109]. One important example is the differences in pain experience and report between males and females. Empirical research has demonstrated that a woman's average pain threshold and tolerance is significantly lower than the average man's and that women are more willing to report pain, therefore experiencing pain for less time than males [114, 115]. These differences are proposed to stem from both first order, biological sex differences and psychosocial factors including gender-role expectations [115].
Further research is required to understand the many facets of foot pain suffering and to identify or develop interventions effective at modifying the 'foot pain experience'. Clinically, this might be particularly useful for pain unresponsive to routine treatment, (e.g. painful diabetic neuropathy, fibromyalgia and complex regional pain syndrome type I) and understanding the complexities of the placebo effect.

The placebo effect – impact of the psychosocial context on treatment response

It is proposed that the psychosocial context (e.g. attitudes and expectations) surrounding an intervention contributes to positive therapeutic outcomes [116118]. This is called the placebo effect and can occur in both clinical trials and clinical practice [119, 120]. In clinical trials, researchers may attempt to isolate the placebo effect from the direct physiological effects of an intervention. This is typically achieved by using a pseudo-intervention devoid of intentional biological activity (e.g. sugar pill or detuned ultrasound) [119], which is colloquially known as a placebo. The 'placebo effect' is the change in outcomes observed following administration of the placebo intervention. Due to the biologically inert nature of the placebo intervention, the changes observed are routinely attributed to the psychosocial context surrounding the intervention [116]. The term 'placebo effect', however, is sometimes used misleadingly. The placebo effect encompasses only those changes that occur as a direct result of the administration of intervention. For example, the placebo effect can encompass the Hawthorne effect, where a person modifies their behaviour because they know they are being observed/monitored [121]. The placebo effect does not include changes that would have occurred if the placebo intervention was not given, including the natural progression or spontaneous resolution of symptoms and/or signs [120].
Overall, distinguishing between the changes that occurred due to the administration of the placebo intervention and those changes that would have occurred regardless is difficult, and in some cases impossible. There is, however, widespread historical acceptance of the proposal that the 'placebo effect' is more than a mere measurement artefact or reflection of normal disease progression [122]. Indeed, the placebo effect has been described as the most effective intervention known to science; having been subjected to more clinical trials than any other intervention, usually surpassing expectations of effectiveness, and being effective against an apparently limitless range of conditions [123, 124]. It is reported that the magnitude of the placebo effect in double-blinded randomised controlled trials has markedly increased since the mid 1980s [125]; now being capable of reducing symptoms by a mean of 35% [120]. Despite such claims, results of meta-analyses evaluating the existence of a placebo effect are contradictory [122, 126]. A Cochrane Collaboration systematic review evaluating the effect of placebo interventions across any clinical condition did not detect a statistically significant placebo effect in trials for binary outcomes (where treatment response is measured as one of two possible outcomes, e.g. death versus alive) or objective outcomes (where outcomes are measured by an observer, e.g. blood pressure) [126]. For self-reported continuous outcomes, however, a moderate placebo effect was detected. This effect was even stronger for self-reported pain outcomes [126].
The placebo effect has been acknowledged in reference to clinical trials of custom-made foot orthoses [127]. As with many physical, mechanical and surgical interventions, however, the development of convincing placebo interventions for custom-made foot orthoses is very difficult, and perhaps impossible. As a result, researchers often employ 'sham' interventions [99, 128]. Sham interventions are designed to have minimal mechanical effect but to look and feel like the genuine intervention. Consequently, these sham devices often produce some mechanical effect. Disentangling a true placebo effect from the potential mechanical effect of the sham orthoses and from the influence of changes that would have occurred without intervention (e.g. natural disease progression) is complex. Despite such limitations, an investigation attempting to understand the mechanisms by which custom-made foot orthoses reduced cavus foot pain reported that the placebo effect accompanying custom-made foot orthoses as an intervention is strong, and capable of producing clinically meaningful changes in symptoms [127].
Many theories attempting to explain the basis for the placebo effect have been proposed, including: (1) increased use of self-distraction strategies; (2) reduced anxiety (a key emotional component of pain); and (3) expectation of improvement due to intervention [117]. At the psycho-physiological level, brain functional imaging has located the neuro-chemical circuitry activated when participants expect they will receive, or believe they are receiving, a pain relieving intervention [116, 118]. In fact, the changes in brain activity are similar to those occurring when genuine interventions are delivered [118, 119, 129]. As such, there is mounting evidence in support of a physiological basis for subjective constructs (e.g. expectancy and value) to produce powerful modulation of basic perceptual, motor and internal homeostatic processes [117]. However, it is proposed that the contributions of various neurotransmitters and neuropeptides involved in this placebo-induced, activity modulation might be disease- and symptom-specific [124]. Presently, no brain imaging studies have evaluated the placebo effect for foot pain interventions.
While it is desirable to minimise the magnitude of the placebo effect in clinical trials, it is possible that clinically meaningful benefits might be achieved by intentionally maximising the placebo effect in clinical practice [118]. More research is needed to determine if (and if so, how) this can be achieved. Until more clinically directive evidence is produced, clinicians should be aware that what the patient thinks, matters.

Summary

In this review of foot pain, we have discussed its prevalence, aetiology and predictors, classification, measurement and impact. We have also described the complexities of foot pain as a sensory and emotional experience and how the psychosocial context can influence treatment response to produce a 'placebo effect'. It is hoped that this paper will provide a platform from which to advance the diagnosis and treatment of foot pain in clinical practice and its evaluation in clinical trials.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://​creativecommons.​org/​licenses/​by/​2.​0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Authors' contributions

FH searched the literature, retrieved articles and drafted the review. JB conceived the review, provided comments on content and made changes to the final document.

Onze productaanbevelingen

BSL Podotherapeut Totaal

Binnen de bundel kunt u gebruik maken van boeken, tijdschriften, e-learnings, web-tv's en uitlegvideo's. BSL Podotherapeut Totaal is overal toegankelijk; via uw PC, tablet of smartphone.

Literatuur
1.
go back to reference Badlissi F, Dunn J, Link C, Keysor J, McKinlay J, Felson D: Foot musculoskeletal disorders, pain, and foot-related functional limitation in older persons. J Am Soc Geriatr Dent. 2005, 53: 1029-1033. 10.1111/j.1532-5415.2005.53315.x. Badlissi F, Dunn J, Link C, Keysor J, McKinlay J, Felson D: Foot musculoskeletal disorders, pain, and foot-related functional limitation in older persons. J Am Soc Geriatr Dent. 2005, 53: 1029-1033. 10.1111/j.1532-5415.2005.53315.x.
2.
go back to reference Hill C, Gill T, Menz H, Taylor A: Prevalence and correlates of foot pain in a population-based study: the North West Adelaide health study. J Foot Ankle Res. 2008, 1 (1): 2-10.1186/1757-1146-1-2.PubMedPubMedCentral Hill C, Gill T, Menz H, Taylor A: Prevalence and correlates of foot pain in a population-based study: the North West Adelaide health study. J Foot Ankle Res. 2008, 1 (1): 2-10.1186/1757-1146-1-2.PubMedPubMedCentral
3.
go back to reference Menz HB, Lord SR: Foot pain impairs balance and functional ability in community-dwelling older people. Journal of the American Podiatric Medical Association. 2001, 91: 222-229.PubMed Menz HB, Lord SR: Foot pain impairs balance and functional ability in community-dwelling older people. Journal of the American Podiatric Medical Association. 2001, 91: 222-229.PubMed
4.
go back to reference Garrow AP, Silman AJ, Macfarlane GJ: The Chesire foot pain and disability survey: a population survey assessing prevalence and associations. Pain. 2004, 110: 378-384. 10.1016/j.pain.2004.04.019.PubMed Garrow AP, Silman AJ, Macfarlane GJ: The Chesire foot pain and disability survey: a population survey assessing prevalence and associations. Pain. 2004, 110: 378-384. 10.1016/j.pain.2004.04.019.PubMed
5.
go back to reference Menz HB, Tiedemann A, Kwan MMS, Plumb K, Lord SR: Foot pain in community-dwelling older people: an evaluation of the Manchester Foot Pain and Disability Index. Rheumatology. 2006, 45: 863-867. 10.1093/rheumatology/kel002.PubMed Menz HB, Tiedemann A, Kwan MMS, Plumb K, Lord SR: Foot pain in community-dwelling older people: an evaluation of the Manchester Foot Pain and Disability Index. Rheumatology. 2006, 45: 863-867. 10.1093/rheumatology/kel002.PubMed
6.
go back to reference Menz HB, Morris ME, Lord SR: Foot and ankle risk factors for falls in older people: a prospective study. J Gerontol. 2006, 61A: 866-870. Menz HB, Morris ME, Lord SR: Foot and ankle risk factors for falls in older people: a prospective study. J Gerontol. 2006, 61A: 866-870.
7.
go back to reference Menz HB, Lord SR: The contribution of foot problems to mobility impairment and falls in community-dwelling older people. Journal of the American Geriatric Society. 2001, 49: 1651-1656. 10.1111/j.1532-5415.2001.49275.x. Menz HB, Lord SR: The contribution of foot problems to mobility impairment and falls in community-dwelling older people. Journal of the American Geriatric Society. 2001, 49: 1651-1656. 10.1111/j.1532-5415.2001.49275.x.
8.
go back to reference Benvenuti F, Ferrucci L, Guralnik JM, Gangemi S, Baroni A: Foot pain and disability in older persons: an epidemiologic survey. J Am Geriatr Soc. 1995, 43: 479-484.PubMed Benvenuti F, Ferrucci L, Guralnik JM, Gangemi S, Baroni A: Foot pain and disability in older persons: an epidemiologic survey. J Am Geriatr Soc. 1995, 43: 479-484.PubMed
9.
go back to reference Novak P, Burger H, Marincek C, Meh D: Influence of foot pain on walking ability of diabetic patients. J Rehabil Med. 2004, 36: 249-252. 10.1080/16501970410029816.PubMed Novak P, Burger H, Marincek C, Meh D: Influence of foot pain on walking ability of diabetic patients. J Rehabil Med. 2004, 36: 249-252. 10.1080/16501970410029816.PubMed
10.
go back to reference Leveille SG, Guralnik JM, Ferrucci L, Hirsch R, Simonsick EM, Hochberg MC: Foot pain and disability in older women. Am J Epidemiol. 1998, 148: 657-665.PubMed Leveille SG, Guralnik JM, Ferrucci L, Hirsch R, Simonsick EM, Hochberg MC: Foot pain and disability in older women. Am J Epidemiol. 1998, 148: 657-665.PubMed
11.
go back to reference Keysor JJ, Dunn JE, Link CL, Badlissi F, Felson DT: Are foot disorders associated with functional limitation and disability among community-dwelling older adults?. J Aging Health. 2005, 17: 734-752. 10.1177/0898264305280998.PubMed Keysor JJ, Dunn JE, Link CL, Badlissi F, Felson DT: Are foot disorders associated with functional limitation and disability among community-dwelling older adults?. J Aging Health. 2005, 17: 734-752. 10.1177/0898264305280998.PubMed
12.
go back to reference Buttke J: Stepping Up Foot Injury Diagnosis: Jones, Lisfranc, and Charcot. Nurse Pract. 2005, 30: 46-52. 10.1097/00006205-200512000-00008.PubMed Buttke J: Stepping Up Foot Injury Diagnosis: Jones, Lisfranc, and Charcot. Nurse Pract. 2005, 30: 46-52. 10.1097/00006205-200512000-00008.PubMed
13.
go back to reference Ertugrul M, Baktiroglu S, Salman S, Unal S, Aksoy M, Berberoglu K, Calangu S: The diagnosis of osteomyelitis of the foot in diabetes: microbiological examination vs. magnetic resonance imaging and labelled leucocyte scanning. Diabet Med. 2006, 23: 649-653. 10.1111/j.1464-5491.2006.01887.x.PubMed Ertugrul M, Baktiroglu S, Salman S, Unal S, Aksoy M, Berberoglu K, Calangu S: The diagnosis of osteomyelitis of the foot in diabetes: microbiological examination vs. magnetic resonance imaging and labelled leucocyte scanning. Diabet Med. 2006, 23: 649-653. 10.1111/j.1464-5491.2006.01887.x.PubMed
14.
go back to reference Crawford F, Atkins D, Edwards J: Interventions for treating plantar heel pain. Cochrane Database Syst Rev. 2003, CD000416- Crawford F, Atkins D, Edwards J: Interventions for treating plantar heel pain. Cochrane Database Syst Rev. 2003, CD000416-
15.
go back to reference Hawke F, Burns J, Radford J, du Toit V: Custom-made foot orthoses for the treatment of foot pain. Cochrane Database Syst Rev. 2008, CD006801- Hawke F, Burns J, Radford J, du Toit V: Custom-made foot orthoses for the treatment of foot pain. Cochrane Database Syst Rev. 2008, CD006801-
16.
17.
go back to reference Mann R: Pain in the foot. 1. Evaluation of foot pain and identification of associated problems. Postgrad Med. 1987, 82: 154-157.PubMed Mann R: Pain in the foot. 1. Evaluation of foot pain and identification of associated problems. Postgrad Med. 1987, 82: 154-157.PubMed
18.
go back to reference Mann R: Pain in the foot. 2. Causes of pain in the hindfoot, midfoot, and forefoot. Postgrad Med. 1987, 82: 167-171.PubMed Mann R: Pain in the foot. 2. Causes of pain in the hindfoot, midfoot, and forefoot. Postgrad Med. 1987, 82: 167-171.PubMed
19.
go back to reference Wood B, Warfield C: Foot pain – from bad shoes to aberrant genes. Hosp Pract (Off Ed). 1987, 22: 107-122. Wood B, Warfield C: Foot pain – from bad shoes to aberrant genes. Hosp Pract (Off Ed). 1987, 22: 107-122.
20.
go back to reference Merskey H, Bogduk N, (Eds): Classification of Chronic Pain. 1994, Seattle: IASP Press, Second Merskey H, Bogduk N, (Eds): Classification of Chronic Pain. 1994, Seattle: IASP Press, Second
21.
go back to reference Bennet RM: Emerging concepts in the neurobiology of chronic pain: evidence of abnormal sensory processing in fibromyalgia. Mayo Clin Proc. 1999, 74: 385-398. Bennet RM: Emerging concepts in the neurobiology of chronic pain: evidence of abnormal sensory processing in fibromyalgia. Mayo Clin Proc. 1999, 74: 385-398.
22.
go back to reference Kidd B, Urban L: Mechanisms of inflammatory pain. Br J Anaesth. 2001, 87: 3-11. 10.1093/bja/87.1.3.PubMed Kidd B, Urban L: Mechanisms of inflammatory pain. Br J Anaesth. 2001, 87: 3-11. 10.1093/bja/87.1.3.PubMed
23.
go back to reference Vanderah TW: Pathophysiology of Pain. Med Clin North Am. 2007, 91: 1-12. 10.1016/j.mcna.2006.10.006.PubMed Vanderah TW: Pathophysiology of Pain. Med Clin North Am. 2007, 91: 1-12. 10.1016/j.mcna.2006.10.006.PubMed
24.
go back to reference Maganaris CN, Narici MV, Almekinders LC, Maffulli N: Biomechanics and pathophysiology of overuse tendon injuries ideas on insertional tendinopathy. Sports Med. 2004, 34: 1005-1017. 10.2165/00007256-200434140-00005.PubMed Maganaris CN, Narici MV, Almekinders LC, Maffulli N: Biomechanics and pathophysiology of overuse tendon injuries ideas on insertional tendinopathy. Sports Med. 2004, 34: 1005-1017. 10.2165/00007256-200434140-00005.PubMed
25.
go back to reference McPoil T, Hunt G: Evaluation and management of foot and ankle disorders: present position and future directions. J Orthop Sports Phys Ther. 1995, 21: 381-PubMed McPoil T, Hunt G: Evaluation and management of foot and ankle disorders: present position and future directions. J Orthop Sports Phys Ther. 1995, 21: 381-PubMed
26.
go back to reference Mueller MJ, Maluf KS: Tissue adaptation to physical stress: a proposed "physical stress theory" to guide physical therapist practice, education, and research. Phys Ther. 2002, 82: 383-403.PubMed Mueller MJ, Maluf KS: Tissue adaptation to physical stress: a proposed "physical stress theory" to guide physical therapist practice, education, and research. Phys Ther. 2002, 82: 383-403.PubMed
27.
go back to reference Garrow A, Papageorgiou A, Silman A, Thomas E, Jayson M, Macfarlane G: The grading of Hallux Valgus: the Manchester scale. J Am Podiatr Med Assoc. 2001, 91: 74-78.PubMed Garrow A, Papageorgiou A, Silman A, Thomas E, Jayson M, Macfarlane G: The grading of Hallux Valgus: the Manchester scale. J Am Podiatr Med Assoc. 2001, 91: 74-78.PubMed
28.
go back to reference McRae R: Clinical orthopaedic examination. 1997, Edinburgh: Churchill Livingstone McRae R: Clinical orthopaedic examination. 1997, Edinburgh: Churchill Livingstone
29.
go back to reference Myerson M, Shereff M: The pathological anatomy of claw and hammer toes. J Bone Joint Surg. 1989, 71: 45-49.PubMed Myerson M, Shereff M: The pathological anatomy of claw and hammer toes. J Bone Joint Surg. 1989, 71: 45-49.PubMed
30.
go back to reference Frey C, Thompson F, Smith J, Sanders M, Horstman H: American Orthopedic Foot and Ankle Society women's shoe survey. Foot Ankle. 1993, 14: 78-81.PubMed Frey C, Thompson F, Smith J, Sanders M, Horstman H: American Orthopedic Foot and Ankle Society women's shoe survey. Foot Ankle. 1993, 14: 78-81.PubMed
31.
go back to reference Menz H, Morris M: Footwear characteristics and foot problems in older people. Gerontology. 2005, 51: 346-351. 10.1159/000086373.PubMed Menz H, Morris M: Footwear characteristics and foot problems in older people. Gerontology. 2005, 51: 346-351. 10.1159/000086373.PubMed
32.
go back to reference Dawson J, Thorogood M, Marks S, Juszczak E, Dodd C, Lavis G, Fitzpatrick R: The prevalence of foot problems in older women: a cause for concern. Journal of Public Health Medicine. 2002, 24: 77-84. 10.1093/pubmed/24.2.77.PubMed Dawson J, Thorogood M, Marks S, Juszczak E, Dodd C, Lavis G, Fitzpatrick R: The prevalence of foot problems in older women: a cause for concern. Journal of Public Health Medicine. 2002, 24: 77-84. 10.1093/pubmed/24.2.77.PubMed
33.
go back to reference Cedraschi C, Nordin M, Nachemson A, Vischer T: Health care providers should use a common language in relation to low back pain patients. Baillieres Clin Rheumatol. 1998, 12: 1-8. 10.1016/S0950-3579(98)80003-4.PubMed Cedraschi C, Nordin M, Nachemson A, Vischer T: Health care providers should use a common language in relation to low back pain patients. Baillieres Clin Rheumatol. 1998, 12: 1-8. 10.1016/S0950-3579(98)80003-4.PubMed
34.
go back to reference Von Korff M, Miglioretti DL: A prognostic approach to defining chronic pain. Pain. 2005, 117: 304-313. 10.1016/j.pain.2005.06.017.PubMed Von Korff M, Miglioretti DL: A prognostic approach to defining chronic pain. Pain. 2005, 117: 304-313. 10.1016/j.pain.2005.06.017.PubMed
35.
go back to reference Katz WA, Rothenberg R: Section 3: the nature of pain: pathophysiology. Journal of Clinical Rheumatology. 2005, 11: S11-S15. 10.1097/01.rhu.0000158686.43637.af.PubMed Katz WA, Rothenberg R: Section 3: the nature of pain: pathophysiology. Journal of Clinical Rheumatology. 2005, 11: S11-S15. 10.1097/01.rhu.0000158686.43637.af.PubMed
36.
go back to reference Besson JM: The neurobiology of pain. Lancet. 1999, 353: 1610-1615. 10.1016/S0140-6736(99)01313-6.PubMed Besson JM: The neurobiology of pain. Lancet. 1999, 353: 1610-1615. 10.1016/S0140-6736(99)01313-6.PubMed
37.
go back to reference Schaible HG, Richter F: Pathophysiology of pain. Langenbecks Arch Surg. 2004, 389: 237-243. 10.1007/s00423-004-0468-9.PubMed Schaible HG, Richter F: Pathophysiology of pain. Langenbecks Arch Surg. 2004, 389: 237-243. 10.1007/s00423-004-0468-9.PubMed
38.
go back to reference Fink WA: The pathophysiology of acute pain. Emerg Med Clin N Am. 2005, 23: 277-284. 10.1016/j.emc.2004.12.001. Fink WA: The pathophysiology of acute pain. Emerg Med Clin N Am. 2005, 23: 277-284. 10.1016/j.emc.2004.12.001.
39.
go back to reference Pasero C: Pathophysiology of neuropathic pain. Pain Manag Nurs. 2004, 5: 3-8. 10.1016/j.pmn.2004.10.002.PubMed Pasero C: Pathophysiology of neuropathic pain. Pain Manag Nurs. 2004, 5: 3-8. 10.1016/j.pmn.2004.10.002.PubMed
40.
go back to reference Donaldson GW, Chapmana CR, Nakamuraa Y, Bradshawa DH, Jacobsona RC, Chapmanb CN: Pain and the defense response: structural equation modeling reveals a coordinated psychophysiological response to increasing painful stimulation. Pain. 2003, 102: 97-108. 10.1016/s0304-3959(02)00351-2.PubMed Donaldson GW, Chapmana CR, Nakamuraa Y, Bradshawa DH, Jacobsona RC, Chapmanb CN: Pain and the defense response: structural equation modeling reveals a coordinated psychophysiological response to increasing painful stimulation. Pain. 2003, 102: 97-108. 10.1016/s0304-3959(02)00351-2.PubMed
41.
go back to reference Schaible HG, Schmelz M, Tegeder I: Pathophysiology and treatment of pain in joint disease. Adv Drug Deliv Rev. 2006, 58: 323-342. 10.1016/j.addr.2006.01.011.PubMed Schaible HG, Schmelz M, Tegeder I: Pathophysiology and treatment of pain in joint disease. Adv Drug Deliv Rev. 2006, 58: 323-342. 10.1016/j.addr.2006.01.011.PubMed
42.
go back to reference Willis W, Westlund K: Neuroanatomy of the pain system and of the pathways that modulate pain. J Clin Neurophysiol. 1997, 14: 2-31. 10.1097/00004691-199701000-00002.PubMed Willis W, Westlund K: Neuroanatomy of the pain system and of the pathways that modulate pain. J Clin Neurophysiol. 1997, 14: 2-31. 10.1097/00004691-199701000-00002.PubMed
43.
go back to reference Melzack R, Wall P: Pain mechanisms: a new theory. Science Wash CD. 1965, 150: 971-979. 10.1126/science.150.3699.971. Melzack R, Wall P: Pain mechanisms: a new theory. Science Wash CD. 1965, 150: 971-979. 10.1126/science.150.3699.971.
44.
go back to reference Jensen TS, Gottrup H, Sindrup SH, Bach FW: The clinical picture of neuropathic pain. Eur J Pharmacol. 2001, 429: 1-11. 10.1016/S0014-2999(01)01302-4.PubMed Jensen TS, Gottrup H, Sindrup SH, Bach FW: The clinical picture of neuropathic pain. Eur J Pharmacol. 2001, 429: 1-11. 10.1016/S0014-2999(01)01302-4.PubMed
45.
go back to reference Koltzenburg M: Stability and plasticity of nociceptor function and their relationship to provoked and ongoing pain. Seminars in Neuroscience. 1995, 7: 199-210. 10.1006/smns.1995.0023. Koltzenburg M: Stability and plasticity of nociceptor function and their relationship to provoked and ongoing pain. Seminars in Neuroscience. 1995, 7: 199-210. 10.1006/smns.1995.0023.
46.
go back to reference Bennett GA: Animal models of neuropathic pain. Progress in Pain Research and Management. Edited by: Gebhart G, Hammond D, Jensen T. 1994, Seattle: IASP Publications, 2: 495-510. Bennett GA: Animal models of neuropathic pain. Progress in Pain Research and Management. Edited by: Gebhart G, Hammond D, Jensen T. 1994, Seattle: IASP Publications, 2: 495-510.
47.
go back to reference Zimmermann M: Pathobiology of neuropathic pain. Eur J Pharmacol. 2001, 429: 23-37. 10.1016/S0014-2999(01)01303-6.PubMed Zimmermann M: Pathobiology of neuropathic pain. Eur J Pharmacol. 2001, 429: 23-37. 10.1016/S0014-2999(01)01303-6.PubMed
48.
go back to reference Waxman SG: The molecular pathophysiology of pain: abnormal expression of sodium channel genes and its contributions to hyperexcitability of primary sensory neurons. Pain. 1999, S133-S140. 10.1016/S0304-3959(99)00147-5. Supplement 6 Waxman SG: The molecular pathophysiology of pain: abnormal expression of sodium channel genes and its contributions to hyperexcitability of primary sensory neurons. Pain. 1999, S133-S140. 10.1016/S0304-3959(99)00147-5. Supplement 6
49.
go back to reference Bogduk N: Complex regional pain syndrome. Curr Opin Anaesthesiol. 2001, 14: 541-546. 10.1097/00001503-200110000-00013.PubMed Bogduk N: Complex regional pain syndrome. Curr Opin Anaesthesiol. 2001, 14: 541-546. 10.1097/00001503-200110000-00013.PubMed
50.
go back to reference Köck F, Borisch N, Koester B, Grifka J: Complex regional pain syndrome type I (CRPS I). Pathophysiology, diagnostics, and therapy. Orthopade. 2003, 32: 418-431. 10.1007/s00132-003-0468-4.PubMed Köck F, Borisch N, Koester B, Grifka J: Complex regional pain syndrome type I (CRPS I). Pathophysiology, diagnostics, and therapy. Orthopade. 2003, 32: 418-431. 10.1007/s00132-003-0468-4.PubMed
51.
go back to reference Scott A, Khan K, Cook J, Duronio V: What is 'inflammation'? Are we ready to move beyond celsus?. Br J Sports Med. 2004, 38: 248-249. 10.1136/bjsm.2003.011221.PubMedPubMedCentral Scott A, Khan K, Cook J, Duronio V: What is 'inflammation'? Are we ready to move beyond celsus?. Br J Sports Med. 2004, 38: 248-249. 10.1136/bjsm.2003.011221.PubMedPubMedCentral
52.
go back to reference Tracy R: The five cardinal signs of inflammation. J Gerontol A Biol Sci Med Sci. 2006, 61: 1051-1052.PubMed Tracy R: The five cardinal signs of inflammation. J Gerontol A Biol Sci Med Sci. 2006, 61: 1051-1052.PubMed
53.
go back to reference Loeser JD, Melzack R: Pain: an overview. Lancet. 1999, 353: 1607-1609. 10.1016/S0140-6736(99)01311-2.PubMed Loeser JD, Melzack R: Pain: an overview. Lancet. 1999, 353: 1607-1609. 10.1016/S0140-6736(99)01311-2.PubMed
54.
go back to reference Dray A: Kinins and their receptors in hyperalgesia. Can J Pharmacol. 1997, 75: 704-712. 10.1139/cjpp-75-6-704. Dray A: Kinins and their receptors in hyperalgesia. Can J Pharmacol. 1997, 75: 704-712. 10.1139/cjpp-75-6-704.
55.
go back to reference Schaible H, Grubb B: Afferent and spinal mechanisms of joint pain. Pain. 1993, 55: 5-54. 10.1016/0304-3959(93)90183-P.PubMed Schaible H, Grubb B: Afferent and spinal mechanisms of joint pain. Pain. 1993, 55: 5-54. 10.1016/0304-3959(93)90183-P.PubMed
56.
go back to reference Dunajcik L: Chronic nonmalignant pain. Pain: Clinical manual. Edited by: McCaffery M, Pasero C. 1999, Mosby: St. Louis, 467-521. Dunajcik L: Chronic nonmalignant pain. Pain: Clinical manual. Edited by: McCaffery M, Pasero C. 1999, Mosby: St. Louis, 467-521.
57.
go back to reference Gibson S, Helme R: Age-related differences in pain perception and report. Clin Geriatr Med. 2001, 17: 433-456. 10.1016/S0749-0690(05)70079-3.PubMed Gibson S, Helme R: Age-related differences in pain perception and report. Clin Geriatr Med. 2001, 17: 433-456. 10.1016/S0749-0690(05)70079-3.PubMed
58.
go back to reference Gagliese L, Katz J, Melzack R: Pain in the elderly. Textbook of Pain. Edited by: Wall P, Melzack R. 1999, New York: Churchill Livingstone Gagliese L, Katz J, Melzack R: Pain in the elderly. Textbook of Pain. Edited by: Wall P, Melzack R. 1999, New York: Churchill Livingstone
59.
go back to reference Gibson S, Helme R: Age-related differences in pain perception and report. Clinics in Geriatric Medicine. 2001, 17: 433-456. 10.1016/S0749-0690(05)70079-3.PubMed Gibson S, Helme R: Age-related differences in pain perception and report. Clinics in Geriatric Medicine. 2001, 17: 433-456. 10.1016/S0749-0690(05)70079-3.PubMed
60.
go back to reference Lautenbacher S, Strian F: Similarities in age differences in heat pain perception and thermal sensitivity. Funct Neurol. 1991, 6 (2): 129-135.PubMed Lautenbacher S, Strian F: Similarities in age differences in heat pain perception and thermal sensitivity. Funct Neurol. 1991, 6 (2): 129-135.PubMed
61.
go back to reference Jensen R, Rasmussen B, Pedersen B, Lous I, Olesen J: Cephalic muscle tenderness and pressure pain threshold in a general population. Pain. 1992, 48: 197-10.1016/0304-3959(92)90059-K.PubMed Jensen R, Rasmussen B, Pedersen B, Lous I, Olesen J: Cephalic muscle tenderness and pressure pain threshold in a general population. Pain. 1992, 48: 197-10.1016/0304-3959(92)90059-K.PubMed
62.
go back to reference Chakour M, Gibson S, Helme R: The effect of age on A delta and C fibre thermal pain perception. Pain. 1996, 64: Chakour M, Gibson S, Helme R: The effect of age on A delta and C fibre thermal pain perception. Pain. 1996, 64:
63.
go back to reference Farrar JT, Portenoy RK, Berlin JA, Kinman JL, Strom BL: Defining the clinically important difference in pain outcome measures. Pain. 2000, 88: 287-294. 10.1016/S0304-3959(00)00339-0.PubMed Farrar JT, Portenoy RK, Berlin JA, Kinman JL, Strom BL: Defining the clinically important difference in pain outcome measures. Pain. 2000, 88: 287-294. 10.1016/S0304-3959(00)00339-0.PubMed
64.
go back to reference Turner JA, Franklin G, Heagerty PJ, Wu R, Egan K, Fulton-Kehoe D, Gluck JV, Wickizer TM: The association between pain and disability. Pain. 2004, 112: 307-314. 10.1016/j.pain.2004.09.010.PubMed Turner JA, Franklin G, Heagerty PJ, Wu R, Egan K, Fulton-Kehoe D, Gluck JV, Wickizer TM: The association between pain and disability. Pain. 2004, 112: 307-314. 10.1016/j.pain.2004.09.010.PubMed
65.
go back to reference Landorf K, Burns J: Chapter 10: Health Outcome Assessment. Merriman's assessment of the lower limb. Edited by: Yates B. 2008, London: Churchill Livingstone, 3: 3 Landorf K, Burns J: Chapter 10: Health Outcome Assessment. Merriman's assessment of the lower limb. Edited by: Yates B. 2008, London: Churchill Livingstone, 3: 3
66.
go back to reference Budiman-Mak E, Conrad K, Roach K: The Foot Function Index: a measure of foot pain and disability. J Clin Epidemiol. 1991, 44: 561-570. 10.1016/0895-4356(91)90220-4.PubMed Budiman-Mak E, Conrad K, Roach K: The Foot Function Index: a measure of foot pain and disability. J Clin Epidemiol. 1991, 44: 561-570. 10.1016/0895-4356(91)90220-4.PubMed
67.
go back to reference Bennett P, C P, Wearing S, Baglioni A: Development and validation of a questionnaire designed to measure foot health status. J Am Podiatr Med Assoc. 1998, 88: 419-428.PubMed Bennett P, C P, Wearing S, Baglioni A: Development and validation of a questionnaire designed to measure foot health status. J Am Podiatr Med Assoc. 1998, 88: 419-428.PubMed
68.
go back to reference Abetz L, Sutton M, Brady L, McNulty P, Gagnon D: The Diabetic Foot Ulcer Scale (DFS): a quality of life instrument for use in clinical trials. Practical Diabetes International. 2002, 19: 167-175. 10.1002/pdi.356. Abetz L, Sutton M, Brady L, McNulty P, Gagnon D: The Diabetic Foot Ulcer Scale (DFS): a quality of life instrument for use in clinical trials. Practical Diabetes International. 2002, 19: 167-175. 10.1002/pdi.356.
69.
go back to reference Garrow A, Papageorgiou A, Silman A, Thomas E, Jayson M, Macfarlane G: Development and validation of a questionnaire to assess disabling foot pain. Pain. 2000, 85: 107-113. 10.1016/S0304-3959(99)00263-8.PubMed Garrow A, Papageorgiou A, Silman A, Thomas E, Jayson M, Macfarlane G: Development and validation of a questionnaire to assess disabling foot pain. Pain. 2000, 85: 107-113. 10.1016/S0304-3959(99)00263-8.PubMed
70.
go back to reference Rowan K: The development and validation of a multi-dimensional measure of chronic foot pain: the ROwan Foot Pain Assessment Questionnaire (ROFPAQ). Foot Ankle Int. 2001, 22: 795-809.PubMed Rowan K: The development and validation of a multi-dimensional measure of chronic foot pain: the ROwan Foot Pain Assessment Questionnaire (ROFPAQ). Foot Ankle Int. 2001, 22: 795-809.PubMed
71.
go back to reference Johanson N, Liang M, Daltroy L, Rudicel S, Richmond J: American Academy of Orthopaedic Surgeons Lower Limb Outcomes Assessment Instruments. Reliability, validity, and sensitivity to change. J Bone Joint Surg. 2004, 86: 902-909.PubMed Johanson N, Liang M, Daltroy L, Rudicel S, Richmond J: American Academy of Orthopaedic Surgeons Lower Limb Outcomes Assessment Instruments. Reliability, validity, and sensitivity to change. J Bone Joint Surg. 2004, 86: 902-909.PubMed
72.
go back to reference Roth-Isigkeit A, Thyen U, Stoven H, Schgwarzenberger J, Schumucker P: Pain among children and adolescents: restrictions in daily living and triggering factors. Pediatrics. 2005, 115: e152-162. 10.1542/peds.2004-0682.PubMed Roth-Isigkeit A, Thyen U, Stoven H, Schgwarzenberger J, Schumucker P: Pain among children and adolescents: restrictions in daily living and triggering factors. Pediatrics. 2005, 115: e152-162. 10.1542/peds.2004-0682.PubMed
73.
go back to reference Reyes-Gibby CC, Aday L, Cleelandm C: Impact of pain on self-rated health on the community dwelling older adults. Pain. 2002, 95: 75-82. 10.1016/S0304-3959(01)00375-X.PubMed Reyes-Gibby CC, Aday L, Cleelandm C: Impact of pain on self-rated health on the community dwelling older adults. Pain. 2002, 95: 75-82. 10.1016/S0304-3959(01)00375-X.PubMed
74.
go back to reference Strassels S, Cynn D, Carr DB: Health status and chronic pain in managed care: Instruments and assessment. Managed Care and Pain. Edited by: Lande SD, Kulich RJ. 2000, American Pain Society, 141-171. Strassels S, Cynn D, Carr DB: Health status and chronic pain in managed care: Instruments and assessment. Managed Care and Pain. Edited by: Lande SD, Kulich RJ. 2000, American Pain Society, 141-171.
75.
go back to reference Hunfeld J, Perquin C, Hazebroek-Kampschreur , Passchier J, van Suijlekom-Smit L, Wouden vd: Physically unexplained chronic pain and its impact on children and their families: The mother's perception. Psychol Psychother. 2002, 75: 251-260. 10.1348/147608302320365172.PubMed Hunfeld J, Perquin C, Hazebroek-Kampschreur , Passchier J, van Suijlekom-Smit L, Wouden vd: Physically unexplained chronic pain and its impact on children and their families: The mother's perception. Psychol Psychother. 2002, 75: 251-260. 10.1348/147608302320365172.PubMed
76.
go back to reference Roelofs , et al: Fear of movement and (re)injury in chronic musculoskeletal pain. Pain. 2007 Roelofs , et al: Fear of movement and (re)injury in chronic musculoskeletal pain. Pain. 2007
77.
go back to reference Palermo T, Kiska R: Subjective sleep disturbances in adolescents with chronic pain: relationship to daily functioning and quality of life. J Pain. 2005, 6: 201-207. 10.1016/j.jpain.2004.12.005.PubMed Palermo T, Kiska R: Subjective sleep disturbances in adolescents with chronic pain: relationship to daily functioning and quality of life. J Pain. 2005, 6: 201-207. 10.1016/j.jpain.2004.12.005.PubMed
78.
go back to reference Hunfeld J, Perquin C, Bertina W, Hazebroek-Kampschreur A, van Suijlekom-Smit L, Koes B, Wouden van der J, Passchier J: Stability of pain parameters and pain-related quality of life in adolescents with persistent pain: a three-year follow-up. Clin J Pain. 2002, 18: 99-106. 10.1097/00002508-200203000-00005.PubMed Hunfeld J, Perquin C, Bertina W, Hazebroek-Kampschreur A, van Suijlekom-Smit L, Koes B, Wouden van der J, Passchier J: Stability of pain parameters and pain-related quality of life in adolescents with persistent pain: a three-year follow-up. Clin J Pain. 2002, 18: 99-106. 10.1097/00002508-200203000-00005.PubMed
79.
go back to reference Scudds R, Robertson J: Pain factors associated with physical disability in a sample of community-dwelling senior citizens. J Gerontol A Biol Sci Med Sci. 2000, 55 (7): M393-M399.PubMed Scudds R, Robertson J: Pain factors associated with physical disability in a sample of community-dwelling senior citizens. J Gerontol A Biol Sci Med Sci. 2000, 55 (7): M393-M399.PubMed
81.
go back to reference Strine T, Hootman J, Chapman D, Okoro C, Balluz L: Health-related quality of life, health risk behaviors, and disability among adults with pain-related activity difficulty. Am J Public Health. 2005, 95: 2042-2048. 10.2105/AJPH.2005.066225.PubMedPubMedCentral Strine T, Hootman J, Chapman D, Okoro C, Balluz L: Health-related quality of life, health risk behaviors, and disability among adults with pain-related activity difficulty. Am J Public Health. 2005, 95: 2042-2048. 10.2105/AJPH.2005.066225.PubMedPubMedCentral
82.
go back to reference Von Korff M, Simon G: The relationship between pain and depression. Br J Psychiatry Suppl. 1996, 30: 101-108.PubMed Von Korff M, Simon G: The relationship between pain and depression. Br J Psychiatry Suppl. 1996, 30: 101-108.PubMed
83.
go back to reference Asghari A, Ghaderi N, Ashory A: The prevalence of pain among residents of nursing homes and the impact of pain on their mood and quality of life. Arch Iran Med. 2006, 9: 368-373.PubMed Asghari A, Ghaderi N, Ashory A: The prevalence of pain among residents of nursing homes and the impact of pain on their mood and quality of life. Arch Iran Med. 2006, 9: 368-373.PubMed
84.
go back to reference Williams D, Robinson M, Geisser M: Pain beliefs: assessment and utility. Pain. 1994, 59: 71-78. 10.1016/0304-3959(94)90049-3.PubMed Williams D, Robinson M, Geisser M: Pain beliefs: assessment and utility. Pain. 1994, 59: 71-78. 10.1016/0304-3959(94)90049-3.PubMed
85.
go back to reference Thomas E, Colleen M, Renier B, Jeanette A, Palcher B: Chronic pain, depression, and quality of life: correlations and predictive value of the SF-36. Pain Med. 2003, 4: 331-339. 10.1111/j.1526-4637.2003.03040.x. Thomas E, Colleen M, Renier B, Jeanette A, Palcher B: Chronic pain, depression, and quality of life: correlations and predictive value of the SF-36. Pain Med. 2003, 4: 331-339. 10.1111/j.1526-4637.2003.03040.x.
86.
go back to reference Skevington S: Investigating the relationship between pain and discomfort and quality of life, using the WHOQOL. Pain. 1998, 76: 395-406. 10.1016/S0304-3959(98)00072-4.PubMed Skevington S: Investigating the relationship between pain and discomfort and quality of life, using the WHOQOL. Pain. 1998, 76: 395-406. 10.1016/S0304-3959(98)00072-4.PubMed
87.
go back to reference Ribu L, Rustoen T, Birkeland K, Hanestad B, Paul S, Miaskowski C: The prevalence and occurrence of diabetic foot ulcer pain and its impact on health-related quality of life. J Pain. 2006, 7: 290-299. 10.1016/j.jpain.2005.12.002.PubMed Ribu L, Rustoen T, Birkeland K, Hanestad B, Paul S, Miaskowski C: The prevalence and occurrence of diabetic foot ulcer pain and its impact on health-related quality of life. J Pain. 2006, 7: 290-299. 10.1016/j.jpain.2005.12.002.PubMed
88.
go back to reference Dysvik E, Lindstrøm TC, Eikeland O-J, Natvig GK: Health-related quality of life and pain beliefs among people suffering from chronic pain. Pain Manag Nurs. 2004, 5: 66-74. 10.1016/j.pmn.2003.11.003.PubMed Dysvik E, Lindstrøm TC, Eikeland O-J, Natvig GK: Health-related quality of life and pain beliefs among people suffering from chronic pain. Pain Manag Nurs. 2004, 5: 66-74. 10.1016/j.pmn.2003.11.003.PubMed
89.
go back to reference Turk D, Okifuji A, Scharff L: Chronic pain and depression: role of perceived impact and perceived control in different age cohorts. Pain. 1995, 61: 93-101. 10.1016/0304-3959(94)00167-D.PubMed Turk D, Okifuji A, Scharff L: Chronic pain and depression: role of perceived impact and perceived control in different age cohorts. Pain. 1995, 61: 93-101. 10.1016/0304-3959(94)00167-D.PubMed
90.
go back to reference Sawyer P, Bodner E, Ritchie C, Allman R: Pain and pain medication use in community-dwelling older adults. Am J Geriatr Pharmacother. 2006, 4: 316-324. 10.1016/j.amjopharm.2006.12.005.PubMed Sawyer P, Bodner E, Ritchie C, Allman R: Pain and pain medication use in community-dwelling older adults. Am J Geriatr Pharmacother. 2006, 4: 316-324. 10.1016/j.amjopharm.2006.12.005.PubMed
91.
go back to reference Simon G, VonKorff M, Piccinelli M, Fullerton C, Ormel J: An international study of the relation between somatic symptoms and depression. N Engl J Med. 1999, 341: 1329-1335. 10.1056/NEJM199910283411801.PubMed Simon G, VonKorff M, Piccinelli M, Fullerton C, Ormel J: An international study of the relation between somatic symptoms and depression. N Engl J Med. 1999, 341: 1329-1335. 10.1056/NEJM199910283411801.PubMed
92.
go back to reference Tugwell P, Shea B, Boers M, Brooks P, Simon L, Strand V, Wells G, (editors): Evidence-based Rheumatology. 2004, London: BMJ books Tugwell P, Shea B, Boers M, Brooks P, Simon L, Strand V, Wells G, (editors): Evidence-based Rheumatology. 2004, London: BMJ books
93.
go back to reference Keeley R, Smith M, Miller J: Somatoform symptoms and treatment nonadherence in depressed family medicine outpatients. Arch Fam Med. 2000, 9: 46-54. 10.1001/archfami.9.1.46.PubMed Keeley R, Smith M, Miller J: Somatoform symptoms and treatment nonadherence in depressed family medicine outpatients. Arch Fam Med. 2000, 9: 46-54. 10.1001/archfami.9.1.46.PubMed
94.
go back to reference Chen J, Devine A, Dick IM, Dhaliwal S, Prince RL: Prevalence of lower extremity pain and its association with functionality and quality of life in elderly women in Australia. J Rheumatol. 2003, 30: 2689-2693.PubMed Chen J, Devine A, Dick IM, Dhaliwal S, Prince RL: Prevalence of lower extremity pain and its association with functionality and quality of life in elderly women in Australia. J Rheumatol. 2003, 30: 2689-2693.PubMed
95.
go back to reference Ware JE, Snow KK, Kosinski M, Gandek B: SF-36 health survey manual & interpretation guide. 2000, Lincoln: QualityMetric Incorporated Ware JE, Snow KK, Kosinski M, Gandek B: SF-36 health survey manual & interpretation guide. 2000, Lincoln: QualityMetric Incorporated
96.
go back to reference Gerstle D, All A, Wallace D: Quality of life and chronic nonmalignant pain. Pain Manag Nurs. 2001, 2: Gerstle D, All A, Wallace D: Quality of life and chronic nonmalignant pain. Pain Manag Nurs. 2001, 2:
97.
go back to reference Katz N: The impact of pain management on quality of life. J Pain Symptom Manage. 2002, 24: S38-S47. 10.1016/S0885-3924(02)00411-6.PubMed Katz N: The impact of pain management on quality of life. J Pain Symptom Manage. 2002, 24: S38-S47. 10.1016/S0885-3924(02)00411-6.PubMed
98.
go back to reference Schlenk E, Erlen JA, Dunbar-Jacob J, McDowell J, Engberg S, Sereika S, al e: Health-related quality of life in chronic disorders: A comparison across studies using the MOS SF-36. Qual Life Res. 1998, 7: 57-65. 10.1023/A:1008836922089.PubMed Schlenk E, Erlen JA, Dunbar-Jacob J, McDowell J, Engberg S, Sereika S, al e: Health-related quality of life in chronic disorders: A comparison across studies using the MOS SF-36. Qual Life Res. 1998, 7: 57-65. 10.1023/A:1008836922089.PubMed
99.
go back to reference Burns J, Crosbie J, Ouvrier R, Hunt A: Effective orthotic therapy for the painful cavus foot. A randomised controlled trial. J Am Podiatr Med Assoc. 2006, 96: 205-211.PubMed Burns J, Crosbie J, Ouvrier R, Hunt A: Effective orthotic therapy for the painful cavus foot. A randomised controlled trial. J Am Podiatr Med Assoc. 2006, 96: 205-211.PubMed
100.
go back to reference Roos E, Engström M, Söderberg B: Foot orthoses for the treatment of plantar fasciitis. Foot Ankle Int. 2006, 27: 606-611.PubMed Roos E, Engström M, Söderberg B: Foot orthoses for the treatment of plantar fasciitis. Foot Ankle Int. 2006, 27: 606-611.PubMed
101.
go back to reference Torkki M, Malmivaara A, Seitsalo S, Hoikka V, Laippala P, Paavolainen P: Surgery vs orthosis vs watchful waiting for hallux valgus: a randomised controlled trial. J Am Med Assoc. 2001, 285: 2474-2480. 10.1001/jama.285.19.2474. Torkki M, Malmivaara A, Seitsalo S, Hoikka V, Laippala P, Paavolainen P: Surgery vs orthosis vs watchful waiting for hallux valgus: a randomised controlled trial. J Am Med Assoc. 2001, 285: 2474-2480. 10.1001/jama.285.19.2474.
102.
go back to reference Gatchel RJ: Perspectives on pain: A historical overview. Psychosocial Factors in Pain Critical Perspectives. Edited by: Gatchel RJ, Turk DC. 1999, New York: Guilford Press, 3-17. Gatchel RJ: Perspectives on pain: A historical overview. Psychosocial Factors in Pain Critical Perspectives. Edited by: Gatchel RJ, Turk DC. 1999, New York: Guilford Press, 3-17.
103.
go back to reference Turk D, Okifuji A: Psychological factors in chronic pain: evolution and revolution. J Consult Clin Psychol. 2002, 70: 678-690. 10.1037/0022-006X.70.3.678.PubMed Turk D, Okifuji A: Psychological factors in chronic pain: evolution and revolution. J Consult Clin Psychol. 2002, 70: 678-690. 10.1037/0022-006X.70.3.678.PubMed
104.
go back to reference Blyth FM, March LM, Brnabic AJ, Jorm LR, Williamson M, Cousins M: Chronic pain in Australia: a prevalence study. Pain. 2001, 89: 127-134. 10.1016/S0304-3959(00)00355-9.PubMed Blyth FM, March LM, Brnabic AJ, Jorm LR, Williamson M, Cousins M: Chronic pain in Australia: a prevalence study. Pain. 2001, 89: 127-134. 10.1016/S0304-3959(00)00355-9.PubMed
105.
go back to reference Morris DB: Sociocultural and religious meanings of pain. Psychosocial factors in pain Critical perspectives. Edited by: Gatchel RJ, Turk DC. 1999, New York: Guilford Press, 118-131. Morris DB: Sociocultural and religious meanings of pain. Psychosocial factors in pain Critical perspectives. Edited by: Gatchel RJ, Turk DC. 1999, New York: Guilford Press, 118-131.
106.
go back to reference Williams DA, Thorn BE: An empirical assessment of pain beliefs. Pain. 1989, 36: 351-358. 10.1016/0304-3959(89)90095-X.PubMed Williams DA, Thorn BE: An empirical assessment of pain beliefs. Pain. 1989, 36: 351-358. 10.1016/0304-3959(89)90095-X.PubMed
107.
go back to reference Hoogendoorn W, van Poppel M, Bongers P, Koes B, Bouter L: Systematic review of psychosocial factors at work and private life as risk factors for back pain. Spine. 2000, 25: 2114-2125. 10.1097/00007632-200008150-00017.PubMed Hoogendoorn W, van Poppel M, Bongers P, Koes B, Bouter L: Systematic review of psychosocial factors at work and private life as risk factors for back pain. Spine. 2000, 25: 2114-2125. 10.1097/00007632-200008150-00017.PubMed
108.
go back to reference Bongers P, Kremer A, ter Laak J: Are psychosocial factors, risk factors for symptoms and signs of the shoulder, elbow, or hand/wrist?: a review of the epidemiological literature. Am J Ind Med. 2002, 41: 315-342. 10.1002/ajim.10050.PubMed Bongers P, Kremer A, ter Laak J: Are psychosocial factors, risk factors for symptoms and signs of the shoulder, elbow, or hand/wrist?: a review of the epidemiological literature. Am J Ind Med. 2002, 41: 315-342. 10.1002/ajim.10050.PubMed
109.
go back to reference Herda C, Siegeris K, Basler H: The pain beliefs and perceptions inventory: Further evidence for a 4-factor structure. Pain. 1994, 57: Herda C, Siegeris K, Basler H: The pain beliefs and perceptions inventory: Further evidence for a 4-factor structure. Pain. 1994, 57:
110.
go back to reference Turner J, Jensen M, Romano J: Do beliefs, coping, and catastrophizing independently predict functioning in patients with chronic pain?. Pain. 2000, 85: Turner J, Jensen M, Romano J: Do beliefs, coping, and catastrophizing independently predict functioning in patients with chronic pain?. Pain. 2000, 85:
111.
go back to reference Stroud M, Thorn B, Jensen M, Boothby J, Rohay J, Bernier M: The relation between pain beliefs, negative thoughts, and psychosocial functioning in chronic-pain patients. Pain. 2000, 84: 347-352. 10.1016/S0304-3959(99)00226-2.PubMed Stroud M, Thorn B, Jensen M, Boothby J, Rohay J, Bernier M: The relation between pain beliefs, negative thoughts, and psychosocial functioning in chronic-pain patients. Pain. 2000, 84: 347-352. 10.1016/S0304-3959(99)00226-2.PubMed
112.
go back to reference Nahit E, Hunt I, Lunt M, Dunn G, Silman A, Macfarlane G: Effects of psychosocial and individual psychological factors on the onset of musculoskeletal pain: common and site-specific effects. Ann Rheum Dis. 2003, 2: 755-760. 10.1136/ard.62.8.755. Nahit E, Hunt I, Lunt M, Dunn G, Silman A, Macfarlane G: Effects of psychosocial and individual psychological factors on the onset of musculoskeletal pain: common and site-specific effects. Ann Rheum Dis. 2003, 2: 755-760. 10.1136/ard.62.8.755.
113.
go back to reference Hartvigsen J, Lings S, Leboeuf-Yde C, Bakketeig L: Psychosocial factors at work in relation to low back pain and consequences of low back pain; a systematic, critical review of prospective cohort studies. Occup Environ Med. 2004, 61: e2-PubMedPubMedCentral Hartvigsen J, Lings S, Leboeuf-Yde C, Bakketeig L: Psychosocial factors at work in relation to low back pain and consequences of low back pain; a systematic, critical review of prospective cohort studies. Occup Environ Med. 2004, 61: e2-PubMedPubMedCentral
114.
go back to reference Chesterton L, Barlas P, Foster N, Baxter G, Wright C: Gender differences in pressure pain threshold in healthy humans. Pain. 2003, 101: 259-266. 10.1016/S0304-3959(02)00330-5.PubMed Chesterton L, Barlas P, Foster N, Baxter G, Wright C: Gender differences in pressure pain threshold in healthy humans. Pain. 2003, 101: 259-266. 10.1016/S0304-3959(02)00330-5.PubMed
115.
go back to reference Wise E, Price D, Myers C, Heft M, Robinson M: Gender role expectations of pain: relationship to experimental pain perception. Pain. 2002, 96: 335-342. 10.1016/S0304-3959(01)00473-0.PubMedPubMedCentral Wise E, Price D, Myers C, Heft M, Robinson M: Gender role expectations of pain: relationship to experimental pain perception. Pain. 2002, 96: 335-342. 10.1016/S0304-3959(01)00473-0.PubMedPubMedCentral
116.
go back to reference Ramos J: Placebo effect and pain: brain bases. Neurologia. 2007, 22: 99-105.PubMed Ramos J: Placebo effect and pain: brain bases. Neurologia. 2007, 22: 99-105.PubMed
117.
go back to reference Benedetti F, Mayberg H, Wager T, Stohler C, Zubieta J: Neurobiological mechanisms of the placebo effect. J Neurosci. 2005, 25: 10390-10402. 10.1523/JNEUROSCI.3458-05.2005.PubMed Benedetti F, Mayberg H, Wager T, Stohler C, Zubieta J: Neurobiological mechanisms of the placebo effect. J Neurosci. 2005, 25: 10390-10402. 10.1523/JNEUROSCI.3458-05.2005.PubMed
118.
go back to reference Kuehn BM: Pain studies illuminate the placebo effect. JAMA. 2005, 294 (14): 1750-1701. 10.1001/jama.294.14.1750.PubMed Kuehn BM: Pain studies illuminate the placebo effect. JAMA. 2005, 294 (14): 1750-1701. 10.1001/jama.294.14.1750.PubMed
119.
go back to reference Haour F: Mechanisms of placebo effect and of conditioning: neurobiological data in human and animals. Med Sci (Paris). 2005, 21: 315-319. Haour F: Mechanisms of placebo effect and of conditioning: neurobiological data in human and animals. Med Sci (Paris). 2005, 21: 315-319.
120.
go back to reference Boussageon R, Gueyffier F, Moreau A, Boussageon V: The difficulty of measurement of placebo effect. Therapie. 2006, 61: 185-190.PubMed Boussageon R, Gueyffier F, Moreau A, Boussageon V: The difficulty of measurement of placebo effect. Therapie. 2006, 61: 185-190.PubMed
121.
go back to reference McCarney R, Warner J, Iliffe S, van Haselen R, Griffin M, Fisher P: The Hawthorne Effect: a randomised, controlled trial. BMC Med Res Methodol. 2007, 7: McCarney R, Warner J, Iliffe S, van Haselen R, Griffin M, Fisher P: The Hawthorne Effect: a randomised, controlled trial. BMC Med Res Methodol. 2007, 7:
122.
go back to reference Hunsley J, Westmacott R: Interpreting the magnitude of the placebo effect: mountain or Molehill?. J Clin Psychol. 2007, 63: 391-399. 10.1002/jclp.20352.PubMed Hunsley J, Westmacott R: Interpreting the magnitude of the placebo effect: mountain or Molehill?. J Clin Psychol. 2007, 63: 391-399. 10.1002/jclp.20352.PubMed
124.
go back to reference de la Fuente-Fernandez R, Stoessl A: The biochemical bases of the placebo effect. Sci Eng Ethics. 2004, 10: 143-150. 10.1007/s11948-004-0071-z.PubMed de la Fuente-Fernandez R, Stoessl A: The biochemical bases of the placebo effect. Sci Eng Ethics. 2004, 10: 143-150. 10.1007/s11948-004-0071-z.PubMed
125.
go back to reference Tiller WA: Human psychophysiology, macroscopic information entanglement, and the placebo effect. J Altern Complement Med. 2006, 12: 1015-1027. 10.1089/acm.2006.12.1015.PubMed Tiller WA: Human psychophysiology, macroscopic information entanglement, and the placebo effect. J Altern Complement Med. 2006, 12: 1015-1027. 10.1089/acm.2006.12.1015.PubMed
126.
go back to reference Hróbjartsson A, Gøtzsche P: Placebo interventions for all clinical conditions. Cochrane Database of Sys Rev. 2004, CD003974- Hróbjartsson A, Gøtzsche P: Placebo interventions for all clinical conditions. Cochrane Database of Sys Rev. 2004, CD003974-
127.
go back to reference Crosbie J, Burns J: Predicting outcomes in the orthotic management of painful, idiopathic pes cavus. Clin J Sport Med. 2007, 17: 337-342.PubMed Crosbie J, Burns J: Predicting outcomes in the orthotic management of painful, idiopathic pes cavus. Clin J Sport Med. 2007, 17: 337-342.PubMed
128.
go back to reference Landorf K, Keenan A, Herbert R: Effectiveness of foot orthoses to treat plantar fasciitis: a randomized trial. Archives of Internal Medicine. 2006, 166: 1305-1310. 10.1001/archinte.166.12.1305.PubMed Landorf K, Keenan A, Herbert R: Effectiveness of foot orthoses to treat plantar fasciitis: a randomized trial. Archives of Internal Medicine. 2006, 166: 1305-1310. 10.1001/archinte.166.12.1305.PubMed
129.
go back to reference Colloca L, Benedetti F: Placebos and painkillers: is mind as real as matter?. Nature Reviews Neuroscience. 2005, 6: 545-552. 10.1038/nrn1705.PubMed Colloca L, Benedetti F: Placebos and painkillers: is mind as real as matter?. Nature Reviews Neuroscience. 2005, 6: 545-552. 10.1038/nrn1705.PubMed
Metagegevens
Titel
Understanding the nature and mechanism of foot pain
Auteurs
Fiona Hawke
Joshua Burns
Publicatiedatum
01-12-2009
Uitgeverij
BioMed Central
Gepubliceerd in
Journal of Foot and Ankle Research / Uitgave 1/2009
Elektronisch ISSN: 1757-1146
DOI
https://doi.org/10.1186/1757-1146-2-1

Andere artikelen Uitgave 1/2009

Journal of Foot and Ankle Research 1/2009 Naar de uitgave