The effect of visually manipulating back size and morphology on back perception, body ownership, and attitudes towards self-capacity during a lifting task.

Body re-sizing illusions can profoundly alter perception of our own body. We investigated whether creating the illusion of a muscled and fit-looking back (Strong) influenced perceived back size, body ownership, and attitudes towards self-capacity during a lifting task. Twenty-four healthy male volunteers performed a standardised lifting task while viewing real-time (delay < 20 ms) video of their own back through a head-mounted display under four different conditions (Normal size, Strong, Reshaped, Large; order randomised). The MIRAGE-mediated reality system was used to modify the shape, size, and morphology of the back. Participants were poor at recognizing the correct appearance of their back, for both implicit (perceived width of shoulders and hips) and explicit (questionnaire) measures of back size. Visual distortions of body shape (Reshaped condition) altered implicit back size measures. However, viewing a muscled back (Strong condition) did not result in a sense of agency or ownership and did not update implicit perception of the back. No conditions improved perceptions/attitudes of self-capacity (perceived back strength, perceived lifting confidence, and perceived back fitness). The results lend support for the importance of the embodiment of bodily changes to induce changes in perception. Further work is warranted to determine whether increased exposure to illusory changes would alter perceptions and attitudes towards self-capacity or whether different mechanisms are involved.

Effect of Graded Sensorimotor Retraining on Pain Intensity in Patients With Chronic Low Back Pain: A Randomized Clinical Trial.

Importance: The effects of altered neural processing, defined as altering neural networks responsible for perceptions of pain and function, on chronic pain remains unclear. Objective: To estimate the effect of a graded sensorimotor retraining intervention (RESOLVE) on pain intensity in people with chronic low back pain. Design, Setting, and Participants: This parallel, 2-group, randomized clinical trial recruited participants with chronic (>3 months) nonspecific low back pain from primary care and community settings. A total of 276 adults were randomized (in a 1:1 ratio) to the intervention or sham procedure and attention control groups delivered by clinicians at a medical research institute in Sydney, Australia. The first participant was randomized on December 10, 2015, and the last was randomized on July 25, 2019. Follow-up was completed on February 3, 2020. Interventions: Participants randomized to the intervention group (n = 138) were asked to participate in 12 weekly clinical sessions and home training designed to educate them about and assist them with movement and physical activity while experiencing lower back pain. Participants randomized to the control group (n = 138) were asked to participate in 12 weekly clinical sessions and home training that required similar time as the intervention but did not focus on education, movement, and physical activity. The control group included sham laser and shortwave diathermy applied to the back and sham noninvasive brain stimulation. Main Outcomes and Measures: The primary outcome was pain intensity at 18 weeks, measured on an 11-point numerical rating scale (range, 0 [no pain] to 10 [worst pain imaginable]) for which the between-group minimum clinically important difference is 1.0 point. Results: Among 276 randomized patients (mean [SD] age, 46 [14.3] years; 138 [50%] women), 261 (95%) completed follow-up at 18 weeks. The mean pain intensity was 5.6 at baseline and 3.1 at 18 weeks in the intervention group and 5.8 at baseline and 4.0 at 18 weeks in the control group, with an estimated between-group mean difference at 18 weeks of -1.0 point ([95% CI, -1.5 to -0.4]; P = .001), favoring the intervention group. Conclusions and Relevance: In this randomized clinical trial conducted at a single center among patients with chronic low back pain, graded sensorimotor retraining, compared with a sham procedure and attention control, significantly improved pain intensity at 18 weeks. The improvements in pain intensity were small, and further research is needed to understand the generalizability of the findings. Trial Registration: ANZCTR Identifier: ACTRN12615000610538.

Implicit Motor Imagery of the Foot and Hand in People with Achilles Tendinopathy: A Left Right Judgement Study.

OBJECTIVE: To determine if impairment in motor imagery processes is present in Achilles tendinopathy (AT), as demonstrated by a reduced ability to quickly and accurately identify the laterality (left-right judgement) of a pictured limb. Additionally, this study aimed to use a novel data pooling approach to combine data collected at 3 different sites via meta-analytical techniques that allow exploration of heterogeneity. DESIGN: Multi-site case-control study. METHODS: Three independent studies with similar protocols were conducted by separate research groups. Each study-site evaluated left/right judgement performance for images of feet and hands using Recognise© software and compared performance between people with AT and healthy controls. Results from each study-site were independently collated, then combined in a meta-analysis. RESULTS: In total, 126 participants (40 unilateral, 22 bilateral AT cases, 61 controls) were included. There were no differences between AT cases and controls for hand image accuracy and reaction time. Contrary to the hypothesis, there were no differences in performance between those with AT and controls for foot image reaction time, however there were conflicting findings for foot accuracy, based on four separate analyses. There were no differences between the affected and unaffected sides in people with unilateral AT. CONCLUSIONS: Impairments in motor imagery performance for hands were not found in this study, and we found inconsistent results for foot accuracy. This contrasts to studies in persistent pain of limbs, face and knee osteoarthritis, and suggests that differences in pathoetiology or patient demographics may uniquely influence proprioceptive representation.

Development and validation of a shoulder-specific body-perception questionnaire in people with persistent shoulder pain.

BACKGROUND: There is evidence that people with persistent shoulder pain exhibit findings consistent with the presence of sensorimotor dysfunction. Sensorimotor impairments can manifest in a variety of ways, and further developing our understanding of sensorimotor dysfunction in shoulder pain may improve current models of care. The Fremantle Back Awareness Questionnaire (FreBAQ) has been developed to assess disturbed body perception specific to the back. The purpose of the present study was to develop a shoulder-specific self-perception questionnaire and evaluate the questionnaire in people with persistent shoulder pain. METHODS: The Fremantle Shoulder Awareness Questionnaire (FreSHAQ-J) was developed by modifying the FreBAQ. One hundred and twelve consecutive people with persistent shoulder pain completed the FreSHAQ-J. Thirty participants completed the FreSHAQ-J again two-weeks later to assess test-retest reliability. Rasch analysis was used to assess the psychometric properties of the FreSHAQ-J. Associations between FreSHAQ-J total score and clinical status was explored using correlational analysis. RESULTS: The FreSHAQ-J has acceptable category order, unidimensionality, no misfitting items, and excellent test-retest reliability. The FreSHAQ-J was moderately correlated with disability and pain catastrophization. CONCLUSIONS: The FreSHAQ-J fits the Rasch measurement model well and is suitable for use with people with shoulder pain. Given the relationship between the FreSHAQ-J score and clinical status, change in body perception may be worth assessing when managing patients with shoulder pain.

The EPIPHA-KNEE trial: Explaining Pain to target unhelpful pain beliefs to Increase PHysical Activity in KNEE osteoarthritis - a protocol for a multicentre, randomised controlled trial with clinical- and cost-effectiveness analysis.

BACKGROUND: Despite well-established benefits of physical activity for knee osteoarthritis (OA), nine of ten people with knee OA are inactive. People with knee OA who are inactive often believe that physical activity is dangerous, fearing that it will further damage their joint(s). Such unhelpful beliefs can negatively influence physical activity levels. We aim to evaluate the clinical- and cost-effectiveness of integrating physiotherapist-delivered pain science education (PSE), an evidence-based conceptual change intervention targeting unhelpful pain beliefs by increasing pain knowledge, with an individualised walking, strengthening, and general education program. METHODS: Two-arm, parallel-design, multicentre randomised controlled trial involving 198 people aged ≥50 years with painful knee OA who do not meet physical activity guideline recommendations or walk regularly for exercise. Both groups receive an individualised physiotherapist-led walking, strengthening, and OA/activity education program via 4x weekly in-person treatment sessions, followed by 4 weeks of at-home activities (weekly check-in via telehealth), with follow-up sessions at 3 months (telehealth) and 5 and 9 months (in-person). The EPIPHA-KNEE group also receives contemporary PSE about OA/pain and activity, embedded into all aspects of the intervention. Outcomes are assessed at baseline, 12 weeks, 6 and 12 months. Primary outcomes are physical activity level (step count; wrist-based accelerometry) and self-reported knee symptoms (WOMAC Total score) at 12 months. Secondary outcomes are quality of life, pain intensity, global rating of change, self-efficacy, pain catastrophising, depression, anxiety, stress, fear of movement, knee awareness, OA/activity conceptualisation, and self-regulated learning ability. Additional measures include adherence, adverse events, blinding success, COVID-19 impact on activity, intention to exercise, treatment expectancy/perceived credibility, implicit movement/environmental bias, implicit motor imagery, two-point discrimination, and pain sensitivity to activity. Cost-utility analysis of the EPIPHA-KNEE intervention will be undertaken, in addition to evaluation of cost-effectiveness in the context of primary trial outcomes. DISCUSSION: We will determine whether the integration of PSE into an individualised OA education, walking, and strengthening program is more effective than receiving the individualised program alone. Findings will inform the development and implementation of future delivery of PSE as part of best practice for people with knee OA. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12620001041943 (13/10/2020).

The effect of multisensory illusions on pain and perceived burning sensations in patients with Burning Mouth Syndrome: A proof-of-concept study.

BACKGROUND: Burning mouth syndrome (BMS) is a chronic pain disorder affecting the oral cavity. Previous work has shown promising analgesic results of bodily illusions in other chronic pain conditions. The aim of this proof-of-concept, pilot study was to investigate whether bodily illusions reduce pain in BMS patients. METHODS: Nine participants diagnosed with BMS underwent bodily illusions using a MIRAGE-mediated reality system. All participants completed four conditions and performed standardised movements of the tongue. First, a baseline condition was performed while the tongue was viewed at normal size and colour. Then, three conditions were performed in random order: resizing shrink, colour-based (blue tongue) and incongruent movement illusions. During each condition, participants rated overall pain intensity and the intensity of burning pain/sensation on the tongue. RESULTS: There was no difference in overall pain intensity ratings between conditions. However, a significant effect of condition was found for burning pain/sensation of the tongue. The colour illusion significantly reduced burning pain compared with baseline (MD = -12.8, 95% CI -20.7 to -4.8), corresponding to an average pain reduction of 32%. Exploratory analyses showed the colour illusion also significantly reduced pain compared with the shrink illusion (MD = -11.7, 95% CI -22.2 to -1.1). CONCLUSION: Using visual illusions to change tongue colour to blue resulted in significant reductions in burning pain/sensations in BMS patients for the duration of the illusion. This proof-of-concept study suggests that BMS patients may benefit from bodily illusions, and supports additional research using larger samples and more comprehensive control conditions.

Differential influence of habitual third-person vision of a body part on mental rotation of images of hands and feet.

Left/right judgement (LRJ) tasks involve determining the laterality of presented hand or feet images. Allocentric images (third-person perspective; 3PP) take longer to identify than egocentric images (first-person perspective; 1PP), supporting that implicit motor imagery (IMI)-mentally manoeuvring one's body to match the shown posture-is used. While numerous cognitive processes are involved during LRJs, it remains unclear whether features of the individual (e.g., visual exposure, experience, task-dependent use) influence the type of recognition strategy used during LRJs (IMI versus non-IMI). To investigate whether an individual's routine visual exposure to hands/feet in 3PP disrupts the typical perspective-reaction time (RT) relationship in LRJs, hand therapists, podiatrists, and healthy controls completed online LRJ tasks of hand and feet images. A group-specific reduction in RT for only allocentric images would represent a switch to non-IMI strategies. The results show that routine visual exposure to feet in 3PP (podiatrists) results in quicker RTs only for allocentric images of feet, suggesting a switch from IMI to non-IMI (e.g., visual object-based recognition) strategies. In contrast, routine visual exposure to hands in 3PP (hand therapists) does not alter RT for allocentric images, suggesting maintenance of IMI. However, hand therapists have quicker RTs (vs other groups) for egocentric hand images, supporting enhanced sensorimotor processing for the hand, consistent with task-dependent use (precise hand use). Higher accuracy in health professionals (vs control) on both tasks supports enhanced body schema. Combined, this suggests that 3PP visual exposure to body parts and task-dependent use contribute to LRJ performance/recognition strategy.

Validation of the Japanese Version of the Fremantle Back Awareness Questionnaire in Patients with Low Back Pain.

BACKGROUND: There is a growing interest in the role of disturbed body perception in people with persistent pain problems such as chronic low back pain (CLBP). A questionnaire, the Fremantle Back Awareness Questionnaire (FreBAQ), was recently developed as a simple and quick way of assessing disturbed perceptual awareness of the back in people with CLBP and appears to have acceptable psychometric properties. The aim of the present study was to develop a Japanese version of the FreBAQ (FreBAQ-J) and evaluate its psychometric properties in a sample of Japanese people with low back pain (LBP). METHODS: Translation of the FreBAQ into Japanese was conducted using a forward-backward method. One hundred participants with LBP completed the resultant FreBAQ-J. A subset of the participants completed the FreBAQ-J again 2 weeks later. Validity was investigated by examining the relationship between the FreBAQ-J and clinical valuables. Rasch analysis was used to assess targeting, category ordering, unidimensionality, person fit, internal consistency, and differential item functioning. RESULTS: The FreBAQ-J was significantly correlated with pain in motion, disability, pain-related catastrophizing, fear of movement, and anxiety symptomatology. The FreBAQ-J had acceptable internal consistency, a minor departure from unidimensionality, and good test-retest reliability, and was functional on the category rating scale. CONCLUSIONS: The FreBAQ-J has acceptable psychometric properties and is suitable for use in people with LBP. Participants with high levels of disturbed body perception are well targeted by the scale. The functioning of one item (item 8) was poor. Further study is warranted to confirm if this item should be excluded.

Relative contributions of spatial weighting, explicit knowledge and proprioception to hand localisation during positional ambiguity.

When vision and proprioception are rendered incongruent during a hand localisation task, vision is initially weighted more than proprioception in determining location, and proprioception gains more weighting over time. However, it is not known whether, under these incongruency conditions, particular areas of space are also weighted more heavily than others, nor whether explicit knowledge of the sensory incongruence (i.e. disconfirming the perceived location of the hand) modulates the effect. Here, we hypothesised that both non-informative inputs coming from one side of space and explicit knowledge of sensory incongruence would modulate perceived location of the limb. Specifically, we expected spatial weighting to shift hand localisation towards the weighted area of space, and we expected greater weighting of proprioceptive input once perceived location was demonstrated to be inaccurate. We manipulated spatial weighting using an established auditory cueing paradigm (Experiment 1, n = 18) and sensory incongruence using the 'disappearing hand trick' (Experiment 2, n = 9). Our first hypothesis was not supported-spatial weighting did not modulate hand localisation. Our second hypothesis was only partially supported-disconfirmation of hand position did lead to more accurate localisations, even if participants were still unaware of their hand position. This raised the possibility that rather than disconfirmation, a simple movement of the hand in view could update the sensory-motor system, by immediately increasing the weighting of proprioceptive input relative to visual input. This third hypothesis was then confirmed (Experiment 3, n = 9). These results suggest that hand localisation is robust in the face of differential weighting of space, but open to modulation in a modality-specific manner, when one sense (vision) is rendered inaccurate.

Can Pain or Hyperalgesia Be a Classically Conditioned Response in Humans? A Systematic Review and Meta-Analysis.

BACKGROUND: Clinical scenarios of repeated pain usually involve both nociceptive and non-nociceptive input. It is likely that associations between these stimuli are learned over time. Such learning may underlie subsequent amplification of pain, or evocation of pain in the absence of nociception. METHODS: We undertook a systematic review and meta-analysis to evaluate the evidence that allodynia or hyperalgesia can be a classically conditioned response. A sensitive search of the literature covered Medline, Embase, CINAHL, AMED, PubMed, Scopus, PsycArticles, PsycINFO, Cochrane Library, and Web of Science. Additional studies were identified by contacting experts and searching published reviews. Two reviewers independently assessed studies for inclusion, evaluated risk of bias, and extracted data. Studies were included if they aimed to elicit or amplify pain using a classical conditioning procedure in healthy, adult humans. Studies were excluded if they did not distinguish between classical conditioning and explicit verbal suggestion as learning sources, or did not use experiential learning. RESULTS: Thirteen studies, with varying risk of bias, were included. Ten studies evaluated classically conditioned hyperalgesia: nine found hyperalgesia; one did not. Pooled effects (n = 8 with full data) showed a significant pain increase after conditioning (mean difference of 7.40 [95%CI: 4.00-10.80] on a 0-100 pain scale). Three studies evaluated conditioned allodynia and found conflicting results. CONCLUSION: The existing literature suggests that classical conditioning can amplify pain. No conclusions can be drawn about whether or not classical conditioning can elicit pain. Rigorous experimental conditioning studies with nociceptive unconditioned stimuli are needed to fill this gap in knowledge.

Local anaesthetic sympathetic blockade for complex regional pain syndrome.

BACKGROUND: This review is an update of a previously published review in the Cochrane Database of Systematic Reviews, 2005, Issue 4 (and last updated in the Cochrane Database of Systematic Reviews, 2013 issue 8), on local anaesthetic blockade (LASB) of the sympathetic chain to treat people with complex regional pain syndrome (CRPS). OBJECTIVES: To assess the efficacy of LASB for the treatment of pain in CRPS and to evaluate the incidence of adverse effects of the procedure. SEARCH METHODS: For this update we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2015, Issue 9), MEDLINE (Ovid), EMBASE (Ovid), LILACS (Birme), conference abstracts of the World Congresses of the International Association for the Study of Pain, and various clinical trial registers up to September 2015. We also searched bibliographies from retrieved articles for additional studies. SELECTION CRITERIA: We considered randomised controlled trials (RCTs) that evaluated the effect of sympathetic blockade with local anaesthetics in children or adults with CRPS compared to placebo, no treatment, or alternative treatments. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures expected by Cochrane. The outcomes of interest were reduction in pain intensity, the proportion who achieved moderate or substantial pain relief, the duration of pain relief, and the presence of adverse effects in each treatment arm. We assessed the evidence using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and created a 'Summary of findings' table. MAIN RESULTS: We included an additional four studies (N = 154) in this update. For this update, we excluded studies that did not follow up patients for more than 48 hours. As a result, we excluded four studies from the previous review in this update. Overall we included 12 studies (N = 461), all of which we judged to be at high or unclear risk of bias. Overall, the quality of evidence was low to very low, downgraded due to limitations, inconsistency, imprecision, indirectness, or a combination of these.Two small studies compared LASB to placebo/sham (N = 32). They did not demonstrate significant short-term benefit for LASB for pain intensity (moderate quality evidence).One small study (N = 36) at high risk of bias compared thoracic sympathetic block with corticosteroid and local anaesthetic versus injection of the same agents into the subcutaneous space, reporting statistically significant and clinically important differences in pain intensity at one-year follow-up but not at short term follow-up (very low quality evidence).Of two studies that investigated LASB as an addition to rehabilitation treatment, the only study that reported pain outcomes demonstrated no additional benefit from LASB (very low quality evidence).Eight small randomised studies compared sympathetic blockade to various other active interventions. Most studies found no difference in pain outcomes between sympathetic block versus other active treatments (low to very low quality evidence).One small study compared ultrasound-guided LASB with non-guided LASB and found no clinically important difference in pain outcomes (very low quality evidence).Six studies reported adverse events, all with minor effects reported. AUTHORS' CONCLUSIONS: This update's results are similar to the previous versions of this systematic review, and the main conclusions are unchanged. There remains a scarcity of published evidence and a lack of high quality evidence to support or refute the use of local anaesthetic sympathetic blockade for CRPS. From the existing evidence, it is not possible to draw firm conclusions regarding the efficacy or safety of this intervention, but the limited data available do not suggest that LASB is effective for reducing pain in CRPS.

Interhemispheric somatosensory differences in chronic pain reflect abnormality of the healthy side.

It is widely accepted that complex regional pain syndrome (CRPS) is associated with shrinkage of the primary somatosensory cortex (S1) representation of the affected limb. However, supporting evidence is surprisingly limited and may be compromised by high risk of bias. This study compared the S1 spatial representation of the hand in 17 patients with upper-limb CRPS to 16 healthy controls, using functional MRI. Innocuous vibration was delivered to digits one (D1) and five (D5) in a block-design. Resultant activation maxima were located within a bilateral S1 mask, determined a priori. Distance between D1 and D5 activation maxima, calculated for both hands, was used as a measure of S1 representation. Analyses were blinded to group and hand. In patients, S1 representation was smaller for the affected hand than it was for the healthy hand (t(11) = 2.02, P = 0.03), as predicted. However, S1 representation of the affected hand was no different to that of either hand in controls. Critically, S1 representation of the healthy hand of patients was larger than that of controls' hands. CRPS seems to be associated with an enlarged representation of the healthy hand, not a smaller representation of the affected hand. These findings raise important questions about neuroplasticity in CRPS.

Evidence for distorted mental representation of the hand in osteoarthritis.

OBJECTIVES: Some chronic pain states are associated with a distortion of the perceived size or shape of the painful area, and multisensory illusions that disrupt these dimensions can modulate pain in healthy controls and people with painful disorders. Illusory hand resizing has recently been found to relieve pain in hand OA, raising the possibility that the illusion corrects some underlying perceptual disturbance. We evaluated this possibility by measuring perceived hand size in healthy controls and those with painful hand OA before and after illusory hand resizing. The aim was to investigate whether people with painful hand OA have distorted representations of hand size and whether these representations are malleable. We hypothesized that hand OA is associated with a distorted mental representation of the painful hand and that perceived hand size can be modulated via multisensory illusion. METHODS: Twelve volunteers with painful hand OA and 12 healthy age-matched controls performed three tasks (hand stretch, hand shrink and no illusion) in a randomized order then estimated the size of their hand using an adjustable photographic image. RESULTS: Our hypotheses were supported: under normal conditions, perceived hand size was smaller for the OA group than for healthy controls, consistent with a distorted mental representation of the painful hand. Furthermore, illusory stretching increased perceived hand size in both groups, while illusory shrinking decreased perceived hand size in healthy controls but not in the OA group. CONCLUSION: These results suggest that hand OA is associated with a distorted mental representation of the painful hand and are consistent with the idea that the pain relief offered by multisensory illusions may work via normalization of this distortion.

Untangling visual and proprioceptive contributions to hand localisation over time.

Previous studies showed that self-localisation ability involves both vision and proprioception, integrated into a single percept, with the tendency to rely more heavily on visual than proprioceptive cues. Despite the increasing evidence for the importance of vision in localising the hands, the time course of the interaction between vision and proprioception during visual occlusion remains unclear. In particular, we investigated how the brain weighs visual and proprioceptive information in hand localisation over time when the visual cues do not reflect the real position of the hand. We tested three hypotheses: Self-localisations are less accurate when vision and proprioception are incongruent; under the same conditions of incongruence, people first rely on vision and gradually revert to proprioception; if vision is removed immediately prior to hand localisation, accuracy increases. Sixteen participants viewed a video of their hands, under three conditions each undertaken with eyes open or closed: Incongruent conditions (right hand movement seen: inward, right hand real movement: outward), Congruent conditions (movement seen congruent to real movement). The right hand was then hidden from view and participants performed a localisation task whereby a moving vertical arrow was stopped when aligned with the felt position of their middle finger. A second experiment used identical methodology, but with the direction of the arrow switched. Our data showed that, in the Incongruent conditions (both with eyes open and closed), participants perceived their right hand close to its last seen position. Over time, the perceived position of the hand shifted towards the physical position. Closing the eyes before the localisation task increased the accuracy in the Incongruent condition. Crucially, Experiment 2 confirmed the findings and showed that the direction of arrow movement had no effect on hand localisation. Our hypotheses were supported: When vision and proprioception were incongruent, participants were less accurate and initially relied on vision and then proprioception over time. When vision was removed, this shift occurred more quickly. Our findings are relevant in understanding the normal and pathological processes underpinning self-localisation.

Painful distortions: people with painful knee osteoarthritis have biased visuospatial perception of the environment.

ABSTRACT: Visuospatial perception is thought to be adaptive-ie, hills are perceived as steeper when capacity is low, or threat is high-guiding appropriate interaction with the environment. Pain (bodily threat) may similarly modulate visuospatial perception, with the extent of modulation influenced by threat magnitude (pain intensity, fear) and associated with behaviour (physical activity). We compared visuospatial perception of the environment between 50 people with painful knee osteoarthritis and 50 age-/sex-matched pain-free control participants using 3 virtual reality tasks (uphill steepness estimation, downhill steepness estimation, and a distance-on-hill measure), exploring associations between visuospatial perception, clinical characteristics (pain intensity, state and trait fear), and behaviour (wrist-worn accelerometry) within a larger knee osteoarthritis group (n = 85). People with knee osteoarthritis overestimated uphill (F1,485 = 19.4, P < 0.001) and downhill (F1,480 = 32.3, P < 0.001) steepness more so than pain-free controls, but the groups did not differ for distance-on-hill measures (U = 1273, P = 0.61). There was also a significant group x steepness interaction for the downhill steepness task (F4,480 = 3.11, P = 0.02). Heightened overestimation in people with knee osteoarthritis relative to pain-free controls increased as downhill slopes became steeper. Results were unchanged in a replication analysis using all knee osteoarthritis participants (n = 85), except the downhill steepness interaction was no longer significant. In people with knee osteoarthritis, higher state fear was associated with greater over-estimation of downhill slope steepness (rho = 0.69, P < 0.001), and greater visuospatial overestimation (distance-on-hill) was associated with lower physical activity levels (rho = -0.22, P = 0.045). These findings suggest that chronic pain may shift perception of the environment in line with protection, with overestimation heightened when threat is greater (steeper hills, more fearful), although impact on real-world behaviour is uncertain.

The effectiveness of peer support interventions for community-dwelling adults with chronic musculoskeletal pain: a systematic review and meta-analysis of randomised trials.

ABSTRACT: This systematic review and meta-analysis critically examined the evidence for peer support interventions to reduce pain and improve health outcomes in community-dwelling adults with chronic musculoskeletal pain (PROSPERO CRD42022356850). A systematic search (inception-January 2023) of electronic databases and grey literature was undertaken to identify relevant randomised controlled trials, with risk of bias and GRADE assessments performed on included studies. Meta-analyses used a generic, inverse-variance, random-effects model, calculating mean difference (MD) or standardised mean difference (SMD). Of 16,445 records identified, 29 records reporting on 24 studies (n = 6202 participants) were included. All evidence had unclear/high risk of bias and low-very low certainty. Peer support interventions resulted in small improvements in pain (medium-term: MD -3.48, 95% CI -6.61, -0.35; long-term: MD -1.97, 95% CI -3.53, -0.42), self-efficacy (medium-term: SMD 0.26, 95% CI 0.16, 0.36; long-term: SMD 0.21, 95% CI 0.07, 0.36), and function (long-term: SMD -0.10, 95% CI -0.19, -0.00) relative to usual care and greater self-efficacy (medium-term: SMD 0.36, 95% CI 0.20, 0.51) relative to waitlist control. Peer support interventions resulted in similar improvement as active (health professional led) interventions bar long-term self-efficacy (MD -0.41, 95% CI -0.77, -0.05), which favoured active interventions. No point estimates reached minimal clinically important difference thresholds. Pooled health service utilisation outcomes showed unclear estimates. Self-management, quality of life, and social support outcomes had mixed evidence. Despite low-very low evidence certainty, peer support interventions demonstrated small improvements over usual care and waitlist controls for some clinical outcomes, suggesting that peer support may be useful as an adjunct to other treatments for musculoskeletal pain.

The influence of threat on visuospatial perception, affordances, and protective behaviour: A systematic review and meta-analysis.

Perception has been conceptualised as an active and adaptive process, based upon incoming sensory inputs, which are modified by top-down factors such as cognitions. Visuospatial perception is thought to be scaled based on threat, with highly threatening objects or contexts visually inflated to promote escape or avoidance behaviours. This meta-analytical systematic review quantified the effect and evidence quality of threat-evoked visuospatial scaling, as well as how visuospatial scaling relates to affordances (perceived action capabilities) and behavioural avoidance/escape outcomes. Databases and grey literature were systematically searched inclusive to 10/04/24. Studies were assessed with a customised Risk of Bias form and meta-analysis was performed using a random-effects model. 12,354 records were identified. Of these, 49 experiments (n = 3027) were included in the review. There was consistent evidence that threat the of height influenced contextual perception (g = 0.66, 95% CI: 0.45, 0.88) and affordances (g = -0.43, 95% CI: -0.84, -0.03). Threatening objects were viewed as larger (g = 0.76, 95% CI: 0.26, 1.26) and as closer (g = 0.30, 95% CI: 0.17, 0.42). Bodily threat (pain) yielded conflicting effects on visuospatial perception/affordances. We conclude that threat may influence visuospatial perception and affordances. However, since behavioural measures were poorly reported, their relationship with visuospatial perception/affordances remains elusive.

People with painful knee osteoarthritis hold negative implicit attitudes towards activity.

ABSTRACT: Negative attitudes/beliefs surrounding osteoarthritis, pain, and activity contribute to reduced physical activity in people with knee osteoarthritis (KOA). These attitudes/beliefs are assessed using self-report questionnaires, relying on information one is consciously aware of and willing to disclose. Automatic (ie, implicit) assessment of attitudes does not rely on conscious reflection and may identify features unique from self-report. We developed an implicit association test that explored associations between images of a person moving/twisting their knee (activity) or sitting/standing (rest), and perceived threat (safe vs dangerous). We hypothesised that people with KOA would have greater implicit threat-activity associations (vs pain-free and non-knee pain controls), with implicit attitudes only weakly correlating with self-reported measures (pain knowledge, osteoarthritis/pain/activity beliefs, fear of movement). Participants (n = 558) completed an online survey: 223 had painful KOA (n = 157 female, 64.5 ± 8.9 years); 207 were pain free (n = 157 female, 49.3 ± 15.3 years); and 99 had non-KOA lower limb pain (n = 74 female, 47.5 ± 15.04 years). An implicit association between "danger" and "activity" was present in those with and without limb pain (KOA: 0.36, 95% CI 0.28-0.44; pain free: 0.13, 95% CI 0.04-0.22; non-KOA lower limb pain 0.11, 95% CI -0.03 to 0.24) but was significantly greater in the KOA group than in the pain free (P < 0.001) and non-KOA lower limb pain (P = 0.004) groups. Correlations between implicit and self-reported measures were nonsignificant or weak (rho = -0.29 to 0.19, P < 0.001 to P = 0.767). People with painful KOA hold heightened implicit threat-activity associations, capturing information unique to that from self-report questionnaires. Evaluating links between implicit threat-activity associations and real-world behaviour, including physical activity levels, is warranted.