Divergent Sensory Phenotypes in Nonspecific Arm Pain: Comparisons With Cervical Radiculopathy

Reliability of a clinical sensory test battery in patients with spine-related leg and arm pain

BACKGROUND

The current standard to evaluate the presence of somatosensory dysfunctions is quantitative sensory testing, but its clinical utility remains limited. Low-cost and time-efficient clinical sensory testing (CST) batteries have thus been developed. Recent studies show moderate to substantial reliability in populations with neuropathic pain. This study evaluates the inter- and intra-tester reliability of people with spine-related leg and arm pain, representing mixed pain mechanisms.

METHODS

Fifty-three patients with spine-related leg (n = 41) and arm pain (n = 12) attended three CST sessions. The CST battery consisted of eleven tests, determining loss and gain of sensory nerve function. CST was performed by the same investigator twice and by an additional investigator to determine inter- and intra-tester reliability. Fleiss' (inter-tester) and Cohen's (intra-tester) kappa were calculated for dichotomized and intraclass correlation coefficients (ICC) for continuous outcomes.

RESULTS

Fleiss' kappa varied among modalities from fair to substantial (κ = 0.23-0.66). Cold, warm, and vibration detection thresholds and cold and pressure pain thresholds reached kappa >0.4 (moderate to substantial reliability). Cohen's kappa ranged from moderate to substantial (κ = 0.45-0.66). The reliability of the windup ratio was poor (ICC <0.18).

CONCLUSION

CST modalities with moderate to substantial inter-tester reliability could be of benefit as a screening tool. The moderate to substantial intra-tester reliability for all sensory modalities (except windup ratio) supports their potential use in clinical practice and research to monitor somatosensory changes over time in patients with spine-related limb pain of mixed pain mechanisms.

SIGNIFICANCE

We already know that most modalities of clinical sensory test (CST) batteries achieve moderate to substantial inter- and intra-tester reliability in populations with neuropathic pain. This study evaluates the reliability of a CST battery in populations with mixed pain mechanisms. We found inter-tester reliability varied from poor to substantial for sensory modalities, questioning the value of some CST modalities. The CST battery showed moderate to substantial intra-tester reliability, suggesting its usefulness to monitor sensory changes over time in this cohort.

Continuum of somatosensory profiles in breast cancer survivors with and without pain, compared to healthy controls and patients with fibromyalgia

CONTEXT

The prevalence of persistent pain among breast cancer survivors (BCS) is high, and it is unclear what distinguishes those with persistent pain from those without. Research suggests that differences in somatosensory function evaluated by quantitative sensory testing (QST) may be responsible.

OBJECTIVES

This study aimed to describe somatosensory profiles in terms of hyper- and hypoesthesia in BCS with and without persistent pain using reference data from healthy controls. Second, QST parameters of BCS with and without pain were compared with those of healthy controls (i.e., a negative control group) and patients with fibromyalgia (i.e., a positive control group).

METHODS

Participants (n = 128) were divided into four equal groups: healthy controls, BCS with persistent pain, BCS without persistent pain, and patients with fibromyalgia. Nine QST parameters were evaluated at the trunk and at a remote location. Somatosensory profiles were determined by Z-score transformation of QST data using normative data from healthy controls.

RESULTS

At the trunk, compared to healthy controls, BCS with persistent pain exhibited sensory aberrations across five out of seven QST parameters: pressure pain threshold, mechanical detection, and thermal thresholds. Pain-free BCS showed similar sensory aberrations across the four QST parameters compared to healthy controls: mechanical detection and thermal thresholds. Temporal summation and conditioned pain modulation were not significantly different between groups.

CONCLUSION

BCS with persistent pain exert aberrations in peripheral processing of nociceptive signals, heightened facilitation of nociceptive signals, and higher psychosocial burden when compared to pain-free BCS, healthy controls, and patients with fibromyalgia.

SIGNIFICANCE

This study investigates the somatosensory function of breast cancer survivors with and without persistent pain using quantitative sensory testing and two control group (i.e., patients with fibromyalgia and healthy controls). Our results indicate somatosensory aberrations within the peripheral, but not central pathways in breast cancer survivors with persistent pain. Our findings contribute to a better understanding of the somatosensory mechanisms underlying persistent pain, which may inform future interventions to prevent the development of persistent pain, and improve treatment modalities.

Inter- and intra-rater-reliability of a clinical framework for spine-related neck-arm pain

OBJECTIVE

A mechanism-based clinical framework for spine-related pain differentiates (i) somatic referred pain, ii) heightened nerve mechanosensitivity, iii) radicular pain, iv) radiculopathy and mixed-pain. This study aimed to determine the reliability of proposed framework.

METHOD

Fifty-one people with unilateral spine-related neck-arm pain were assessed and categorized by examiner-1. The classifications were compared to those made by two other examiners, based on written documentation of examiner-1. Cohens kappa was calculated between examiner-pairs; Fleiss Kappa among all examiners to assess agreement in classifying subgroups and entire framework.

RESULT

Inter-rater-reliability showed moderate to almost perfect reliability (somatic: no variation, mechanosensitivity: 0.96 (95% CI 0.87-1.0) to 1.0 (95% CI: 1.0-1.0), radicular pain: 0.46 (95% CI: 0.19-0.69) to 0.62 (95% CI: 0.42-0.81), radiculopathy: 0.65 (95% CI: 0.43-0.84) to 0.80 (95% CI: 0.63-0.96) mixed-pain: 0.54 (95% CI: 0.21-0.81) to 0.75 (95% CI: 0.48-0.94). There was almost perfect to moderate reliability among all examiners (somatic: no variation, mechanosensitivity: 0.97 (95% CI: 0.82-1.0), radicular pain: 0.56 (95% CI: 0.40-0.71), radiculopathy: 0.74 (95% CI: 0.58-0.90), mixed-pain: 0.63 (95% CI: 0.47-0.79), entire framework: 0.64 (95% CI: 0.57-0.71)). Intra-rater-reliability showed substantial to almost perfect reliability (somatic: no variation, mechanosensitivity: 0.96 (95% CI: 0.87-1.0), radicular pain: 0.76 (95% CI: 0.57-0.92), radiculopathy: 0.84 (95% CI: 0.67-0.96), mixed-pain: 0.83 (95% CI: 0.60-1.0), entire framework: 0.80 (95% CI: 0.61-0.92).

CONCLUSION

Moderate to almost perfect reliability in subgrouping people with spine-related neck-arm pain and substantial reliability for entire framework support this classification's reliability.

Reflections of the sensory findings in the central nervous system in patients with neuropathic pain

This study aimed to evaluate whether there was a difference in functional magnetic resonance imaging (fMRI) findings in patients who were found having hyperalgesia or hypoesthesia according to Quantitative Sensory Tests (QST). Forty participants were included in the study: 20 with neuropathic pain (NP) due to cervical disc pathology (NP group) and 20 healthy volunteers. After obtaining the socio-demographic and clinical data of the participants, the painDETECT questionnaire was administered, followed by QST analysis to show the presence of hypoesthesia and/or hyperalgesia, and fMRI examinations, which included sensory stimulation of both extremities. Sensory threshold tests were found to be higher in the NP group compared with the healthy volunteers, and the heat pain threshold was found to be lower in the tests showing pain thresholds in the intergroup analyses (p < 0.05). The changes described were found in both painful and non-painful limbs. In the hypoesthetic NP group, a lower somatosensory cortex activity was found in non-painful limbs compared with the healthy volunteers (p < 0.05). In the unilateral hyperalgesic NP group, a lower somatosensory cortex activity was found on the painful side, and if the hyperalgesia was widespread, lower blood oxygen-level-dependent activity was also found in the operculum and insular cortex (p < 0.05). The patients with different phenotypes of NP had different activities in the areas related to the processing of pain, and were more prominent in patients with widespread hyperalgesia. Studies with larger numbers of patients are required for a definite statement.

Effect of manual therapy with exercise in patients with chronic cervical radiculopathy: a randomized clinical trial

BACKGROUND

Research that has examined the effects of cervical spine mobilization on hypoesthesia and hypersensitivity characteristics in patients with cervical radiculopathy is scarce. The aim of this study was to examine the short-term effects of vertebral mobilization on the sensory features in patients with cervical radiculopathy.

METHODS

Twenty-eight participants with chronic cervical radiculopathy were randomly allocated to (1) an experimental group [cervical vertebral mobilization technique and exercise] or (2) a comparison group [minimal superficial circular pressure on the skin and exercise]. Participants received a total of 6 sessions for 3-5 weeks. Numeric Pain Rating Scale (NPRS), Neck Disability Index (NDI), pressure pain threshold (PPT), heat/cold pain threshold (HPT/CPT), and active cervical range of motion (ROM) were measured at baseline immediately after the first session and after the sixth session.

RESULTS

The experimental group showed improvements from baseline to session 6 in NPRS [mean difference 2.6; 95% confidence interval: -4.6, -0.7], NDI [14; -23.3, -4.3], and active cervical ROM in extension [14°; 2.3, 25.5], rotation [16°; 8.8, 22.5], and lateral flexion to the affected side [10°; 2.3, 16.8]. Improvements were also found in PPT at the neck [124 kPa; 57, 191.1] and C7 level at the hand [99 kPa; 3.6, 194.9]. There were no changes in the HPT and CPT at any tested area (P>0.050).

CONCLUSIONS

Cervical vertebral mobilization for patients with chronic cervical radiculopathy reduced localized mechanical, but not thermal, pain hypersensitivity.

TRIAL REGISTRATION

ClinicalTrials.gov ( NCT03328351 ). Registered on November 1, 2017, retrospectively registered.

Sensory Perception in Lumbosacral Radiculopathy with Radicular Pain: Feasibility Study of Multimodal Bedside-Suitable Somatosensory Testing

Background

Somatosensory testing could be useful in stratifying pain patients and improving pain treatment guidelines. Bedside-suitable techniques are searched for application in daily clinical practice. This study aimed to characterize chronic unilateral lumbosacral radiculopathy (LSR) patients with radicular pain using multimodal bedside-suitable somatosensory testing.

Materials and methods

We evaluated 50 chronic unilateral LSR patients with radicular pain (LSR group) and 24 controls (Control group). Sensory testing was performed using a battery of bedside sensory tests (10g monofilament, 200–400 mN brush, Lindblom rollers with controlled 25°C and 40°C temperature, and 40g neurological pin and investigator’s finger pressure). Participants had to rate their sensory perceptions on both legs at multiple test points within L3 to S2 dermatomes. Characteristics of the testing process and sensory disturbances were analyzed.

Results

LSR group showed sensory disturbances in 82% of patients. The Control group showed no sensory disturbances. Sensory testing took longer (p < 0.001) in the LSR group (29.3 ± 6.5 minutes per patient) than in the Control group (20.5 ± 5.2). Nine sensory phenotypes were detected in the LSR group according to individual sensory disturbances within 5 superficial tests.

Conclusions

The applied multimodal bedside-suitable somatosensory testing battery is suitable for sensory evaluation and characterization of LSR patients. Grouping of allied sensory phenotypes revealed some tendencies in pain intensity characteristics.

Masterclass: A pragmatic approach to pain sensitivity in people with musculoskeletal disorders and implications for clinical management for musculoskeletal clinicians

INTRODUCTION

Research on musculoskeletal disorders indicates that pain sensitivity can be an important consideration for musculoskeletal clinicians in the holistic view of a patient presentation. However, diversity in research findings in this field can make this a difficult concept for clinicians to navigate. Limited integration of the concept of pain sensitivity into clinical practice for musculoskeletal clinicians has been noted.

PURPOSE

The purpose of this masterclass is to provide a framework for the consideration of pain sensitivity as a contributing factor in the presentation of people with musculoskeletal pain. It provides pragmatic synthesis of the literature related to pain sensitivity through a lens of how this information can inform clinical practice for musculoskeletal clinicians. Guidance is provided in a 'how to' format for integration of this knowledge into the clinical encounter to facilitate personalised care.

IMPLICATIONS

The relationship of pain sensitivity with pain and disability is not clear or linear. The real importance of pain sensitivity in a clinical presentation may be: (1) the potential for pain sensitivity to modify the effect of common treatments utilised by musculoskeletal clinicians, or (2) the effect of pain sensitivity on the prognosis/course of a disorder. Screening tools and subjective features have been highlighted to indicate when physical assessment of pain sensitivity should be prioritised in the physical examination. A pragmatic blueprint for specific assessment related to pain sensitivity has been outlined. A framework for integrating assessment findings into clinical reasoning to formulate management plans for the pain sensitive patient is provided.

Application and utility of a clinical framework for spinally referred neck-arm pain: A cross-sectional and longitudinal study protocol

BACKGROUND

The clinical presentation of neck-arm pain is heterogeneous with varying underlying pain types (nociceptive/neuropathic/mixed) and pain mechanisms (peripheral/central sensitization). A mechanism-based clinical framework for spinally referred pain has been proposed, which classifies into (1) somatic pain, (2) neural mechanosensitivity, (3) radicular pain, (4) radiculopathy and mixed pain presentations. This study aims to (i) investigate the application of the clinical framework in patients with neck-arm pain, (ii) determine their somatosensory, clinical and psychosocial profile and (iii) observe their clinical course over time.

METHOD

We describe a study protocol. Patients with unilateral neck-arm pain (n = 180) will undergo a clinical examination, after which they will be classified into subgroups according to the proposed clinical framework. Standardized quantitative sensory testing (QST) measurements will be taken in their main pain area and contralateral side. Participants will have to complete questionnaires to assess function (Neck Disability Index), psychosocial factors (Tampa Scale of Kinesiophobia, Pain Catastrophizing Scale, Depression, anxiety and stress scale), neuropathic pain (Douleur Neuropathique 4 Questions, PainDETECT Questionnaire) and central sensitization features (Central Sensitization Inventory). Follow-ups at three, six and 12 months include the baseline questionnaires. The differences of QST data and questionnaire outcomes between and within groups will be analyzed using (M)AN(C)OVA and/or regression models. Repeated measurement analysis of variance or a linear mixed model will be used to calculate the differences between three, six, and 12 months outcomes. Multiple regression models will be used to analyze potential predictors for the clinical course.

CONCLUSION

The rationale for this study is to assess the usability and utility of the proposed clinical framework as well as to identify possible differing somatosensory and psychosocial phenotypes between the subgroups. This could increase our knowledge of the underlying pain mechanisms. The longitudinal analysis may help to assess possible predictors for pain persistency.

Somatosensory profiles in patients with non-specific neck-arm pain with and without positive neurodynamic tests

Despite normal neurological integrity tests, some patients with non-specific neck-arm pain (NSNAP) have heightened nerve mechanosensitivity upon neurodynamic testing. The aim of this study was to determine whether or not a nerve dysfunction is present in patients with positive neurodynamic tests compared to those with negative neurodynamic tests or healthy controls. Somatosensory profiling using quantitative sensory testing (QST) was established in 40 consecutive patients with unilateral NSNAP; 23 had positive upper limb neurodynamic tests (ULNT_POS) and 17 had negative neurodynamic tests (ULNT_NEG) and in 26 healthy controls. QST included measurement of thermal and mechanical detection and pain thresholds in the maximal pain area on the symptomatic side as well as the corresponding contralateral area. Fifty-seven percent of patients with NSNAP had positive neurodynamic tests. Somatosensory profiling revealed a loss of function phenotype in NSNAP patients compared to healthy controls both in the maximal pain area and asymptomatic side. Hyperalgesia (cold, heat and pressure) was present bilaterally in both NSNAP groups. Direct comparison between the patient groups revealed no significant differences in somatosensory profiles. However, the ULNT_POS group demonstrated sensory loss compared to healthy controls in more parameters than the ULNT_NEG group. The ULNT_NEG subgroup represented an intermediate phenotype between ULNT_POS patients and healthy controls in most detection thresholds as well as thermal and pressure pain thresholds. Even though patients with NSNAP present as a spectrum, it remains unclear whether the sensory changes are indicative of a nerve dysfunction/lesion or rather a marker of altered central pain processing.

Neck pain in South Africa: An overview of the prevalence, assessment and management for the contemporary clinician

BACKGROUND

Neck pain is a prevalent condition and is associated with high levels of disability and pain. The long-term prognosis can be poor, and therefore effective management in the acute stage is important.

OBJECTIVES

To provide an overview of the prevalence of neck pain and physiotherapy management and to provide evidence-informed recommendations for clinical practice within a South African context.

METHOD

The literature was reviewed considering prevalence, risk factors and examination. Management recommendations were derived from the highest levels of evidence of clinical practice guidelines, systematic reviews and randomised clinical trials.

RESULTS

Neck pain is classified into four grades, and three trajectories of recovery have been identified. Although the incidence of neck pain globally is high, in the South African context the majority of the population have limited access to physiotherapy management. Sound clinical reasoning is important in the assessment and decision-making process for management. Exercise, and mobilisation or manipulation are effective treatment options in the management of most types of neck pain. Other physical modalities such as needling, transcutaneous electrical nerve stimulation, laser and intermittent traction may be used as an adjunct to management.

CONCLUSION

The burden of neck pain globally is high; however, there is a lack of information on current practice, prevalence and burden of neck pain in the South African context. Sound evidence-informed clinical reasoning to inform a working diagnosis and to enable patient-centred management is important.

CLINICAL IMPLICATIONS

A thorough assessment is essential to gather information to formulate hypotheses regarding diagnosis and prognosis for neck pain. Exercise, and mobilisation or manipulation are effective management options.

Concurrent validity of a low-cost and time-efficient clinical sensory test battery to evaluate somatosensory dysfunction

Background

This study describes a low‐cost and time‐efficient clinical sensory test (CST) battery and evaluates its concurrent validity as a screening tool to detect somatosensory dysfunction as determined using quantitative sensory testing (QST).

Method

Three patient cohorts with carpal tunnel syndrome (CTS, n = 76), non‐specific neck and arm pain (NSNAP, n = 40) and lumbar radicular pain/radiculopathy (LR, n = 26) were included. The CST consisted of 13 tests, each corresponding to a QST parameter and evaluating a broad spectrum of sensory functions using thermal (coins, ice cube, hot test tube) and mechanical (cotton wool, von Frey hairs, tuning fork, toothpicks, thumb and eraser pressure) detection and pain thresholds testing both loss and gain of function. Agreement rate, statistical significance and strength of correlation (phi coefficient) between CST and QST parameters were calculated.

Results

Several CST parameters (cold, warm and mechanical detection thresholds as well as cold and pressure pain thresholds) were significantly correlated with QST, with a majority demonstrating >60% agreement rates and moderate to relatively strong correlations. However, agreement varied among cohorts. Gain of function parameters showed stronger agreement in the CTS and LR cohorts, whereas loss of function parameters had better agreement in the NSNAP cohort. Other CST parameters (16 mN von Frey tests, vibration detection, heat and mechanical pain thresholds, wind‐up ratio) did not significantly correlate with QST.

Conclusion

Some of the tests in the CST could help detect somatosensory dysfunction as determined with QST. Parts of the CST could therefore be used as a low‐cost screening tool in a clinical setting.

Significance

Quantitative sensory testing, albeit considered the gold standard to evaluate somatosensory dysfunction, requires expensive equipment, specialized examiner training and substantial time commitment which challenges its use in a clinical setting. Our study describes a CST as a low‐cost and time‐efficient alternative. Some of the CST tools (cold, warm, mechanical detection thresholds; pressure pain thresholds) significantly correlated with the respective QST parameters, suggesting that they may be useful in a clinical setting to detect sensory dysfunction.

Are measures of pain sensitivity associated with pain and disability at 12-month follow up in chronic neck pain?

OBJECTIVES

Pain sensitivity and psychosocial issues are prognostic of poor outcome in acute neck disorders. However, knowledge of associations between pain sensitivity and ongoing pain and disability in chronic neck pain are lacking. We aimed to investigate associations of pain sensitivity with pain and disability at the 12-month follow-up in people with chronic neck pain.

METHODS

The predictor variables were: clinical and quantitative sensory testing (cold, pressure); neural tissue sensitivity; neuropathic symptoms; comorbidities; sleep; psychological distress; pain catastrophizing; pain intensity (for the model explaining disability at 12 months only); and disability (for the model explaining pain at 12 months only). Data were analysed using uni- and multivariate regression models to assess associations with pain and disability at the 12-month follow-up (n = 64 at baseline, n = 51 at follow-up).

RESULTS

Univariable associations between all predictor variables and pain and disability were evident (r > 0.3; p < 0.05), except for cold and pressure pain thresholds and cold sensitivity. For disability at the 12-month follow-up, 24.0% of the variance was explained by psychological distress and comorbidities. For pain at 12 months, 39.8% of the variance was explained primarily by baseline disability.

CONCLUSIONS

Neither clinical nor quantitative measures of pain sensitivity were meaningfully associated with long-term patient-reported outcomes in people with chronic neck pain, limiting their clinical application in evaluating prognosis.

Sensory profiles are comparable in patients with distal and proximal entrapment neuropathies, while the pain experience differs

OBJECTIVE

Distal and proximal entrapment neuropathies such as carpal tunnel syndrome (CTS) and cervical radiculopathy (CR) share similar etiologies. Experimental models suggest that, despite comparable etiology, pathomechanisms associated with injuries of the peripheral and central axon branches are distinct. This study therefore compared self-reported and elicited sensory profiles in patients with distal and proximal entrapment neuropathies.

METHODS

Patients with electrodiagnostically confirmed CTS (n = 103) and patients with CR (n = 23) were included in this study. A group of healthy participants served as controls (n = 39). Symptoms and sensory profiles were evaluated using quantitative sensory testing (QST) and a self-reported neuropathic pain questionnaire (painDETECT).

RESULTS

Both patient groups were characterized by a loss of function in thermal and mechanical detection in the main pain area and dermatome compared to healthy reference data (p < .001). There was no significant difference between patients with CTS and CR in pain and detection thresholds except for reduced vibration sense in the main pain area (p < .001) and reduced pressure pain sensitivity in the dermatome in patients with CR (p < .001). However, patients with CR reported higher pain intensities (p = .008), more severe pain attacks (p = .009) and evoked pain by light pressure (p = .002) compared to patients with CTS.

CONCLUSION

While QST profiles were similar between patients with CTS and CR, self-reported pain profiles differed and may suggest distinct underlying mechanisms in these patient cohorts.

The Potential Role of Sensory Testing, Skin Biopsy, and Functional Brain Imaging as Biomarkers in Chronic Pain Clinical Trials: IMMPACT Considerations

Valid and reliable biomarkers can play an important role in clinical trials as indicators of biological or pathogenic processes or as a signal of treatment response. Currently, there are no biomarkers for pain qualified by the U.S. Food and Drug Administration or the European Medicines Agency for use in clinical trials. This article summarizes an Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials meeting in which 3 potential biomarkers were discussed for use in the development of analgesic treatments: 1) sensory testing, 2) skin punch biopsy, and 3) brain imaging. The empirical evidence supporting the use of these tests is described within the context of the 4 categories of biomarkers: 1) diagnostic, 2) prognostic, 3) predictive, and 4) pharmacodynamic. Although sensory testing, skin punch biopsy, and brain imaging are promising tools for pain in clinical trials, additional evidence is needed to further support and standardize these tests for use as biomarkers in pain clinical trials.

PERSPECTIVE

The applicability of sensory testing, skin biopsy, and brain imaging as diagnostic, prognostic, predictive, and pharmacodynamic biomarkers for use in analgesic treatment trials is considered. Evidence in support of their use and outlining problems is presented, as well as a call for further standardization and demonstrations of validity and reliability.

Pain sensitization in people with knee osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

Emerging evidence suggests that pain sensitization plays an important role in pain associated with knee osteoarthritis (OA). This systematic review and meta-analysis examined the evidence for pain sensitization in people with knee OA and the relationship between pain sensitization and symptom severity.

METHODS

A search of electronic databases and reference lists was carried out. All full text observational studies published between 2000 and 2014 with the aim of investigating pain sensitization in humans with knee OA using quantitative sensory testing (QST) measures of hyperalgesia and central hyperexcitability were eligible for inclusion. Meta-analysis of data was carried out using a random effects model, which included results comparing knee OA participants to controls, and results comparing high symptom severity to low symptom severity.

RESULTS

Fifteen studies were identified following screening and quality appraisal. For the meta-analysis, pressure pain threshold (PPT) and heat pain threshold (HPT) means and standard deviations were pooled using random effects models. The point estimate was large for differences in PPTs between knee OA participants and controls [-0.85; confidence interval (CI): -1.1 to -0.6], and moderate for PPT differences between knee OA participants with high symptom severity vs those with low symptom severity (0.51; CI: -0.73 to -0.30). A small point estimate was found for differences in HPTs between knee OA participants and controls (-0.42; CI: -0.87 to 0.02).

CONCLUSION

Evidence from this systematic review and meta-analysis suggests that pain sensitization is present in people with knee OA and may be associated with knee OA symptom severity.