Application of the IASP Grading System to Identify Underlying Pain Mechanisms in Patients with Knee Osteoarthritis: A Prospective Cohort Study.

OBJECTIVES: This study aimed to apply the International Association for the Study of Pain (IASP) grading system for identifying nociplastic pain in knee osteoarthritis (KOA) awaiting total knee arthroplasty (TKA) and propose criteria to finetune decision-making. Additionally, the study aimed to characterize a 'probable' versus 'no or possible' nociplastic pain mechanism using biopsychosocial variables and compare both groups in their one-year post-TKA response. METHODS: A secondary analysis of baseline data of a longitudinal prospective study involving 197 KOA patients awaiting total knee arthroplasty in Belgium and the Netherlands was performed. Two approaches, one considering four and the other three pain locations (step 2 of the grading system), were presented. Linear mixed model analyses were performed to compare the 'probable' and 'no or possible' nociplastic pain mechanism groups for several preoperative biopsychosocial-related variables and one-year postoperative pain. Also, a sensitivity analysis, comparing exclusively 'probable' versus 'no' nociplastic pain mechanism groups, was performed. RESULTS: Thirty (15.22% - approach four pain locations) and 46 (23.35% - approach three pain locations) participants were categorized under 'probable' nociplastic pain. Irrespective of the pain location approach or sensitivity analysis, the 'probable' nociplastic pain group included more woman, were younger, exhibited worse results on various preoperative pain-related and psychological variables, and had more pain one-year post-TKA compared to the other group. DISCUSSION: This study proposed additional criteria to finetune the grading system for nociplastic pain (except for discrete/regional/multifocal/widespread pain) and characterized a subgroup of KOA patients with 'probable' nociplastic pain. Future research is warranted for further validation.

Unravelling relationships between obesity, diabetes, and factors related to somatosensory functioning in knee osteoarthritis patients.

OBJECTIVE: This study explores the association between obesity, diabetes, and somatosensory functioning in patients with knee osteoarthritis (OA), aiming to understand how metabolic conditions are related to pain mechanisms in this patient population. We hypothesized that higher body mass index (BMI), fat mass, and glycated hemoglobin levels (HbA1c) are associated with signs of altered somatosensory functioning. METHODS: A cross-sectional analysis was conducted as part of a larger multicentre prospective cohort study. Data were collected from patients awaiting total knee arthroplasty in Belgium and the Netherlands. Associations between BMI, fat mass, HbA1c, and various pain-related variables were examined employing Pearson and Spearman correlation analyses which were further analyzed with linear regression techniques. RESULTS: The study included 223 participants. Analysis revealed a significant although weak negative correlation between fat mass and pressure pain thresholds (PPT) at multiple locations, suggesting a link between higher fat mass and increased mechanical hyperalgesia. There were no significant correlations between BMI and pain-related outcomes. HbA1c levels showed very weak positive correlations with pain measures but did not withstand correction for multiple testing. CONCLUSION: The findings indicate that fat mass may be closely associated with altered somatosensory functioning in patients with knee OA. However, no significant correlations were found between BMI or HbA1c levels and pain-related outcomes. Future research should focus on longitudinal studies to elucidate the causal relationships and further explore the impact of metabolic factors on pain mechanisms in this patient population. Key Points • The findings indicate that fat mass may be closely associated with altered somatosensory functioning in patients with knee OA.

Preoperative glycaemic control, number of pain locations, structural knee damage, self-reported central sensitisation, satisfaction and personal control are predictive of 1-year postoperative pain, and change in pain from pre- to 1-year posttotal knee arthroplasty.

PURPOSE: The aim of this study was to identify preoperative predictors for 1-year posttotal knee arthroplasty (TKA) pain and pre- to post-TKA pain difference in knee osteoarthritis (KOA) patients. METHODS: From March 2018 to July 2023, this prospective longitudinal cohort study enrolled KOA patients awaiting TKA from four hospitals in Belgium and the Netherlands. Different biopsychosocial predictors were assessed preoperatively by questionnaires and physical examinations (input variables). The Knee injury and Osteoarthritis Outcome Score (KOOS) subscale pain was used to measure pain intensity. The absolute KOOS subscale pain score 1-year post-TKA and the difference score (ΔKOOS = 1-year postoperative - preoperative) were used as primary outcome measures (output variables). Two multivariable linear regression analyses were performed. RESULTS: Two hundred and twenty-three participants were included after multiple imputation. Worse absolute KOOS subscale pain scores 1-year post-TKA and negative or closer to zero ΔKOOS subscale pain scores were predicted by self-reported central sensitisation, lower KOA grade and preoperative satisfaction, and higher glycated haemoglobin, number of pain locations and personal control (adjusted R2 = 0.25). Additional predictors of negative or closer to zero ΔKOOS subscale pain scores were being self-employed, higher preoperative pain and function (adjusted R2 = 0.37). CONCLUSION: This study reports different biopsychosocial predictors for both outcomes that have filtered out other potential predictors and provide value for future studies on developing risk assessment tools for the prediction of chronic TKA pain. PROTOCOL REGISTRATION: The protocol is registered at clinicaltrials.gov (NCT05380648) on 13 May 2022. LEVEL OF EVIDENCE: Level II.

Does pain intensity after total knee arthroplasty depend on somatosensory functioning in knee osteoarthritis patients? A prospective cohort study.

The objective of this study is to determine whether the change in pain intensity over time differs between somatosensory functioning evolution profiles in knee osteoarthritis (KOA) patients undergoing total knee arthroplasty (TKA). This longitudinal prospective cohort study, conducted between March 2018 and July 2023, included KOA patients undergoing TKA in four hospitals in Belgium and the Netherlands. The evolution of the Knee Injury and Osteoarthritis Outcome Score (KOOS) subscale pain over time (baseline, 3 months, and 1 year post-TKA scores) was the outcome variable. The evolution scores of quantitative sensory testing (QST) and Central Sensitization Inventory (CSI) over time (baseline and 1 year post-TKA scores) were used to make subgroups. Participants were divided into separate normal, recovered, and persistent disturbed somatosensory subgroups based on the CSI, local and widespread pressure pain threshold [PPT] and heat allodynia, temporal summation [TS], and conditioned pain modulation [CPM]. Linear mixed model analyses were performed. Two hundred twenty-three participants were included. The persistent disturbed somatosensory functioning group had less pronounced pain improvement (based on CSI and local heat allodynia) and worse pain scores 1 year post-TKA (based on CSI, local PPT and heat allodynia, and TS) compared to the normal somatosensory functioning group. This persistent group also had worse pain scores 1 year post-TKA compared to the recovered group (based on CSI). The study suggests the presence of a "centrally driven central sensitization" subgroup in KOA patients awaiting TKA in four of seven grouping variables, comprising their less pain improvement or worse pain score after TKA. Future research should validate these findings further. The protocol is registered at clinicaltrials.gov (NCT05380648).

Clinical prediction model for interdisciplinary biopsychosocial rehabilitation in osteoarthritis patients.

BACKGROUND: Osteoarthritis (OA) is a heterogenous condition, in which different subgroups are present. Individualized interdisciplinary multimodal pain treatments (IMPT) based on the biopsychosocial model have resulted in positive improvement of pain, health and disability in OA patients. Moreover, predictive factors for treatment success of IMPT in different musculoskeletal pain populations have been examined, but a clinical prediction model which informs whether an OA patient is expected to benefit or not from IMPT is currently lacking. AIM: The aim was to develop and internally validate a clinical prediction model to inform patient-tailored care based on identified predictors for positive or negative outcomes of IMPT in patients with OA. DESIGN: Longitudinal prospective cohort study. SETTING: Center for Integral Rehabilitation at six locations in the Netherlands. POPULATION: Chronic OA patients. METHODS: Data in this study were collected during January 2019 until January 2022. Participants underwent a 10-week IMPT program based on the biopsychosocial model. Treatment success was defined by a minimal decrease from baseline of 9 points on the Pain Disability Index (PDI). Candidate predictors were selected by experts in IMPT and literature review. Backward logistic regression analysis was performed to develop the clinical predication model and bootstrap validation was performed for internal validation. RESULTS: Overall, 599 OA patients were included, of which 324 experienced treatment success. Thirty-four variables were identified as possible predictors for good IMPT outcome. Age, gender, number of pain locations, PDI baseline score, maximal pain severity, use of pain medication and alcohol, work ability, brief illness perceptions questionnaire subscales timeline, consequences, identity and treatment control, pain catastrophizing scale and self-efficacy questionnaire score were found as predictors for treatment success. The internally validated model has an acceptable discriminative power of 0.71. CONCLUSIONS: This study reports a specific clinical prediction model for good outcome of IMPT in patients with OA. The internally validated model has an acceptable discriminative power of 0.71. CLINICAL REHABILITATION IMPACT: After external validation, this model could be used to develop a clinically useful decision tool.

Identification of Metabolic Factors and Inflammatory Markers Predictive of Outcome after Total Knee Arthroplasty in Patients with Knee Osteoarthritis: A Systematic Review.

OBJECTIVE: To identify metabolic factors and inflammatory markers that are predictive of postoperative total knee arthroplasty (TKA) outcome. METHOD: A systematic search of the existing literature was performed using the electronic databases PubMed, Web of Science and Embase until the 1st of August 2022. Studies that evaluated the influence of metabolic or inflammatory markers (I) on postsurgical outcome (O) in end-stage knee osteoarthritis patients awaiting primary TKA (P) were included in this review. RESULTS: In total, 49 studies were included. Risk of bias of the included studies was low for one study, moderate for 10 studies and high for the remaining 38 studies. Conflicting evidence was found for the influence of body mass index, diabetes, cytokine levels and dyslipidaemia on pain, function, satisfaction and quality of life at more than six months after TKA. CONCLUSIONS: Several limitations such as not taking into account known confounding factors, the use of many different outcome measures and a widely varying follow-up period made it challenging to draw firm conclusions and clinical implications. Therefore large-scaled longitudinal studies assessing the predictive value of metabolic and inflammatory factors pre-surgery in addition to the already evidenced risk factors with follow-up of one year after TKA are warranted.

Evolution of somatosensory processing signs after nociceptive targeted surgery in patients with musculoskeletal disorders: a systematic review.

ABSTRACT: Surgery is often advised when conservative treatment fails in musculoskeletal pain conditions, but a substantial proportion still suffers chronic pain after surgery. Somatosensory processing system (SPS) signs were previously studied as potential predictors for chronic postsurgical pain, but results are inconsistent. Therefore, studying the evolution of SPS signs could be of added value. The aim was to summarize all studies that measured how SPS signs evolved after nociceptive targeted surgery in musculoskeletal disorders and to find preoperative, perioperative, and postoperative predictors for the evolution of these SPS signs. Data were summarized, and risk of bias and level of evidence and recommendation were determined. Twenty-one studies were included. Five scored a low, 3 a moderate, and 13 a high risk of bias. In general, no consistent evolution of SPS signs comparing preoperative and postoperative values and predictors for this evolution in musculoskeletal disorders could be found. In most cases, static quantitative sensory testing (QST) did not change or conflicting results were found. On the other hand, dynamic QST mostly improved after surgery. Worthfully mentioning is that worsening of SPS signs was only seen at a follow-up of <3 months after surgery, that conclusions are stronger when evaluating dynamic QST with a follow-up of ≥3 months after surgery, and that pain improvement postsurgery was an important predictor. Future high-quality research should focus on the evolution of SPS signs after nociceptive targeted surgery, accounting for pain improvement groups and focusing on preoperative, perioperative, and postoperative predictors of this evolution.

Prehabilitation before total knee arthroplasty: A systematic review on the use and efficacy of stratified care.

BACKGROUND: Preoperative rehabilitation (hereafter called "prehabilitation") has been proposed as a potentially effective treatment to target preoperative risk factors to prevent insufficient outcome after total knee arthroplasty (TKA). PURPOSE: We aimed to assess whether previous clinical trials of non-surgical, non-pharmacological prehabilitation in individuals with knee osteoarthritis (KOA) awaiting TKA focused on specific clinical phenotypes or specific individual characteristics and whether the content of the prehabilitation was stratified accordingly. Second, we aimed to summarize and compare the long-term effects of stratified and non-stratified care on pain, satisfaction, function and quality of life. METHODS: A systematic literature search of PubMed, Web of Science, Scopus and Embase was performed. All relevant articles published up to April 19, 2021 reporting "(randomized controlled) clinical trials or prospective cohort studies" (S) related to the key words "total knee arthroplasty" (P), "preoperative conservative interventions" (I), "pain, function, quality of life and/or satisfaction" (O) were included. RESULTS: After screening 3498 potentially eligible records, 18 studies were assessed for risk of bias. Twelve studies had low, 2 moderate, 3 serious, and one high risk of bias. The latter study was excluded, resulting in 17 included studies. Five studies investigated a"stratified prehabilitation care" and 12 "non-stratified prehabilitation care". Stratified prehabilitation in 4 studies meant that the study sample was chosen considering a predefined intervention, and in the fifth study, the prehabilitation was stratified to individuals' needs. No direct comparison between the 2 approaches was possible. We found weak evidence for a positive effect of biopsychosocial prehabilitation compared to no prehabilitation on function (stratified studies) and pain neuroscience education prehabilitation compared to biomedical education on satisfaction (non-stratified studies) at 6 months post-TKA. We found strong evidence for positive effects of exercise prehabilitation compared to no prehabilitation on pain at 6 months and on function at 12 months post-TKA (non-stratified studies). CONCLUSION: More research is needed of stratified prehabilitation care focusing on individual characteristics in people with KOA awaiting TKA. REGISTRATION NUMBER: This systematic review was prospectively registered at PROSPERO on March 22, 2021 (no. CRD42021221098).

Personal influencing factors for pressure pain threshold in healthy people: A systematic review and meta-analysis.

All studies that investigated personal factors influencing pressure pain threshold (PPT) in healthy people were synthesized. Data was summarized, and risk of bias (RoB) and level of evidence were determined. Results were pooled per influencing factor, grouped by body region and included in meta-analyses. Fifty-four studies were eligible. Five had low, nine moderate, and 40 high RoB. Following meta-analyses, a strong conclusion was found for the influence of scapular position, a moderate for the influence of gender, and a weak for the influence of age (shoulder/arm region) and blood pressure on PPT. In addition, body mass index, gender (leg region), alcohol consumption and pain vigilance may not influence PPT. Based on qualitative summary, depression and menopause may not influence PPT. For other variables there was only preliminary or conflicting evidence. However, caution is advised, since the majority of included studies showed a high RoB and several were not eligible to include in meta-analyses. Heterogeneity was high in the performed meta-analyses, and most conclusions were weak. More standardized research is necessary.

The effect of one dry needling session on pain, central pain processing, muscle co-contraction and gait characteristics in patients with knee osteoarthritis: a randomized controlled trial.

OBJECTIVES: To assess the immediate and three days postintervention effect of one dry needling session compared to one sham needling session on pain, central pain processing, muscle co-contraction and spatiotemporal parameters during gait in knee osteoarthritis patients. METHODS: A double-blind randomized controlled trial was conducted. Sixty-one knee osteoarthritis patients were randomly assigned to the dry needling or sham needling group. Primary outcomes were pain and central pain processing. Secondary outcomes included muscle co-contraction and spatiotemporal parameters during gait. Patients were assessed at baseline and 15 min after the intervention, and pain also three days after the intervention. Linear mixed models were used to examine between- and within-group differences. RESULTS: No significant between-group differences for pain were found, but within-group scores showed a significant decrease 15 min after sham needling and three days after dry needling. The mean conditioned pain modulation effect measured at the m. Trapezius worsened significantly 15 min after sham needling compared to after dry needling (between-group difference). However, individual conditioned pain modulation percentage scores remained stable over time. Various significant within-group differences were found 15 min after sham needling: a decrease of conditioned pain modulation measured at m. Quadriceps and m. Trapezius and stride- and step-time scores, and an increase in step length and widespread pain pressure threshold. A significant decrease in muscle co-contraction index of the m. Vastus Medialis and Semitendinosus was found as within-group difference 15 min after dry needling. CONCLUSIONS: Dry needling has no larger effect on pain, central pain processing, muscle co-contraction and gait pattern 15 min and three days postintervention compared to sham needling. Mean conditioned pain modulation scores worsened after sham needling compared to after dry needling. Further research remains necessary.