Psychological influences on repetition-induced summation of activity-related pain in patients with chronic low back pain

Through the Lens of Movement-Evoked Pain: A Theoretical Framework of the "Pain-Movement Interface" to Guide Research and Clinical Care for Musculoskeletal Pain Conditions

Over 120 million Americans report experiencing pain in the past 3 months. Among these individuals, 50 million report chronic pain and 17 million report pain that limits daily life or work activities on most days (ie, high-impact chronic pain). Musculoskeletal pain conditions in particular are a major contributor to global disability, health care costs, and poor quality of life. Movement-evoked pain (MEP) is an important and distinct component of the musculoskeletal pain experience and represents an emerging area of study in pain and rehabilitation fields. This focus article proposes the "Pain-Movement Interface" as a theoretical framework of MEP that highlights the interface between MEP, pain interference, and activity engagement. The goal of the framework is to expand knowledge about MEP by guiding scientific inquiry into MEP-specific pathways to disability, high-risk clinical phenotypes, and underlying individual influences that may serve as treatment targets. This framework reinforces the dynamic nature of MEP within the context of activity engagement, participation in life and social roles, and the broader pain experience. Recommendations for MEP evaluation, encompassing the spectrum from high standardization to high patient specificity, and MEP-targeted treatments are provided. Overall, the proposed framework and recommendations reflect the current state of science in this emerging area of study and are intended to support future efforts to optimize musculoskeletal pain management and enhance patient outcomes. PERSPECTIVE: Movement-evoked pain (MEP) is a distinct component of the musculoskeletal pain experience and emerging research area. This article introduces the "Pain-Movement Interface" as a theoretical framework of MEP, highlighting the interface between MEP, pain interference, and activity engagement. Evaluating and treating MEP could improve rehabilitation approaches and enhance patient outcomes.

Test-Retest Reliability of Pain Sensitivity Measures in Individuals with Shoulder Pain

Background

Central sensitization (CS) has been proposed as a possible contributor to persistent shoulder pain. Measures of sensitivity, such as quantitative sensory tests (QSTs) and sensitivity to movements evoked pain (SMEP), have been increasingly used to investigate CS in a wide range of painful conditions. However, there is a lack of data on whether QST and SMEP are reliable among individuals with shoulder pain. Therefore, the present study aimed to investigate the intra-rater test-retest reliability of QST and SMEP in individuals with chronic shoulder pain.

Materials and Methods

Forty-seven individuals with chronic shoulder pain were enrolled in the study. The QST measures, including pressure pain threshold (PPT) and mechanical temporal summation (MTS), were tested, and SMEP was measured with a lifting task. Relative and absolute reliability were analyzed using intraclass correlation coefficients (ICC 3,1) and standard error of the measurement (SEM), respectively.

Results

The results showed that the ICC coefficients for all sensitivity measures were moderate to good, ranging from 0.63 to 0.86. The SEM% for the QST measures at all sites ranged from 21.4% to 36%, with TS at the forearm demonstrating a high SEM% (greater than 30%). The SMEP measure also showed a high SEM% (46%).

Conclusion

The results showed that the sensitivity measures had moderate to good reliability among individuals with shoulder pain. Acceptable limits of accuracy of measurements were demonstrated for TS and PPT measures, while SMEP demonstrated high error, highlighting the need for further refinement of this measure among these populations.

The biobehavioural pain and movement questionnaire (BioPMovQ): development and psychometric validation of a new questionnaire

Objective

The purpose of this research was to design and psychometrically validate a new instrument (the Biobehavioural Pain and Movement Questionnaire/BioPMovQ), which assesses the relationship between pain and various factors related to motor behaviour from a biobehavioural perspective.

Methods

A mixed-method design combining a qualitative study with an observational and cross-sectional study was employed to develop (content validity) and psychometrically validate (construct validity, reliability and concurrent/discriminant validity) a new instrument. A total of 200 patients with chronic musculoskeletal pain were recruited.

Results

According to the exploratory factor analysis, the final version of the BioPMovQ consists of 16 items distributed across 4 subscales (1, disability, 2, self-efficacy for physical activity; 3, movement avoidance behaviours; and 4, self-perceived functional ability), all with an eigen value greater than 1, explaining 55.79% of the variance. The BioPMovQ showed high internal consistency (Cronbach's α = 0.82; McDonald's ω = 0.83). The intraclass correlation coefficient was 0.86 (95% confidence interval 0.76 to 0.91), which was considered to demonstrate excellent test-retest reliability. The standard error of measurement and minimal detectable change were 3.43 and 8.04 points, respectively. No floor or ceiling effects were identified. There was a positive, significant and moderate magnitude correlation with the Graded Chronic Pain Scale (r = 0.54), kinesiophobia (r = 0.60), pain catastrophising (r = 0.44) and chronic pain self-efficacy (r = -0.31).

Conclusion

The BioPMovQ showed good psychometric properties. Based on the findings of this study, the BioPMovQ can be used in research and clinical practice to assess patients with chronic musculoskeletal pain.

How do people with chronic low back pain pick a pencil off the floor?

BACKGROUND

Picking objects off the floor is provocative for people with chronic low back pain (CLBP). There are no clinically applicable methods evaluating movement strategies for this task. The relationship between strategy and multidimensional profiles is unknown.

OBJECTIVE

Develop a movement evaluation tool (MET) to examine movement strategies in people with CLBP (n = 289) picking a pencil off the floor. Describe those movement strategies, and determine reliability of the MET. Explore differences across multidimensional profiles and movement strategies.

METHODS

An MET was developed using literature and iterative processes, and its inter-rater agreement determined. Latent class analysis (LCA) derived classes demonstrating different strategies using six movement parameters as indicator variables. Differences between classes across multidimensional profiles were investigated using analysis of variance, Kruskal-Wallis, or chi-squared tests.

RESULTS

Six movement parameters were evaluated. There was substantial inter-rater agreement (Cohen's Kappa = 0.39-0.79) across parameters. LCA derived three classes with different strategies: Class 1 (71.8%) intermediate trunk inclination/knee flexion; Class 2 (24.5%) greater forward trunk inclination, lower knee flexion; Class 3 (3.7%) lower forward trunk inclination, greater knee flexion. Pain duration differed across all classes (p ≤ .001). Time taken to complete forward bends differed between Class 3 and other classes (p = .024).

CONCLUSIONS

Movement strategies can be reliably assessed using the MET. Three strategies for picking lightweight objects off the floor were derived, which differed across pain duration and speed of movement.

Pain Catastrophizing: Controversies, Misconceptions and Future Directions

Recent reports have pointed to problems with the term "pain catastrophizing." Critiques of the term pain catastrophizing have come from several sources including individuals with chronic pain, advocates for individuals with chronic pain, and pain scholars. Reports indicate that the term has been used to dismiss the medical basis of pain complaints, to question the authenticity of pain complaints, and to blame individuals with pain for their pain condition. In this paper, we advance the position that the problems prompting calls to rename the construct of pain catastrophizing have little to do with the term, and as such, changing the term will do little to solve these problems. We argue that continued calls for changing or deleting the term pain catastrophizing will only divert attention away from some fundamental flaws in how individuals with pain conditions are assessed and treated. Some of these fundamental flaws have their roots in the inadequate training of health and allied health professionals in evidence-based models of pain, in the use of psychological assessment and intervention tools for the clinical management of pain, and in gender equity and antiracism. Critiques that pain scholars have leveled against the defining, operational, and conceptual bases of pain catastrophizing are also addressed. Arguments for reconceptualizing pain catastrophizing as a worry-related construct are discussed. Recommendations are made for remediation of the problems that have contributed to calls to rename the term pain catastrophizing. PERSPECTIVE: The issues prompting calls to rename the construct of pain catastrophizing have their roots in fundamental flaws in how individuals with pain are assessed and treated. Efforts to address these problems will require more than a simple change in terminology.

Psychological factors are associated with pain extent in patients with carpal tunnel syndrome

INTRODUCTION

Widespread pain may be related to psychosocial aspects in several musculoskeletal conditions, but the literature on carpal tunnel syndrome (CTS) is scarce.

OBJECTIVE

To determine the relationship between pain extent and psychological factors (catastrophizing, kinesiophobia, anxiety symptoms, and depression) in people with CTS.

METHODS

A cross-sectional study was conducted. The independent variables were: pain intensity, disability (QuickDASH), duration of symptoms, anxiety and depressive symptoms, catastrophizing, and kinesiophobia. The main outcome was: pain extent (% of total area and categories "pain within the median nerve-innervated territory" versus "extra-median nerve pain"). Correlation analysis was performed using Spearman's correlation coefficient. A linear regression model and binary logistic regression (both with forward selection) were performed to determine the main predictors of pain extent.

RESULTS

Forty-eight participants were included. A moderate positive correlation was found between catastrophizing (r = 0.455; p = 0.024) and disability (r = 0.448; p = 0.024) with total pain extent area. Regression models indicated that catastrophizing explained 22% of the variance in the pain extent (β = 0.003; 95% CI: 0.002-0.005), while kinesiophobia was the variable that best explained the distribution of pain in the extra-median territory (R2 Nagelkerke = 0.182). Null or weak correlations were found for the rest of the associations.

CONCLUSION

Catastrophizing and kinesiophobia were the main indicators of pain extent in people with CTS. Clinicians are advised to use specific questionnaires to check for the presence of catastrophizing or kinesiophobia in people with CTS and wider pain extension.

Changes in spinal motor behaviour are associated with reduction in disability in chronic low back pain: A longitudinal cohort study with 1-year follow-up

BACKGROUND

The need to improve spinal motor behaviour in chronic low back pain (CLBP) rehabilitation remains unclear. The objective of this study was to test if changes in spinal motor behaviour were associated with changes in disability after an interdisciplinary rehabilitation program (IRP) in patients with CLBP.

METHODS

Seventy-one patients with CLBP participating in an IRP were included. Spinal motor behaviour was assessed with biomechanical (lumbar angular amplitude and velocity, erector spinae muscle activity and duration of the task), cognitive-emotional (task-specific fear [PRF]) and pain-related (movement-evoked pain [MEP]) measures during a lifting task before and after the IRP. Disability was measured before and after the IRP, and at 3-month and 1-year follow-ups.

RESULTS

After adjusting for confounders, changes in disability were significantly associated with MEP changes (β adj. = 0.49, p < 0.001) and PRF changes (β adj. = 0.36, p = 0.008), but not with changes in any of the biomechanical measures. MEP at the end of IRP was also associated with disability at 3 months (β adj. = 0.37, p = 0.001) and 1 year (β adj. = 0.42, p = 0.01). Biomechanical measures at the end of the IRP were not associated with disability, except for the duration of the task that was significantly associated with reduction of disability at 3 months (β non-adj = 0.5, p < 0.001).

CONCLUSIONS

Pain-related and cognitive-emotional measures of spinal motor behaviour were associated with reduction in disability following an IRP. Future research is needed to further investigate causal relationships between spinal motor behaviour and disability.

SIGNIFICANCE STATEMENT

This study supports a multidimensional understanding and analysis of spinal motor behaviour, integrating the cognitive-emotional, pain-related and biomechanical domains. It also supports the consideration of spinal motor behaviour as a potentially important treatment target in chronic low back pain management. Moreover, it suggests that reducing movement-evoked pain and task-specific fear may have more influence on disability than changing lumbar amplitude, lumbar angular velocity or erector muscle activity, which may have important implications for rehabilitation.

Are biomarkers associated with sensitivity to physical activity?

BACKGROUND

Activity-based treatments play an integral role in managing musculoskeletal conditions including low back pain. However, while therapeutic exercise has been shown to reduce pain in such conditions, certain individuals experience a paradoxical pain increase in response to exercise. The physiological processes underlying this sensitivity to physical activity (SPA) are not fully understood, however stress and inflammation have been shown to contribute to SPA. The present cross-sectional study investigated whether physiological indicators of stress (cortisol) and inflammation (IL-6) help explain SPA.

METHODS

Twenty-seven patients with chronic low back pain and 21 healthy controls completed a 1-h exercise session of standardized physical tasks. SPA was calculated from the difference between post- and pre-exercise pain levels. Participant's saliva was collected at several timepoints for cortisol and IL-6 levels quantification. Their waking cortisol response was calculated to reflect their cortisol regulation. Reactivity of IL-6 and cortisol was calculated to reflect changes in these measures during exercise.

RESULTS

IL-6 reactivity was significantly and positively correlated with SPA among participants with low back pain. In contrast, neither cortisol waking response nor cortisol reactivity was significantly correlated within the low back pain group. No significant differences in IL-6 reactivity, cortisol reactivity or cortisol waking response were observed.

CONCLUSION

These findings are the first to link SPA to an objective biomarker among people with low back pain. These findings help describe the physiological mechanisms of SPA and can support new clinical research that targets the inflammatory response of patients with chronic low-back pain and elevated SPA.

SIGNIFICANCE

This study reveals a correlation between SPA and an objective salivary biomarker of IL-6 in people with low back pain, improving our understanding of this clinically relevant subjective experience.

Predicting chronic postsurgical pain: current evidence and a novel program to develop predictive biomarker signatures

ABSTRACT

Chronic pain affects more than 50 million Americans. Treatments remain inadequate, in large part, because the pathophysiological mechanisms underlying the development of chronic pain remain poorly understood. Pain biomarkers could potentially identify and measure biological pathways and phenotypical expressions that are altered by pain, provide insight into biological treatment targets, and help identify at-risk patients who might benefit from early intervention. Biomarkers are used to diagnose, track, and treat other diseases, but no validated clinical biomarkers exist yet for chronic pain. To address this problem, the National Institutes of Health Common Fund launched the Acute to Chronic Pain Signatures (A2CPS) program to evaluate candidate biomarkers, develop them into biosignatures, and discover novel biomarkers for chronification of pain after surgery. This article discusses candidate biomarkers identified by A2CPS for evaluation, including genomic, proteomic, metabolomic, lipidomic, neuroimaging, psychophysical, psychological, and behavioral measures. Acute to Chronic Pain Signatures will provide the most comprehensive investigation of biomarkers for the transition to chronic postsurgical pain undertaken to date. Data and analytic resources generatedby A2CPS will be shared with the scientific community in hopes that other investigators will extract valuable insights beyond A2CPS's initial findings. This article will review the identified biomarkers and rationale for including them, the current state of the science on biomarkers of the transition from acute to chronic pain, gaps in the literature, and how A2CPS will address these gaps.

Test-retest reliability of movement-evoked pain and sensitivity to movement-evoked pain in patients with rotator cuff-related shoulder pain

BACKGROUND

The number of researchers and clinicians using movement-evoked pain and sensitivity to movement-evoked pain to assess shoulder pain has increased. However, the intrarater test-retest reliability of movement-evoked pain and sensitivity to movement-evoked pain in people with rotator cuff-related shoulder pain (RCRSP) is still unknown.

OBJECTIVE

We examined the intrarater test-retest reliability of movement-evoked pain and sensitivity to movement-evoked pain in participants with RCRSP.

METHODS

Seventy-four participants with RCRSP performed five trials of active shoulder abduction to elicit pain under two experimental conditions: active shoulder abduction to the onset of pain and maximum range of motion (ROM). The primary outcome measures were pain intensity and ROM. Test-retest reliability of movement-evoked pain and sensitivity to movement-evoked pain was examined using intraclass correlation coefficient (ICC3,1) and minimal detectable change (MDC90).

RESULTS

The reliability of movement-evoked pain under both experimental conditions was good to excellent (ICC: 0.81 to 0.95), while the reliability of sensitivity to movement-evoked pain was poor in both conditions (ICC≤0.45). The MDC90 for pain intensity was 1.6 and 1.8 during shoulder abduction to the onset of pain and maximum ROM, respectively. The MDC90 for ROM was 17.5° and 11.2° during shoulder abduction to the onset of pain and maximum ROM condition, respectively.

CONCLUSION

This study confirms movement-evoked pain testing during active shoulder abduction to the onset of pain or maximum ROM condition is reliable to assess pain associated with movement in patients with RCRSP. The minimal detectable change score of movement-evoked pain can guide clinicians and researchers on how to interpret changes in these outcomes.

Movement-Evoked Pain Versus Widespread Pain: A Longitudinal Comparison in Older Adults With Chronic Low Back Pain From the Delaware Spine Studies

It is currently unknown which pain-related factors contribute to long-term disability and poorer perceived health among older adults with chronic low back pain (LBP). This investigation sought to examine the unique influence of movement-evoked pain (MeP) and widespread pain (WP) on longitudinal health outcomes (ie, gait speed, perceived disability, and self-efficacy) in 250 older adults with chronic LBP. MeP was elicited with 3 standardized functional tests, while presence of WP was derived from the McGill Pain Map. Robust regression with HC3 standard errors was used to examine associations between these baseline pain variables and health outcomes at 12-month follow-up. Covariates for these models included age, sex, body mass index, resting and recall LBP intensity, LBP duration, depression, pain catastrophizing, and baseline outcome (eg, baseline gait speed). Greater MeP was independently associated with worse 12-month LBP-related disability (b = .384, t = 2.013, P = .046) and poorer self-efficacy (b = -.562, t = -2.074, P = .039); but not gait speed (P > .05). In contrast, WP and resting and recall LBP intensity were not associated with any prospective health outcome after adjustment (all P > .05). Compared to WP and resting and recall LBP intensity, MeP is most strongly related to longitudinal health outcomes in older adults with chronic LBP. PERSPECTIVE: This article establishes novel independent associations between MeP and worse perceived disability and self-efficacy at 12-months in older adults with chronic LBP. MeP likely has biopsychosocial underpinnings and consequences and may therefore be an important determinant of health outcomes in LBP and other geriatric chronic pain populations.

Task-based measures of sensitivity to physical activity predict daily life pain and mood among people living with back pain

BACKGROUND

Clinical interventions aim to improve the daily life experiences of patients. However, past research has highlighted important discrepancies between commonly used assessments (e.g. retrospective questionnaires) and patients' daily life experiences of pain. These gaps may contribute to flawed clinical decision-making and ineffective care. Recent work suggests that real-time, task-based clinical assessments may help reduce these discrepancies by adding predictive value in explaining daily life pain experiences. This study aimed to investigate these relationships by evaluating whether task-based measures of sensitivity to physical activity (SPA) predict daily life pain and mood, beyond traditional pain-related questionnaires.

METHODS

Adults with back pain (<6-month onset) answered pain-related questionnaires and completed a standardized lifting task. SPA-Pain, SPA-Sensory and SPA-Mood were, respectively, assessed as task-evoked changes in pain intensity, pressure pain threshold (back, hands), situational catastrophizing. Over the next 9 days, daily life pain and mood were assessed using smartphone-based ecological momentary assessment (EMA-Pain and EMA-Mood, respectively) with stratified random sampling. Data analyses estimated fixed effects (b) using multilevel linear modelling with random intercepts.

RESULTS

Median EMA completion per participant was 66.67% (n = 67 participants). After controlling for covariates, SPA-Pain was associated with EMA-Pain (b = 0.235, p = 0.002) and SPA-Psych approached significance with EMA-Mood (b = -0.159, p = 0.052).

CONCLUSIONS

Task-based assessment of SPA helps explain daily life pain and mood among adults with back pain, beyond traditional questionnaires. Adding task-based assessment of SPA may achieve a more complete picture of pain and mood in daily life, offering clinicians better guidance when prescribing activity-based interventions that are designed to modify daily life behaviour, such as graded activity.

SIGNIFICANCE

This study found that, among people with back pain, task-based measures of sensitivity to physical activity contribute additional predictive value for daily life pain and mood beyond self-report questionnaires. Findings suggest that real-time, task-based measures may help mitigate some of the shortcomings that are commonly associated with retrospective questionnaires.

Reduction in pain-related fear is not associated with improvement in spinal biomechanics but with decrease in movement-evoked pain in patients with chronic low back pain

BACKGROUND AND AIMS

While a causal relationship between pain-related fear and spinal movement avoidance in patients with chronic low back pain (CLBP) has frequently been postulated, evidence supporting this relationship is limited. This study aimed to test if decreases in pain-related fear or catastrophizing were associated with improvements in spinal biomechanics, accounting for possible changes in movement-evoked pain.

METHODS

Sixty-two patients with CLBP were assessed before and after an interdisciplinary rehabilitation program (IRP). Pain-related fear was assessed with general and task-specific measures. Lower and upper lumbar angular amplitude and velocity as well as paraspinal muscle activity were recorded during five daily-life tasks to evaluate spinal biomechanics. Relationships were tested with multivariable linear regression analyses.

RESULTS

The large decreases in pain-related fear and catastrophizing following the IRP were scarcely and inconsistently associated with changes in spinal biomechanics (< 3% of the models reported a statistically significant association). Results remained comparable for activities inducing more or less fear, for specific or general measures of pain-related fear, and for analyses performed on the entire population or limited to subgroups of patients with higher levels of task-specific fear. In contrast, reductions in task-specific pain-related fear were significantly associated with decreases in movement-evoked pain in all tasks (r = 0.26-0.62, p ≤ 0.02).

CONCLUSION

This study does not support an association between pain-related fear and spinal movement avoidance. However, it provides evidence supporting a direct relationship between decreased pain-related fear and decreased movement-evoked pain, possibly explaining some mechanisms of the rehabilitation programs.

Experimental Pain Measurements Do Not Relate to Pain Intensity and Pain Cognitions in People Scheduled for Surgery for Lumbar Radiculopathy

OBJECTIVE

The present cross-sectional study aims to unravel associations of pain intensity and cognitions with quantitative sensory testing in people scheduled for surgery for lumbar radiculopathy. Additionally, insight will be provided into the presence of dysfunctional nociceptive processing and maladaptive pain cognitions in this population.

DESIGN

Cross-sectional study.

SETTING

Data from three hospitals in Belgium.

SUBJECTS

The final sample comprised 120 participants with lumbar radiculopathy scheduled for surgery, included between March 2016 and April 2019.

METHODS

Self-reported pain intensity was assessed on a visual analog scale, and pain cognitions were assessed with self-reported questionnaires (Pain Catastrophizing Scale, Tampa Scale for Kinesiophobia, and Pain Vigilance and Awareness Questionnaire). Quantitative sensory testing (detection thresholds, pain thresholds, temporal summation, and conditioned pain modulation) was evaluated, as well.

RESULTS

Evidence was found for the presence of an impaired inhibitory response to nociceptive stimuli and maladaptive pain cognitions in this population. Kinesiophobia was found to be present to a maladaptive degree in the majority of the patients (n = 106 [88%]). Significant, but weak, associations between electrical pain thresholds at the sural nerves and leg pain intensity (sural nerve symptomatic side: r = -0.23; P = 0.01; non-symptomatic side: r = -0.22; P = 0.02) and kinesiophobia levels (sural nerve non-symptomatic side: r = -0.26; P = 0.006) were identified.

CONCLUSIONS

Electrical detection thresholds and correlates for endogenous nociceptive facilitation and inhibition were not found to be related to any of the pain cognitions or to pain intensity in people scheduled to undergo surgery for lumbar radiculopathy.

An Exploration of the Influence of Non-Biomechanical Factors on Lifting-Related LBP

Objective: The primary objective was to compare non-biomechanical factors between manual workers with and without a history of LBP related to lifting. A secondary objective was to investigate associations between the change in pain intensity during repeated lifting (termed pain ramp) and non-biomechanical factors tested in the LBP group. Methods: Manual workers currently in lifting occupations with and without a history of lifting-related LBP were recruited (21 LBP and 20 noLBP) and took part in a repeated (100) lift task. A series of non-biomechanical factors, including psychological, work-related, lifestyle, whole health and psychophysical factors, were collected. Psychophysical factors (pressure pain thresholds (PPTs) and fatigue) were also measured at different time points. Associations between pain ramp during lifting and non-biomechanical factors were investigated with linear regression. Results: The LBP group reported worse perceived sleep quality, more musculoskeletal pain sites other than LBP and greater symptoms related to gastrointestinal complaints and pseudo-neurology compared to the group with no history of LBP. The group with LBP were also slightly more worried about the lifting task and felt more fatigued at the end of the lifting task. The feeling of fatigue during lifting was positively associated with pain ramp in the LBP group. Anxiety and gastrointestinal complaints were weakly negatively associated with pain ramp during lifting. Conclusions: The group differences of poorer perceived sleep, greater non-specific health complaints, slightly more worry about the lifting task and more perceived fatigue in the LBP group highlight the complex and multi-factorial nature of LBP related to lifting. The feeling of fatigue was positively associated with pain ramp in the LBP group, suggesting a close relationship with pain and fatigue during lifting that requires further exploration.

Activity-related pain predicts pain and functional outcomes in people with knee osteoarthritis: A longitudinal study

Knee Osteoarthritis (OA) is a prevalent musculoskeletal condition, commonly resulting in pain and disability. However, pain and disability in this population are poorly related with the degree of structural joint damage. Underlying pain mechanisms, including activity-related pain and sensitization assessed via Quantitative Sensory Testing (QST), may better predict pain and functional outcomes of those with knee OA. Therefore, the aim of this study was to explore whether activity-related pain and sensitization assessed via QST predict future pain, function, fatigue, physical performance and quality of life outcomes in those living in the community with knee OA. Eighty-six participants with knee OA were recruited in Dunedin, New Zealand. Those eligible to participate underwent baseline testing including QST as well as measures of activity-related pain including Movement-evoked Pain (MEP) and Sensitivity to Physical Activity (SPA). Outcome measures exploring pain, function, fatigue and quality of life outcomes were collected at baseline, and two follow-up periods (two and nine weeks). Univariable linear regression models were developed followed by multivariable linear regression models for each prognostic marker adjusting for age, gender, BMI, OA duration, baseline pain intensity and socioeconomic status. Activity-related measures of pain, including MEP and SPA, demonstrated predictive associations with pain and functional outcomes prospectively in those with knee OA. Therefore, those demonstrating activity-related pain are at future risk of greater pain, disability and reduced quality of life. Larger, externally validated longitudinal studies are required which include individuals with more severe knee OA.

Sensitivity to movement-evoked pain, central sensitivity symptoms, and pro-nociceptive profiles in people with chronic shoulder pain: A parallel-group cross-sectional investigation

OBJECTIVE

To investigate whether sensitivity to movement-evoked pain (SMEP), central sensitivity symptom burden, and quantitative sensory testing (QST) outcomes differ between healthy controls and people with chronic shoulder pain.

METHODS

People with chronic shoulder pain (n = 39) and healthy controls (n = 26) completed validated questionnaires measuring demographic, pain characteristics, psychological factors, social support, sleep quality, central sensitivity inventory (CSI), and physical activity levels. A blinded assessor administered QST measuring pressure pain threshold, temporal summation, conditioned pain modulation, and cold hyperalgesia. All participants performed repeated lifting of weighted canisters and reported severity of pain over successive lifts of the weighted canisters. Between-group differences in the QST, SMEP and CSI scores were investigated. Demographic and psychosocial variables were adjusted in the analyses.

RESULTS

Dynamic mechanical allodynia, mechanical temporal summation, movement-evoked pain scores, SMEP index, and CSI scores were significantly (p ≤ 0.05) higher in the chronic shoulder pain group than in healthy controls. A significant proportion of people with chronic shoulder pain presented with pro-nociceptive profiles and experienced higher pain severity, interference, and disability.

CONCLUSIONS

People with chronic shoulder pain displayed symptoms and signs of central sensitization. Future research should investigate the predictive role of central sensitization on clinical outcomes in shoulder pain.

Algometry for the assessment of central sensitisation to pain in fibromyalgia patients: a systematic review

INTRODUCTION

The pathophysiology of fibromyalgia (FM) is related to central sensitisation (CS) to pain. Algometry allows assessing CS based on dynamic evoked pain. However, current algometrýs protocols require optimising, unifying and updating.

OBJECTIVES

1) identify the dynamic pain measures used most frequently to effectively assess CS processes in FM, and 2) consider the future of the algometry assessing CS in these patients.

METHODS

Cochrane Collaboration guidelines and PRISMA statements were followed. The protocol was registered in PROSPERO database (ID: CRD42021270135). The selected articles were evaluated using the Cochrane risk of bias (ROB) assessment tool. The PubMed, Scopus, and Web of Science databases were searched.

RESULTS

Thirty-four studies were selected, including measures such as temporal summation of pain (TSP), aftersensations (AS), spatial summation of pain (SSP), the noxious flexion reflex (NFR) threshold, conditioned pain modulation (CPM), cutaneous silent period (CuSP), and slowly repeated evoked pain (SREP); and evoked pain combined with neuroimaging. Each measure offered various advantages and limitations. According to ROB, 28 studies were of low quality, 3 of moderate quality, and 3 of high quality.

CONCLUSIONS

Several pain indicators have been demonstrated to successfully examine CS involvement in FM in the last years. Algometry, especially when it involves diverse body sites and tissues, might provide further insight into (1) the evaluation of psychological factors known to influence pain experience, (2) new dynamic pain indicators, and (3) the simultaneous use of certain neuroimaging techniques. Further research clarifying the mechanisms underlying some of these measures, and homogenisation and optimisation of the algometrýs protocols, are needed. KEY MESSAGESAlgometry allows for assessing Central Sensitisation by applying dynamic evoked pain.The future of algometry could relapse in its combination with neuroimaging.Recently-emerged pain indicators should be considered for algometrýs new protocols.

Factors associated with disability and pain intensity in patients with complex regional pain syndrome

PURPOSE

To examine the associations between psychological factors (pain catastrophizing, pain-related anxiety, and fear of pain) and level of pain and disability in patients with complex regional pain syndrome (CRPS).

METHODS

One hundred and two patients with CRPS were recruited from tertiary care centers with the different upper limb injuries were evaluated for pain, disability, and psychological factors. Patients completed the Disabilities of the Arm, Shoulder, and Hand (DASH) Questionnaire, Patient Rated Wrist Evaluation (PRWE), Pain Catastrophizing Scale (PCS), Tampa Scale of Kinesiophobia (TSK-11), and Depression, Anxiety, and Stress Scale (DASS). The associations of pain and disability with presence of these behavioral and mental health factors were examined using bivariate and multivariable analyses. These models were adjusted for age, sex, injured dominant hand, and previous surgery.

RESULTS

A higher pain catastrophizing score (β = 0.55, p = 0.00) was associated with greater disability. A higher pain catastrophizing score (β = 0.35, p = 0.001) and female gender (β = 0.24, p = 0.01) were associated with greater pain at rest (PAR). A higher pain catastrophizing score and having a surgical history were associated with greater pain with movement (β = 0.25, p = 0.02). Scores of ≥18.5 in PCS, ≥57.5 on TSK, and ≥15.5 on DASS were associated with higher risk of experiencing pain and disability.

CONCLUSIONS

Pain catastrophizing, female sex, and surgical intervention are associated with poor outcomes. Physiologic, psychological factors, and treatment factors interact to influence outcomes. The results of this study further validate the associations of chronic pain and disability with pain catastrophizing in patients with CRPS. The novel finding of this study is introducing cut-off scores for TSK, PCS, and DASS as a screening tool to predict pain, functional limitations.Implication for rehabilitationPain catastrophizing has a vital role in the magnitude of disability and pain in patients with CRPS.The novel finding of this paper was the cut-off scores on the psychological evaluations that can enable using them as screening tool for bad outcomes in patients with CRPS.Cut off scores from different psychological evaluations can be used as a yellow flag for clinician's for detecting patients with increased risk of pain and disability.The identification of a cut-off can also have implications for implementing change in clinical practice by identifying the need for early and intensive interventions.

It Hurts to Move! Intervention Effects and Assessment Methods for Movement-Evoked Pain in Patients With Musculoskeletal Pain: A Systematic Review with Meta-analysis

OBJECTIVES

To estimate the effects of musculoskeletal rehabilitation interventions on movementevoked pain and to explore the assessment methods/protocols used to evaluate movement-evoked pain in adults with musculoskeletal pain.

DESIGN

Systematic review with meta-analysis.

LITERATURE SEARCH

Three electronic databases (PubMed, Web of Science, and Scopus) were searched.

STUDY SELECTION CRITERIA

Randomized controlled trials investigating musculoskeletal rehabilitation interventions for movement-evoked pain in adults with musculoskeletal pain were included.

DATA SYNTHESIS

Meta-analysis was conducted for outcomes with homogeneous data from at least 2 trials. The mean change in movementevoked pain was the primary outcome measure. Certainty of evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation framework.

RESULTS

Thirty-eight trials were included, and 60 different interventions were assessed. There was moderate-certainty evidence of a beneficial effect of exercise therapy compared to no treatment (standardized mean difference [SMD], -0.65; 95% confidence interval [CI]: -0.83, -0.47; P<.001) on movement-evoked pain in adults with musculoskeletal pain. There was low-certainty evidence of a beneficial effect of transcutaneous electrical nerve stimulation compared to no treatment (SMD, -0.46; 95% CI: -0.71, -0.21; P = .0004). There was no benefit of transcutaneous electrical nerve stimulation when compared to sham transcutaneous electrical nerve stimulation (SMD, -0.28; 95% CI: -0.60, 0.05; P = .09; moderate-certainty evidence).

CONCLUSION

There was moderate-certainty evidence that exercise therapy is effective for reducing movement-evoked pain in patients with musculoskeletal pain compared to no treatment. Consider exercise therapy as the first-choice treatment for movement-evoked pain in clinical practice. J Orthop Sports Phys Ther 2022;52(6):345-374. Epub: 05 Feb 2022. doi:10.2519/jospt.2022.10527.

Do psychological factors relate to movement-evoked pain in people with musculoskeletal pain? A systematic review and meta-analysis

BACKGROUND

A growing body of evidence has demonstrated the importance of implementing movement-evoked pain in conventional pain assessments, with a significant role for psychological factors being suggested. Whether or not to include these factors in the assessment of movement-evoked pain has not yet been determined.

OBJECTIVES

The aim of this systematic review is to explore the association between psychological factors and movement-evoked pain scores in people with musculoskeletal pain.

METHODS

For this systematic review with meta-analysis, four electronic databases (PubMed, Medline, WOS, and Scopus) were searched. Cross-sectional studies, longitudinal cohort studies, and randomized controlled trials investigating the association between movement-evoked pain and psychological factors in adults with musculoskeletal pain were considered. Meta-analysis was conducted for outcomes with homogeneous data from at least 2 studies. Fischer-Z transformations were used as the measure of effect. Quality of evidence was assessed using the National Institutes of Health's Quality assessment tool for observational cohort and cross-sectional studies and Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework.

RESULTS

Meta-analyses and grading the quality of evidence revealed moderate evidence for a relation between movement-evoked pain and depressive symptoms (Fisher-z=0.27; 95%CI: 0.17, 0.36; 5 studies (n=440)), pain-related fear (Fisher-z=0.35; 95%CI: 0.26, 0.44; 6 studies (n=492)), and pain catastrophizing (Fisher-z=0.47; 95%CI: 0.36, 0.58; 4 studies (n=312)) in people with musculoskeletal pain.

CONCLUSIONS

Movement-evoked pain is weakly to moderately associated to depressive symptoms, pain-related fear, and pain catastrophizing in people with musculoskeletal pain.

A Standardized Assessment of Movement-evoked Pain Ratings Is Associated With Functional Outcomes in Older Adults With Chronic Low Back Pain

OBJECTIVE

Despite high prevalence estimates, chronic low back pain (CLBP) remains poorly understood among older adults. Movement-evoked pain (MeP) is an understudied factor in this population that may importantly contribute to disability. This study investigated whether a novel MeP paradigm contributed to self-reported and performance-based function in older adults with CLBP.

MATERIALS AND METHODS

This secondary analysis includes baseline data from 230 older adults with CLBP in the context of a prospective cohort study. The Repeated Chair Rise Test, Six Minute Walk Test, and Stair Climbing Test were used to elicit pain posttest LBP ratings were aggregated to yield the MeP variable. Self-reported and performance-based function were measured by the Late Life Function and Disability Index (LLFDI) scaled function score and Timed Up-and-Go Test (TUG), respectively. Robust regression with HC3 standard errors was used to model adjusted associations between MeP and both functional outcomes; age, sex, body mass index, and pain characteristics (ie, intensity, quality, and duration) were utilized as covariates.

RESULTS

MeP was present in 81.3% of participants, with an average rating of 5.09 (SD=5.4). Greater aggregated posttest MeP was associated with decreased LLFDI scores (b=-0.30, t=-2.81, P=0.005) and poorer TUG performance (b=0.081, t=2.35, P=0.020), independent of covariates. LBP intensity, quality and duration were not associated with the LLFDI or TUG, (all P>0.05).

DISCUSSION

Aggregated posttest MeP independently contributed to worse self-reported and performance-based function among older adults with CLBP. To understand long-term consequences of MeP, future studies should examine longitudinal associations between MeP and function in this population.

The Prospective Prognostic Value of Biopsychosocial Indices of Sensitivity to Physical Activity Among People With Back Pain

OBJECTIVES

Many people living with musculoskeletal pain conditions experience a range of negative biopsychosocial responses to physical activity, referred to as increased sensitivity to physical activity (SPA), that may undermine successful rehabilitation. This exploratory study aims to provide the first prospective analysis of the potential prognostic value of 3 biopsychosocial indices of SPA in relation to rehabilitation outcomes. This study also aimed to shed light on the cross-sectional interrelationships between these 3 biopsychosocial indices of SPA.

MATERIALS AND METHODS

Adults with back pain were evaluated upon starting physical therapy and then again 3 months later. The initial testing session consisted of self-reported pain-related questionnaires and assessment of activity-related changes in pressure pain thresholds (SPA-Sensory), pain intensity ratings (SPA-Pain), and situational catastrophizing (SPA-Psych). The 3-month follow-up consisted of self-reported disability and pain questionnaires. Correlational and hierarchical linear regression analyses were conducted.

RESULTS

A total of 97 participants completed both the initial visit and 3-month follow-up. The SPA-Pain index and the SPA-Psych index were significantly intercorrelated, but neither were correlated with the SPA-Sensory index. The SPA-Sensory index was not correlated with outcomes. The SPA-Pain index was correlated only with cross-sectional disability and pain outcomes. The SPA-Psych index was the only SPA index significantly correlated with outcomes both cross-sectionally and at 3-month follow-up. After controlling for baseline pain/disability and pain catastrophizing, SPA-Psych was no longer a significant prognostic factor for pain, but remained a significant prognostic factor for disability at 3-month follow-up (β=0.272, t=2.674, P=0.008, R2 Δ=5.60%).

DISCUSSION

This study highlights the importance of conceptualizing and measuring SPA as a biopsychosocial (rather than unidimensional) construct and points toward the added prognostic value of this construct. Implications for future research and practice are discussed.

Pain Catastrophizing and Pain Self-Efficacy Mediate Interdisciplinary Pain Rehabilitation Program Outcomes at Posttreatment and Follow-Up

BACKGROUND

Decreasing pain catastrophizing and improving self-efficacy to self-manage chronic pain symptoms are important treatment targets in the context of interdisciplinary cognitive behavioral therapy for chronic pain. Greater pain catastrophizing has been shown to be associated with greater impact of pain symptoms on functioning, while conversely, greater pain self-efficacy has been associated with lower pain intensity and lower levels of disability.

OBJECTIVE

To prospectively evaluate interdisciplinary cognitive behavioral therapy for pain outcomes, as well as to the mediating effects of both pain catastrophizing and pain self-efficacy on outcome.

METHODS

Participants were 315 patients with chronic pain between April 2017 and April 2018 who completed a three-week interdisciplinary pain rehabilitation program. Pain severity, pain interference, pain catastrophizing, pain self-efficacy, quality of life, and depressive symptom questionnaires, and measures of physical performance were assessed at pre- and posttreatment. Follow-up questionnaires were returned by 163 participants. Effect size and reliable change analyses were conducted from pre- to posttreatment and pretreatment to 6-month follow-up. Mediation analyses were conducted to determine the mediating effect of pain catastrophizing and pain self-efficacy on pain outcome.

RESULTS

Significant improvements from pre- to posttreatment in pain outcomes were observed, and over 80% evidenced reliable change in at least one pain-relevant measure. Pain catastrophizing and pain self-efficacy mediated the relationship between changes in pain outcomes.

CONCLUSIONS

Interdisciplinary pain rehabilitation is an effective treatment and decreasing pain catastrophizing and increasing pain self-efficacy can influence maintenance of treatment gains.

Exploring lumbar and lower limb kinematics and kinetics for evidence that lifting technique is associated with LBP

Purpose

To investigate if lumbar and lower limb kinematics or kinetics are different between groups with and without a history of LBP during lifting. Secondly, to investigate relationships between biomechanical variables and pain ramp during repeated lifting.

Methods

21 LBP and 20 noLBP participants completed a 100-lift task, where lumbar and lower limb kinematics and kinetics were measured during lifting, with a simultaneous report of LBP intensity every 10 lifts. Lifts were performed in a laboratory setting, limiting ecological validity.

Results

The LBP group used a different lifting technique to the noLBP group at the beginning of the task (slower and more squat-like). Kinetic differences at the beginning included less peak lumbar external anterior shear force and greater peak knee power demonstrated by the LBP group. However, at the end of the task, both groups lifted with a much more similar technique that could be classified as more stoop-like and faster. Peak knee power remained greater in the LBP group throughout and was the only kinetic difference between groups at the end of the lifting task. While both groups lifted using a more comparable technique at the end, the LBP group still demonstrated a tendency to perform a slower and more squat-like lift throughout the task. Only one of 21 variables (pelvic tilt at box lift-off), was associated with pain ramp in the LBP group. Conclusions: Workers with a history of LBP, lift with a style that is slower and more squat-like than workers without any history of LBP. Common assumptions that LBP is associated with lumbar kinematics or kinetics such as greater lumbar flexion or greater forces were not observed in this study, raising questions about the current paradigm around ‘safe lifting’.

Influence of Stabilization Techniques Used in the Treatment of Low Back Pain on the Level of Kinesiophobia

The aim of this study was to try to compare the effectiveness of manual therapy techniques in combination with stabilization techniques: the so-called Australian method and the Neurac method in relation to pain sensations and the level of kinesiophobia. A total of 69 people were examined, divided into three groups of 23 people each. The Visual Analogue Scale was used to assess the antalgic effect, and the Kinesiophobia Causes Scale questionnaire was used to assess the level of kinesiophobia. Patients improved over four weeks, during which they were assessed three times. The evaluation of the desired parameters was also performed over a 24-week period to assess long-term performance. Stabilization techniques are an effective extension of manual therapy techniques in patients with low back pain. People in the groups additionally improved in terms of stabilization techniques, which are characterized by a lower level of kinesiophobia. Its lowest level was found in the group additionally improved with the Neurac method. In the long-term study, the level of kinesiophobia in this group was still maintained at a reduced level. The use of stabilization techniques involving patients in action may significantly affect the level of kinesiophobia, and thus have a much wider effect than just pain reduction.

A Cumulative Impact of Psychological and Sensitization Risk Factors on Pain-Related Outcomes

OBJECTIVE

Risk constructs based on psychological risk factors (eg, pain catastrophizing, PC) and sensitization risk factors (eg, pressure pain threshold, PPT) are important in research and clinical practice. Most research looks at individual constructs but does not consider how different constructs might interact within the same individual. An evaluation of the cumulative impact of psychological and sensitization risk factors on pain-related outcomes may help guide us in the risk assessment of patients with pain conditions. The aim of this study is to evaluate the cumulative impact of these psychological (PC) and sensitization (PPT) risk factors on pain-related outcomes (activity avoidance, pain severity, and disability) considering covariates.

METHODS

We included 109 participants (70.60% women; mean ± SD age 53.6 ± 12.3 years) with chronic musculoskeletal pain for data analysis, who completed all measures of this study. Participants completed a single testing session that included measures of risk factors (PC and PPT) and pain-related outcomes (self-reported avoidance, functional avoidance, disability, and pain severity). Subgroups were constructed by dichotomizing of PC and PPT scores, resulting in four groups: (1) low catastrophizing and low sensitivity (N = 26), (2) high catastrophizing and low sensitivity (N = 27), (3) low catastrophizing and high sensitivity (N = 25), and (4) high catastrophizing and high sensitivity (N = 31).

RESULTS

One-way analysis of variance (ANOVA) revealed significant group differences (P < 0.05, η²  = 0.08 to 0.14) in all outcomes of this study (except functional avoidance), and post hoc analysis indicated the significant differences are between group 1 and 4. A cumulative impact is reflected by large effect sizes between group 1 and 4 (d = 0.8 to 1). The group 2 and 3 (one risk dimension groups: either high-PC or high-PPT) represent 47% of the total participants.

CONCLUSIONS

The study suggests both higher level of PC and pressure sensitivity have a cumulative impact on risk screening for pain-related outcomes, considering gender in functional avoidance (task-related outcome). A clinical presentation with high-PC (one dimension of risk) is not associated with high-PPT (another dimension of risk). This finding has important clinical and theoretical implications.

Impaired exercise-induced hypoalgesia in individuals reporting an increase in low back pain during acute exercise

OBJECTIVES

Exercise therapy is recommended for low back pain (LBP) although the immediate effects on pain are highly variable. In 96 individuals with LBP this cross-sectional study explored (a) the magnitude of exercise-induced hypoalgesia (EIH) and (b) measures of pain sensitivity and clinical pain manifestations in individuals reporting a clinical relevant increase in back pain during physical activity compared with individuals reporting low or no increase in back pain during physical activity.

METHODS

Cuff algometry was performed at baseline on the leg to assess pressure pain threshold (cPPT), tolerance (cPTT) and temporal summation of pain (cTSP). Manual PPTs were assessed on the back and leg before and after a 6-min walk test (6MWT). Back pain was scored on a numerical rating scale (NRS) after each minute of walking. The EIH-effect was estimated as the increase in PPTs after the walk exercise.

RESULTS

Twenty-seven individuals reported an increase of ≥2/10 in pain NRS scores during walking and compared with the individuals with <2/10 NRS scores: cPPT and EIH-effects were lower whereas cTSP, pain intensity and disability were increased (p < 0.03). Baseline NRS scores, EIH and pain thresholds were associated with the likelihood of an increase of ≥2/10 in back pain intensity during walking (p < 0.05).

CONCLUSIONS

Pain flares in response to physical activity in individuals with LBP seem to be linked with baseline pain sensitivity and pain intensity, and impair the beneficial EIH. Such information may better inform when individuals with LBP will have a beneficial effect of physical activity.

SIGNIFICANCE

Pain flares in response to physical activity in individuals with LBP seem to be linked with baseline pain sensitivity and pain intensity, and impair the beneficial exercise-induced hypoalgesia. Such information may better inform when individuals with LBP will have a beneficial effect of physical activity.

Determining the feasibility of a trial to evaluate the effectiveness of phototherapy versus placebo at reducing pain during physical activity for people with knee osteoarthritis: a pilot randomized controlled trial

BACKGROUND

Although practice guidelines recommend physical activity and exercise for the management of knee osteoarthritis, pain is a common barrier to participation. Phototherapy has been shown to reduce pain intensity for people with knee osteoarthritis, but it is unclear if it reduces pain during physical activity or contributes to improved rehabilitation outcomes.

OBJECTIVE

The aim of this study is to assess the feasibility of performing a fully powered randomized controlled trial (RCT) comparing an active phototherapy intervention versus placebo on pain during physical activity for people with knee osteoarthritis.

METHODS

A pilot RCT was conducted to test the feasibility of a trial comparing 8-sessions (4 weeks) of active phototherapy versus placebo. People were able to participate if they (1) were an English speaking adult (> 18 years of age), (2) had received a diagnosis of knee osteoarthritis from a physician, and (3) self-reported experiencing pain and disability related to their knee osteoarthritis for > 3 months. Primary outcomes were the feasibility of participant recruitment, retention, assessment procedures, and maintaining high treatment fidelity. Secondary outcomes piloted for a full trial included pain during physical activity (primary outcome of full trial); self-reported pain severity, physical function, stiffness, adherence to prescribed exercise, global rating of change, patient satisfaction, and adverse events; 6-min walk test; and pressure pain threshold.

RESULTS

Twenty participants (4 men; 16 women) with knee osteoarthritis and a mean age of 63.95 (SD: 9.27) years were recruited over a 3-week period (6.7 participants per week). Fifteen out of 20 (75%) of participants completed the primary outcome assessment at 4 weeks and 19/20 (95%) of participants were retained and completed the final 16-week assessment. Overall, 89% of all assessment items were completed by participants across all time-points. Fifteen out of 20 participants (75%) completed all 8 treatment sessions. Treatment fidelity was 100% for all completed treatment sessions. No adverse events were reported by participants in either group.

CONCLUSIONS

Results suggest that the trial methodology and intervention are feasible for implementation in a fully powered randomized controlled trial to determine the effectiveness of phototherapy at reducing pain during physical activity for people with knee osteoarthritis.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT04234685 , January 21, 2020-Retrospectively registered.

Comparing Novel and Existing Measures of Sensitivity to Physical Activity Among People With Chronic Musculoskeletal Pain: The Importance of Tailoring Activity to Pain

OBJECTIVES

Increasing pain during physical activity is an important, but often poorly assessed, barrier to engaging in activity-based rehabilitation among people with chronic musculoskeletal pain. Preliminary work has addressed this problem by developing new clinical measures of sensitivity to physical activity (SPA). Indices of SPA are generated by evaluating how pain changes in relation to brief physical tasks. Three strategies have been identified for structuring SPA-related physical tasks (self-paced, standardized, and tailored). This cross-sectional study aimed to comparatively estimate the extent of the 3 SPA tasks' evoked pain responses, predictive value of pain severity and pain interference, and their underlying psychological and sensory constructs, among 116 adults with chronic musculoskeletal pain.

MATERIALS AND METHODS

Testing included questionnaires, quantitative sensory testing, and the 3 SPA measures (self-paced, standardized, and tailored). The primary analysis estimated the predictive value of each SPA measure for pain severity and pain interference. Correlational analyses were first conducted between all variables of interest to determine what variables will be included in the hierarchical regression analysis, which in turn was conducted for each outcome.

RESULTS

Analyses revealed that the tailored SPA index was most effective at evoking activity-related pain, was uniquely associated with temporal summation of pain, and was a unique predictor of pain and pain-related interference, even when controlling for established psychological and sensory risk factors.

DISCUSSION

This study further emphasizes SPA as an important and unique attribute of the pain experience and reveals the added value of using a tailored approach to assess SPA.

Composite Score Is a Better Reflection of Patient Response to Chronic Pain Therapy Compared With Pain Intensity Alone

OBJECTIVE

The pain Numeric Rating Scale (NRS) score became standard when pain was introduced as the fifth vital sign in the 1990s. Although plagued with issues, it remains the basis for primary outcome measures in clinical trials for chronic pain therapies. Multidimensional composite scoring that considers all aspects of the chronic pain experience may provide a more meaningful response measure. Herein we propose a multidimensional responder index.

MATERIALS AND METHODS

Data were extracted from an ongoing prospective, multicenter study on DeRidder Burst spinal cord stimulation (B-SCS) for chronic back and/or leg pain (NCT03082261). The analysis cohort consisted of subjects who completed the NRS, Pain Catastrophizing Scale (PCS), EuroQol-5D (EQ-5D), and eight-item Patient-Reported Outcomes Measurement Information System Physical Function preoperatively and at 12 months after implant.

RESULTS

A principal component analysis showed that each of the four measures contributed equally to the variance in the data set, confirming that pain score should not be used alone. Subjects who failed to respond on NRS responded on both PCS and EQ-5D. Eighty-one percent of subjects responded on at least two measures. The responder algorithm yielded an 84% success rate at both 6- and 12-month time points.

CONCLUSIONS

Our study suggests that therapeutic response, similar to the chronic pain experience, is multidimensional. Careful consideration should be made to incorporate composite endpoints in future SCS clinical trials.

Task-Specific Sensitivity in Physical Function Testing Predicts Outcome in Patients With Low Back Pain

OBJECTIVE

To investigate the prognostic value of task-specific sensitivity in patients with low back pain by exploring whether task-specific sensitivity during physical function testing was associated with self-reported change in pain and disability.

DESIGN

Prospective cohort study nested in a randomized controlled trial.

METHODS

The study included 260 patients with low back pain, referred for evaluation in a secondary care setting. All patients completed questionnaires and underwent clinical examination by a physical therapist. Patients rated their pain intensity before and after completing a test battery measuring physical function and were classified into 4 categories-worse, unchanged, better, or no pain-depending on their pain response. At 3-month follow-up, outcomes were obtained by a postal questionnaire.

RESULTS

Task-specific sensitivity significantly predicted pain, after adjusting for known prognostic factors. Patients in the no pain, better, and unchanged groups improved their pain score significantly more than patients in the worse pain group. Patients in the no pain group also improved their disability score significantly more compared to patients in the worse pain group, after adjusting for known prognostic factors.

CONCLUSION

Task-specific sensitivity predicted pain intensity after 3 months in patients with low back pain. The prognostic value appears limited with respect to disability. J Orthop Sports Phys Ther 2020;50(4):206-213. Epub 30 Oct 2019. doi:10.2519/jospt.2020.8953.

Identifying pain perceptual biases related to fear of pain and threat in a pain-free sample

BACKGROUND

The association between fear of pain (FOP) and pain intensity has remained unclear. This study aimed to examine whether highly pain-fearful participants showed pain perceptual biases to general painful stimulus or to specific threatening painful stimulus.

METHODS

Fifty-nine undergraduates were recruited into low (n = 30) and high (n = 29) FOP groups and completed a threatening pain perception task with two tasks. Task 1 assessed pain perceptual biases by calculating the percentage of near-threshold pain stimulus judged as painful and assessing the average pain intensity ratings to those painful stimuli. Task 2 assessed pain perceptual biases by measuring pain ratings to each single threshold (low intensity) and twice-threshold (high intensity) pain stimulus.

RESULTS

Results from task 1 indicated that higher FOP levels were associated with higher pain sensitivity when pain was appraised as a threat, reflected as high FOP group reporting higher pain intensity to those stimuli judged as painful in high threat condition than in low threat condition. Consistently, results from task 2 observed that when noxious stimulus intensity increased to threshold pain and twice threshold pain levels, high FOP group also generally reported higher pain intensity in high threat condition than in low threat condition. However, for both tasks, no such threat level differences were observed in low FOP group.

CONCLUSIONS

The current research emphasized that participants with higher FOP level showed pain perceptual biases to specific threatening painful stimulus. Threat appraisal of pain played a key role in the positive association between pain-related fear and pain perceptual biases.

SIGNIFICANCE

The findings highlight the modulatory influence of threat appraisal of pain in the positive association between pain-related fear and pain perceptual biases.

Biopsychosocial Influences on Shoulder Pain: Analyzing the Temporal Ordering of Postoperative Recovery

Shoulder surgery is a primary intervention for shoulder pain, yet many individuals experience persistent postoperative pain. Previously, we found individuals categorized as having a high-risk phenotype (comprised of COMT variation and pain catastrophizing) had approximately double the chance of not reaching a 12-month pain recovery criterion. As a means to better understand the development of persistent postoperative shoulder pain, this study advanced our previous work by examining temporal ordering of postoperative shoulder recovery based on potential mediating factors, and expansion of outcomes to include movement-evoked pain and shoulder active range of motion. Before surgery, individuals were categorized as either high-risk (high pain catastrophizing, COMT-genotype linked to low enzyme activity [n = 41]) or low-risk (low pain catastrophizing, COMT-genotype linked to normal enzyme activity [n = 107]). We then compared potential mediating variables at 3, 6, and 12 months postoperatively 1) endogenous pain modulation defined by a conditioned pain modulation paradigm; and 2) and emotion factors such as anxiety, fear of movement, and depressive symptoms. At 3 months, the high-risk subgroup had higher fear and movement-evoked pain, and causal mediation analysis confirmed the direct effect of risk subgroup on 12-month movement evoked pain. However, baseline to 12-month change in depressive symptoms were found to mediate 53% of the total effect of risk subgroup on 12-month movement-evoked pain. This study introduces potential temporal components and relationships to the development of persistent postoperative shoulder pain, which future studies will confirm and assess for potential therapeutic targets. PERSPECTIVE: This study expands upon postoperative shoulder recovery measures to include movement-evoked pain and depressive symptoms, and provides preliminary indication of temporal ordering to postoperative shoulder recovery for a preidentified high-risk subgroup. Future studies will distinguish temporal components of shoulder surgery that may optimize treatment targets of postoperative recovery.

Psychological and physical factors related to disability in chronic low back pain

BACKGROUND

Chronic low back pain (CLBP) is a public health problem that causes high levels of disability. Psychological and physical factors could play a critical role in the disability perception of patients.

OBJECTIVE

The objective was to identify the psychological and physical factors associated with CLBP disability in patients and assess differences between asymptomatic subjects and CLBP patients through physical tests and psychological self-reports.

METHODS

A cross-sectional study was performed. Total sample of 80 participants were classified into two groups: patients with CLBP (n= 49) and asymptomatic subjects (i.e. the control group) (n= 31). The physical tests included lower back range of motion (LBROM), postural stability, lower back strength (LBS), and lumbopelvic motor control tests. The psychological self-reports included low back disability (Roland Morris Disability Questionnaire), self-efficacy, pain catastrophizing, and pain-related fear.

RESULTS

Self-efficacy and LBS displayed moderate negative correlations with disability in patients with CLBP (R=-0.47 and -0.40, respectively). Disability was predicted by self-efficacy and LBROM (β=-0.45 and -033 respectively, p< 0.01), explaining 30% of the variance in these patients. The comparative analysis showed statistically significant differences between groups in the physical/psychological variables (p< 0.01); however, the effect-sizes were small for all these variables.

CONCLUSIONS

The results of this study highlight the relevance of psychological and physical factors in CLBP patient disability. Evaluation and treatment in CLBP patients should take these factors into account.

Parental Proxy PROMIS Pain Interference Scores are Only Modestly Concordant With Their Child's Scores: An Effect of Child Catastrophizing

OBJECTIVES

Pediatric patients with chronic musculoskeletal conditions such as idiopathic scoliosis awaiting surgical correction can experience pain that interferes with their daily functioning. Reports of this interference are commonly gathered from patients through the Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Interference Scale and through parent-proxy scores. However, the child and parent/caregiver reports vary. To provide appropriate treatment for young patients with pain, the nature of the discrepancies and under which circumstances the reports differ needs to be understood. This report offers new information on the level of concordance among parent and child report of pain interference within this patient population, and which parent and child characteristics may influence concordance rates.

METHODS

Youth (age=10 to 17 y) with a history of musculoskeletal disorders, including idiopathic scoliosis, under consideration for surgical correction of that scoliosis and parent/caregiver dyads (n=103) completed the PROMIS Pain Interference Scale during an orthopedic presurgical visit. The current data was taken from a larger study examining postsurgical pain among patients undergoing orthopedic surgical procedures to correct scoliosis. The purpose of the current study was to measure the degree of agreement between parent and child reports of pain interference and discovery of relationships among predictors of pain interference score correspondence among dyads.

RESULTS

Correspondence between parent/caregiver and child reports of pain interference was modest (intraclass correlation coefficient=0.530). In total, 46% of dyads had similar pain interference scores, whereas 24% of parents reported higher pain interference in comparison to their child, the remaining 30% reported lower pain interference in relation to their child's report. Among children where discrepancies appeared, using logistic regression models, only child catastrophizing scores were associated with differences in parent and child estimation of child's pain interference scores. No parental characteristics predicted discrepancies between dyad pain interference reports.

DISCUSSION

Parent-proxy and child reports generally correspond, but when discrepant, 24% of parents reported higher pain interference in relationship to the child report of pain interference and 31% noted less intense pain interference than their child's pain interference. Given these results, care should be taken when interpreting parent reports of child pain interference, especially when a child reports higher degrees of pain interference.

Somatosensory and Motor Differences between Physically Active Patients with Chronic Low Back Pain and Asymptomatic Individuals

Background and Objectives: Chronic low back pain (CLBP) is the most common occupational disorder due to its associated disability and high risk of recurrence and chronicity. However, the mechanisms underlying physical and psychological variables in patients with CLBP remain unclear. The main objective of this study was to assess whether there were differences between physically active patients with nonspecific CLBP compared with asymptomatic individuals in sensorimotor and psychological variables. Materials and Methods: This was an observational cross-sectional design with a nonprobabilistic sample. The sample was divided into two groups: individuals with nonspecific CLBP (n = 30) and asymptomatic individuals as a control (n = 30). The psychological variables assessed were low back disability, fear of movement, pain catastrophizing, and self-efficacy. The sensorimotor variables assessed were two-point discrimination, pressure pain threshold, lumbopelvic stability, lumbar flexion active range of motion, and isometric leg and back strength. Results: Statistically significant differences between the groups in terms of catastrophizing levels (p = 0.026) and fear of movement (p = 0.001) were found, but no statistically significant differences between groups were found in self-efficacy (p > 0.05). No statistically significant differences between the groups in any of the sensorimotor variables were found (p > 0.05). Conclusion: No sensorimotor differences were found between patients with asymptomatic and chronic low back pain, but differences were found in the psychological variables of catastrophizing and fear of movement.

Sensitivity to Physical Activity Predicts Daily Activity Among Pain-Free Older Adults

Objective

Prior research indicates that older adults with knee osteoarthritis have increased sensitivity to physical activity (SPA) and respond to physical activities of stable intensity with increases in pain. Whether SPA is present in healthy older adults without chronic pain and predicts functional outcomes remains relatively unexplored. The purpose of this study was to determine the degree of SPA in healthy older adults in response to a standardized walking task, and whether SPA was associated with temporal summation of pain, pain-related fear of movement, and functional outcomes.

Methods

Fifty-two older adults without chronic pain completed self-reported measures of activity-related pain and physical function, completed the Six-Minute Walk Test (6MWT), underwent quantitative sensory testing to measure temporal summation of heat pain, and wore an accelerometer for one week to measure physical activity behavior. Subjects rated overall bodily discomfort (0-100 scale) prior to and during each minute of the 6MWT. An SPA index was created by subtracting the initial bodily discomfort ratings from the peak ratings.

Results

Repeated-measures analysis of variance indicated that bodily discomfort significantly increased across the walking task, with approximately 60% of the sample experiencing SPA. Hierarchical regressions indicated that greater SPA was associated with fewer average steps per day and greater activity-related pain. Additionally, analyses revealed that temporal summation of pain and pain-related fear of movement significantly predicted the degree of SPA on the walking task.

Conclusions

These findings shed light on potential mechanisms underlying SPA in older adults and suggest that SPA might be a risk factor for reduced physical activity.

Chronic low back pain is highly individualised: patterns of classification across three unidimensional subgrouping analyses

BACKGROUND AND AIMS

Chronic low back pain (CLBP) is a complex disorder where central and peripheral nociceptive processes are influenced by factors from multiple dimensions associated with CLBP (e.g. movement, pain sensitivity, psychological). To date, outcomes for treatments matched to unidimensional subgroups (e.g. psychologically-based) have been poor. Therefore, unidimensional subgrouping may not reflect the complexity of CLBP presentations at an individual level. The aim of this study was therefore to explore patterns of classification at an individual level across the three previously-published, data-driven, within-dimension subgrouping studies.

METHODS

Cross-sectional, multidimensional data was collected in 294 people with CLBP. Statistical derivation of subgroups within each of three clinically-important dimensions (pain sensitivity, psychological profile, pain responses following repeated spinal bending) was briefly reviewed. Patterns of classification membership were subsequently tabulated across the three dimensions.

RESULTS

Of 27 possible patterns across these dimensions, 26 were represented across the cohort.

CONCLUSIONS

This result highlights that while unidimensional subgrouping has been thought useful to guide treatment, it is unlikely to capture the full complexity of CLBP. The amount of complexity important for best patient outcomes is currently untested.

IMPLICATIONS

For clinicians this study highlights the high variability of presentations of people with CLBP at the level of the individual. For example, clinician's should not assume that those with high levels of pain sensitivity will also have high psychological distress and have pain summation following repeated spinal bending. A more flexible, multidimensional, clinically-reasoned approach to profile patient complexity may be required to inform individualised, patient-centred care. Such individualised care might improve treatment efficacy. This study also has implications for researchers; highlighting the inadequacy of unidimensional subgrouping processes and methodological difficulties in deriving subgroups across multidimensional data.

Exercise-Induced Hypoalgesia in Pain-Free and Chronic Pain Populations: State of the Art and Future Directions

Exercise is considered an important component of effective chronic pain management and it is well-established that long-term exercise training provides pain relief. In healthy, pain-free populations, a single bout of aerobic or resistance exercise typically leads to exercise-induced hypoalgesia (EIH), a generalized reduction in pain and pain sensitivity that occurs during exercise and for some time afterward. In contrast, EIH is more variable in chronic pain populations and is more frequently impaired; with pain and pain sensitivity decreasing, remaining unchanged or, in some cases, even increasing in response to exercise. Pain exacerbation with exercise may be a major barrier to adherence, precipitating a cycle of physical inactivity that can lead to long-term worsening of both pain and disability. To optimize the therapeutic benefits of exercise, it is important to understand how EIH works, why it may be impaired in some people with chronic pain, and how this should be addressed in clinical practice. In this article, we provide an overview of EIH across different chronic pain conditions. We discuss possible biological mechanisms of EIH and the potential influence of sex and psychosocial factors, both in pain-free adults and, where possible, in individuals with chronic pain. The clinical implications of impaired EIH are discussed and recommendations are made for future research, including further exploration of individual differences in EIH, the relationship between exercise dose and EIH, the efficacy of combined treatments and the use of alternative measures to quantify EIH. PERSPECTIVE: This article provides a contemporary review of the acute effects of exercise on pain and pain sensitivity, including in people with chronic pain conditions. Existing findings are critically reviewed, clinical implications are discussed, and recommendations are offered for future research.

STarT Back Tool risk stratification is associated with changes in movement profile and sensory discrimination in low back pain: A study of 290 patients

BACKGROUND

Investigation of movement and sensory profiles across STarT Back risk subgroups.

METHODS

A chronic low back pain cohort (n = 290) were classified as low, medium or high risk using the STarT Back Tool, and completed a repeated spinal bending task and quantitative sensory testing. Pain summation, time taken and the number of protective behaviours with repeated bending were measured. Sensory tests included two-point discrimination, temporal summation, pressure/thermal pain thresholds and conditioned pain modulation. Subgroups were profiled against movement and sensory variables.

RESULTS

The high-risk subgroup demonstrated greater pain summation following repeated forward bending (p < 0.001). The medium-risk subgroup demonstrated greater pain summation following repeated backward bending (p = 0.032). Medium- and high-risk subgroups demonstrated greater forward/backward bend time compared to the low-risk subgroup (p = 0.001, p = 0.005, respectively). Medium- and high-risk subgroups demonstrated a higher number of protective behaviours per forward bend compared to the low-risk subgroup (p = 0.008). For sensory variables, only two-point discrimination differed between subgroups, with medium- and high-risk subgroups demonstrating higher thresholds (p = 0.016).

CONCLUSIONS

This study showed altered movement characteristics and sensory discrimination across SBT risk subgroups in people with CLBP. Membership of the high SBT risk subgroup was associated with greater pain and disability levels, greater pain summation following repeated bending, slower bending times, a greater number of protective behaviours during forward bending, and a higher TPD threshold. Treatment outcomes for higher risk SBT subgroups may be enhanced by interventions specifically targeting movement and sensory alterations.

SIGNIFICANCE

In 290 people with chronic low back pain movement profile and two-point discrimination threshold differed across risk subgroups defined by the STarT Back Tool. Conversely, pain sensitivity did not differ across these subgroups. These findings may add further guidance for targeted care in these subgroups.

Examining Injustice Appraisals in a Racially Diverse Sample of Individuals With Chronic Low Back Pain

Injustice perception has emerged as a risk factor for problematic musculoskeletal pain outcomes. Despite the prevalence and impact of chronic low back pain (CLBP), no study has addressed injustice appraisals specifically among individuals with CLBP. In addition, despite racial/ethnic disparities in pain, existing injustice research has relied almost exclusively on white/Caucasian participant samples. The current study examined the associations between perceived injustice and pain, disability, and depression in a diverse community sample of individuals with CLBP (N = 137) -51 (37.2%) white, 43 (31.4%) Hispanic, 43 (31.4%) black or African American). Anger variables were tested as potential mediators of these relationships. Controlling for demographic and pain-related covariates, perceived injustice accounted for unique variance in self-reported depression and disability outcomes, but not pain intensity. State and trait anger, and anger inhibition mediated the association between perceived injustice and depression; no additional mediation by anger was observed. Significant racial differences were also noted. Compared with white and Hispanic participants, black participants reported higher levels of perceived injustice related to CLBP, as well as higher depression and pain-related disability. Black participants also reported higher pain intensity than white participants. Current findings provide initial evidence regarding the role of injustice perception specifically in the context of CLBP and within a racially diverse participant sample. Results highlight the need for greater diversity within injustice and CLBP research as well as research regarding socially informed antecedents of injustice appraisals. Perspective: Perceived injustice predicted worse outcomes in CLBP, with effects partially mediated by anger. Black participants reported worse pain outcomes and higher injustice perception than their white or Hispanic counterparts. Given racial inequities within broader health and pain-specific outcomes, this topic is critical for CLBP and perceived injustice research.

Predictive Value of the Fear-Avoidance Model on Functional Capacity Evaluation

Purpose Measuring the predictive value of the Fear-Avoidance Model (FAM) on lifting tasks in Functional Capacity Evaluation (FCE), and on reasons for stopping the evaluation (safe maximal effort, versus self-limited). Methods A monocentric prospective study was conducted on 298 consecutive inpatients. Components of the FAM were analyzed using the Cumulative Psychosocial Factor Index (CPFI: kinesiophobia, catastrophizing, depressive mood) and perceived disability (Hand/Spinal Function Sort: HFS/SFS). Floor-to-waist, waist-to-overhead and dominant-hand lifting tests were measured according to the FCE guidelines. Maximal safe performance was judged by certified FCE assessors. Analyses were conducted with linear multiple regression models. Results The CPFI was significantly associated with the 3 FCE lifting tests: floor-to-waist (ß = - 1.12; p = 0.039), waist-to-overhead (ß = - 0.88; p = 0.011), and dominant-handed lifting (ß = - 1.21; p = 0.027). Higher perceived disability was also related to lower performances: floor-to-waist (ß = 0.09; p < 0.001), waist-to-overhead (ß = 0.04; p < 0.001), and dominant-handed lifting (ß = 0.06; p < 0.001). The CPFI was not related to performances of patients with self-limited effort despite higher psychological scores, while a relationship was found for patients who achieved a safe maximal performance. Higher perceived disability was related to performances in both situations. Conclusions FAM components should be taken into account when interpreting maximal physical performance in FCE. This study also suggests that factors other than pain-related fears may influence patients with self-limited effort.

Validation of an index of Sensitivity to Movement-Evoked Pain in patients with whiplash injuries

Introduction: Sensitivity to Movement-Evoked Pain is a pain summation phenomenon identified in various chronic pain populations. Objectives: This study investigated the validity of a procedure used to assess pain summation in response to a repeated lifting task in individuals with whiplash injuries. Methods: Sixty-five participants completed measures of pain severity and duration, Temporal Summation (TS) of pinprick pain, pain catastrophizing and fear of movement, and work-related disability before lifting a series of 18 weighted canisters. An index of Sensitivity to Movement-Evoked Pain was computed as the increase in pain reported by participants over successive lifts of the weighted canisters. An index of TS was computed by dividing the pain reported in response to the final pinprick by the pain reported in response to the 1st pinprick in a train of 10 pinpricks. Results: Analyses replicated previous findings showing a repetitive lifting task-induced pain summation in approximately 20% to 25% of a sample of individuals with whiplash injuries. Analyses also revealed significant correlations between SMEP, TS, and pain-related psychological variables. Hierarchical regression analyses showed that TS and pain catastrophizing made significant unique contributions to the prediction of SMEP. These findings join a growing body of research on movement-evoked pain in persistent spinal pain conditions. Conclusion: The repeated lifting task used in this study successfully induced pain summation in a group of patients with whiplash injuries.

Role of kinesiophobia on pain, disability and quality of life in people suffering from chronic musculoskeletal pain: a systematic review

Objective

(1) To explore the level of association between kinesiophobia and pain, disability and quality of life in people with chronic musculoskeletal pain (CMP) detected via cross-sectional analysis and (2) to analyse the prognostic value of kinesiophobia on pain, disability and quality of life in this population detected via longitudinal analyses.

Design

A systematic review of the literature including an appraisal of the risk of bias using the adapted Newcastle Ottawa Scale. A synthesis of the evidence was carried out.

Data sources

An electronic search of PubMed, AMED, CINAHL, PsycINFO, PubPsych and grey literature was undertaken from inception to July 2017.

Eligibility criteria for selecting studies

Observational studies exploring the role of kinesiophobia (measured with the Tampa Scale for Kinesiophobia) on pain, disability and quality of life in people with CMP.

Results

Sixty-three articles (mostly cross-sectional) (total sample=10 726) were included. We found strong evidence for an association between a greater degree of kinesiophobia and greater levels of pain intensity and disability and moderate evidence between a greater degree of kinesiophobia and higher levels of pain severity and low quality of life. A greater degree of kinesiophobia predicts the progression of disability overtime, with moderate evidence. A greater degree of kinesiophobia also predicts greater levels of pain severity and low levels of quality of life at 6 months, but with limited evidence. Kinesiophobia does not predict changes in pain intensity.

Summary/conclusions

The results of this review encourage clinicians to consider kinesiophobia in their preliminary assessment. More longitudinal studies are needed, as most of the included studies were cross-sectional in nature.

Trial registration number

CRD42016042641.

A Machine Learning-based Surface Electromyography Topography Evaluation for Prognostic Prediction of Functional Restoration Rehabilitation in Chronic Low Back Pain

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to investigate the feasibility and applicability of support vector machine (SVM) algorithm in classifying patients with LBP who would obtain satisfactory or unsatisfactory progress after the functional restoration rehabilitation program.

SUMMARY OF BACKGROUND DATA

Dynamic surface electromyography (SEMG) topography has demonstrated the potential use in predicting the prognosis of functional restoration rehabilitation for patients with low back pain (LBP). However, processing from raw SEMG topography to make prediction is not easy to clinicians.

METHODS

A total of 30 patients with nonspecific LBP were recruited and divided into "responding" and "non-responding" group according to the change of Visual analog pain rating scale and Oswestry Disability Index. Each patient received a 12-week functional restoration rehabilitation program. A normal database was calculated from a control group from 48 healthy participants. Root-mean-square difference (RMSD) was extracted from the recorded dynamic SEMG topography during symmetrical and asymmetrical trunk-movement. SVM and cross-validation were applied to the prediction based on the optimized features selected by the sequential floating forward selection (SFFS) algorithm.

RESULTS

RMSD feature parameters following rehabilitation in the "responding" group showed a significant difference (P < 0.05) with the one in the "nonresponding" group. The SVM classifier with Quadratic kernel based on SFFS-selected features showed the best prediction performance (accuracy: 96.67%, sensitivity: 100%, specificity: 93.75%, average area under curve [AUC]: 0.8925) comparing with linear kernel (accuracy: 80.00%, sensitivity: 85.71%, specificity: 75.00%, average AUC: 0.7825), polynomial kernel (accuracy: 93.33%, sensitivity: 92.86%, specificity: 93.75%, average AUC: 0.9675), and radial basis function (RBF) kernel (accuracy: 86.67%, sensitivity: 85.71%, specificity: 87.50%, average AUC: 0.7900).

CONCLUSION

The use of SVM-based classifier of SEMG topography can be applied to identify the patient responding to functional restoration rehabilitation, which will help the healthcare worker to improve the efficiency of LBP rehabilitation.

LEVEL OF EVIDENCE

3.

Sensitivity to Movement-Evoked Pain and Multi-Site Pain are Associated with Work-Disability Following Whiplash Injury: A Cross-Sectional Study

Objectives Previous research has shown that sensitivity to movement-evoked pain is associated with higher scores on self-report measures of disability in individuals who have sustained whiplash injuries. However, it remains unclear whether sensitivity to movement-evoked pain is associated with work-disability. The aim of the present study was to examine the relation between sensitivity to movement-evoked pain and occupational status in individuals receiving treatment for whiplash injury. Methods A sample of 105 individuals with whiplash injuries participated in a testing session where different measures of pain (i.e. spontaneous pain, multi-site pain, sensitivity to movement-evoked pain) were collected during the performance of a simulated occupational lifting task. Results Hierarchical logistic regression analysis revealed that the measures of multisite pain and sensitivity to movement-evoked pain made significant independent contributions to the prediction of work-disability. Discussion The findings suggest that including measures of multisite pain and sensitivity to movement evoked pain in assessment protocols has the potential to increase the value of pain assessments for the prediction of occupational disability associated with whiplash injury. Clinical and theoretical implications of the findings are addressed.