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

Preoperative pain sensitivity and its correlation with postoperative acute and chronic pain: a systematic review and meta-analysis

BACKGROUND

Preoperative pain sensitivity (PPS) can be associated with postsurgical pain. However, estimates of this association are scarce. Confirming this correlation is essential to identifying patients at high risk for severe postoperative pain and for developing analgesic strategy. This systematic review and meta-analysis summarises PPS and assessed its correlation with postoperative pain.

METHODS

PubMed, Scopus, Cochrane Library, and PsycINFO were searched up to October 1, 2023, for studies reporting the association between PPS and postsurgical pain. Two authors abstracted estimates of the effect of each method independently. A random-effects model was used to combine data. Subgroup analyses were performed to investigate the effect of pain types and surgical procedures on outcomes.

RESULTS

A total of 70 prospective observational studies were included. A meta-analysis of 50 studies was performed. Postoperative pain was negatively associated with pressure pain threshold (PPT; r=-0.15, 95% confidence interval [CI] -0.23 to -0.07]) and electrical pain threshold (EPT; r=-0.28, 95% CI -0.42 to -0.14), but positively correlated with temporal summation of pain (TSP; r=0.21, 95% CI 0.12-0.30) and Pain Sensitivity Questionnaire (PSQ; r=0.25, 95% CI 0.13-0.37). Subgroup analysis showed that only TSP was associated with acute and chronic postoperative pain, whereas PPT, EPT, and PSQ were only associated with acute pain. A multilevel (three-level) meta-analysis showed that PSQ was not associated with postoperative pain.

CONCLUSIONS

Lower PPT and EPT, and higher TSP are associated with acute postoperative pain while only TSP is associated with chronic postoperative pain. Patients with abnormal preoperative pain sensitivity should be identified by clinicians to adopt early interventions for effective analgesia.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO (CRD42023465727).

Differences in self-reported signs related to central sensitization and pressure pain threshold related to knee osteoarthritis and sarcopenia

PURPOSE

Neuroinflammation, which occurs in knee osteoarthritis and sarcopenia, has attracted attention as a mechanism of central sensitization, but the relationship between central sensitization and these conditions has not been widely studied. This study investigates differences in self-reported signs of central sensitization and pressure pain threshold in individuals with knee osteoarthritis and sarcopenia.

METHODS

We examined 340 patients (mean age ± standard deviation: 76 ± 5.9, women were 86.9%) with knee osteoarthritis scheduled to undergo total knee arthroplasty. For comparison, 129 community-dwelling older people (mean age ± standard deviation: 76 ± 5.5, women were 68.9%) individuals without a history of knee osteoarthritis or any other diagnosed illnesses were matched for age and sex. We assessed central sensitization inventory-9, pressure pain threshold, pain-related factors, skeletal muscle mass index, and hand grip strength. ANCOVA using 2 (patients with knee osteoarthritis and community older people without knee osteoarthritis) × 2 (sarcopenia and robust) was performed to assess outcome measurements.

RESULTS

The prevalence of sarcopenia among patients with knee osteoarthritis was 50.3%. ANCOVA revealed an interaction effect for the central sensitization inventory-9. For the main effect of knee osteoarthritis, there was a significant difference in central sensitization inventory-9, and for the main effect of sarcopenia, there was a significant difference in pressure pain threshold.

CONCLUSIONS

Discrepancies in the evaluation of central sensitization were identified between knee osteoarthritis and sarcopenia. Individuals with knee osteoarthritis had elevated score of self-reported indications of central sensitization, whereas sarcopenic patients had reduced pressure pain thresholds.

Association of Muscle Quality and Pain in Adults With Symptomatic Knee Osteoarthritis, Independent of Muscle Strength: Findings From a Cross-Sectional Study

OBJECTIVE

Knee osteoarthritis (OA) is a leading cause of chronic pain in adults and shows wide interindividual variability, with peripheral and central factors contributing to the pain experience. Periarticular factors, such as muscle quality (eg, echo intensity [EI] and shear wave velocity [SWV]), may contribute to knee OA pain; however, the role of muscle quality in OA symptoms has yet to be fully established.

METHODS

Twenty-six adults (age >50 years) meeting clinical criteria for knee OA were included in this cross-sectional study. Quantitative ultrasound imaging was used to quantify EI and SWV in the rectus femoris of the index leg. Pearson correlations followed by multiple linear regression was used to determine associations between muscle quality and pain, controlling for strength, age, sex, and body mass index.

RESULTS

EI and SWV were significantly associated with movement-evoked pain (b = 0.452-0.839, P = 0.024-0.029). Clinical pain intensity was significantly associated with SWV (b = 0.45, P = 0.034), as were pressure pain thresholds at the medial (b = -0.41, P = 0.025) and lateral (b = -0.54, P = 0.009) index knee joint line, adjusting for all covariates. Pain interference was significantly associated with knee extension strength (b = -0.51, P = 0.041).

CONCLUSION

These preliminary findings suggest that EI and SWV may impact knee OA pain and could serve as malleable treatment targets. Findings also demonstrate that muscle quality is a unique construct, distinct from muscle strength, which may impact pain and treatment outcomes. More research is needed to fully understand the role of muscle quality in knee OA.

Diminished vibration perception and greater pressure pain sensitivity are associated with worse knee osteoarthritis outcomes across sex and race

OBJECTIVE

To examine associations of vibration sensitivity and pressure pain sensitivity with knee osteoarthritis (OA) outcomes across sex and race, which may relate to known sex and race disparities in clinical outcomes.

DESIGN

Data were from the 2013-2015 visit of the Johnston County Osteoarthritis Project. Exposures were vibration perception threshold (VPT) measured at the bilateral medial femoral condyle (MFC) and first metatarsophalangeal joint (MTP), and pressure pain threshold (PPT) measured at the bilateral upper trapezius. Outcomes were knee pain severity and presence of knee symptoms, radiographic knee OA, and symptomatic knee OA in each knee. Cross-sectional associations of the exposures with the outcomes were examined using logistic regression models, overall and separately by sex and race.

RESULTS

In the VPT and PPT analyses, 851 and 862 participants (mean age 71 years, 68% female, 33% Black, body mass index 31 kg/m2) and 1585 and 1660 knees were included, respectively. Higher VPT (lower vibration sensitivity) at the MFC and first MTP joint was associated with all outcomes. Lower PPT (greater pressure pain sensitivity) was associated with greater knee pain severity. Associations of VPT and PPT with all outcomes were similar among females and males and Black and White individuals.

CONCLUSIONS

Diminished vibration perception and greater pressure pain sensitivity were cross-sectionally associated with worse knee OA outcomes. Despite differences in VPT and PPT among females and males and Black and White adults, associations with knee OA outcomes did not differ by sex or race, suggesting neurophysiological differences do not relate to established disparities.

Prognostic value of preoperative mechanical hyperalgesia and neuropathic pain qualities for postoperative pain after total knee replacement

BACKGROUND

Total knee replacement (TKR) is the gold standard treatment for end-stage chronic osteoarthritis pain, yet many patients report chronic postoperative pain after TKR. The search for preoperative predictors for chronic postoperative pain following TKR has been studied with inconsistent findings.

METHODS

This study investigates the predictive value of quantitative sensory testing (QST) and PainDETECT for postoperative pain 3, 6 and 12 months post-TKR. We assessed preoperative and postoperative (3 and 6 months) QST measures in 77 patients with knee OA (KOA) and 41 healthy controls, along with neuropathic pain scores in patients (PainDETECT). QST parameters included pressure pain pressure threshold (PPT), pain tolerance threshold (PTT), conditioned pain modulation (CPM) and temporal summation (TS) using cuff algometry, alongside mechanical hyperalgesia and temporal summation to repeated pinprick stimulation.

RESULTS

Compared to healthy controls, KOA patients at baseline demonstrated hyperalgesia to pinprick stimulation at the medial knee undergoing TKR, and cuff pressure at the calf. Lower cuff algometry PTT and mechanical pinprick hyperalgesia were associated with preoperative KOA pain intensity. Moreover, preoperative pinprick pain hyperalgesia explained 25% of variance in pain intensity 12 months post-TKR and preoperative neuropathic pain scores also captured 30% and 20% of the variance in postoperative pain at 6 and 12 months respectively. A decrease in mechanical pinprick hyperalgesia from before surgery to 3 months after TKR was associated with lower postoperative pain at the 12 months post-TKR follow-up.

CONCLUSION

Our findings suggest that preoperative pinprick hyperalgesia and neuropathic-like pain symptoms show predictive value for the development of chronic post-TKR pain.

SIGNIFICANCE STATEMENT

This study's findings hold significant implications for chronic pain management in knee osteoarthritis patients, particularly those undergoing total knee replacement surgery (TKR). Mechanical hyperalgesia and neuropathic pain-like characteristics predict postoperative pain 1 year after TKR, emphasizing the importance of understanding pain phenotypes in OA for selecting appropriate pain management strategies. The normalization of hyperalgesia after surgery correlates with better long-term outcomes, further highlighting the therapeutic potential of addressing abnormal pain processing mechanisms pre- and post-TKR.

Microbial Symphony: Exploring the Role of the Gut in Osteoarthritis-Related Pain. A Narrative Review

One of the most common musculoskeletal disorders, osteoarthritis (OA), causes worldwide disability, morbidity, and poor quality of life by degenerating articular cartilage, modifying subchondral bone, and inflaming synovial membranes. OA pathogenesis pathways must be understood to generate new preventative and disease-modifying therapies. In recent years, it has been acknowledged that gut microbiota (GM) can significantly contribute to the development of OA. Dysbiosis of GM can disrupt the "symphony" between the host and the GM, leading to a host immunological response that activates the "gut-joint" axis, ultimately worsening OA. This narrative review summarizes research supporting the "gut-joint axis" hypothesis, focusing on the interactions between GM and the immune system in its two main components, innate and adaptive immunity. Furthermore, the pathophysiological sequence of events that link GM imbalance to OA and OA-related pain is broken down and further investigated. We also suggest that diet and prebiotics, probiotics, nutraceuticals, exercise, and fecal microbiota transplantation could improve OA management and represent a new potential therapeutic tool in the light of the scarce panorama of disease-modifying osteoarthritis drugs (DMOADs). Future research is needed to elucidate these complex interactions, prioritizing how a particular change in GM, i.e., a rise or a drop of a specific bacterial strain, correlates with a certain OA subset to pinpoint the associated signaling pathway that leads to OA.

Pre-operative pain pressure threshold association with patient satisfaction following Total Knee Arthroplasty

Background

Total knee arthroplasty (TKA) is commonly performed for the treatment of knee osteoarthritis (KOA). Poor satisfaction continues to be seen after TKA. Whilst reasons for poor patient satisfaction are multifactorial, there is a strong correlation with persistent pain following TKA. Studies have shown an association between local and remote mechanical hypersensitivity, measured using pressure pain thresholds (PPTs), and severity of knee osteoarthritis and functional status. We aimed to determine if the pre-operative PPTs were associated with patient satisfaction following TKA.

Methods

A prospective longitudinal study of 77 individuals was undertaken. Regression modelling assessed the relationship between Patient Satisfaction using the Knee Society Score (satisfaction subscale) following TKA for KOA, and PPTs recorded pre-operatively locally and remote to the affected knee, while accounting for potentially confounding patient demographic and psychosocial factors.

Results

Lower PPTs (indicating increased mechanical hypersensitivity) locally and remote to the operative knee were modestly associated with lower patient satisfaction in the short-term (six weeks) following TKA (β 0.25-0.28, adjR2 = 0.14-0.15), independent of demographic or psychosocial influences. However, this relationship progressively diminished in the intermediate and long-term post TKA.

Conclusion

While pre-operative PPT measures may provide some foresight to patient satisfaction post TKA in the short term, these measures appear to provide little insight to patient satisfaction in the intermediate and longer term.

Psychometric properties of the Turkish version of Central Sensitization Inventory-9 in patients with chronic musculoskeletal pain

The aim of the study was to assess the psychometric properties of the Turkish version of Central Sensitization Inventory-9 (CSI-9) in patients with chronic musculoskeletal pain. The methodological study included 92 patients with chronic musculoskeletal pain. The original version of the CSI-9 was translated and culturally adapted into Turkish. The internal consistency and test-retest reliability were evaluated with Cronbach's α and the intraclass correlation coefficient (ICC), respectively. The assessment of reproducibility was conducted with the standard error of measurement (SEM) and minimal detectable difference (MDD) values. Convergent validity was explored by correlation analysis between the CSI-9 and Central Sensitization Inventory (CSI-25), Brief Pain Inventory (BPI), and European Quality of Life Survey-5 Dimensions (EQ-5D). The structural validity was assessed with factor analysis. Floor and ceiling effects were also analyzed. We found a very good internal consistency (Cronbach's α of 0.83) and excellent test-retest reliability (ICC of 0.96) of the Turkish CSI-9. The SEM demonstrated a range between 0.19 and 1.12, and the MDD was observed to vary from 1.17 to 1.35. The CSI-9 correlated significantly with the CSI-25 ( r  = 0.77, P  < 0.001), the pain severity subscale of the BPI ( r  = 0.41 to 0.53, P  < 0.001), the pain interference subscale of the BPI ( r  = 0.21 to 0.58, P  = 0.02 to P  < 0.001), the EQ-5D ( r  = 0.24 to 0.48, P  < 0.05), and the EQ-5D visual analog scale ( r  = -0.41, P  < 0.001). One factor was identified within the CSI-9. Our data suggest that the Turkish CSI-9 is reliable and valid outcome measure for assessing CS in patients with chronic musculoskeletal pain.

Clinical Assessment of Osteoarthritis Pain: Contemporary Scenario, Challenges, and Future Perspectives

The multifaceted nature of osteoarthritis (OA) pain presents a challenge in understanding and managing the condition. The diverse pain experiences, progression rates, individual responses to treatments, and complex disease mechanisms contribute to heterogeneity in the clinical studies outcomes. The lack of a standardized methodology for assessing and classifying OA pain challenges healthcare practitioners. This complicates the establishment of universally applicable protocols or standardized guidelines for treatment. This article explores the heterogeneity observed in clinical studies evaluating OA pain treatments, highlighting the necessity for refined methodologies, personalized patient categorization, and consistent outcome measures. It discusses the role of the multidimensional nature of OA pain, underlying pain mechanisms, and other contributing factors to the heterogeneity in outcome measures. Addressing these variations is crucial to establishing a more consistent framework for evidence-based treatments and advancing care of the patient with OA pain.

Microenvironmental interference with intra-articular stem cell regeneration influences the onset and progression of arthritis

Studies have indicated that the preservation of joint health and the facilitation of damage recovery are predominantly contingent upon the joint's microenvironment, including cell-cell interactions, the extracellular matrix's composition, and the existence of local growth factors. Mesenchymal stem cells (MSCs), which possess the capacity to self-renew and specialize in many directions, respond to cues from the microenvironment, and aid in the regeneration of bone and cartilage, are crucial to this process. Changes in the microenvironment (such as an increase in inflammatory mediators or the breakdown of the extracellular matrix) in the pathological context of arthritis might interfere with stem cell activation and reduce their ability to regenerate. This paper investigates the potential role of joint microenvironmental variables in promoting or inhibiting the development of arthritis by influencing stem cells' ability to regenerate. The present status of research on stem cell activity in the joint microenvironment is also outlined, and potential directions for developing new treatments for arthritis that make use of these intervention techniques to boost stem cell regenerative potential through altering the intra-articular environment are also investigated. This review's objectives are to investigate these processes, offer fresh perspectives, and offer a solid scientific foundation for the creation of arthritic treatment plans in the future.

Structural alterations and pain perception at the ankle joint in patients with haemophilia

BACKGROUND

Patients with haemophilia (PwH) suffer from chronic pain due to joint alterations induced by recurring haemorrhage.

OBJECTIVES

This study aimed to investigate the relationship between structural alterations and pain perception at the ankle joint in PwH.

PATIENTS/METHODS

Ankle joints of 79 PwH and 57 healthy controls (Con) underwent ultrasound examination (US) and assessment of pain sensitivity via pressure pain thresholds (PPT). US discriminated between joint activity (synovitis) and joint damage (cartilage and/or bone degeneration) applying the HEAD-US protocol. Based on US-findings, five subgroups were built: PwH with activity/damage, PwH with activity/no damage, PwH with no activity/no damage, controls with activity/no damage and controls with no activity/no damage.

RESULTS

Joint activity and joint damage were significantly increased in ankles of PwH compared to Con (p ≤.001). Subgroup analysis revealed that structural alterations negatively impact pain perception. This is particularly evident when comparing PwH with both activity/damage to PwH with no activity/no damage at the tibiotalar joint (p = .001). At the fibulotalar joint, no significant differences were observed between PwH subgroups. Further analysis showed that both joint activity and joint damage result in an increase in pain sensitivity (p ≤.001).

CONCLUSION

The data suggest a relation between joint activity, joint damage and pain perception in PwH. Even minor changes due to synovitis appear to affect pain perception, with the effect not intensifying at higher levels of inflammation. In terms of joint damage, severe degeneration leads to a sensitised pain state most robustly, whereas initial changes do not seem to significantly affect pain perception.

EEG-Based Cortical Alterations in Individuals With Chronic Knee Pain Secondary to Osteoarthritis: A Cross-sectional Investigation

Chronic painful knee osteoarthritis (OA) is a disabling physical health condition. Alterations in brain responses to arthritic changes in the knee may explain persistent pain. This study investigated source localized, resting-state electroencephalography activity and functional connectivity in people with knee OA, compared to healthy controls. Adults aged 44 to 85 years with knee OA (n = 37) and healthy control (n = 39) were recruited. Resting-state electroencephalography was collected for 10 minutes and decomposed into infraslow frequency (ISF) to gamma frequency bands. Standard low-resolution electromagnetic brain tomography statistical nonparametric maps were conducted, current densities of regions of interest were compared between groups and correlation analyses were performed between electroencephalography (EEG) measures and clinical pain and functional outcomes in the knee OA group. Standard low-resolution electromagnetic brain tomography nonparametric maps revealed higher (P = .006) gamma band activity over the right insula (RIns) in the knee OA group. A significant (P < .0001) reduction in ISF band activity at the pregenual anterior cingulate cortex, whereas higher theta, alpha, beta, and gamma band activity at the dorsal anterior cingulate cortex, pregenual anterior cingulate cortex, the somatosensory cortex, and RIns in the knee OA group were identified. ISF activity of the dorsal anterior cingulate cortex was positively correlated with pain measures and psychological distress scores. Theta and alpha activity of RIns were negatively correlated with pain interference. In conclusion, aberrations in infraslow and faster frequency EEG oscillations at sensory discriminative, motivational-affective, and descending inhibitory cortical regions were demonstrated in people with chronic painful knee OA. Moreover, EEG oscillations were correlated with pain and functional outcome measures. PERSPECTIVE: This study confirms alterations in the rsEEG oscillations and its relationship with pain experience in people with knee OA. The study provides potential cortical targets and the EEG frequency bands for neuromodulatory interventions for managing chronic pain experience in knee OA.

Altered static and dynamic functional brain network in knee osteoarthritis: A resting-state functional magnetic resonance imaging study: Static and dynamic FNC in KOA

This study aimed to investigate altered static and dynamic functional network connectivity (FNC) and its correlation with clinical symptoms in patients with knee osteoarthritis (KOA). One hundred and fifty-nine patients with KOA and 73 age- and gender-matched healthy subjects (HS) underwent resting-state functional magnetic resonance imaging (rs-fMRI) and clinical evaluations. Group independent component analysis (GICA) was applied, and seven resting-state networks were identified. Patients with KOA had decreased static FNC within the default mode network (DM), visual network (VS), and cerebellar network (CB) and increased static FNC between the subcortical network (SC) and VS (p < 0.05, FDR corrected). Four reoccurring FNC states were identified using k-means clustering analysis. Although abnormalities in dynamic FNCs of KOA patients have been found using the common window size (22 TR, 44 s), but the results of the clustering analysis were inconsistent when using different window sizes, suggesting dynamic FNCs might be an unstable method to compare brain function between KOA patients and HS. These recent findings illustrate that patients with KOA have a wide range of abnormalities in the static and dynamic FNCs, which provided a reference for the identification of potential central nervous therapeutic targets for KOA treatment and might shed light on the other musculoskeletal pain neuroimaging studies.

Study on the treatment of osteoarthritis by acupuncture combined with traditional Chinese medicine based on pathophysiological mechanism: A review

Osteoarthritis (OA) is a major contributor to disability and social costs in the elderly. As the population ages and becomes increasingly obese, the incidence of the disease is higher than in previous decades. In recent years, important progress has been made in the causes and pathogenesis of OA pain. Modern medical treatment modalities mainly include the specific situation of the patient and focus on the core treatment, including self-management and education, exercise, and related weight loss. As an important part of complementary and alternative medicine, TCM has remarkable curative effect, clinical safety, and diversity of treatment methods in the treatment of OA. Traditional Chinese Medicine treatment of OA has attracted worldwide attention. Therefore, this article will study the pathophysiological mechanism of OA based on modern medicine, and explore the treatment of OA by acupuncture combined with Chinese Medicine.

Deficient gait function despite effect index of the Western Ontario and McMaster university osteoarthritis index score considered cured one year after bilateral total knee arthroplasty

BACKGROUND

To clarify the value of gait analysis and its consistency with traditional scoring scales for the evaluation of knee joint function after total knee arthroplasty (TKA).

METHODS

This study included 25 patients with knee osteoarthritis (KOA) who underwent bilateral TKA, and 25 conditionally matched healthy individuals, categorised into the experimental and control groups, respectively. Patients in the experimental group underwent gait analysis and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) evaluation before and 1 year after TKA. Weight-bearing balance and walking stability were assessed using discrete trends of relevant gait indicators. Pearson's correlation analysis was performed on the gait and WOMAC score data of the experimental group before and after TKA.

RESULTS

One year after TKA, patients' gait indices (except gait cycle) were significantly better than before surgery, but significantly worse than that of the control group (P < 0.01). The shape of patients' plantar pressure curves did not return to normal. Additionally, the discrete trend of related gait indicators reflecting weight-bearing balance and walking stability were smaller than before TKA, but still greater than that of the control group. The WOMAC scores of patients 1 year after TKA were significantly lower than those before TKA (P < 0.001), and the efficacy index was > 80%. The WOMAC scores and gait analysis results were significantly correlated before TKA (P < 0.05).

CONCLUSIONS

Gait analysis should be used in conjunction with scoring scales to assess joint functions.

Activity-related pain and sensitization predict within- and between-person pain experience in people with knee osteoarthritis: An ecological momentary assessment study

Background and objectives

Knee Osteoarthritis (OA) is a prevalent musculoskeletal condition that often results in pain and disability. Determining factors predicting variability in pain experience is critical to improving clinical outcomes. Underlying pain sensitization and its clinical manifestations, such as activity-related pain, may better predict the knee OA pain experience. This study aimed to determine whether Quantitative Sensory Testing (QST) derived sensitization measures and activity-related pain predict knee OA pain experiences collected via smartphone ecological momentary assessment (EMA).

Design

Individuals with knee OA were recruited from an urban community in New Zealand. Those eligible to participate underwent baseline QST with clinical measures of activity-related pain also being collected. The knee OA pain experience was collected via smartphone EMA three times daily for two weeks. Mixed effects location scale models were developed using a multilevel modelling approach.

Results

Eighty-six participants with knee OA participated in the study. Mean age was 67.3 years, with most of the participants being female (64%) and New Zealand European (90.6%). Activity-related pain predicted worse and more variable pain intensity, pain interference, and bothersomeness outcomes within and between individuals with knee OA. Widespread cold hyperalgesia and local mechanical hyperalgesia were shown to predict higher within-person variability in pain intensity and pain interference respectively, while mechanical temporal summation predicted less within-person variability in pain intensity and interference.

Discussion

Those demonstrating activity-related pain and sensitization could be at risk of experiencing worse and more variable knee OA pain in the subsequent weeks. Testing for sensitization in clinical practice could therefore identify those at greatest risk of higher and more variable knee OA pain experiences and in greatest need of treatment. Larger validation studies are required, which include individuals with more severe knee OA.

Transcranial Direct Current Stimulation for Knee Osteoarthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

OBJECTIVE

The effects of transcranial direct current stimulation (tDCS) in the treatment of knee osteoarthritis (KOA) is still unclear. The objective is to evaluate the efficacy and safety of tDCS in improving symptoms in patients with KOA.

METHODS

The following electronic databases were searched for eligible randomized controlled trials (RCTs): PubMed, Embase, Web of Science, and the Cochrane Library. The search was performed from the inception dates to April 30, 2023. Data extraction and quality assessment were performed by two independent reviewers. Standard mean differences (SMDs) with 95% confidence intervals (95% CIs) for pooled data were calculated. A random-effects model was used for the data analyses. The primary outcomes were pain and physical function. Secondary outcomes included stiffness, mobility performance, quality of life, pressure pain tolerance, and plasma levels of brain-derived neurotrophic factor (BDNF).

RESULTS

This meta-analysis included 13 RCTs. tDCS was significantly associated with pain decrease compared with sham tDCS (SMD = -0.62, 95% CI -0.87 to -0.37, P < 0.00001). When comparing tDCS plus other non-tDCS with sham tDCS plus other non-tDCS, there was no longer a significant association with pain decrease (SMD = -0.45, 95% CI -1.08 to 0.17, P = 0.16). The changes in physical function were not significantly different between the tDCS and sham tDCS groups (SMD = -0.09, 95% CI -0.56 to 0.38, P = 0.71). When comparing tDCS plus other non-tDCS with sham tDCS plus other non-tDCS, there was still no significant association with improvement in physical function (SMD = -0.66, 95% CI -1.63 to 0.30, P = 0.18). There was no significant difference with improvement in stiffness (SMD = -0.21, 95% CI -0.77 to 0.34, P = 0.45), mobility performance (SMD = 4.58, 95% CI -9.21 to 18.37, P = 0.51), quality of life (SMD = -7.01, 95% CI -22.61 to 8.59, P = 0.38), and pressure pain tolerance (SMD = 0.30, 95% CI -0.09 to 0.69, P = 0.13). There was a statistically significant reduction in plasma levels of BDNF (SMD = -13.57, 95% CI -24.23 to -2.92, P = 0.01).

CONCLUSION

In conclusion, tDCS could significantly alleviate pain, but it might have no efficacy in physical function, stiffness, mobility performance, quality of life, and pressure pain tolerance among patients with KOA.

The effectiveness of a combined exercise and psychological treatment programme on measures of nervous system sensitisation in adults with chronic musculoskeletal pain - a systematic review and meta-analysis

BACKGROUND

Quantitative sensory testing (QST) offers information regarding underlying mechanisms contributing to chronic pain (CP) in adults with musculoskeletal disorders. This review examined the use of QST measures in adults with CP following participation in a combined exercise and psychological intervention.

METHODS

The review was conducted in accordance with the PRISMA guidelines. Five databases were searched from inception to November 2022. All study designs which evaluated the effects of a combined exercise and psychological treatment on measures of nervous system sensitivity in adults with chronic musculoskeletal pain were included.

RESULTS

A total of 13 studies met the selection criteria, 10 of which were included in a meta-analysis. Local pressure pain thresholds were the most frequently used measure (n = 12 studies). Meta-analysis revealed statistically significantly improvements in favour of the combined exercise and psychological intervention group, compared to a control group, for local pressure pain threshold measures [SMD = 0.44, 95% CI 0.08-0.81, I2 = 84%], pain intensity scores [SMD=-0.89, 95% CI -1.66- -0.13, I2 = 94%] and the Central Sensitisation Inventory [SMD=-0.69, 95% CI -1.37- -0.02, I2 = 87%]. There were no significant differences found between groups for remote pressure pain thresholds, temporal summation or conditioned pain modulation.

CONCLUSIONS

The results suggest that a combined exercise and psychological intervention may lead to greater improvements in local pressure pain threshold, pain intensity and Central Sensitisation Inventory scores when compared to a control intervention in adults with CP, however these findings must be interpreted with caution as a large degree of heterogeneity was present in these results (I2: 84-94%). Further large, longitudinal studies are required using standardised QST measurement procedures and patient reported outcome measures to explore changes in nervous system sensitisation.

TRIAL REGISTRATION

This systematic review is registered with PROSPERO, ID Number CRD42022380464.

Myostatin and CXCL11 promote nervous tissue macrophages to maintain osteoarthritis pain

Pain is the most debilitating symptom of knee osteoarthritis (OA) that can even persist after total knee replacement. The severity and duration of pain do not correlate well with joint tissue alterations, suggesting other mechanisms may drive pain persistence in OA. Previous work identified that macrophages accumulate in the dorsal root ganglia (DRG) containing the somas of sensory neurons innervating the injured knee joint in a mouse OA model and acquire a M1-like phenotype to maintain pain. Here we aimed to unravel the mechanisms that govern DRG macrophage accumulation and programming. The accumulation of F4/80+iNOS+ (M1-like) DRG macrophages was detectable at day 3 after mono-iodoacetate (MIA)-induced OA in the mouse. Depletion of macrophages prior to induction of OA resolved pain-like behaviors by day 7 without affecting the initial development of pain-like behaviors. Analysis of DRG transcript identified CXCL11 and myostatin. CXCL11 and myostatin were increased at 3 weeks post OA induction, with CXCL11 expression partially localized in satellite glial cells and myostatin in sensory neurons. Blocking CXCL11 or myostatin prevented the persistence of OA pain, without affecting the initiation of pain. CXCL11 neutralization reduced the number of total and F4/80+iNOS+ DRG macrophages, whilst myostatin inhibition diminished the programming of F4/80+iNOS+ DRG macrophages. Intrathecal injection of recombinant CXCL11 did not induce pain-associated behaviors. In contrast, intrathecal myostatin increased the number of F4/80+iNOS+ DRG macrophages concurrent with the development of mechanical hypersensitivity that was prevented by macrophages depletion or CXCL11 blockade. Finally, myostatin inhibition during established OA, resolved pain and F4/80+iNOS+ macrophage accumulation in the DRG. In conclusion, DRG macrophages maintain OA pain, but are not required for the induction of OA pain. Myostatin is a key ligand in neuro-immune communication that drives the persistence of pain in OA through nervous tissue macrophages and represent a novel therapeutic target for the treatment of OA pain.

Understanding muscle coordination during gait based on muscle synergy and its association with symptoms in patients with knee osteoarthritis

OBJECTIVE

We aimed to investigate the muscle coordination differences between a control group and patients with mild and severe knee osteoarthritis (KOA) using muscle synergy analysis and determine whether muscle coordination was associated with symptoms of KOA.

METHOD

Fifty-three women with medial KOA and 19 control patients participated in the study. The gait analyses and muscle activity measurements of seven lower limb muscles were assessed using a motion capture system and electromyography. Gait speed and knee adduction moment impulse were calculated. The spatiotemporal components of muscle synergy were extracted using non-negative matrix factorization, and the dynamic motor control index during walking (walk-DMC) was computed. The number of muscle synergy and their spatiotemporal components were compared among the mild KOA, severe KOA, and control groups. Moreover, the association between KOA symptoms with walk-DMC and other gait parameters was evaluated using multi-linear regression analysis.

RESULTS

The number of muscle synergies was lower in mild and severe KOA compared with those in the control group. In synergy 1, the weightings of biceps femoris and gluteus medius in severe KOA were higher than that in the control group. In synergy 3, the weightings of higher tibial anterior and lower gastrocnemius lateralis were confirmed in the mild KOA group. Regression analysis showed that the walk-DMC was independently associated with knee-related symptoms of KOA after adjusting for the covariates.

CONCLUSIONS

Muscle coordination was altered in patients with KOA. The correlation between muscle coordination and KOA may be attributed to the knee-related symptoms. Key points • Patients with knee osteoarthritis (OA) experienced a deterioration in muscle coordination when walking. • Loss of muscle coordination was associated with severe knee-related symptoms in knee OA. • Considering muscle coordination as a knee OA symptom-related factor may provide improved treatment.

Subgrouping of facilitatory or inhibitory conditioned pain modulation responses in patients with chronic knee pain. Explorative analysis from a multicentre trial

BACKGROUND

Facilitatory and inhibitory conditioned pain modulation (CPM) responses are observed in healthy volunteers and chronic pain patients, but the clinical implications for phenotyping are unknown. This study aimed to subgroup and compare chronic knee pain patients according to their CPM responses.

METHODS

This explorative, cross-sectional study included 127 patients with chronic knee pain (osteoarthritis or following total knee arthroplasty). Individual CPM responses were categorized as facilitatory (test stimuli pain intensity increased when conditioning stimuli were applied), as inhibitory (test stimuli pain intensity decreased) or as no change (defined as less than 5.3% change in pain intensity). Outcomes were clinical pain intensities, temporal summation, widespread pain, self-reported physical function, PainDETECT questionnaire and Pain Quality Assessment Scale. Data were analysed as comparisons between the inhibitory and the facilitatory groups and using multivariate linear regression models.

RESULTS

Fifty-four patients had facilitatory CPM responses, 49 had inhibitory CPM responses, and 24 showed no change in CPM response. A between-group difference was observed for self-reported physical function, with the facilitatory CPM group reporting better function (54.4 vs. 46.0, p = 0.028) and the facilitatory CPM group reported more deep pain sensations (3.2 vs. 2.0, p = 0.021). The remaining outcomes showed no between-group differences. Higher clinical pain intensity and facilitated temporal summation were associated in the facilitated CPM group but not in the inhibitory CPM group.

CONCLUSION

These explorative findings indicated that quantitative clinical and experimental differences exist between facilitatory or inhibitory CPM responses in a chronic knee pain patient population. Differences in patients' CPM responses should be further investigated to unravel possible clinical importance.

SIGNIFICANCE

Our findings confirm that conditioned pain modulation consist of inhibitory and facilitatory responders among a patient population with chronic knee pain. This explorative study indicates that patients with either facilitatory or inhibitory conditioned pain modulation could exhibit differences in pain outcomes. Subgrouping of chronic pain patients depending on individual conditioned pain modulation responses could be considered in phenotyping patients prior to inclusion in clinical trials or used for personalizing the management regime.

Mechanical hyperalgesia and neuropathic pain qualities impart risk for chronic postoperative pain after total knee replacement

Total knee replacement (TKR) is the gold-standard treatment for end-stage chronic osteoarthritis pain, yet many patients report chronic postoperative pain after TKR. The search for preoperative predictors for chronic postoperative pain following TKR has been studied with inconsistent findings. This study investigates the predictive value of quantitative sensory testing (QST) and PainDETECT for postoperative pain 3, 6, and 12 months post-TKR. We assessed baseline and postoperative (3- and 6-months) QST measures in 77 patients with knee OA (KOA) and 41 healthy controls, along with neuropathic pain scores in patients (PainDETECT). QST parameters included pressure pain pressure threshold (PPT), pain tolerance threshold (PTT), conditioned pain modulation (CPM), and temporal summation (TS) using cuff algometry, alongside mechanical hyperalgesia, and mechanical temporal summation to repeated pinprick stimulation. Compared to healthy controls, KOA patients at baseline demonstrated hyperalgesia to pinprick stimulation at the medial OA-affected knee and cuff pressure on the ipsilateral calf. Lower cuff algometry PTT and mechanical pinprick hyperalgesia were associated with baseline KOA pain intensity. Moreover, baseline pinprick pain hyperalgesia explained 25% of variance in pain intensity 12 months post-TKR and preoperative neuropathic pain scores also captured 30% and 20% of the variance in postoperative pain at 6- and 12-months, respectively. A decrease in mechanical pinprick hyperalgesia from before surgery to 3 months after TKR was associated with lower postoperative pain at the 12 months post-TKR follow-up, and vice-versa. Our findings suggest that preoperative pinprick hyperalgesia and PainDETECT neuropathic-like pain symptoms show predictive value for the development of chronic post-TKR pain.

Self-regulation training for people with knee osteoarthritis: a protocol for a feasibility randomised control trial (MiNT trial)

Introduction

Knee osteoarthritis (OA) is a chronic secondary musculoskeletal pain condition resulting in disability, reduced quality of life, and high societal costs. Pain associated with knee OA is linked to increased sensitivity in sensory, cognitive, and emotional areas of the brain. Self-regulation training targeting brain functioning related to pain experience could reduce pain and its associated disability. Self-regulatory treatments such as mindfulness meditation (MM) and electroencephalography neurofeedback (EEG-NF) training improve clinical outcomes in people with knee OA. A feasibility clinical trial can address factors that could inform the design of the full trial investigating the effectiveness of self-regulation training programmes in people with knee OA. This clinical trial will evaluate the feasibility, safety, acceptability, experience and perceptions of the self-regulatory training programmes.

Methods

The proposed feasibility trial is based on a double-blind (outcome assessor and investigators), three-arm (MM usual care, EEG-NF + usual care and usual care control group) randomised controlled parallel clinical trial. Participants with knee OA will be recruited from the community and healthcare practices. A research assistant (RA) will administer both interventions (20-min sessions, four sessions each week, and 12 sessions over three successive weeks). Feasibility measures (participant recruitment rate, adherence to interventions, retention rate), safety, and acceptability of interventions will be recorded. An RA blinded to the group allocation will record secondary outcomes at baseline, immediately post-intervention (4th week), and 3 months post-intervention. The quantitative outcome measures will be descriptively summarised. The qualitative interviews will evaluate the participants' experiences and perceptions regarding various aspects of the trial, which includes identifying the barriers and facilitators in participating in the trial, evaluating their opinions on the research procedures, such as their preferences for the study site, and determining the level of acceptability of the interventions as potential clinical treatments for managing knee OA. Māori participant perceptions of how assessment and training practices could be acceptable to a Māori worldview will be explored. The interviews will be audio-recorded and analysed thematically.

Discussion

This trial will provide evidence on the feasibility, safety, and acceptability of the MM and EEG-NF training in people with knee OA, thus informing the design of a full randomised clinical control trial.

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.

Pathology of knee osteoarthritis pain: contribution of joint structural changes and pain sensitization to movement-evoked pain in knee osteoarthritis

Introduction

Movement-evoked pain (MEP) is the primary symptom in patients with knee osteoarthritis (KOA).

Objectives

This study aimed to investigate the contribution of joint structural changes and pain sensitization to the mechanisms of MEP in patients with KOA.

Methods

A total of 86 patients were assessed for demographic characteristics, osteoarthritis severity, Whole-Organ Magnetic Resonance Imaging Score-Hoffa synovitis and bone marrow lesions, pressure pain threshold and temporal summation of pain at the knee and forearm, Central Sensitization Inventory-9, and MEP. In measure of MEP, knee pain was scored using a numerical rating scale (NRS, 0-10) before and every minute during a 6-minute walking test (6MWT), and the MEP index was defined as the change in NRS pain score from baseline to the sixth minute of walking.

Result

On average, pain during 6MWT increased by 1.4 ± 1.5 points on the NRS relative to baseline, with 30.2% of patients showing an increase of 2 points or more. The hierarchical linear regression analysis revealed that Hoffa synovitis, pressure pain threshold at the forearm, and temporal summation of pain at the knee were associated with the MEP index.

Conclusion

The findings of this study suggest that both synovitis and neural mechanisms, such as pain sensitization, play a role in the development of MEP in KOA.

Investigation of Reaction Time, Proprioception, and Shaped Pathway Walking Performance in Older Patients with Total Knee Arthroplasty

OBJECTIVES

The existing literature on total knee arthroplasty (TKA) does not provide clear data on step reaction time and proprioception and gait in shaped pathways. This study investigated the relationship between proprioception and reaction time with walking performance in shaped pathways in older patients undergoing TKA.

DESIGN

A cross-sectional observational study.

SETTING AND PARTICIPANTS

An orthopedic outpatient clinic with 103 older patients with TKA after a minimum of 6 months after surgery.

METHODS

Participants were evaluated with Figure-of-8 Walk Test (F8WT), L Test, Tinnetti Gait Test (TGT), proprioception measurement with an app-based inclinometer, and step reaction time (SRT) test. The same assessor carried out all evaluations.

RESULTS

F8WT showed a strong correlation with SRT-right, SRT-left, and Tinetti Gait Test (TGT), respectively (r1 = 0.628, r2 = 0.619, r3 = -0.615, P < .01). In addition, F8WT was moderately correlated with Right Leg Proprioception Test (RLPT) and Left Leg Proprioception Test (LLPT), respectively (r1 = 0.487, r2 = 0.439, P < .01). There was a moderate correlation between L Test with RLRT, LLRT, and TGT, respectively (r1 = 0.597, r2 = 0.584, r3 = -0.542, P < .01). Besides, there was a weak positive correlation between L Test with RLPT and LLPT, respectively (r1 = 0.394, r2 = 0.335, P < .01). A regression model showed that the L test was related to RLRT, LLRT, and TGT (R2 = 0.432, P < .001). The higher ability of the L test was weakly associated with higher levels of TGT (standardized β = -0.28, P = .0012). Besides, regression analysis also proved that F8WT was related to RLRT, LLRT, and TGT (R2 = 0.522, P < .001). The most highly associated parameter was LLRT (standardized β = 0.958, P = .003).

CONCLUSIONS AND IMPLICATIONS

Gait in shaped pathways is associated with proprioception, reaction time, and balance ability in older patients with TKA. Therefore, proprioception, reaction time, and balance should be considered to improve the shaped pathway walking performance of patients after bilateral, right, or left TKA surgery.

Strength Training vs. Aerobic Training for Managing Pain and Physical Function in Patients with Knee Osteoarthritis: A Systematic Review and Meta-Analysis

(1) Background: Strength training (ST) and aerobic training (AT) are the most recommended interventions in patients with knee OA. These recommendations are supported by high-quality evidence, but it is still unknow whether one type of exercise is superior to the other. Thus, the aim was to investigate whether one type of exercise (ST or AT) is superior to the other for improving pain and physical function in patients with knee osteoarthritis. (2) Methods: A systematic review and meta-analysis was carried out following the PRISMA statement. The search strategy was conducted in PubMed, PEDro, Scopus, Web of Science and Cochrane Library databases. Randomized controlled trials comparing ST and AT on pain intensity and physical function in patients with knee osteoarthritis were included. Methodological quality and risk of bias were assessed with a PEDro scale and risk-of-bias tool, respectively. The certainty of evidence was evaluated using GRADE guidelines. (3) Results: Four studies (6 publications) were included. The qualitative and quantitative synthesis showed that ST produces no more improvement in pain intensity (SMD after intervention: 0.02; 95%CI: -0.15, 0.19; I2: 0%; three studies; 426 patients) and physical function (SMD after intervention: 0.07; 95%CI: -0.10, 0.24; I2: 0%; three studies; 426 patients) compared to AT in patients with knee osteoarthritis. The certainty of evidence was rated as very low. (4) Conclusions: Both type of exercises showed clinical benefits in people with knee osteoarthritis, but no differences between ST and AT were found.

Central sensitization negatively influences the level of disability in female patients with anterior knee pain

PURPOSE

To define the prevalence of Central Sensitization (CS) in patients with Anterior Knee Pain (AKP) and determine whether there is an association between CS and the magnitude of pain, disability, quality-of-life and psychological impairment.

METHODS

The data of a total of 44 AKP female patients with a mean age of 27.7 years (15-50) recruited consecutively from hospital outpatient knee clinics were prospectively included in this study. The patients had no antecedents of knee trauma or surgery and no history of injury or disease of the nervous system. There were also 50 healthy female controls with a mean age of 26.1 years (16-46). CS was evaluated using the Central Sensitization Inventory (CSI). Quality-of-life was evaluated using the EuroQoL-5D questionnaire. Self-reporting of clinical pain intensity was obtained using the Visual Analogue Scale. The Kujala Knee Scale and IKDC form were used to evaluate disability. Anxiety and depression were evaluated using the Hospital Anxiety and Depression Subscale (HAD). Kinesiophobia was measured with the Tampa Scale for Kinesiophobia (TSK-11) and catastrophizing by means of the Pain Catastrophizing Scale (PCS).

RESULTS

Sixteen AKP patients (36%), and 2 (4%) of the healthy controls presented with central sensitization (p < 0.01). AKP patients with CS have a greater degree of disability based on the Kujala Scale and higher levels of anxiety and depression than AKP patients without CS. The score of AKP patients in the CSI correlated weakly with disability and quality of life and moderately with anxiety and depression. However, no association was seen between CSI score and pain intensity, nor with catastrophizing and kinesiophobia. A multivariate logistic regression analysis showed that only depression was statistically significant in the prediction of the presence of CS (odds ratio 1.45; 95% CI 1.07 to 1.96).

CONCLUSIONS

AKP patients have a significantly higher prevalence of CS in comparison with what has been reported for the general population. This finding suggests the presence of altered pain modulation in a subgroup of AKP patients.

LEVEL OF EVIDENCE

Level III.

Exercise-induced hypoalgesia with end-stage knee osteoarthritis during different blood flow restriction levels: Sham-controlled crossover study

BACKGROUND

Blood flow restriction (BFR) training could be a valuable treatment to induce exercise-induced hypoalgesia (EIH) in patients with end-stage knee osteoarthritis. However, the use of BFR in these patients is poorly explored and there is no evidence about the training dosage needed.

OBJECTIVE

To evaluate the effect of resistance training protocols with different occlusion levels of blood flow restriction (BFR) on EIH in patients with end-stage knee osteoarthritis.

DESIGN

Crossover study.

SETTING

University physical exercise laboratory.

PARTICIPANTS

26 adults with end-stage knee osteoarthritis.

INTERVENTIONS

Patients performed four sets (30, 15, 15, and 15 repetitions) separated by 1-minute rests of three protocols/sessions of low-load (30% one-repetition-maximum) seated knee extensions with elastic bands and BFR: placebo (sham BFR), BFR at 40% arterial occlusion pressure (AOP) and BFR at 80% AOP.

MAIN OUTCOME MEASURES

Pressure Pain Thresholds (PPT) and Visual Analog Scale (VAS) collected before, immediately after session, and after 10 minutes.

RESULTS

No differences in EIH were found between the different levels of BFR. However, 80% AOP protocol worsened VAS scores immediately (mean difference [MD]: -21.2 (95% confidence interval [CI] -33.9 to -8.5) while improving PPT immediately (MD affected limb: -.6 [95% CI -1.1 to -.2]); contralateral: -.6 (95% CI -1.0 to -.2]) and at 10 minutes (MD affected limb: -.6 [95% CI) -1.2 to -.1]; contralateral: -.7 [95% CI -1.1 to -.2]; and forearm: -.5 [95% CI -.9 to -.05]) post-exercise compared to baseline.

CONCLUSIONS

There is no EIH difference after using different occlusion levels. EIH is modulated by pain-related psychological constructs and self-perceived health status.

Low central sensitisation inventory score is associated with better post-operative outcomes of osteotomy around the knee

PURPOSE

The purpose of this study was to investigate the potential association between central sensitisation inventory (CSI) scores and post-operative patient-reported outcomes (PROs) in patients underwent osteotomy around the knee (OAK), with a CSI cut-off score specific for knee osteoarthritis.

METHODS

CSI scores were collected from 173 patients who underwent OAK, along with their knee injury and osteoarthritis outcome score (KOOS) and pain numeric rating scale (NRS) scores. Patients were divided into high-CSI score group and low-CSI score group with a cut-off score of 17. Multivariate linear regression was performed to test the association between CSI scores and post-operative outcomes. Pre-surgery KOOS and NRS scores and the rate of attainment of minimal clinically important difference (MCID) of KOOS scores was analysed as secondary outcomes.

RESULTS

Low-CSI score group had significantly higher post-operative KOOS scores and lower pain NRS scores compared to the high-CSI score group (< p = 0.01) after adjusting for confounding factors. For pre-operative scores, only the KOOS-Symptom score was significantly different between the groups (64.7 ± 20.1 when CSI < 17 vs.55.1 ± 19.7 when CSI ≥ 17; p = 0.008). The low-CSI score group had significantly higher MCID achievement rates of KOOS-Pain, Symptom, and ADL than the high-CSI score group (86% vs. 68%; 74% vs. 55%; 86% vs. 67%, respectively; P < 0.05).

CONCLUSIONS

This study established an association between post-operative CSI scores ≥ 17 and poorer outcomes following OAK, highlighting the potential value of the CSI in identifying patients in need of more comprehensive peri-operative pain management.

LEVEL OF EVIDENCE

Level III. Retrospective comparative study.

Feasibility of pain informed movement program for people with knee osteoarthritis

Objective

To establish the feasibility of an intervention consisting of neuromuscular exercise, mind-body techniques, and pain neuroscience education (PNE), referred to as Pain Informed Movement in people with knee Osteoarthritis (KOA). This program has the potential to improve our understanding of intrinsic pain modulation and its role in the management of chronic pain.

Methods

This was a single-arm feasibility trial with a nested qualitative component. Primary outcome: complete follow-up. Inclusion criteria: age ≥40 years, KOA clinical diagnosis or meeting KOA NICE criteria, and pain intensity ≥3/10. The program consisted of 8-week in-person and at-home exercise sessions. PNE and mind-body techniques were provided as videos and integrated into the exercise sessions. Participants completed questionnaires and physical assessments including blood draws at baseline and program completion. Secondary feasibility outcomes: acceptability of the intervention, burden, rates of recruitment, compliance and adherence, and adverse events. A priori success criteria were identified. Participants were invited to an online focus group.

Results

19 participants were enrolled, with a complete follow-up rate of 74% (mean age 63.3 years (SD 10.5), 73% female), indicating modifications were necessary to proceed. All other success criteria were met. The focus groups revealed that the video content pertaining to the mind-body techniques would benefit from on screen demonstrations.

Conclusion

The Pain Informed Movement program is deemed feasible, with minor modifications needed to proceed. A pilot two-arm RCT will be conducted to establish the feasibility and explore potential effects of Pain Informed Movement compared to conventional neuromuscular exercise and standard OA education.

The Potential Role of Probiotics in the Management of Osteoarthritis Pain: Current Status and Future Prospects

PURPOSE OF REVIEW

This narrative review article comprehensively explains the pathophysiology of osteoarthritis (OA) pain perception, how the gut microbiota is correlated with it, possible molecular pathways involved in probiotics-mediated OA pain reduction, limitations in the current research approaches, and future perspectives.

RECENT FINDINGS

The initiation and progression of OA, including the development of chronic pain, is intricately associated with activation of the innate immune system and subsequent inflammatory responses. Trauma, lifestyle (e.g., obesity and metabolic disease), and chronic antibiotic treatment can disrupt commensal homeostasis of the human microbiome, thereby affecting intestinal integrity and promoting leakage of bacterial endotoxins and metabolites such as lipopolysaccharides (LPS) into circulation. Increased level of LPS is associated with knee osteophyte severity and joint pain. Both preclinical and clinical studies strongly suggest that probiotics may benefit patients with OA pain through positive gut microbiota modulation and attenuating low-grade inflammation via multiple pathways. Patent data also suggests increased interest in the development of new innovations that involve probiotic use for reducing OA and joint pain. Recent data suggest that probiotics are attracting more and more attention for OA pain management. The advancement of knowledge in this area may pave the way for developing different probiotic strains that can be used to support joint health, improve treatment outcomes in OA, and reduce the huge impact of the disease on healthcare systems worldwide.

The interrater and test-retest reliability of 3 modalities of quantitative sensory testing in healthy adults and people with chronic low back pain or rheumatoid arthritis

Introduction

Quantitative Sensory Testing (QST) modalities used to assess central pain mechanisms require different protocols in people with different musculoskeletal conditions.

Objectives

We aimed to explore the possible effects of musculoskeletal diagnosis and test site on QST interrater and test-retest reliability.

Methods

The study included participants with rheumatoid arthritis (RA, n = 18; QST conducted on lower leg) and low back pain (LBP, n = 25; QST conducted on forearm), plus 45 healthy control participants (n = 20 QST on lower leg and n = 25 QST on forearm). Test-retest reliability was assessed from QST conducted 1 to 3 weeks apart. Quantitative sensory testing modalities used were pressure pain detection threshold (PPT) at a site distant to tissue pathology, temporal summation (TS), and conditioned pain modulation (CPM). Temporal summation was calculated as difference or ratio of single and repeated punctate stimuli and unconditioned thresholds for CPM used single or mean of multiple PPTs. Intraclass correlation coefficients (ICCs) were compared between different subgroups.

Results

High to very high reliability was found for all assessments of PPT and TS across anatomical sites (lower leg and forearm) and participants (healthy, RA, and LBP) (ICC ≥ 0.77 for PPT and ICC ≥ 0.76 for TS). Reliability was higher when TS was calculated as a difference rather than a ratio. Conditioned pain modulation showed no to moderate reliability (ICC = 0.01-0.64) that was similar between leg or forearm, and between healthy people and those with RA or LBP.

Conclusion

PPT and TS are transferable tools to quantify pain sensitivity at different testing sites in different musculoskeletal diagnoses. Low apparent reliability of CPM protocols might indicate minute-to-minute dynamic pain modulation.

The Impact and Correlation of Anxiety and Depression on Pressure Pain Threshold of Acupoints in Patients with Chronic Pelvic Inflammatory Disease

Background

Chronic pelvic inflammatory disease (CPID) is a clinically common gynecological disease. Patients experience chronic pelvic pain and often accompany with emotional dysfunction. However, the impact and correlation of anxiety and depression on pain sensitization is not completely known.

Objective

To explore the differences and correlations among anxiety, depression, and pressure pain threshold (PPT) of acupoints in patients with CPID.

Methods

One hundred and forty-seven patients with CPID were recruited. The Visual Analog Scale (VAS) and short-form McGill Pain Questionnaire (SF-MPQ) were used to assess pain. Self-Rating Anxiety Scale (SAS) and Self-Rating Depression Scale (SDS) were used to evaluate the emotional state of patients. The PPT of acupoints was collected using an electronic Von Frey by two licensed acupuncturists.

Results

The CPID patients were divided into anxiety-depression group (group A) or nonanxiety-depression group (group B), according to the SAS and SDS scores. Finally, there were 73 patients in group A and 74 patients in group B. Group A had significantly higher SAS, SDS, VAS, and SF-MPQ scores than group B (P < 0.05). In addition, significant differences were observed in the PPTs of ST28 (R), ST29 (R), SP10 (R), SP9 (R), SP9 (L), ST36 (R), and LR3 (L) between the two groups (P < 0.05). No considerable differences in PPTs at the other acupoints were observed between the two groups. SAS scores showed a positive correlation with PPTs of ST29 (R), SP10 (R), SP9 (L), ST36 (R), and LR3 (L). No remarkable correlation was observed between the SDS scores and PPTs.

Conclusion

Anxiety and depression can affect the PPT of some acupoints in CPID patients, which may provide a reference for acupoint selection for acupuncture treatment of CPID with emotional disorders. This trial is registered with ChiCTR2100052632.

Thermal Grill Illusion in Post-Stroke Patients: Analysis of Clinical Features and Lesion Areas

Purpose

In the thermal grill illusion, participants experience a feeling similar to burning pain. The illusion is induced by simultaneously touching warm and cool stimuli in alternating positions. In post-stroke pain, central sensitization is caused by a variety of factors, including damage to the spinothalamic tract and shoulder pain. Because the thermal grill illusion depends on central mechanisms, it has recently been suggested that it may be a useful indicator of central sensitization. Therefore, we hypothesized that post-stroke patients who are more likely to experience central sensitization may also be more likely to experience a thermal grill sensation of pain and discomfort than the likelihood among those who are less likely to experience central sensitization. However, the effects of the thermal grill illusion in post-stroke patients have not yet been reported. In this pilot study, we conducted the thermal grill illusion procedure in post-stroke patients and analyzed the relationship between clinical somatosensory functions and thermal grill sensations. We also conducted brain imaging analysis to identify brain lesion areas that were associated with thermal grill sensations.

Patients and Methods

Twenty patients (65.7 ± 11.9 years old) with post-stroke patients participated in this study. The thermal grill illusion procedure was performed as follows: patients simultaneously touched eight water-filled copper bars, with the water temperature adjusted to provide alternate warm (40°C) and cold (20°C) stimuli.

Results

Thermal grill sensation of pain and discomfort tended to be associated with the wind-up phenomenon in bedside quantitative sensory testing and thermal grill sensation of discomfort was also related to damage to the thalamic lateral nucleus.

Conclusion

These findings suggest that the thermal grill illusion might measure central sensitization, and that secondary brain hyperactivity might lead to increased thermal grill sensations.

Injection of kaolin/carrageenan in the rat knee joint induces progressive experimental knee osteoarthritis

ABSTRACT

Osteoarthritis (OA), the most common joint disorder worldwide, is characterized by progressive degeneration of articular and periarticular structures, leading to physical and emotional impairments that greatly affect the quality of life of patients. Unfortunately, no therapy has been able to halt the progression of the disease. Owing to the complexity of OA, most animal models are only able to mimic a specific stage or feature of the human disorder. In this work, we demonstrate the intraarticular injection of kaolin or carrageenan leads to the progressive degeneration of the rat's knee joint, accompanied by mechanical hyperalgesia and allodynia, gait impairments (reduced contact area of the affected limb), and radiological and histopathological findings concomitant with the development of human grade 4 OA. In addition, animals also display emotional impairments 4 weeks after induction, namely, anxious and depressive-like behaviour, important and common comorbidities of human OA patients. Overall, prolonging kaolin or carrageenan-induced monoarthritis mimics several important physical and psychological features of human OA in both male and female rodents and could be further applied in long-term studies of OA-associated chronic pain.

Patient, clinician, and performance-based measures provide different information about clinical symptoms in patients with severe knee osteoarthritis presenting with depressive symptoms: a cross-sectional study

BACKGROUND AND PURPOSE

Clinical status of subjects with knee osteoarthritis (KOA) is influenced by a complex interaction of several biopsychosocial factors. The use of patient-reported measures (PROM) is considered the gold standard for their evaluation. However, considering that 1 in 5 subjects with KOA present with depressive symptoms, it is necessary to analyse how this psychological domain may influence the subjective perception of PROM. The objective was to study the impact that depressive symptoms have on functional outcome assessments, according to the degree of objectivity of diverse outcome measures.

METHODS

Cross-sectional study. Subjects with severe KOA, verified with clinical and radiological symptoms, were assessed with patient-reported (Oxford Knee Score), clinician-reported (knee range of motion), and performance-based (Timed up and go test) measures. The existence of depressive symptoms was assessed with the Yesavage scale, and participants were classified for having no-, mild- or severe-symptoms. Linear correlations (r) and one-way analysis of variance compared groups (95% CI).

RESULTS

244 participants were analysed, of which 75 (30.7%) had depressive symptoms. These symptoms had an inverse moderate association with Oxford Knee Score (r = -0.387). However, the correlation with the Timed up and go test was low (r = 0.176), while there was no correlation with knee ROM (r = -0.087).

CONCLUSIONS

This study supports that patient-reported questionnaires may offer biased information on the clinical status of patients with severe knee osteoarthritis who present with depressive symptoms. Consideration of such symptoms may be critical to ensure data collected to accurately reflect patients' capacities and perceptions.

Active Neurodynamics at Home in Patients with Knee Osteoarthritis: A Feasibility Study

The aim was to evaluate the feasibility of a home-based neurodynamic programme for patients with knee osteoarthritis (KO). Thirty participants (70% women) ≥ 50 years old with KO (Kellgren-Lawrence grades I-II) were included. Active mobilisation of the femoral nerve was performed at home over a period of 6-8 weeks. The feasibility of the programme was assessed using a survey that included questions related to understanding of the activity; adherence to the intervention; the burden caused by the intervention; self-perceived effects on the participant; follow-up; the barriers; and facilitators. Pain intensity, using the numerical rating scale (NRS); pressure pain thresholds (PPT); temporal assessment; pain modulation; Knee Injury and Osteoarthritis Outcome Score (KOOS), 12-item Short Form Survey questionnaire (SF-12), and the Central Sensitization Inventory questionnaire (CSI) were also collected, before and after the intervention. All patients performed the intervention, completed at least 42 days of activity, and considered the exercise adequate, with 28 participants (93.3%) reporting that the intervention was good for them. Statistically significant values (p < 0.05) were found for NRS, elbow PPT, external knee PPT, internal knee PPT, elbow CPM, CSI, and KOOS. Home-based active neurodynamic treatment has been shown to be a feasible and safe intervention for KO patients. In addition, this intervention has shown positive effects on pain and function.

Summarizing the effects of different exercise types in chronic neck pain - a systematic review and meta-analysis of systematic reviews

BACKGROUND

To date, no consensus exists as to whether one exercise type is more effective than another in chronic neck pain. This systematic review and meta-analysis of systematic reviews aimed to summarize the literature on the effect of various exercise types used in chronic neck pain and to assess the certainty of the evidence.

METHODS

We searched the databases Ovid MEDLINE, Embase, Cochrane Library, SportDiscus, and Web of Science (Core Collection) for systematic reviews and meta-analyses on adults between 18 and 70 years with chronic neck pain lasting ≥ 12 weeks which investigated the effects of exercises on pain and disability. The included reviews were grouped into motor control exercise (MCE), Pilates exercises, resistance training, traditional Chinese exercise (TCE), and yoga. Study quality was assessed with AMSTAR-2 and the level of certainty for the effects of the exercise through GRADE. A narrative analysis of the results was performed and in addition, meta-analyses when feasible.

RESULTS

Our database search resulted in 1,794 systematic reviews. We included 25 systematic reviews and meta-analyses including 17,321 participants (overlap not accounted for). The quality of the included reviews ranged from critically low to low (n = 13) to moderate to high (n = 12). We found low to high certainty of evidence that MCE, Pilates exercises, resistance training, TCE, and yoga have short-term positive effects on pain and that all exercise types except resistance training, show positive effects on disability compared to non-exercise controls. We found low to moderate certainty of evidence for conflicting results on pain and disability when the exercise types were compared to other exercise interventions in the short-term as well as in intermediate/long-term apart for yoga, as no long-term results were available.

CONCLUSION

Overall, our findings show low to high certainty of evidence for positive effects on pain and disability of the various exercise types used in chronic neck pain compared to non-exercise interventions, at least in the short-term. Based on our results, no optimal exercise intervention for patients with chronic neck pain can be recommended, since no large differences between the exercise types were shown here. Because the quality of the included systematic reviews varied greatly, future systematic reviews need to increase their methodological quality.

TRIAL REGISTRATION

Prospero CRD42022336014.

Structural and functional brain changes in people with knee osteoarthritis: a scoping review

Background

Knee osteoarthritis is a highly prevalent disease worldwide that leads to functional disability and chronic pain. It has been shown that not only changes are generated at the joint level in these individuals, but also neuroplastic changes are produced in different brain areas, especially in those areas related to pain perception, therefore, the objective of this research was to identify and compare the structural and functional brain changes in knee OA versus healthy subjects.

Methodology

Searches in MEDLINE (PubMed), EMBASE, WOS, CINAHL, SCOPUS, Health Source, and Epistemonikos databases were conducted to explore the available evidence on the structural and functional brain changes occurring in people with knee OA. Data were recorded on study characteristics, participant characteristics, and brain assessment techniques. The methodological quality of the studies was analysed with Newcastle Ottawa Scale.

Results

Sixteen studies met the inclusion criteria. A decrease volume of the gray matter in the insular region, parietal lobe, cingulate cortex, hippocampus, visual cortex, temporal lobe, prefrontal cortex, and basal ganglia was found in people with knee OA. However, the opposite occurred in the frontal lobe, nucleus accumbens, amygdala region and somatosensory cortex, where an increase in the gray matter volume was evidenced. Moreover, a decreased connectivity to the frontal lobe from the insula, cingulate cortex, parietal, and temporal areas, and an increase in connectivity from the insula to the prefrontal cortex, subcallosal area, and temporal lobe was shown.

Conclusion

All these findings are suggestive of neuroplastic changes affecting the pain matrix in people with knee OA.

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.

Accessing care during the pandemic: A UK wide survey of people with rheumatoid arthritis and adult juvenile inflammatory arthritis during the COVID-19 pandemic

COVID-19 drastically changed healthcare delivery models for rheumatology services. We sought to understand the impact of these changes for patients with Rheumatoid Arthritis (RA) and adult Juvenile Inflammatory Arthritis (AJIA) in established patients and those newly diagnosed during the pandemic. RESULTS: Of the 316 participants, a significant proportion regularly used analgesics (45.4%, n = 119), corticosteroids (17.9%, n = 47) and Non-Steroidal Anti-Inflammatory Drugs [(NSAIDs) (36.6%, n = 96)]. Two thirds of participants (66.5%, n = 210) did not know their Disease Activity Score-28 (DAS28). Of the remaining third, moderate disease activity (12%, n = 38) was most reported. We found that 16.8% (n = 53) felt their condition was managed well during the pandemic. The remainder felt more negatively. For the newly diagnosed cohort, 34.5% (n = 10) delayed seeking GP help because of COVID-19 concerns. Once assessed, a quarter (24.1%, n = 7) were referred to rheumatology after 4 or more consultations. We found 47% (n = 77) expressed positive opinions on remote consultations, whereas 36% (n = 59) had concerns. The lack of clinical examination (42.5%, n = 25) was flagged. Changing the dynamic from health worker to a patient centred approach was the most wished for improvement (20.3%, n = 64). CONCLUSIONS: Most participants did not know their disease activity status, which is of concern. With a push towards patient-centred and patient-led care, education and supported self-management is critically important. There is high use of NSAIDs and corticosteroids. Pathways of care underwent change with subsequent delays in specialist assessment. The introduction of patient-initiated follow-up (PIFU) and virtual consultations further distances healthcare professionals from patients and could affect outcomes.

Assessment of Prevalence and Risk Factors for Central Sensitization Related to Shoulder Osteoarthritis and Rotator Cuff Tears Using the Central Sensitization Inventory: A Cross-Sectional Study in Shoulder Surgery Patients

Shoulder disorders occasionally cause intractable pain. Central sensitization (CS) may be involved in such pain. Identifying risk factors associated with CS is crucial for effective pain control. This study aimed to determine the effects of shoulder osteoarthritis and rotator cuff tears (RCT) on CS and associated factors. This study included patients evaluated for CS using the Central Sensitization Inventory (CSI) before surgery for shoulder osteoarthritis, RCT, or cuff tear arthropathy. Patients with a CSI score of 40 or higher were defined as having CS. The relationships between glenohumeral osteoarthritis (GHOA), RCT size, and CS were statistically analyzed. Multiple regression analysis was performed to examine the factors affecting CSI scores. Subjects included 167 patients: 131 patients had RCT without GHOA, 23 had GHOA with RCT, and 13 had GHOA without RCT. The GHOA group had a significantly higher CSI score (27.5 [10.8-40.5] vs. 18.0 [10.0-27.5]) and CS prevalence (27.8% vs. 8.4%) than the RCT without GHOA group. There was no significant correlation between RCT size and CSI scores. Multiple regression analysis showed that female sex, severe pain, and long pain duration were associated with higher CSI scores. Considering the risk factors for CS might be helpful in shoulder treatment.

Functional and Neural Correlates Associated with Conditioned Pain Modulation in Patients with Chronic Knee Osteoarthritis Pain: A Cross-Sectional Study

Background: In this study, we aimed to assess the factors that predict a dysfunctional conditioned pain modulation (CPM) in chronic knee OA. Methods: This is a cross-sectional analysis of patients with chronic knee OA from a prospective cohort study in Brazil (n = 85). We performed linear and logistic multivariate regression models using the purposeful selection approach to test the relationship between the CPM in both knees (average) as a dependent variable and demographics, clinical, and neurophysiological as independent variables. Results: A significant negative association between WOMAC pain scores and CPM (β: -0.13) was found. This association was modified by the subjects' race, being stronger in the non-white subjects. In our logistic regression models, pain intensity indexed with the WOMAC pain scale remained a significant association with dichotomized CPM. Furthermore, a significant CPM association with balance, indexed with the Berg Balance score, was evidenced (β: 0.04). Neurophysiological variables showed a significant negative relationship with CPM, such as the relative power of delta oscillations in the frontal area (β: -3.11) and central area (β: -3.23). There was no significant relationship between CPM and the following domains: cognitive, emotion, sleep, opioid receptor polymorphisms, and intrinsic variables of OA disease. There was no association of CPM with TMS-indexed inhibitory markers. Conclusions: These results may indicate that less function of the pain descending inhibitory system in patients with OA is correlated with higher activity-related pain (WOMAC), less balance, and cortical plasticity especially with increased low-frequency (delta) brain oscillations. These associations seem modified by race.

Recommendations for terminology and the identification of neuropathic pain in people with spine-related leg pain. Outcomes from the NeuPSIG working group

ABSTRACT

Pain radiating from the spine into the leg is commonly referred to as "sciatica," "Sciatica" may include various conditions such as radicular pain or painful radiculopathy. It may be associated with significant consequences for the person living with the condition, imposing a reduced quality of life and substantial direct and indirect costs. The main challenges associated with a diagnosis of "sciatica" include those related to the inconsistent use of terminology for the diagnostic labels and the identification of neuropathic pain. These challenges hinder collective clinical and scientific understanding regarding these conditions. In this position paper, we describe the outcome of a working group commissioned by the Neuropathic Pain Special Interest Group (NeuPSIG) of the International Association for the Study of Pain (IASP) which was tasked with the following objectives: (1) to revise the use of terminology for classifying spine-related leg pain and (2) to propose a way forward on the identification of neuropathic pain in the context of spine-related leg pain. The panel recommended discouraging the term "sciatica" for use in clinical practice and research without further specification of what it entails. The term "spine-related leg pain" is proposed as an umbrella term to include the case definitions of somatic referred pain and radicular pain with and without radiculopathy. The panel proposed an adaptation of the neuropathic pain grading system in the context of spine-related leg pain to facilitate the identification of neuropathic pain and initiation of specific management in this patient population.

Assessment of Pain in Osteoarthritis of the Knee

Knee osteoarthritis (KOA) pain is a subjective and personal experience, making it challenging to characterise patients' experiences and assess their pain. In addition, there is no global standard for the assessment of pain in KOA. Therefore, this article examines the possible methods of assessing and characterising pain in patients with KOA using clinical symptoms, pain assessment tools, and imaging. We examine the current methods of assessment of pain in KOA and their application in clinical practice and clinical trials. Furthermore, we explore the possibility of creating individualised pain management plans to focus on different pain characteristics. With better evaluation and standardisation of pain assessment in these patients, it is hoped that patients would benefit from improved quality of life. At the same time, improvement in pain assessment would enable better data collection regarding symptom response in clinical trials for the treatment of osteoarthritis.

Central Sensitization in Cancer Survivors and Its Clinical Implications: State of the Art

Although the prevalence of cancer pain is 47% after treatment, cancer pain is often underestimated, and many patients are undertreated. The complexity of cancer pain contributes to the lack of its management. Recently, as the mechanism of cancer pain, it has become clear that central sensitization (CS) influences chronic pain conditions and the transition from acute to chronic pain. In this state-of-the-art review, we summarized the association of CS or central sensitivity syndrome with pain and the treatment for pain targeting CS in cancer survivors. The management of patients with CS should not only focus on tissue damage in either the affected body regions or within the central nervous system; rather, it should aim to target the underlying factors that sustain the CS process. Pain neuroscience education (PNE) is gaining popularity for managing chronic musculoskeletal pain and could be effective for pain and CS in breast cancer survivors. However, there is a study that did not demonstrate significant improvements after PNE, so further research is needed. Precision medicine involves the classification of patients into subgroups based on a multifaceted evaluation of disease and the implementation of treatment tailored to the characteristics of each patient, which may play a central role in the treatment of CS.

Effects of a foot-ankle muscle strengthening program on pain and function in individuals with knee osteoarthritis: a randomized controlled trial

BACKGROUND

Foot-ankle exercises could improve pain and function of individuals with KOA and need to be tested.

OBJECTIVE

To investigate whether an 8-week foot-ankle muscle strengthening program is effective for individuals with KOA to reduce pain and improve function.

METHODS

In this randomized controlled trial, individuals diagnosed with clinical and radiographic KOA were randomized into the intervention (supervised foot-ankle strengthening exercise program three times a week for 8 weeks) or control (usual care and recommendations of the healthcare team) group. Effectiveness was assessed by changes in clinical and functional outcomes between baseline and 8 weeks with pain as the primary outcome. ANCOVA tests using the intervention group as a reference and sex, body mass index, and baseline values as covariates assessed between-group differences.

RESULTS

The intervention group showed lower pain scores (-4.4 units; 95%CI = -7.5, -1.1), better function (-7.1 units; 95%CI = -12.7, -1.4), higher total functional score (-11.9 units; 95%CI = -20.7, -3.1), with confidence intervals indicating a potential for the differences to be clinically meaningful, and better scores for the 30-s chair stand test (2.7 repetitions; 95%CI = 1.1, 4.1), with a confidence interval indicating a moderate clinically meaningful difference, compared to the controls.

CONCLUSION

The 8-week foot-ankle exercise program showed positive, and potentially clinically meaningful, effects on knee pain and physical function among individuals with KOA, when compared to usual care.

TRIAL REGISTRATION

NCT04154059. https://clinicaltrials.gov/ct2/show/NCT04154059.

The widespread myofascial pain of fibromyalgia is sympathetically maintained and immune mediated

The recent demonstration of antibody-induced passive transfer of pain hypersensitivity from fibromyalgia (FM) subjects to mice brings renewed focus to the role of the immune system in generating FM pain. However, this data must be interpreted in the context of known myofascial pathology in FM, which includes impaired muscle relaxation and elevated intramuscular pressure. In addition, FM fascial biopsies demonstrate elevated inflammatory and oxidative stress markers and increased endomysial collagen deposition. This article proposes a unifying hypothesis for FM pain generation that connects known muscle and fascia abnormalities with the newly discovered role of antibodies. FM is characterized by persistent sympathetic nervous system hyperactivity which results in both pathologic muscle tension and an impaired tissue healing response. Although autoantibodies play a key role in normal tissue healing, sympathetic nervous system hyperactivity impairs the resolution of inflammation, and promotes autoimmunity and excessive autoantibody production. These autoantibodies can then bind with myofascial-derived antigen to create immune complexes, which are known to trigger neuronal hyperexcitability in the dorsal root ganglion. These hyperexcited sensory neurons activate the surrounding satellite glial cells and spinal microglia leading to pain hypersensitivity and central sensitization. Although immune system modulation may become an important treatment tool in FM, direct manual treatments that lessen myofascial inflammation and tension must not be neglected. Myofascial release therapy significantly reduces FM pain, with residual benefits even after the conclusion of treatment. Self-myofascial release techniques and gentle stretching programs also ease fibromyalgia pain, as do trigger point injections and dry-needling.