A mechanism-based pain sensitivity index to characterize knee osteoarthritis patients with different disease stages and pain levels

Cross-cultural adaption, validity, and reliability of the Japanese version of the Central Aspects of Pain in the Knee (CAP-Knee-J) questionnaire in patients with knee pain: a validation study

BACKGROUND

Knee pain is a prominent concern among older individuals, influenced by the central nervous system. This study aimed to translate the Central Aspects of Pain in the Knee (CAP-Knee) questionnaire into Japanese and investigate its reliability and validity in older Japanese individuals with knee pain.

METHODS

Using a forward-backward method, CAP-Knee was translated into Japanese, and data from 110 patients at an orthopedic clinic were analyzed. The Japanese version (CAP-Knee-J) was evaluated regarding pain intensity during walking, central sensitization inventory, and pain catastrophizing scale. Statistical analyses confirmed internal validity and test-retest reliability. Concurrent validity was assessed through a single correlation analysis between CAP-Knee-J and the aforementioned measures. Exploratory factor analysis was employed on each CAP-Knee-J item to examine structural validity.

RESULTS

CAP-Knee-J showed good internal consistency (Cronbach's α = 0.86) and excellent test-retest reliability (intraclass correlation coefficient = 0.77). It correlated significantly with pain intensity while walking, central sensitization inventory scores, and pain catastrophizing scale scores. Exploratory factor analysis produced a three-factor model.

CONCLUSIONS

CAP-Knee-J is a reliable and valid questionnaire for assessing central pain mechanisms specific to knee pain in older Japanese individuals, with moderate correlations with the CSI and weak with the PCS, thus indicating construct validity. This study supports the development of effective knee pain treatments and prognosis predictions.

Pressure pain mapping of equine distal joints: feasibility and reliability

Background

Osteoarthritis is a prevalent degenerative joint disease initiating chronic pain and lameness in horses. While several objective gait analysis systems have been developed and validated to quantify lameness severity in horses, methods to evaluate whether peripheral sensitization contributes to the pain experienced are missing.

Objectives

To evaluate whether periarticular pressure pain mapping could be proposed as an auxiliary assessment tool in horses. Specific aims were to evaluate the feasibility and intra- and inter-rater reliability of pressure pain thresholds (PPT) determination at sites overlying the distal thoracic limb joints of clinically healthy horses.

Study design

Prospective, randomized validation study.

Methods

For feasibility assessment, PPT were measured with a hand-held digital algometer at six periarticular landmarks (2 sites per joint, 3 joints) bilaterally on the distal thoracic limb of 40 healthy horses (20 warmblood and 20 Freiberger). The joints tested were the metacarpophalangeal, on the latero-palmar and dorsal aspects (L-MCP and D-MCP), the proximal interphalangeal, on the dorsal and palmar aspect (D-PIP and P-PIP) and the distal interphalangeal, on the dorsal and lateral aspect (D-DIP and L-DIP). A feasibility score, ranging from 0 to 5, was attributed to each testing session. For intra- and inter-rater reliability assessment, L-MCP and D-MCP were selected to be tested again at 2 weeks intervals in 20 out of the 40 horses. Data were analyzed using a mixed-effect linear model to test differences in threshold per site and limb. Intra- and inter-rater correlation was calculated. Bland-Altman plots were performed to evaluate the variability of the measures.

Results

The procedure was considered feasible (score <2) in 95% of horses (95% CI 88%-100%). Overall, median [interquartile range (IQR)] PPT was 9.4 (7.5-11.3) N. No significant side differences were found. P-PIP and D-DIP recorded significantly lower PPT (p < 0.001 and p = 0.002, respectively) than L-MCP. Median (IQR) were 9.9 (7.3-12.4) N, 8.4 (6.1-10.5) N and 9.0 (7.4-10.6) N for L-MCP, P-PIP and D-DIP, respectively. The intra-rater agreement was 0.68 (95% CI 0.35-0.86) for L-MCP, and 0.50 (95% CI 0.08-0.76) for D-MCP. Inter-rater agreement was 0.85 (95% CI 0.66-0.94) for L-MCP and 0.81 (0.57, 0.92) for D-MCP.

Main limitations

Evaluation of feasibility was performed only for distal thoracic limbs joints; no data are provided for hind limbs or proximal joints. Only warmblood and Freiberger horses were included. Intra- and inter-rater reliability assessments were performed exclusively on data collected at the MCP joint.

Conclusion

Pressure pain mapping of distal thoracic limb joints was feasible in horses. Local sensitivity differed among sites and no side differences were noticed. Data collected from the MCP joint suggest highly variable, subject dependent intra-rater reliability, ranging from poor to good, and good to excellent inter-rater reliability. Further studies evaluating pathologic vs. healthy joints are needed before recommendations can be made about clinical usability and diagnostic validity.

Conditioned pain modulation (CPM) paradigm type affects its sensitivity as a biomarker of fibromyalgia

Fibromyalgia (FM) is a widespread chronic pain syndrome, possibly associated with the presence of central dysfunction in descending pain inhibition pathways. Conditioned Pain Modulation (CPM) has been proposed as a biomarker of FM. Nonetheless, the wide variety of methods used to measure CPM has hampered robust conclusions being reached. To clarify the validity of CPM as a biomarker of FM, we tested two CPM paradigms (parallel and sequential) in a sample of 23 female patients and 23 healthy women by applying test (mechanical) stimuli and conditioning (pressure cuff) stimuli. We evaluated whether CPM indices could correctly classify patients and controls, and we also determined the correlations between the indices and clinical variables such as symptomatology, disease impact, depression, quality of life, pain intensity, pain interference, fatigue and numbness. In addition, we compared the clinical status of CPM responders (efficient pain inhibitory mechanism) and non-responders. We observed that only parallel CPM testing correctly classified about 70% of patients with FM. In addition, more than 80% of healthy participants were found to be responders, while the rate was about 50% in the FM patients. The sequential CPM test was not as sensitive, with a decrease of up to 40% in the response rate for both groups. On the other hand, we did not observe any correlation between CPM measures and clinical symptoms. In summary, our findings demonstrate the influence of the CPM paradigm used and confirm that CPM may be a useful marker to complement FM diagnosis. However, the findings also cast doubts on the sensitivity of CPM as a marker of pain severity in FM.

Mediating Effect of Pain Sensitization on the Paradoxical Relation of Taking Opioids to Pain Severity in Knee Osteoarthritis: The Multicenter Osteoarthritis Study

OBJECTIVE

One of the less understood adverse effects while taking opioids is the paradoxical increase in pain, known as opioid-induced hyperalgesia (OIH). We sought to determine whether pain sensitization mediates the relation of taking an opioid to pain severity in people with knee osteoarthritis (OA).

METHODS

We included participants in a National Institutes of Health-funded cohort study of people with or at risk of knee OA. Participants were categorized into opioid and nonopioid analgesic groups at baseline. Western Ontario McMaster Universities OA Index (WOMAC) pain two years later was assessed as the outcome. We used causal mediation analysis to assess the mediating role of pain sensitization, quantified by changes in pressure pain threshold (PPT) at the wrist and patella over two years, on the effect of taking an opioid on WOMAC pain two years later.

RESULTS

We included 296 participants who took opioids and 1,070 participants who took nonopioid analgesics. Compared with taking nonopioid analgesics, taking opioids was associated with greater pain two years later. This relation was mediated by 0.05- and 0.08-unit changes in wrist PPT (95% confidence interval [CI] 0.01-0.10) and patellar PPT (95% CI 0.02-0.14), respectively. When we assessed any worsening in WOMAC pain score over two years, taking opioids, compared with taking nonopioid analgesics, had 2% and 5% higher odds of experiencing any worsening pain mediated by changes in wrist PPT (95% CI 0.99-1.04) and patellar PPT (95% CI 1.01-1.09), respectively.

CONCLUSION

Pain sensitization had small mediating effects on the paradoxical phenomenon of OIH, suggesting that pain sensitization may not play a major role and/or that PPT is an inadequate tool to assess OIH.

Quantitative sensory testing, psychological factors, and quality of life as predictors of current and future pain in patients with knee osteoarthritis

ABSTRACT

Substantial interindividual variability characterizes osteoarthritis (OA) pain. Previous findings identify quantitative sensory testing (QST), psychological factors, and health-related quality of life as contributors to OA pain and predictors of treatment outcomes. This exploratory study aimed to explain baseline OA pain intensity and predict OA pain after administration of a nonsteroidal anti-inflammatory drug in combination with paracetamol for 3 weeks. The Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score was used to estimate OA pain presentation. One hundred one patients were assessed at baseline and follow-up using QST (pressure pain thresholds and temporal summation of pain [TSP]), symptoms of depression and anxiety, pain catastrophizing scales (PCSs), and health-related quality of life. Linear regression with backward selection identified that PCS significantly explained 34.2% of the variability in baseline KOOS pain, with nonsignificant contributions from TSP. Pain catastrophizing score and TSP predicted 29.3% of follow-up KOOS pain, with nonsignificant contributions from symptoms of anxiety. When assessed separately, PCS was the strongest predictor (32.2% of baseline and 24.1% of follow-up pain), but QST, symptoms of anxiety and depression, PCS, and quality of life also explained some variability in baseline and follow-up knee OA pain. Further analyses revealed that only TSP and PCS were not mediated by any other included variables, highlighting their role as unique contributors to OA pain presentation. This study emphasizes the importance of embracing a multimodal approach to OA pain and highlights PCS and TSP as major contributors to the baseline OA pain experience and the OA pain experience after OA treatment.

An overview of systematic reviews examining the quantitative sensory testing-derived hypoalgesic effects of manual therapy for musculoskeletal pain

BACKGROUND

Changes in quantitative sensory testing (QST) after manual therapy can provide insight into pain relief mechanisms. Prior systematic reviews have evaluated manual-therapy-induced QST change. This overview of systematic reviews aims to consolidate this body of literature and critically review evidence on the hypoalgesic effects of manual therapy in clinical populations.

METHODS

A comprehensive search was conducted on PubMed, CINAHL, PsycInfo, and Embase. Peer-reviewed systematic reviews with or without meta-analysis were eligible if the reviews examined the effect of manual therapy compared to non-manual therapy interventions on QST outcomes in clinical populations. Methodological quality was assessed with the AMSTAR 2 tool. Meta-analysis results and qualitative (non-meta-analysis) interpretations were summarized by type of manual therapy. Overlap of studies was examined with the corrected covered area (CCA) index.

RESULTS

Thirty systematic reviews, including 11 meta-analyses, met inclusion. There was a slight overlap in studies (CCA of 1.72% for all reviews and 1.69% for meta-analyses). Methodological quality was predominantly low to critically low. Eight (27%) reviews examined studies with a range of manual therapy types, 13 (43%) reviews focused on joint-biased manual therapy, 7 (23%) reviews focused on muscle-biased manual therapy, and 2 (7%) reviews focused on nerve-biased manual therapy. Twenty-nine (97%) reviews reported on pressure pain threshold (PPT). Meta-analytic results demonstrated conflicting evidence that manual therapy results in greater hypoalgesic effects compared to other interventions or controls.

CONCLUSION

Our overview of QST effects, which has relevance to mechanisms underlying hypoalgesia, shows conflicting evidence from mostly low to critically low systematic reviews.

Factors associated with pain pressure threshold in both local and remote sites in knee osteoarthritis

BACKGROUND

Knee osteoarthritis (KOA) is a prevalent condition, and its most frequent symptom is pain that often leads to disability. Pain sensitization is a core feature of KOA, and it can be measured through quantitative sensory testing protocols such as pain pressure threshold (PPT). However, there is a lack of understanding about the factors that may influence changes in PPTs in the KOA population.

OBJECTIVE

To explore the clinical and functional factors associated with PPTs in a sample of people with chronic KOA pain and to compare models of local (knees) and remote (thenar regions) sites.

DESIGN

Cross-sectional analysis of a prospective cohort.

SETTING

Primary care in public institution.

PARTICIPANTS

113 adults with KOA.

INTERVENTION

N/A.

MAIN OUTCOME MEASURES

Multivariable regression analyses evaluating demographic, clinical, and functional variables that could be associated with local and remote PPTs (main outcomes) were performed.

RESULTS

Both thenar region (adjusted-R2 : 0.29) and knee (adjusted-R2 : 0.45) models had the same significant negative association with being a female, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain levels (thenar: β: -0.15, p = .002; knee: β: -0.2, p < .001), and the 10-Meter Walking Test (thenar: β: -0.05, p = .038; knee: β: -0.08, p = .004). A small significant positive association with depressive symptoms was identified in both models, which acted as a confounder for WOMAC pain and was likely affected by unmeasured confounders.

CONCLUSIONS

PPTs in KOA pain are associated with functional outcomes such as the 10-Meter Walking Test and activity-related pain intensity; thus more disability is associated with smaller pain thresholds. Similarity between models may suggest central sensitization.

Quantitative sensory testing, psychological profiles and clinical pain in patients with psoriatic arthritis and hand osteoarthritis experiencing pain of at least moderate intensity

BACKGROUND

Chronic pain is the hallmark symptom of joint diseases. This study examined the differences in quantitative sensory testing between patients with psoriatic arthritis (PsA), hand osteoarthritis (hand-OA) and a pain-free control group and differences between patients with and without concomitant fibromyalgia (cFM).

METHODS

All patients and pain-free controls were assessed using pressure pain thresholds (PPT), temporal summation of pain (TSP), conditioned pain modulation (CPM) and clinical pain intensities. Psychological distress was assessed with the Hospital Anxiety and Depression Scale, Pain Catastrophizing Scale, and Pittsburgh Sleep Quality Index. Disability was assessed with the Health Assessment Questionnaire and pain quality with the painDETECT questionnaire. cFM was identified using the revised 2016 American College of Rheumatology diagnostic criteria.

RESULTS

Patients with hand-OA (n = 75) or PsA (n = 58) had statistically significant lower PPTs and CPM, greater TSP, and higher scores of psychological distress (p < 0.05) than controls (n = 20). Patients with cFM (58%) had higher scores of depression (p = 0.001), anxiety (p = 0.004), catastrophizing (p = 0.012), disability (p < 0.001), higher painDETECT score (p = 0.001), TSP (p = 0.027), and reduced sleep quality (p = 0.021) when compared to patients without cFM.

CONCLUSION

Patients with hand-OA and PsA exhibited signs of pain sensitization and a higher degree of psychological distress and disability than pain-free individuals. Patients with cFM had greater TSP, painDETECT score, disability, catastrophizing, and reduced sleep quality, than patients without, indicating greater degree of pain sensitization, psychological burden, and disability.

STATEMENT OF SIGNIFICANCE

This paper shows that a significant proportion of patients with hand osteoarthritis and psoriatic arthritis with moderate pain intensity have significantly increased signs of pain sensitization and markers of psychological distress. A large proportion of these patients fulfil the criteria for concomitant fibromyalgia and these patients show even greater propensity towards pain sensitization and psychological distress.

Pain history and experimental pressure pain responses in adolescents: Results from a population-based birth cohort

BACKGROUND

Sensitized pain mechanisms are often reported in musculoskeletal pain conditions, but population-based paediatric studies are lacking. We assessed whether adolescents with musculoskeletal pain history had evidence of increased responsiveness to experimental pressure stimuli.

METHODS

Data were from 1496 adolescents of the Generation XXI birth cohort. Pain history was collected using the Luebeck Pain Questionnaire (self-reported at 13, parent-reported at 7 and 10 years). Two case definitions for musculoskeletal pain were considered: (1) cross-sectional-musculoskeletal pain lasting more than 3 months at age 13 and (2) longitudinal-musculoskeletal pain at age 13 with musculoskeletal pain reports at ages 7 and/or 10. Lower limb cuff pressure algometry was used to assess pain detection and tolerance thresholds, conditioned pain modulation effects (CPM, changes in thresholds in the presence on painful conditioning) and temporal summation of pain effects (TSP, changes in pain intensity to 10 phasic painful cuff stimulations).

RESULTS

Adolescents with musculoskeletal pain at age 13 plus a history of pain in previous evaluations (longitudinal definition) had lower pain tolerance thresholds compared to the remaining sample (40.2 v. 49.0 kPa, p = 0.02), but showed no differences in pain detection threshold, CPM effect and TSP effect. Pain sensitivity, CPM effects and TSP effects were not significantly different when the current pain only case definition (cross-sectional) was used.

CONCLUSIONS

Adolescents with current musculoskeletal pain who had a history of pain since childhood had lower tolerance to cuff stimulation. This may suggest long-standing musculoskeletal pain since childhood may contribute to sensitisation, rather than the presence of current pain only.

SIGNIFICANCE

Repeated musculoskeletal pain up to age 13 years may contribute to higher pain sensitivity (particularly lowered pressure pain tolerance) in the general adolescent population. This does not seem to be the case when reported pain experiences are recent or when the outcomes are temporal pain summation or CPM. In this community-based paediatric sample, the vast majority showed no sign of altered pain processing, but a small fraction may reveal some pain sensitization at 13 years of age.

Sex moderates the association between quantitative sensory testing and acute and chronic pain after total knee/hip arthroplasty

OBJECTIVES

Acute postsurgical pain (APSP) may persist over time and become chronic. Research on predictors for APSP and chronic postsurgical pain (CPSP) has produced inconsistent results. This observational study aimed to analyze psychological and psychophysical variables associated with APSP and CPSP after total knee or hip arthroplasty, and to explore the role of sex.

METHODS

Assessments were conducted before surgery, 48 h, and 3 months postsurgery, including questionnaires (sociodemographic, pain related, and psychological) and quantitative sensory testing (QST). Hierarchical linear regression models analyzed potential predictors of APSP and CPSP, and moderation analyses evaluated the role of sex.

RESULTS

The study included 63 participants undergoing total knee (34, 54%) or hip (29, 46%) arthroplasty. Thirty-one (49.2%) were female and 32 (50.8%) were male. APSP (48 h) was associated with impaired conditioned pain modulation (CPM) (β = 0.301, p = 0.019). CPSP (3 months) was associated with being female (β = 0.282, p = 0.029), longer presurgical pain duration (β = 0.353, p = 0.006), knee arthroplasty (β = -0.312, p = 0.015), higher APSP intensity (β = 373, p = 0.004), and impaired CPM (β = 0.126, p = 0.004). In multivariate analysis, these clinical variables were significant predictors of CPSP, unlike sex, and CPM (adj. R 2 = 0.349). Moderation analyses showed that wind-up ratio (WUR) was a significant predictor of APSP in men (WUR × sex: b = -1.373, p = 0.046) and CPM was a significant predictor of CPSP in women (CPM × sex: b = 1.625, p = 0.016).

CONCLUSIONS

Specific QST parameters could identify patients at risk for high-intensity APSP and CPSP, with sex as a moderator. This has important clinical implications for patient care, paving the way for developing tailored preventive pain management strategies.

Impact of central sensitization on pain, disability and psychological distress in patients with knee osteoarthritis and chronic low back pain

BACKGROUND

Central sensitization (CS) is becoming increasingly recognized as a significant factor in many chronic pain conditions, including knee osteoarthritis (KOA) and chronic low back pain (CLBP). Yet it presently remains unclear how strong is the involvement of CS in KOA and CLBP and which factors are involved in CS in these two chronic disabling diseases.

METHODS

This is a cross-sectional study in which included a total of 178 patients with KOA and 118 patients with CLBP. Inclusion criteria for eligible participants for the KOA group were a confirmed diagnosis of KOA according to the American College of Rheumatology criteria, and for the CLBP group a chronic low back pain for more than 3 months. Subjects were excluded if they presented with a diagnosed psychiatric disorder or if they lacked the capacity to provide informed consent, understand study questionnaires or perform physical performance tests. In each group, were assessed; CS-related symptoms using the Central Sentization Inventory (CSI); demographic and clinical characteristics such as disease duration, pain intensity on a visual analog scale, self-reported function using the Lequesne index for KOA patients and the Oswestry Disability index for CLBP patients, and physical performance with the 6 minutes' walk test; as well as psychosocial risk factors using the Patient Health Questionnaire for depression (PHQ-9), the Generalized Anxiety Disorder (GAD-7) and the Pain Catastrophizing Scale (PCS).

RESULTS

CSI scores significantly correlated with pain intensity and disability in KOA and CLBP patients, and were highly correlated with self-reported symptoms of depression, anxiety and pain catastrophizing. Depression significantly predicted the CSI score in both groups.

CONCLUSION

These findings provide further evidence for the impact of CS on pain, function and physical performance in KOA and CLBP patients. Psychosocial symptoms such as pain catastrophizing, anxiety and depression should also be considered as they are also associated with CS.

Negative correlation between central sensitization and forgotten joint score-12 after total hip arthroplasty

BACKGROUND

Central sensitization is a condition in which even mild stimuli cause pain due to increased neuronal reactivity in the dorsal horn of the spinal cord. It is one of factors of chronic pain in patients with osteoarthritis. However, it is unknown whether central sensitization relates to clinical outcomes after total hip arthroplasty (THA). This study aimed to clarify whether preoperative central sensitization relates to the forgotten joint score-12 (FJS) after THA. Moreover, the secondary outcome was to identify which items in the FJS were most related by central sensitization.

METHODS

This retrospective analysis included 263 hips (263 patients; 51 males and 212 females) that underwent primary THA in our institute and were available for evaluation one year postoperatively. The average patient age was 64.8 ± 11.9 years. The Central Sensitization Inventory (CSI) part A, which is a patient-reported outcome, was used to measure preoperative central sensitization. The correlation between preoperative CSI and postoperative FJS and the association between postoperative FJS and preoperative CSI severity were determined. Moreover, difference in each FJS item was evaluated by CSI severity.

RESULTS

Twenty-six patients (9.9%) had central sensitization preoperatively. Preoperative CSI scores and postoperative FJS were negatively correlated (r =  - 0.331, p < 0.0001). The postoperative FJS was significantly lower in patients with moderate or higher preoperative CSI severity than that in patients with subclinical or mild preoperative CSI severity (p < 0.05). FJS items with movement of daily life were significantly worse in the moderate or higher CSI severity compared with subclinical group (p < 0.05 or p < 0.01).

CONCLUSION

Central sensitization prior to THA negatively related to postoperative FJS. In particular, the relationship of central sensitization was found to be significant in FJS items with movement, which would lead to lower patient satisfaction after THA. To get better postoperative outcomes in patients with preoperative central sensitization, improving central sensitization would be important.

Clinical Outcomes of Unicompartmental Knee Arthroplasty in Patients with Full-versus Partial-Thickness Cartilage Loss: A Systematic Review and Meta-Analysis

OBJECTIVE

The objective of the study was to compare postoperative patient-reported outcomes and reoperation rates following unicompartmental knee arthroplasty (UKA) between patients with full-thickness cartilage loss (FTCL) and partial-thickness cartilage loss (PTCL).

DESIGN

Multiple databases, including PubMed, Embase, Cochrane Library, and CNKI, were searched until October 2019 for studies comparing the Oxford Knee Score (OKS), American Knee Society (AKS) score, and reoperation rates between patients with FTCL and PTCL following UKA. Data analysis was performed using Review Manager software.

RESULTS

A total of 613 UKA cases from 5 retrospective cohort studies were included. The mean difference in postoperative OKSs was significantly higher by 2.92 in FTCL group than in PTCL group (95% confidence interval [CI] = -5.29 to -0.55; P = 0.02). Improvement in OKS was significantly higher by 2.69 in FTCL group than in PTCL group (95% CI = -4.79 to -0.60; P = 0.01). However, the differences in OKSs were not clinically significant. The mean difference in AKS knee scores was similar between the 2 groups (95% CI = -9.14 to -3.34; P = 0.36), whereas the pooled mean difference in AKS function scores was higher by 5.63 in FTCL group than in PTCL group (95% CI = -9.27 to -1.98; P = 0.002), which was clinically relevant. The reoperation rates were statistically higher in PTCL group than in FTCL group (odds ratio = 2.24; 95% CI = 1.15 to 4.38; P = 0.02).

CONCLUSIONS

Patients with FTCL achieved superior postoperative patient-reported outcomes and lower reoperation rates following UKA compared with those with PTCL. Thus, we believe this procedure should only be applied to end-stage medial osteoarthritis of the knee joint.

Reference intervals and sources of variation of pressure pain threshold for quantitative sensory testing in a Japanese population

Quantitative sensory testing (QST) is useful when analysing musculoskeletal pain disorders. A handheld algometer is most commonly used for pressure pain threshold (PPT) tests. However, reference intervals for PPTs are not elucidated. We assessed reference intervals of PPTs for QST in 158 healthy adult Japanese with no history of musculoskeletal or neurological problems. A handheld algometer was used to record PPT at five different assessment sites on the body: lumbar paravertebral muscle, musculus gluteus maximus, quadriceps, tibialis anterior muscle, and anterior talofibular ligament. Multiple regression analysis was performed to explore sources of variation of PPT according to sex, age, body mass index, UCLA Activity Level Rating, and Tegner Activity Score. Reference intervals were determined parametrically by Gaussian transformation of PPT values using the two-parameter Box-Cox formula. Results of multiple regression analysis revealed that age was significantly associated with PPT of lumbar paravertebral muscle and musculus gluteus maximus. In females, body mass index showed significant positive correlation with PPT of anterior talofibular ligament, and UCLA Activity Level Rating also showed significant positive association with tibialis anterior muscle and anterior talofibular ligament. Site-specific reference intervals of PPTs for Japanese are of practical relevance in fields of pain research using a handheld algometer.

Quantitative sensory testing as an assessment tool to predict the response to standard pain treatment in knee osteoarthritis: a systematic review and meta-analysis

Emerging evidence suggest that quantitative sensory testing (QST) may predict the treatment response to pain-relieving therapies. This systematic review and meta-analysis focus on the predictive value of QST for pain management of knee osteoarthritis (OA). MEDLINE and EMBASE were systematically searched for all studies from year 2000 to 2023 on pretreatment QST and treatment of OA including surgical, pharmaceutical, and nonsurgical and nonpharmaceutical therapies. Preclinical studies and reviews were excluded. The systematic review followed the PRISMA guidelines and was pre-registered on the Open Science Framework website (link: https://osf.io/4FETK/, Identifier: DOI 10.17605/OSF.IO/4FETK). Meta-analysis were conducted to demonstrate the strength of the pre-treatment QST predictions on pain outcomes after OA treatments. Sixteen surgical (all on total knee arthroplasty [TKA], N = 1967), 5 pharmaceutical (4 on non-steroidal anti-inflammatory drugs [NSAIDs], N = 271), and 4 exercise-based therapy studies (N = 232) were identified. Pretreatment QST parameters predicted pain-relieving treatment outcomes in 81% of surgical, 100% of pharmaceutical, and 50% of exercise-based therapy studies. Meta-analyses found pretreatment QST profiles to predicted pain outcomes after TKA (random effects: 0.309, 95% confidence interval [CI]: 0.206-0.405, P < 0.001), NSAIDs (random effects: 0.323, 95% CI: 0.194-0.441, P < 0.001), and exercise-based therapies (random effects: 0.417, 95% CI: 0.138-0.635, P = 0.004). The overall risk of bias for the included studies was low to moderate. This systematic review and meta-analysis demonstrate weak-to-moderate associations between pretreatment QST and pain outcomes after standard OA pain treatments. Based on this work, it is hypothesized that a subset of specific pain sensitive patients with OA exist and that these patients do not respond adequately to standard OA pain treatments.

Reliability and minimal detectable difference of pressure pain thresholds in a pain-free population

The objective of this work was to evaluate the inter-rater and intra-rater reliability and minimal detectable difference (MDD) of pressure pain thresholds (PPTs) in pain-free participants with two examiners over two consecutive days in a cross-sectional study design. Examiners used a standardized method to measure and locate a specific testing site over tibialis anterior for PPT testing with a hand-held algometer. The mean of each examiner's three PPT measurements was used to calculate the intraclass correlation coefficient, inter-rater reliability, and intra-rater reliability. The minimal detectable difference (MDD) was calculated. Eighteen participants were recruited (11 female). The inter-rater reliability was 0.94 and 0.96 on day 1 and day 2, respectively. Intra-rater reliability for the examiners was 0.96 and 0.92 on day 1 and day 2, respectively. The MDD on day 1 was 1.24 kg/cm2 (CI: 0.76-2.03) and the MDD on day 2 was 0.88 kg/cm2 (CI: 0.54-1.43). This study demonstrates high inter- and intra-rater reliability and the MDD values for this method of pressure algometry.

Investigation of pain sensitivity following 3 nights of disrupted sleep in healthy individuals

BACKGROUND

Poor quality sleep is a common complaint among people with chronic pain. The co-occurrence of poor sleep quality and chronic pain often comes with increased pain intensity, more disability and a higher cost of healthcare. Poor sleep has been suggested to affect measures of peripheral and central pain mechanisms. To date, sleep provocations are the only models proven to affect measures of central pain mechanisms in healthy subjects. However, there are limited studies investigating the effect of several nights of sleep disruption on measures of central pain mechanisms.

METHODS

The current study implemented three nights of sleep disruption with three planned awakenings per night in 30 healthy subjects sleeping at home. Pain testing was conducted at the same time of day at baseline and follow-up for each subject. Pressure pain thresholds were assessed bilaterally on the infraspinatus and gastrocnemius muscles. Using handheld pressure algometry, suprathreshold pressure pain sensitivity and area were also investigated on the dominant infraspinatus muscle. Cuff-pressure pain detection and tolerance thresholds, temporal summation of pain and conditioned pain modulation were investigated using cuff-pressure algometry.

RESULTS

Temporal summation of pain was significantly facilitated (p = 0.022), suprathreshold pain areas (p = 0.005) and intensities (p < 0.05) were significantly increased, and all pressure pain thresholds were decreased (p < 0.005) after sleep disruption compared to baseline.

CONCLUSIONS

The current study found that three consecutive nights of sleep disruption at home induced pressure hyperalgesia and increased measures of pain facilitation in healthy subjects, which is consistent with previous findings.

SIGNIFICANCE

Poor quality of sleep is often experienced by patients with chronic pain, with the most common complaint being nightly awakenings. This exploratory study is the first to investigate changes in measures of central and peripheral pain sensitivity in healthy subjects after sleep disruptions for three consecutive nights without any restrictions on total sleep time. The findings suggest that disruptions to sleep continuity in healthy individuals can induce increased sensitivity to measures of central and peripheral pain sensitization.

The Effectiveness of Tuina in Relieving Pain, Negative Emotions, and Disability in Knee Osteoarthritis: A Randomized Controlled Trial

OBJECTIVE

To evaluate the effectiveness of Tuina in relieving the pain, negative emotions, and disability of patients with knee osteoarthritis (KOA).

DESIGN

Single-center, parallel, randomized controlled trial.

SETTING

Shanghai Guanghua Integrated Chinese and Western Medicine Hospital, Shanghai, China.

SUBJECTS

Adult patients with KOA who were able to speak Chinese and self-report symptoms were eligible.

METHODS

A total of 104 patients were randomly allocated to receive the 6-week treatment of Tuina (Tuina group) or celecoxib (celecoxib group). Data on pain, negative emotions, and disability were collected at baseline, at week 2, 4, and 6, and follow-up (1 month after the last treatment). The primary outcomes were the pressure pain thresholds. The secondary outcomes were: (1) numerical rating scale at rest and with movement; (2) Hamilton Anxiety Scale; (3) Hamilton Depression Scale; (4) Western Ontario and McMaster Universities Osteoarthritis Index; and (5) clinical effective rate. The adverse events of the trial were evaluated.

RESULTS

In total, 99 patients completed the follow-up. Generalized linear mixed models were constructed to analyse the between-group differences. Statistically significant differences were found in the interaction effects (P < .05). In evaluating the group effect, statistical differences were found at week 6 and follow-up (P < .05). Further, all variables showed a time effect (P < .05). A statistical difference in the clinical effective rate was found between the Tuina and celecoxib groups (P < .05).

CONCLUSIONS

Tuina produced superior effects for pain, negative emotions, and disability over time, as compared to celecoxib in patients with KOA.

Predicting pain after standard pain therapy for knee osteoarthritis - the first steps towards personalized mechanistic-based pain medicine in osteoarthritis

OBJECTIVES

The prevalence of osteoarthritis (OA) is rising, and pain is the hallmark symptom of OA. Pain in OA is complicated and can be influenced by multiple joint-related factors and factors related to, e.g., physiological, epigenetic, and pain sensory profiles. Increasing evidence suggests that a subset of patients with OA are pain sensitive. This can be assessed using quantitative sensory testing (QST). Common treatments of OA are total knee arthroplasty (TKA) and administration of 3-weeks of non-steroidal anti-inflammatory drugs (NSAIDs), which provide pain relief to many patients with OA. However, approx. 20% of patients experience chronic postoperative pain after TKA, whereas NSAIDs provide an average pain relief of approx. 25%. The current topical review focuses on the emerging evidence linking pretreatment QST to the treatment response of TKA and NSAID treatments.

CONTENT

MEDLINE was systematically searched for all studies from 2000 to 2022 on pretreatment QST, TKA, and NSAIDs. Pre-clinical studies, reviews, and meta-analyses were excluded.

SUMMARY

Currently, 14 studies on TKA and four studies on NSAIDs have been published with the aim to attempt prediction of the treatment response. The QST methodologies in the studies are inconsistent, but 11/14 (79%) studies on TKA and 4/4 (100%) studies on NSAIDs report statistically significant associations between pretreatment QST and chronic postoperative pain after TKA or analgesic effect after NSAID treatment. The strength of the associations remains low-to-moderate. The most consistent pretreatment QST predictors are pressure pain thresholds, temporal summation of pain, and conditioned pain modulation.

OUTLOOK

The use of QST as predictors of standard OA treatment is interesting, but the predictive strength remains low-to-moderate. A transition of QST from a research-based setting and into the clinic is not advised until the predictive strength has been improved and the methodology has been standardized.

A combination of high preoperative pain and low radiological grade of arthritis is associated with a greater intensity of persistent pain 12 months after total knee arthroplasty

Aims

Despite new technologies for total knee arthroplasty (TKA), approximately 20% of patients are dissatisfied. A major reason for dissatisfaction and revision surgery after TKA is persistent pain. The radiological grade of osteoarthritis (OA) preoperatively has been investigated as a predictor of the outcome after TKA, with conflicting results. The aim of this study was to determine if there is a difference in the intensity of pain 12 months after TKA in relation to the preoperative radiological grade of OA alone, and the combination of the intensity of preoperative pain and radiological grade of OA.

Methods

The preoperative data of 300 patients who underwent primary TKA were collected, including clinical information (age, sex, preoperative pain), psychological variables (depression, anxiety, pain catastrophizing, anticipated pain), and quantitative sensory testing (temporal summation, pressure pain thresholds, conditioned pain modulation). The preoperative radiological severity of OA was graded according to the Kellgren-Lawrence (KL) classification. Persistent pain in the knee was recorded 12 months postoperatively. Generalized linear models explored differences in postoperative pain according to the KL grade, and combined preoperative pain and KL grade. Relative risk models explored which preoperative variables were associated with the high preoperative pain/low KL grade group.

Results

Pain 12 months after TKA was not associated with the preoperative KL grade alone. Significantly increased pain 12 months after TKA was found in patients with a combination of high preoperative pain and a low KL grade (p = 0.012). Patients in this group were significantly more likely to be male, younger, and have higher preoperative pain catastrophizing, higher depression, and lower anxiety (all p ≤ 0.05).

Conclusion

Combined high preoperative pain and low radiological grade of OA, but not the radiological grade alone, was associated with a higher intensity of pain 12 months after primary TKA. This group may have a more complex cause of pain that requires additional psychological interventions in order to optimize the outcome of TKA. Cite this article: Bone Joint J 2022;104-B(11):1202–1208.

A Randomised Controlled Trial of YOGa and Strengthening Exercise for Knee OsteoArthritis: Protocol for a Comparative Effectiveness Trial (YOGA Trial)

Osteoarthritis (OA) is a common joint disorder for which there is no cure. Current treatments are suboptimal. Exercise is a core treatment for knee OA, with muscle strengthening exercise commonly recommended. Yoga is a mind-body exercise intervention that can improve flexibility, muscle strength, balance, and fitness and potentially reduce symptoms of OA. However, there is a scarcity of robust, high-quality conclusive evidence on the efficacy of yoga in knee OA. We are currently conducting the first randomised comparative effectiveness and cost-effectiveness trial of a yoga program compared with a strengthening exercise program in patients with symptomatic knee OA. This study protocol describes the design and conduct of this trial. The YOGA study is a phase III, single-centre, parallel, superiority, randomised, active-controlled trial which will be conducted in Hobart, Australia. One hundred and twenty-six participants (63 in each arm) aged over 40 years with symptomatic knee OA will be recruited from the community and randomly allocated to receive either a 24-week yoga program (3×/week) or a strengthening exercise program (3×/week). The primary outcome will be change in knee pain over 12 weeks, assessed using a 100 mm visual analogue scale (VAS). The secondary outcomes include change in knee pain, patient global assessment, physical function, quality of life, gait speed, biomarkers, and others over 12 and 24 weeks. We will also assess whether the presence of neuropathic pain moderates the effects of yoga compared to strengthening exercise. Additional data, such as cost and resource utilization, will be collected for the cost-effectiveness analysis. The primary analysis will be conducted using an intention-to-treat approach. Adverse events will be monitored throughout the study. Once completed, this trial will contribute to the knowledge of whether yoga can be used as a simple, effective, low-cost option for the management of knee OA, thus saving economic costs in the healthcare system.

A simple, bed-side tool to assess evoked pressure pain intensity

OBJECTIVES

Existing equipment for quantitative sensory testing is generally expensive and not easily applicable in a clinical setting thus simple bed-side devices are warranted. Pressure hyperalgesia is a common finding in patients with musculoskeletal pain and an experimental model is delayed-onset muscle soreness (DOMS). DOMS is characterised by muscle hyperalgesia and some studies report facilitation of temporal summation of pain. This study aimed to detect DOMS induced muscle hyperalgesia and temporal summation of pain using a newly developed bed-side quantitative sensory testing device to deliver standardised pressure.

METHODS

Twenty-two healthy participants participated in two sessions with the second session approximately 48 h after baseline. Pressure pain intensities were assessed from the gastrocnemius muscle with four probes calibrated to apply 2, 4, 6 and 8 kg, respectively. Temporal summation of pain (10 stimuli delivered at 0.5 Hz using the 6 kg probe) intensities were assessed from the same location. DOMS was evoked in the gastrocnemius muscle by an eccentric exercise. Sleepiness and physical activity were measured with the Epworth Sleepiness Scale and the Global Physical Activity Questionnaire to investigate if they were associated with the quantitative sensory testing measures.

RESULTS

Pressure pain intensity was significantly increased 48 h after induction of DOMS when compared to baseline for all four probes (p<0.05). Temporal summation of pain was not statistically significant affected by DOMS and sleep quality and physical activity did not associate with any of the measures.

CONCLUSIONS

This study introduces a simple, bed-side assessment tool for the assessment of pressure pain intensity and hence hyperalgesia and temporal summation of pain.

Chronic Postoperative Pain after Total Knee Arthroplasty: The Potential Contributions of Synovitis, Pain Sensitization, and Pain Catastrophizing - An Explorative Study

Background

A subset of osteoarthritis patients will experience chronic postoperative pain after total knee arthroplasty (TKA), but the source of pain is unclear. The aim of this exploratory study was to assess patients with and without postoperative pain after TKA using magnetic resonance imaging (MRI), quantitative sensory testing (QST), clinical assessment of pain and assessments of catastrophizing thoughts.

Methods

Forty‐six patients completed the 6‐month postoperative assessment. MRI findings were scored according to the MRI Osteoarthritis Knee Score recommendation for Hoffa synovitis, effusion size and bone marrow lesions. QST included assessment of pressure pain thresholds (PPTs), temporal summation of pain (TSP) and conditioned pain modulation (CPM). Pain catastrophizing was assessed using the Pain Catastrophizing Scale (PCS). Clinical pain assessment was conducted using a visual analogue scale (VAS, 0–10 cm), and groups of moderate‐to‐severe (VAS > 3) and none‐to‐mild postoperative pain (VAS ≤ 3) were identified.

Results

Patients with moderate‐to‐severe postoperative pain (N = 15) demonstrated higher grades of Hoffa synovitis (p < 0.001) and effusion size (p < 0.001), lower PPTs (p = 0.039), higher TSP (p = 0.001) and lower CPM (p = 0.014) when compared with patients with none‐to‐mild postoperative pain (N = 31). No significant difference was found in PCS scores between the two groups. Multiple linear regression models found synovitis (p = 0.036), effusion size (p = 0.003), TSP (p = 0.013) and PCS (p < 0.001) as independent parameters contributing to the postoperative pain intensity.

Conclusion

These exploratory findings could indicate that chronic postoperative pain after TKA is a combination of joint‐related synovitis and effusion, sensitization of central pain mechanisms and potentially pain catastrophizing thoughts, but larger studies are needed to confirm this.

Significance

The end‐stage treatment of knee osteoarthritis is total knee arthroplasty. Some patients experience chronic postoperative pain after total knee arthroplasty, but the mechanism for chronic postoperative pain is widely unknown. The current study indicates that higher levels postoperative of synovitis and effusion, higher temporal summation of pain and higher pain catastrophizing scores could be associated with higher chronic postoperative pain.

Investigating the effects of mobilization with movement and exercise on pain modulation processes in shoulder pain - a single cohort pilot study with short-term follow up

OBJECTIVE

To explore the association between manual therapy and exercise and pain modulation and clinical characteristics in people with musculoskeletal shoulder pain.

METHODS

This is a prospective, longitudinal, single cohort pilot study. People with shoulder pain for longer than 6 weeks underwent 4 weeks of glenohumeral mobilization with movement and shoulder exercises. Measures of pain modulation, shoulder pain, disability, range of motion and psychosocial factors were assessed at baseline and immediately after the 4-week period of treatment. Treatment effectiveness was assessed through parametric, non-parametric and multilevel modeling statistics.

RESULTS

Twenty-three individuals participatedwith no loss to follow-up. Significant and meaningful improvements in shoulder pain (NRS mean change 1.6/10, 95% CI 0.4 to 2.7), disability (SPADI mean change 20.5/100, 95% CI 13.1 to 27.9) and range of motion (mean change 33°, 95% CI 23 to 43°) were observed following treatment. Statistical but non-clinically meaningful changes were observed in temporal summation of pain (mean change 0.3/10, 95% CI 0.1 to 0.4) and anxiety (mean change 0.86/21, 95% CI 0.18 to 1.55). Significant reductions were observed in temporal summation of pain (mean change 0.3/10, 95% CI 0.1 to 0.4) and anxiety (mean change 0.86/21, 95% CI 0.18 to 1.55), however these were not considered clinically important. No association was found between clinical characteristics and sensory measures. No association was found between clinical characteristics and sensory measures.

CONCLUSION

Glenohumeral mobilization with movement and exercise did not improve pain modulation, despite improvements in pain, function and range of motion, in people with shoulder pain.

High Prevalence of Pain Sensitization in Knee Osteoarthritis: A Meta-Analysis with Meta-Regression

OBJECTIVE

The aim of this meta-analysis was to study the evidence on pain sensitization in knee osteoarthritis (OA), providing a quantitative synthesis of its prevalence and impact. Factors associated with pain sensitization were also investigated.

METHODS

Meta-analysis; PubMed (MEDLINE), Cochrane Central Register (CENTRAL), and Web of Science were searched on February 2021. Level I to level IV studies evaluating the presence of pain sensitization in patients with symptomatic knee OA, documented through a validated method (questionnaires or quantitative sensory testing), were included. The primary outcome was the prevalence of pain sensitization. Factors influencing the prevalence were also evaluated, as well as differences in terms of pain thresholds between knee OA patients and healthy controls.

RESULTS

Fifty-three articles including 7,117 patients were included. The meta-analysis of proportion documented a prevalence of pain sensitization of 20% (95% confidence interval [CI] = 16%-26%) with a significant heterogeneity of results (I² = 89%, P < 0.001). The diagnostic tool used was the main factor influencing the documented prevalence of pain sensitization (P = 0.01). Knee OA patients presented higher pain sensitivity compared with healthy controls, both in terms of local pressure pain threshold (standardized mean difference [SMD] = -1.00, 95% CI = -1.67 to -0.32, P = 0.007) and distant pressure pain threshold (SMD = -0.54, 95% CI = -0.76 to -0.31, P < 0.001).

CONCLUSIONS

Knee OA pain presents features that are consistent with a significant degree of pain sensitization. There is a high heterogeneity in the reported results, mainly based on the diagnostic tool used. The identification of the best methods to detect pain sensitization is warranted to correctly evaluate and manage symptoms of patients affected by knee OA.

REGISTRATION

PROSPERO CRD42019123347.

Multimodal prediction of pain and functional outcomes 6 months following total knee replacement: a prospective cohort study

BACKGROUND

Knee osteoarthritis (OA) is among the most common and disabling persistent pain conditions, with increasing prevalence and impact around the globe. In the U.S., the rising prevalence of knee OA has been paralleled by an increase in annual rates of total knee arthroplasty (TKA), a surgical treatment option for late-stage knee OA. While TKA outcomes are generally good, post-operative trajectories of pain and functional status vary substantially; a significant minority of patients report ongoing pain and impaired function following TKA. A number of studies have identified sets of biopsychosocial risk factors for poor post-TKA outcomes (e.g., comorbidities, negative affect, sensory sensitivity), but few prospective studies have systematically evaluated the unique and combined influence of a broad array of factors.

METHODS

This multi-site longitudinal cohort study investigated predictors of 6-month pain and functional outcomes following TKA. A wide spectrum of relevant biopsychosocial predictors was assessed preoperatively by medical history, patient-reported questionnaire, functional testing, and quantitative sensory testing in 248 patients undergoing TKA, and subsequently examined for their predictive capacity.

RESULTS

The majority of patients had mild or no pain at 6 months, and minimal pain-related impairment, but approximately 30% reported pain intensity ratings of 3/10 or higher. Reporting greater pain severity and dysfunction at 6 months post-TKA was predicted by higher preoperative levels of negative affect, prior pain history, opioid use, and disrupted sleep. Interestingly, lower levels of resilience-related "positive" psychosocial characteristics (i.e., lower agreeableness, lower social support) were among the strongest, most consistent predictors of poor outcomes in multivariable linear regression models. Maladaptive profiles of pain modulation (e.g., elevated temporal summation of pain), while not robust unique predictors, interacted with psychosocial risk factors such that the TKA patients with the most pain and dysfunction exhibited lower resilience and enhanced temporal summation of pain.

CONCLUSIONS

This study underscores the importance of considering psychosocial (particularly positively-oriented resilience variables) and sensory profiles, as well as their interaction, in understanding post-surgical pain trajectories.

Gaining more insight into ankle pain in haemophilia: A study exploring pain, structural and functional evaluation of the ankle joint

INTRODUCTION

Ankle arthropathy is highly prevalent among people with haemophilia (PwH), even with prophylaxis, and leads to pain and disability. Mechanisms and consequences of painful symptoms related to ankle arthropathy have not been extensively studied.

METHODS

A consecutive sample of 30 adult PwH was included (60 ankles). Ankle structure was assessed with magnetic resonance imaging (IPSG-MRI) and ultrasound (HEAD-US). The HJHS 2.1 assessed function of ankles and knees. Physical functioning was assessed with the Timed Up and Go test, the 2-Minute Walking Test and activity limitations with the HAL questionnaire. Health-related quality of life was evaluated using the EQ-5D-5L questionnaire. Overall pain severity was examined using the Brief Pain Inventory questionnaire and ankle pain intensity with a visual analogue scale. Pressure pain thresholds with an algometer assessed pain sensitivity. Spearman correlations were used to calculate interrelations between joint structure, function and pain.

RESULTS

Twenty-five PwH (83%) reported ≥1 painful joint, with 67% reporting the ankle as most painful joint. MRI-confirmed abnormalities were seen in 76% of talocrural and 55% of subtalar joints. HEAD-US abnormalities were seen in 93% of the ankles. A large variation was seen in pain sensitivity at the ankle. While moderate to high correlations were observed between ankle structure and HJHS, no meaningful correlations were found between MRI-scores and pain intensity or sensitivity.

CONCLUSIONS

Structural joint damage is present in many ankles but is not related to pain in PwH. Further studies should consider somatosensory nervous system dysfunction in PwH as contributing factor to painful ankle arthropathy.

Use of the painDETECT to discriminate musculoskeletal pain phenotypes

Background

Musculoskeletal pain patients present similar pain characteristics regardless of the clinical diagnosis. PainDETECT questionnaire is useful for screening neuropathic-like symptoms in many musculoskeletal conditions. However, no previous studies compared pain phenotypes of patients with musculoskeletal pain using the painDETECT. Therefore, the current study aimed to compare the pain characteristics of patients with musculoskeletal pain classified according to the painDETECT as nociceptive pain, unclear, and neuropathic-like symptoms.

Methods

A cross-sectional study was conducted in 308 participants with musculoskeletal pain. Demographic and clinical characteristics of the participants were examined. Neuropathic-like symptoms, pain intensity, pain area, Central Sensitization-related sign and symptoms, functional limitation, and conditioned pain modulation were assessed in patients with musculoskeletal pain. Independent one-way analysis of variance (ANOVA) was used to test for between-group differences for the outcome measures with continuous variables and Pearson chi-square test verified between-group differences on the efficiency of the conditioned pain modulation.

Results

Participants had a mean age of 52.21 (±15.01) years old and 220 (71.42%) were females. One hundred seventy-three (56.16%) participants present nociceptive pain, 69 (22.40%) unclear, and 66 (21.42%) neuropathic-like symptoms. A one-way ANOVA showed differences for the pain intensity [F (2,305) = 20.097; p < .001], pain area [F (2,305) = 28.525; p < .001], Central Sensitization-related sign and symptoms [F (2,305) = 54.186; p < .001], and functional limitation [F (2,256) = 8.061; p < .001]. However, conditioned pain modulation was similarly impaired among the three groups (X² = 0.333, p = 0.847).

Conclusion

Patients with neuropathic-like symptoms revealed unfavorable pain characteristics compared to their counterparts, including pain intensity, generalized pain, Central Sensitization-related sign and symptoms, and functional limitation.

Development of a bedside tool-kit for assessing sensitization in patients with chronic osteoarthritis knee pain or chronic knee pain after total knee replacement

ABSTRACT

Different pathophysiological mechanisms contribute to the pain development in osteoarthritis (OA). Sensitization mechanisms play an important role in the amplification and chronification of pain and may predict the therapeutic outcome. Stratification of patients according to their pain mechanisms could help to target pain therapy. This study aimed at developing an easy-to-use, bedside tool-kit to assess sensitization in patients with chronic painful knee OA or chronic pain after total knee replacement (TKR). In total, 100 patients were examined at the most affected knee and extrasegmentally by the use of 4 standardized quantitative sensory testing parameters reflecting sensitization (mechanical pain threshold, mechanical pain sensitivity, dynamic mechanical allodynia, and pressure pain threshold), a bedside testing battery of equivalent parameters including also temporal summation and conditioned pain modulation, and pain questionnaires. Machine learning techniques were applied to identify an appropriate set of bedside screening tools. Approximately half of the patients showed signs of sensitization (46%). Based on machine learning techniques, a composition of tests consisting of 3 modalities was developed. The most adequate bedside tools to detect sensitization were pressure pain sensitivity (pain intensity at 4 mL pressure using a 10-mL blunted syringe), mechanical pinprick pain sensitivity (pain intensity of a 0.7 mm nylon filament) over the most affected knee, and extrasegmental pressure pain sensitivity (pain threshold). This pilot study presents a first attempt to develop an easy-to-use bedside test to probe sensitization in patients with chronic OA knee pain or chronic pain after TKR. This tool may be used to optimize individualized, mechanism-based pain therapy.

Modulation of offset analgesia in patients with chronic pain and healthy subjects - a systematic review and meta-analysis

OBJECTIVES

Offset analgesia (OA) induces a brief pain inhibition and studies suggest OA impairment in patients with chronic pain when compared to healthy subjects. Conditioned pain modulation remains the most studied descending pain inhibitory control mechanism and is modulated by centrally-acting analgesics. Since OA may be mediated by similar neural substrates as conditioned pain modulation, understanding if OA is a peripheral or central proxy of pain modulation is important. The modulatory effect of centrally-acting drugs on OA in healthy and chronic pain populations has not yet been systematically reviewed and meta-analyzed, and this systematic review and meta-analysis aimed to identify studies employing interventions for modulating OA magnitude.

METHODS

A systematic search of PubMed, Embase, Web of Science, and the Cochrane Library yielded 146 records of which 11 (172 healthy pain-free subjects, 106 chronic pain patients) were eligible for qualitative synthesis, and 10 for meta-analysis on overall modulatory effect of interventions on OA, and subgroup analysis of patients and healthy pain-free subjects.

RESULTS

Risk of bias was evident for study participation and study confounding in the included studies. Several different methods for assessing and calculating OA magnitude were identified, which may affect interpretability of findings and warrants standardization. The meta-analysis showed no modulatory effects on OA overall (standardized mean difference (SMD) [95%CI]: 0.04 [-0.22, 0.30], Z=0.29, p=0.77), or in the subgroup analysis for patients (SMD [95%CI]: -0.04 [-0.63, 0.71], Z=0.13, p=0.90) or healthy pain-free subjects (SMD [95%CI]: 0.01 [-0.21, 0.24], Z=0.11, p=0.91). Moderate to substantial heterogeneity was found for the overall analysis (I2=47%, p=0.03) and patient subgroup analysis (I2=75%, p=0.003).

CONCLUSIONS

The current systematic review and meta-analysis conclude that centrally-acting drugs and exercise do not influence OA. Evidence on the peripheral contribution to OA response requires further investigations. Preclinical models of OA should be established to identify the neurophysiology and -biology behind OA.

Quantitative sensory testing: identifying pain characteristics in patients with osteoarthritis

OBJECTIVE

This review outlines the most commonly used quantitative sensory tests to identify pain sensitization. We examine cross-sectional associations between quantitative sensory testing (QST) measures and OA symptoms and severity, along with longitudinal associations between QST findings and response to surgical and non-surgical treatments for OA.

DESIGN

We conducted a search in PubMed for English language papers including 'osteoarthritis' and 'quantitative sensory testing' as search terms. Papers that did not pertain specifically to OA or QST were excluded.

RESULTS

Pressure Pain Threshold (PPT), Conditioned Pain Modulation (CPM), and Temporal Summation (TS) are the QST measures used most frequently to identify pain sensitization. Findings indicate that persons with knee OA often exhibit lower PPT thresholds, inefficient CPM, and facilitated TS as compared with controls who do not have OA, supporting the discriminant validity of QST. Pre-treatment QST has shown some success in identifying persons who experience less pain relief from surgical and non-surgical treatments for knee OA. Post-treatment QST has shown that sometimes PPT and CPM can normalize (PPT thresholds increase, and CPM becomes efficient) in patients for whom joint replacement is successful. Recent studies indicate that QST measures are more closely associated with pain severity than OA radiographic severity, suggesting that sensitization may be a trait rather than a state.

CONCLUSIONS

QST may have a role in identifying persons who are susceptible to chronic pain and may offer an opportunity for personalized, more effective treatment of OA.

A mechanism-based proof of concept study on the effects of duloxetine in patients with painful knee osteoarthritis

BACKGROUND

The global burden of osteoarthritis (OA) is steadily increasing due to demographic and lifestyle changes. The nervous system can undergo peripheral and central neuroplastic changes (sensitization) in patients with OA impacting the options to manage the pain adequately. As a result of sensitization, patients with OA show lower pressure pain thresholds (PPTs), facilitated temporal summation of pain (TSP), and impaired conditioned pain modulation (CPM). As traditional analgesics (acetaminophen and non-steroidal anti-inflammatory drugs) are not recommended for long-term use in OA, more fundamental knowledge related to other possible management regimes are needed. Duloxetine is a serotonin-noradrenalin reuptake inhibitor, and analgesic effects are documented in patients with OA although the underlying fundamental mechanisms remain unclear. The descending pain inhibitory control system is believed to be dependent on serotonin and noradrenalin. We hypothesized that the analgesic effect of duloxetine could act through these pathways and consequently indirectly reduce pain and sensitization. The aim of this mechanistic study is to investigate if PPTs, TSP, CPM, and clinical pain parameters are modulated by duloxetine.

METHODS

This proof of concept study is a randomized, placebo-controlled, double-blinded, crossover trial, which compares PPTs, TSP, and CPM before and after 18 weeks of duloxetine and placebo in forty patients with knee OA. The intervention periods include a titration period (2 weeks), treatment period (60 mg daily for 14 weeks), and a discontinuation period (2 weeks). Intervention periods are separated by 2 weeks.

DISCUSSION

Duloxetine is recommended for the treatment of chronic pain, but the underlying mechanisms of the analgesic effects are currently unknown. This study will investigate if duloxetine can modify central pain mechanisms and thereby provide insights into the underlying mechanisms of the analgesic effect.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04224584 . Registered on January 6, 2020. EudraCT 2019-003437-42 . Registered on October 22, 2019. The North Denmark Region Committee on Health Research Ethics N-20190055. Registered on October 31, 2019.

Bedside clinical tests to assess sensitization in office workers with chronic neck pain

OBJECTIVE

This study aimed to assess pain sensitization in individual office workers with chronic neck pain through simple bedside quantitative sensory tests (QST) and to associate the findings with pain intensity and pain catastrophizing.

METHODS

One hundred-and-four office workers with chronic neck pain were assessed using pressure pain threshold (PPT) considering pain sensitive if PPTs were lower than 155 kPa in the upper trapezius and 245 kPa in the tibialis anterior. Pain sensitive to temporal summation of pain (TSP) was considered if there was a difference of two points in the visual analogue scale (VAS) comparing the first and last stimulus. Pain sensitive was considered to conditioned pain modulation (CPM) if the CPM-effect was less than -7.5%. Pain intensity and catastrophizing were measured using VAS and with the Pain Catastrophizing Scale.

RESULTS

There was at least one pain sensitive QST finding in 66 office workers (63.5%). TSP findings were the most common (48.1%), followed by PPT's (31.7%) and CPM (20.2%). Based on the QST findings, office workers were divided based on the number of individual QST findings, and higher pain intensity and pain catastrophizing scores were found in office workers with one (N = 38, P < 0.05) or two (N = 28, P < 0.05) compared with office workers with no QST findings (N = 38).

CONCLUSION

This study demonstrated that most office workers with chronic neck pain exhibit either widespread pressure hyperalgesia, facilitated TSP or impaired CPM, indicating pain sensitization within the central nervous system. This was associated with increased clinical pain and pain catastrophizing rumination scores.

The Impact of Psychological Factors and Their Treatment on the Results of Total Knee Arthroplasty

➤

There is a growing body of evidence implicating psychosocial factors, including anxiety, depression, kinesiophobia, central sensitization, and pain catastrophizing, as negative prognostic factors following total knee arthroplasty (TKA).

➤

Symptoms of anxiety and depression likely represent risk factors for negative outcomes in patients undergoing TKA. However, few studies have assessed the impact of preoperative interventions for these conditions on postoperative outcomes.

➤

The Tampa Scale of Kinesiophobia and the Central Sensitization Inventory have demonstrated value in the diagnosis of kinesiophobia and central sensitization. Higher preoperative indices of kinesiophobia and central sensitization predict worse patient-reported outcomes postoperatively.

➤

Although evidence is limited, cognitive-behavioral therapy for kinesiophobia and duloxetine for central sensitization may help to diminish the negative impact of these preoperative comorbidities. It is important to note, however, that outside the realm of TKA, cognitive-behavioral therapy has been recognized as a more effective treatment for central sensitization than medical treatment.

➤

Awareness of these issues will allow surgeons to better prepare patients regarding postoperative expectations in the setting of a comorbid psychosocial risk factor. Further research into the role of preoperative assessment and possible treatment of these conditions in patients undergoing TKA is warranted.

Pain Catastrophizing, Self-reported Disability, and Temporal Summation of Pain Predict Self-reported Pain in Low Back Pain Patients 12 Weeks After General Practitioner Consultation: A Prospective Cohort Study

OBJECTIVES

Patients with low back pain (LBP) often demonstrate pain sensitization, high degree of pain catastrophizing, and psychological distress. This study investigated whether pain sensitization mechanisms, the Pain Catastrophizing Scale (PCS), and Start Back Screening Tool were associated with pain in recurrent LBP patients 12 weeks after consulting their general practitioner (GP).

MATERIALS AND METHODS

In 45 LBP patients, pressure pain thresholds, temporal summation of pain (TSP), conditioned pain modulation (CPM), the Roland Morris Disability Questionnaire (RMDQ), and the PCS were assessed before consultation. Patients were classified into low to medium or high risk of poor prognosis on the basis of the Start Back Screening Tool. Worst pain within the last 24 hours was assessed on a visual analogue scale (VAS) at inclusion and 12 weeks after GP consultation.

RESULTS

VAS scores were reduced after 12 weeks in the low-to-medium (N=30, P<0.05), but not the high-risk group (N=15, P=0.40). RMDQ was reduced after 12 weeks (P<0.001), but with no difference between the groups. PCS was reduced in the low-to-medium and the high-risk group (P<0.05). TSP was significantly higher at follow-up in the high-risk group compared with the low-to-medium-risk group (P<0.05). A linear regression model explained 54.9% of the variance in VAS scores at follow-up utilizing baseline assessments of TSP, RMDQ, and PCS.

DISCUSSION

This study indicate that patients with LBP and high self-reported disability, high pain catastrophizing, and facilitated TSP assessed when consulting the GP might predictive poor pain progression 12 weeks after the consultation.

Sensitization in office workers with chronic neck pain in different pain conditions and intensities

OBJECTIVES

Office workers with chronic neck pain demonstrates signs of widespread hyperalgesia, less efficient descending pain modulation, which could indicate sensitization of central pain pathways. No studies have assessed a wide variety of office workers with different chronic neck pain disorders and assessed the impact of pain intensity on assessments of central pain pathways. This study aimed to assessed pressure pain thresholds (PPTs), temporal summation of pain (TSP) and conditioned pain modulation (CPM) and to associate these with pain intensity and disability in subgroups of office workers.

METHODS

One hundred-and-seventy-one office workers were distributed into groups of asymptomatic and chronic neck pain subjects. Chronic neck pain was categorized as chronic trapezius myalgia and chronic non-specific neck pain and as 'mild-pain' (Visual Analog Scale [VAS]≤3) and 'moderate-pain' (VAS>3) groups. PPTs, TSP, CPM, and Copenhagen Psychosocial Questionnaire II were assessed in all subjects. Neck Disability Index and Pain Catastrophizing Scale were assessed in all the symptomatic office workers.

RESULTS

PPTs were lower in moderate pain (n=49) and chronic trapezius myalgia (n=56) compared with asymptomatic subjects (n=62, p<0.05). TSP was facilitated in moderate pain group compared with mild pain (n=60, p<0.0001) group and asymptomatic subjects (p<0.0001). No differences were found in CPM comparing the different groups (p<0.05). Multiple regression analysis identified Neck Disability Index and TSP as independent factors for prediction of pain intensity in chronic trapezius myalgia (R²=0.319) and chronic non-specific neck pain (R²=0.208). Somatic stress, stress and sleep as independent factors in chronic non-specific neck pain (R²=0.525), and stress in moderate pain group (R²=0.494) for the prediction of disability.

CONCLUSIONS

Office workers with chronic trapezius myalgia and moderate pain intensity showed significant signs of widespread pressure hyperalgesia. Moreover, the moderate pain group demonstrated facilitated TSP indicating sensitization of central pain pathways. Neck Disability Index and TSP were independent predictors for pain intensity in pain groups. Sleep and stress were independent predictors for disability.

Pressure pain thresholds in individuals with knee pain: a cross-sectional study

Background

Knee osteoarthritis (KOA), chronic widespread pain (CWP) and overweight/obesity are public health problems that often coincide, and there is a multifactorial and unclear relationship between them. The study aimed to (1) investigate pain sensitivity, assessed by pressure pain thresholds (PPTs), among women and men with knee pain and (2) associations with, respectively, radiographic KOA (rKOA), CWP, and overweight/obesity.

Methods

Baseline data from an ongoing longitudinal study involving 280 individuals with knee pain in the 30–60 age group. Pain sensitivity was assessed by PPTs on eight different tender points using a pressure algometer. The participants’ knees were x-rayed. Self-reported CWP and number of pain sites were assessed with a pain figure, and overweight/obesity was measured using body mass index (BMI), visceral fat area (VFA), and body fat percentage, assessed with a bioimpedance. Associations were analysed using regression analyses.

Results

Women reported lower PPTs than men (p < 0.001), but no PPTs differences were found between those with and without rKOA. Low PPTs was associated with female sex, more pain sites, CWP, and a higher VFA and body fat percentage. The tender points second rib and the knees were most affected. The prevalence of CWP was 38 %.

Conclusions

The modifiable factors, increased VFA, and body fat could be associated with increased pain sensitivity among individuals with knee pain. Longitudinal studies are needed to further investigate the associations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04408-0.

Pain referral area is reduced by remote pain

BACKGROUND

Endogenous pain inhibitory mechanisms are known to reduce pain intensity, but whether they influence the size and distribution of pain referral is unclear. This study aimed to determine if referred pain is reduced by applying a remote, conditioning painful stimulus.

METHODS

Twenty-four healthy men participated in this randomized, crossover study with a control and conditioning session. Referred pain was induced from the infraspinatus muscle (dominant side) by a painful pressure for 60 s. When applying pressure, the intensity was adjusted to a local pain intensity of 7/10 on a numerical rating scale. In the conditioning session, tonic painful pressure was simultaneously applied to the non-dominant leg during induction of referred pain. The area of referred pain was drawn onto a digital body chart and size extracted for data analysis.

RESULTS

For the total group and in a subgroup with distinct patterns of referred pain (n = 15/24), the pain area perceived in the back and front+back was smaller during the conditioning compared with the control (p < 0.05). No significant difference was found between sessions in a subgroup only demonstrating local pain (n = 9/24).

CONCLUSIONS

Engaging the descending noxious inhibitory control reduced the size of pain areas predominately when distinct pain referral was present. Assuming a conditioning effect of descending inhibitory control acting on dorsal horn neurons, these findings may indicate that mechanisms underlying pain referral can be modulated by endogenous control. The findings may indicate that referred pain may be a useful proxy to evaluate sensitivity of central pain mechanisms as previously suggested.

SIGNIFICANCE

The current results indicate a link between endogenous inhibition and pain referral. Descending inhibitory control effects on pain referral support a spinal mechanism involved in pain referral. Future studies should investigate whether the spatial characteristics of referred pain (e.g. size, frequency of affected body regions and distribution away from the primary nociceptive stimulus) can useful to evaluate the efficiency of endogenous pain modulation.

The Central Aspects of Pain in the Knee (CAP-Knee) questionnaire; a mixed-methods study of a self-report instrument for assessing central mechanisms in people with knee pain

OBJECTIVES

Pain is the prevailing symptom of knee osteoarthritis. Central sensitisation creates discordance between pain and joint pathology. We previously reported a Central Pain Mechanisms trait derived from eight discrete characteristics: Neuropathic-like pain, Fatigue, Cognitive-impact, Catastrophising, Anxiety, Sleep disturbance, Depression, and Pain distribution. We here validate and show that an 8-item questionnaire, Central Aspects of Pain in the Knee (CAP-Knee) is associated both with sensory- and affective- components of knee pain severity.

METHODS

Participants with knee pain were recruited from the Investigating Musculoskeletal Health and Wellbeing study in the East Midlands, UK. CAP-Knee items were refined following cognitive interviews. Psychometric properties were assessed in 250 participants using Rasch-, and factor-analysis, and Cronbach's alpha. Intra-class correlation coefficients tested repeatability. Associations between CAP-Knee and McGill Pain questionnaire pain severity scores were assessed using linear regression.

RESULTS

CAP-Knee targeted the knee pain sample well. Cognitive interviews indicated that participants interpreted CAP-Knee items in diverse ways, which aligned to their intended meanings. Fit to the Rasch model was optimised by rescoring each item, producing a summated score from 0 to 16. Internal consistency was acceptable (Cronbach's alpha = 0.74) and test-retest reliability was excellent (ICC2,1 = 0.91). Each CAP-Knee item contributed uniquely to one discrete 'Central Mechanisms trait' factor. High CAP-Knee scores associated with worse overall knee pain intensity, and with each of sensory- and affective- McGill Pain Questionnaire scores.

CONCLUSION

CAP-Knee is a simple and valid self-report questionnaire, which measures a single 'Central Mechanisms' trait, and may help identify and target centrally-acting treatments aiming to reduce the burden of knee pain.

Strength training in addition to neuromuscular exercise and education in individuals with knee osteoarthritis-the effects on pain and sensitization

BACKGROUND

There is a lack of evidence of the relative effects of different exercise modes on pain sensitization and pain intensity in individuals with knee osteoarthritis (KOA).

METHODS

Ninety individuals with radiographic and symptomatic KOA, ineligible for knee replacement surgery, were randomized to 12 weeks of twice-weekly strength training in addition to neuromuscular exercise and education (ST+NEMEX-EDU) or neuromuscular exercise and education alone (NEMEX-EDU). Outcomes were bilateral, lower-leg, cuff pressure pain- and tolerance thresholds (PPT, PTT), temporal summation (TS), conditioned pain modulation (CPM), self-reported knee pain intensity and number of painful body sites.

RESULTS

After 12 weeks of exercise, we found significant differences in increases in PPT (-5.01 kPa (-8.29 to -1.73, p = .0028)) and PTT (-8.02 kPa (-12.22 to -3.82, p = .0002)) in the KOA leg in favour of ST+NEMEX-EDU. We found no difference in effects between groups on TS, CPM or number of painful body sites. In contrast, there were significantly greater pain-relieving effects on VAS mean knee pain during the last week (-8.4 mm (-16.2 to -0.5, p = .0364) and during function (-16.0 mm (-24.8 to -7.3, p = .0004)) in favour of NEMEX-EDU after 12 weeks of exercise.

CONCLUSION

Additional strength training reduced pain sensitization compared to neuromuscular exercise and education alone, but also attenuated the reduction in pain intensity compared to neuromuscular exercise and education alone. The study provides the first dose- and type-specific insight into the effects of a sustained exercise period on pain sensitization in KOA. Future studies are needed to elucidate the role of different exercise modes.

SIGNIFICANCE

This study is an important step towards better understanding the effects of exercise in pain management of chronic musculoskeletal conditions. We found that strength training in addition to neuromuscular exercise and education compared with neuromuscular exercise and education only had a differential impact on pain sensitization and pain intensity, but also that regardless of the exercise mode, the positive effects on pain sensitization and pain intensity were comparable to the effects of other therapeutic interventions for individuals with knee osteoarthritis.

The predictive value of quantitative sensory testing: a systematic review on chronic postoperative pain and the analgesic effect of pharmacological therapies in patients with chronic pain

Studies have suggested that quantitative sensory testing (QST) might hold a predictive value for the development of chronic postoperative pain and the response to pharmacological interventions. This review systematically summarizes the current evidence on the predictive value of QST for chronic postoperative pain and the effect of pharmacological interventions. The main outcome measures were posttreatment pain intensity, pain relief, presence of moderate-to-severe postoperative pain, responders of 30% and 50% pain relief, or validated questionnaires on pain and disability. A systematic search of MEDLINE and EMBASE yielded 25 studies on surgical interventions and 11 on pharmacological interventions. Seventeen surgical and 11 pharmacological studies reported an association between preoperative or pretreatment QST and chronic postoperative pain or analgesic effect. The most commonly assessed QST modalities were pressure stimuli (17 studies), temporal summation of pain (TSP, 14 studies), and conditioned pain modulation (CPM, 16 studies). Of those, the dynamic QST parameters TSP (50%) and CPM (44%) were most frequently associated with chronic postoperative pain and analgesic effects. A large heterogeneity in methods for assessing TSP (n = 4) and CPM (n = 7) was found. Overall, most studies demonstrated low-to-moderate levels of risk of bias in study design, attrition, prognostic factors, outcome, and statistical analyses. This systematic review demonstrates that TSP and CPM show the most consistent predictive values for chronic postoperative pain and analgesic effect, but the heterogeneous methodologies reduce the generalizability and hence call for methodological guidelines.

The Modulatory Effect of QST in Shoulder Pain: A Systematic Review and Meta-Analysis

BACKGROUND

The underlying mechanisms for shoulder pain (SP) are still widely unknown. Previous reviews report signs of altered pain processing in SP measured using quantitative sensory testing (QST). Evidence suggests that QST might hold predictive value for SP after intervention, yet it is not known whether QST profiles can be modulated in response to different treatments. Therefore, this systematic review and meta-analysis aimed to assess if QST-parameters can be modified by interventions for patients with SP.

METHODS

Three databases were searched to identify eligible studies. Eligible studies had a prospective design, with at least one QST variable as an outcome in conjunction with an intervention measured before and after intervention. Studies that involved SP caused by spinal or brain injury and studies looking at combined chronic neck/shoulder pain were excluded.

RESULTS

19 studies investigating SP were eligible for inclusion for this review. Pressure pain threshold (PPT) was the most frequently used QST-parameter investigating local and widespread hyperalgesia. A meta-analysis was performed with data from 10 studies with a total of 16 interventions. Results demonstrated an overall acute effect (<24 hours after intervention) of interventions in favour of local decreased pain sensitivity and of remote decreased pain sensitivity comparing PPTs before and after interventions.

CONCLUSIONS

This study demonstrates that interventions such as exercise and manual therapy can modulate PPTs acutely both locally and remotely in patients with shoulder pain. Further research investigating the acute and long-term modulatory ability of these interventions on other QST-parameters is needed in patients with shoulder pain.

Quantitative Sensory Testing Discriminates Central Sensitization Inventory Scores in Participants with Chronic Musculoskeletal Pain: An Exploratory Study

BACKGROUND

The Central Sensitization Inventory (CSI) is often used in clinical settings to screen for the presence of central sensitization. However, various cutoff scores have been reported for this tool, and scores have not been consistently associated with widespread pain sensitivity as measured with quantitative sensory testing (QST). The purpose of this study was to compare QST profiles among asymptomatic controls and participants with chronic musculoskeletal pain (CMP), and to determine the association between self-report questionnaires and QST in participants with CMP.

METHODS

Twenty asymptomatic controls and 46 participants with CMP completed the CSI, PROMIS-29, and QST assessments of mechanical and thermal pain thresholds remote to the area of pain. Receiver Operating Characteristic analysis revealed a cutoff score of 33.5 for the CSI. PROMIS-29 Quality of Life (QOL) inventory and QST measures were compared between low and high CSI groups.

RESULTS

The high CSI group (n = 19) had significantly lower mechanical and thermal pain thresholds, and larger impairments in QOL measures, compared to the low CSI group (n = 27) and asymptomatic controls. Participants with CSI scores < 33.5 presented similarly to asymptomatic controls. Anxiety, pain interference, and CSI scores demonstrated the highest number of significant associations to QST measures.

CONCLUSION

A cutoff score of 33.5 on the CSI may be useful for discriminating widespread pain sensitivity and quality of life impairments in participants with CMP. Future studies should consider how the presence of high or low CSI may impact differential diagnosis, prognosis, and treatment responsiveness for patients with primary or secondary CMP.

Patient Profiling Based on Spectral Clustering for an Enhanced Classification of Patients with Tension-Type Headache

Profiling groups of patients in clusters can provide meaningful insights into the features of the population, thus helping to identify people at risk of chronification and the development of specific therapeutic strategies. Our aim was to determine if spectral clustering is able to distinguish subgroups (clusters) of tension-type headache (TTH) patients, identify the profile of each group, and argue about potential different therapeutic interventions. A total of 208 patients (n = 208) with TTH participated. Headache intensity, frequency, and duration were collected with a 4-week diary. Anxiety and depressive levels, headache-related burden, sleep quality, health-related quality of life, pressure pain thresholds (PPTs), dynamic pressure thresholds (DPT) and evoked-pain, and the number of trigger points (TrPs) were evaluated. Spectral clustering was used to identify clusters of patients without any previous assumption. A total of three clusters of patients based on a main difference on headache frequency were identified: one cluster including patients with chronic TTH (cluster 2) and two clusters including patients with episodic TTH (clusters 0–1). Patients in cluster 2 showed worse scores in all outcomes than those in clusters 0–1. A subgroup of patients with episodic TTH exhibited pressure pain hypersensitivity (cluster 0) similarly to those with chronic TTH (cluster 2). Spectral clustering was able to confirm subgrouping of patients with TTH by headache frequency and to identify a group of patients with episodic TTH with higher sensitization, which may need particular attention and specific therapeutic programs for avoiding potential chronification.

Somatosensory Testing in Pediatric Patients with Chronic Pain: An Exploration of Clinical Utility

We aimed to evaluate the utility of clinical somatosensory testing (SST), an office adaptation of laboratory quantitative sensory testing, in a biopsychosocial assessment of a pediatric chronic somatic pain sample (N = 98, 65 females, 7–18 years). Stimulus–response tests were applied at pain regions and intra-subject control sites to cutaneous stimuli (simple and dynamic touch, punctate pressure and cool) and deep pressure stimuli (using a handheld pressure algometer, and, in a subset, manually inflated cuff). Validated psychological, pain-related and functional measures were administered. Cutaneous allodynia, usually regional, was elicited by at least one stimulus in 81% of cases, most frequently by punctate pressure. Central sensitization, using a composite measure of deep pressure pain threshold and temporal summation of pain, was implied in the majority (59.2%) and associated with worse sleep impairment and psychological functioning. In regression analyses, depressive symptoms were the only significant predictor of pain intensity. Functional interference was statistically predicted by deep pressure pain threshold and depressive symptoms. Manually inflated cuff algometry had comparable sensitivity to handheld pressure algometry for deep pressure pain threshold but not temporal summation of pain. SST complemented standard biopsychosocial assessment of pediatric chronic pain; use of SST may facilitate the understanding of disordered neurobiology.

Correlation Between Central Sensitization and Remote Muscle Performance in Individuals With Chronic Low Back Pain

OBJECTIVE

The purpose of this study was to examine associations between the degree of central sensitization (CS) and remote muscle performance in people with chronic low back pain (CLBP).

METHODS

The 2011 fibromyalgia (FM) criteria and severity scales (2011 FM survey) were used as a surrogate measure of CS to divide the participants into 2 groups: FM-positive CLBP and FM-negative CLBP. Measures related to central sensitization included the 2011 FM survey and pressure pain threshold of the thumbnail. Measures related to muscle performance included neck flexor muscle strength and endurance and plantar flexor muscle strength. Between-groups and correlation analyses were performed.

RESULTS

Sixty people with CLBP were enrolled (30 FM-positive, 30 FM-negative). There was no significant difference between the subgroups in age, sex, or pain duration (P > .05). The FM-positive CLBP group showed poorer neck flexor muscle endurance (P = .01) and plantar flexor muscle strength (P = .002) than the FM-negative CLBP group, whereas neck flexor muscle strength was not different between the groups (P = .175). Scores for FM and values for pressure pain thresholds of the thumbnail were associated with neck flexor muscle strength (respectively, r = -0.320, P = .013, and r = 0.467, P < .001), endurance (r = -0.242, P < .001, and r = 0.335, P = .009), and plantar flexor muscle strength (r = -0.469, P < .001, and r = 0.500, P < .001).

CONCLUSION

We found associations between the degree of CS and remote muscle strength and endurance, suggesting that poor remote muscle performance is possibly a clinical sign of CS in people with CLBP.

Short term relief of multisite chronicpain with Bowen Therapy: A double-blind, randomized controlled trial

INTRODUCTION

Bowen Therapy, a form of soft tissue manipulation, is commonly used to treat musculoskeletal conditions; yet, there is little evidence for its efficacy. The goal of the study was to investigate the impact of Bowen Therapy on pain and function in people with chronic pain in multiple locations. Additionally, we examined the mechanisms of effect through monitoring the nociceptive and autonomic nervous systems.

METHOD

The study was a double-blind, randomized controlled trial involving 31 people with chronic pain. Participants were randomized into real and sham therapy groups. Each group received 6 sessions of therapy over 8 weeks. The primary outcome measures of pain and function were assessed using standard questionnaires. Quantitative sensory testing was used to assess the nociceptive system, while recordings of heart rate variability and skin conductance were used to assess the autonomic nervous system. Outcome measures were assessed at baseline and at 1- and 6-weeks following completion of the intervention.

RESULTS

The real therapy group had a significantly lower pain score 1-week following the intervention compared to the sham group. There were no differences between groups at the final follow-up or in the function measures. There was no significant change in the nociceptive measures but there was evidence of increased activation of the sympathetic nervous system.

DISCUSSION

Bowen Therapy gave rise to a short-term reduction in pain that was not evident in a sham therapy group. The mechanisms of action of Bowen Therapy remain uncertain but may involve sympathoexcitation.

Patient and Disease Characteristics Associate With Sensory Testing Results in Chronic Pancreatitis

BACKGROUND

Abdominal pain is the most common symptom in chronic pancreatitis (CP) and has an extensive impact on patients' lives. Quantitative sensory testing (QST) provides information on sensitivity to pain and mechanisms that can help quantify pain and guide treatment. The aims of this study were (1) to explore sensitivity to pain in patients with CP using QST and (2) to associate patient and disease characteristics with QST results.

METHODS

Ninety-one patients with painful CP and 28 healthy control participants completed a QST paradigm using static tests (muscle pressure stimulation and electrical skin stimulations) to unravel segmental and widespread hyperalgesia as a consequence of visceral pain. A dynamic conditioned pain modulation (CPM) paradigm was used as a proxy of pain modulation from the brainstem to inhibit incoming nociceptive barrage, and questionnaires were used to gather information on pain experience and quality of life.

RESULTS

Patients had impaired CPM compared with controls (18.0±29.3% vs. 30.9±29.3%, P=0.04) and were hypersensitive to pressure stimulation, specifically in the pancreatic (Th10) dermatome (P<0.001). The capacity of CPM was associated with clinical pain intensity (P=0.01) and (in the univariate analysis only) the use of opioids was associated with hyperalgesia to pressure stimulation (P<0.05).

CONCLUSIONS

Sensitivity to pain in CP patients can be characterized by a simple bedside QST. Severe clinical pain in CP was associated with reduced CPM function and should be targeted in management.