Knee Osteoarthritis, Potential Mediators, and Risk of All-Cause Mortality: Data From the Osteoarthritis Initiative

Baicalin nanodelivery system based on functionalized metal-organic framework for targeted therapy of osteoarthritis by modulating macrophage polarization

Intra-articular drugs used to treat osteoarthritis (OA) often suffer from poor pharmacokinetics and stability. Nano-platforms as drug delivery systems for drug delivery are promising for OA therapy. In this study, we reported an M1 macrophage-targeted delivery system Bai@FA-UIO-66-NH2 based on folic acid (FA) -modified metal-organic framework (MOF) loaded with baicalin (Bai) as antioxidant agent for OA therapy. With outstanding biocompatibility and high drug loading efficiency, Bai@FA-UIO-66-NH2 could be specifically uptaken by LPS-induced macrophages to serve as a potent ROS scavenger, gradually releasing Bai at the subcellular level to reduce ROS production, modulate macrophage polarization to M2, leading to alleviation of synovial inflammation in OA joints. The synergistic effect of Bai@FA-UIO-66-NH2 on macrophage polarization and ROS scavenging significantly improved the therapeutic efficacy of OA, which may provide a new insight into the design of OA precision therapy.

Assessing the association of epigenetic age acceleration with osteoarthritis in the Multicenter Osteoarthritis Study (MOST)

PURPOSE

Advancing age is one of the strongest risk factors for osteoarthritis (OA). DNA methylation-based measures of epigenetic age acceleration may provide insights into mechanisms underlying OA.

METHODS

We analyzed data from the Multicenter Osteoarthritis Study in a subset of 671 participants ages 45-69 years with no or mild radiographic knee OA. DNA methylation was assessed with the Illumina Infinium MethylationEPIC 850K array. We calculated predicted epigenetic age according to Hannum, Horvath, PhenoAge, and GrimAge epigenetic clocks, then regressed epigenetic age on chronological age to obtain the residuals. Associations between the residuals and knee, hand, and multi-joint OA were assessed using logistic regression, adjusted for chronological age, sex, clinical site, smoking status, and race.

RESULTS

Twenty-three percent met criteria for radiographic hand OA, 25% met criteria for radiographic knee OA, and 8% met criteria for multi-joint OA. Mean chronological age (SD) was 58.4 (6.7) years. Mean predicted epigenetic age (SD) according to Horvath, Hannum, PhenoAge, and GrimAge epigenetic clocks was 64.9 (6.4), 68.6 (5.9), 50.5 (7.7), and 67.0 (6.2), respectively. Horvath epigenetic age acceleration was not associated with an increased odds of hand OA, odds ratio (95% confidence intervals) = 1.03 (0.99-1.08), with similar findings for knee and multi-joint OA. We found similar magnitudes of associations for Hannum epigenetic age, PhenoAge, and GrimAge acceleration compared to Horvath epigenetic age acceleration.

CONCLUSIONS

Epigenetic age acceleration as measured by various well-validated epigenetic clocks based on DNA methylation was not associated with increased risk of knee, hand, or multi-joint OA independent of chronological age.

The Association of Stair Climbing Behaviors With Hazard of All-Cause Mortality in Adults With or At Risk of Knee Osteoarthritis

OBJECTIVE

To investigate the association of stair climbing difficulty and stair climbing frequency with the risk of all-cause mortality over 13 years in adults with or at high risk for knee OA.

METHODS

We used data from the Osteoarthritis Initiative (OAI), a prospective cohort study of community-dwelling adults with or at high risk for symptomatic knee OA. The exposures were stair climbing difficulty and frequency, assessed at baseline using self-report questionnaires. The outcome was all-cause mortality, assessed from baseline through 13 years of follow-up. Kaplan-Meier survival curves and Cox proportional hazards regression were used to investigate the association between stair climbing exposures and all-cause mortality.

RESULTS

Three hundred seven (6.81%) and 310 (6.84%) participants in the difficulty and frequency samples, respectively, died during 13 years of follow-up. Those who were limited in any capacity in terms of their stair climbing ability had 54% to 84% greater hazard of all-cause mortality, and those who climbed at least 7 flights of stairs per week had 38% lower hazard of all-cause mortality.

CONCLUSION

Adults with or at high risk for knee OA who report difficulty with climbing stairs or who infrequently use stairs are at greater hazard of all-cause mortality. Stair climbing difficulty and frequency are simple to collect and changes may occur early in OA progression, allowing for early intervention. Brief questions about stair climbing behaviors can serve as a functional vital sign within the clinician's toolbox.

Effects of an Early Exercise Program with Cryotherapy on Range of Motion, Pain, Swelling, and Gait in Patients with Total Knee Arthroplasty: A Randomized Controlled Trial

Background: This study aimed to investigate the effects of cryotherapy on range of motion, pain, swelling, and gait in patients who underwent total knee arthroplasty. Methods: Forty-three patients who underwent TKA (total knee arthroplasty) and met the inclusion criteria were randomly divided into two groups. The experimental (n = 21) and control (n = 22) groups underwent cryotherapy and non-cryotherapy treatments, respectively, six times a week for two weeks, and once each before and after exercise for 3 min. Both groups followed a similar initial rehabilitation exercise program using a continuous passive motion device. Results: The results showed a significant difference in knee flexion range of motion, pain, edema, and 10 MWT comparisons from pre- to post-test (p < 0.001). The above values were also significantly different in the comparison between the two groups (p < 0.05). Conclusions: Therefore, this study confirmed that an initial rehabilitation exercise program accompanied by cryotherapy could be an effective intervention method for range of motion, pain, edema, and walking in patients undergoing total knee arthroplasty.

Acupuncture-Related Therapy for Knee Osteoarthritis: A Narrative Review of Neuroimaging Studies

Acupuncture has been widely applied for treating knee osteoarthritis (KOA). Numerous studies have found that acupuncture can effectively alleviate KOA symptoms. With the advancement of neuroimaging techniques, integrating neuroimaging with in-depth investigations of acupuncture mechanisms has emerged as a hot topic in traditional Chinese medical neuroscience research. This review aimed to analyze the study design and main findings from neuroimaging studies of acupuncture-related therapy for KOA to provide a reference for future research. Original studies were sourced from English databases (PubMed, Embase, and Cochrane Library) and Chinese databases (Chinese National Knowledge Infrastructure, Chinese Biomedical Literature Database, the Chongqing VIP database, and Wanfang database). As a result, thirteen articles were ultimately included in this review. Functional magnetic resonance imaging was the most frequently used neuroimaging technique to explore cerebral responses to acupuncture-related therapy for KOA. Findings suggested that acupuncture-related therapy could regulate some brain regions in patients with KOA. Specifically, for acupuncture, it showed that the medial pain pathway and the limbic system were involved in the regulation of KOA. Meanwhile, moxibustion induced a wide range of functional activity throughout the entire brain.

Therapeutic targets and potential delivery systems of melatonin in osteoarthritis

Osteoarthritis (OA) is a highly prevalent age-related musculoskeletal disorder that typically results in chronic pain and disability. OA is a multifactorial disease, with increased oxidative stress, dysregulated inflammatory response, and impaired matrix metabolism contributing to its onset and progression. The neurohormone melatonin, primarily synthesized by the pineal gland, has emerged as a promising therapeutic agent for OA due to its potential to alleviate inflammation, oxidative stress, and chondrocyte death with minimal adverse effects. The present review provides a comprehensive summary of the current understanding regarding melatonin as a promising pharmaceutical agent for the treatment of OA, along with an exploration of various delivery systems that can be utilized for melatonin administration. These findings may provide novel therapeutic strategies and targets for inhibiting the advancement of OA.

Validity of the Brief Illness Perception Questionnaire in people with knee pain: a Rasch analysis

OBJECTIVE

The Brief Illness Perception Questionnaire (B-IPQ) is a frequently used measure of illness perception (IP). The aim of this study was to explore the psychometric properties of the questionnaire when used in elderly people with knee pain.

METHOD

Based on data from the Frederiksberg Cohort on elderly people reporting knee pain (N = 836), the psychometric properties of the eight B-IPQ items (1 'Consequences', 2 'Timeline', 3 'Personal control', 4 'Treatment control', 5 'Identity', 6 'Concern', 7 'Coherence', and 8 'Emotions') were analysed using Rasch analysis to establish whether the questionnaire provides reliable and valid measures of IP.

RESULTS

Threshold disordering was found on the 1-10 rating scale in all items. When rescaling to a 0-2 rating scale, disordering was resolved in six items. Item goodness-of-fit analyses revealed that two items displayed underfit misfit and four items overfit misfit; hence, the B-IPQ does not present unidimensionality. The person separation index indicated that items separate respondents into only two IP levels. Finally, floor and ceiling effects were found, indicating that the B-IPQ may not fully describe the extent of IP in this population.

CONCLUSION

The 1-10 rating scale used in the Danish B-IPQ targeting knee pain is suboptimal, while a 0-2 scale improves the psychometric properties of the scale. The B-IPQ does not present unidimensionality and the use of a sum score is therefore not recommended when assessing IP. The B-IPQ may not cover the extent of IP in elderly people with knee pain.

Economic and Humanistic Burden of Osteoarthritis: An Updated Systematic Review of Large Sample Studies

OBJECTIVE

A previous systematic literature review demonstrated a significant economic and humanistic burden on patients with osteoarthritis (OA). The aim of this study was to systematically review and update the burden of OA reported by large sample studies since 2016.

METHODS

We searched Medline (via Ovid) and Embase using the updated search strategy based on the previous review. Those studies with a sample size ≥ 1000 and measuring the cost (direct or indirect) or health-related quality of life (HRQL) of OA were included. Pairs of reviewers worked independently and in duplicate. An arbitrator was consulted to resolve discrepancies between reviewers. The Kappa value was calculated to examine the agreement between reviewers. All costs were converted to 2021 US dollars according to inflation rates and exchange rates.

RESULTS

A total of 1230 studies were screened by title and abstract and 159 by full text, and 54 studies were included in the review. The Kappa value for the full-text screening was 0.71. Total annual OA-related direct costs ranged from US$326 in Japan to US$19,530 in the US. Total annual all-cause direct costs varied from US$173 in Italy to US$41,433 in the US. The annual indirect costs ranged from US$736 in the US to US$18,884 in the Netherlands. Thirty-four studies reported HRQL, with EQ-5D (13, 38%) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) (6, 18%) being the most frequently used instruments. The EQ-VAS and utility scores ranged from 41.5 to 81.7 and 0.3 to 0.9, respectively. The ranges of WOMAC pain (range 0-20, higher score for worse health), stiffness (range 0-8), and physical functioning (range 0-68) were 2.0-3.0, 1.0-5.0, and 5.8-42.8, respectively.

CONCLUSION

Since 2016, the ranges of direct costs of OA became wider, while the HRQL of patients remained poor. More countries outside the US have published OA-related disease burden using registry databases.

Network meta-analysis of 7 acupuncture therapies for knee osteoarthritis

OBJECTIVE

With the progression of society aging demographic, the prevalence of knee osteoarthritis (KOA) continues to rise steadily, exerting a significant impact on individuals' quality of life. Acupuncture therapy has garnered extensive utilization in the management of osteoarthritis; however, a comprehensive systematic review integrating acupuncture with traditional Chinese medicine remains absent. This study compared the clinical efficacy of 7 acupuncture methods (electroacupuncture, conventional acupuncture, warm needle, floating needle, fire needle, needle knife, and silver needle) for the treatment of KOA through a network meta-analysis.

METHODS

This study examined the databases-PubMed, EMbase, The Cochrane Library, the China Biology Medicine, Chinese Journal Full-text Database, Wanfang Database, and VIP Database-for randomized controlled trials of the 7 methods for KOA treatment. The search time spanned from the database establishment to March 5, 2022. The primary outcome indicator was the total effective rate, and the secondary outcome indicator was the visual analog scale. After the layer-by-layer screening, the quality of the literature was assessed using the Cochrane systematic reviewer manual 5.1.0 bias risk assessment tool for randomized controlled trials. After data extraction, the R4.0.1 software was used for network meta-analysis.

RESULTS

Based on the network meta-analysis, the ranking of interventions based on the surface under the cumulative ranking curve for the total effective rate is as follows: silver needle (0.99) > floating needle (0.97) > needle knife (0.66) > fire needle (0.56) > warm needle (0.44) > conventional acupuncture (0.35) > electroacupuncture (0.13). Regarding the improvement in visual analog scale scores, the surface under the cumulative ranking curve ranking is as follows: silver needle (0.97) > conventional acupuncture (0.67) > needle knife (0.64) > floating needle (0.51) > warm needle (0.44) > fire needle (0.14) > electroacupuncture (0.09).

CONCLUSION

Based on the network meta-analysis, silver needle therapy emerged as the most efficacious and analgesic intervention for KOA. Nevertheless, given the notable variations in the quality and quantity of studies encompassing diverse treatment modalities, the findings of this research necessitate further substantiation through forthcoming high-quality multicenter, large-sample, randomized double-blind trials.

Researchers in rheumatology should avoid categorization of continuous predictor variables

BACKGROUND

Rheumatology researchers often categorize continuous predictor variables. We aimed to show how this practice may alter results from observational studies in rheumatology.

METHODS

We conducted and compared the results of two analyses of the association between our predictor variable (percentage change in body mass index [BMI] from baseline to four years) and two outcome variable domains of structure and pain in knee and hip osteoarthritis. These two outcome variable domains covered 26 different outcomes for knee and hip combined. In the first analysis (categorical analysis), percentage change in BMI was categorized as ≥ 5% decrease in BMI, < 5% change in BMI, and ≥ 5% increase in BMI, while in the second analysis (continuous analysis), it was left as a continuous variable. In both analyses (categorical and continuous), we used generalized estimating equations with a logistic link function to investigate the association between the percentage change in BMI and the outcomes.

RESULTS

For eight of the 26 investigated outcomes (31%), the results from the categorical analyses were different from the results from the continuous analyses. These differences were of three types: 1) for six of these eight outcomes, while the continuous analyses revealed associations in both directions (i.e., a decrease in BMI had one effect, while an increase in BMI had the opposite effect), the categorical analyses showed associations only in one direction of BMI change, not both; 2) for another one of these eight outcomes, the categorical analyses suggested an association with change in BMI, while this association was not shown in the continuous analyses (this is potentially a false positive association); 3) for the last of the eight outcomes, the continuous analyses suggested an association of change in BMI, while this association was not shown in the categorical analyses (this is potentially a false negative association).

CONCLUSIONS

Categorization of continuous predictor variables alters the results of analyses and could lead to different conclusions; therefore, researchers in rheumatology should avoid it.

Effects of Self-management Program as Adjunctive to Usual Rehabilitation Exercise on Pain and Functional Outcomes in Knee Osteoarthritis: A Randomized Controlled Trial

BACKGROUND

Home-based exercise (HBE) and patient education (EDU) have been reported as beneficial additions to usual knee osteoarthritis (KOA) rehabilitation. However, previous trials mostly examined the effects of HBE and EDU separately. Thus, this study aimed to evaluate the effects of a structured combined HBE and EDU program in addition to usual KOA rehabilitation on pain score, functional mobility, and disability level.

STUDY DESIGN

A parallel-group, single-blinded randomized controlled trial.

METHODS

Eighty adults with KOA were randomly allocated to experimental (n=40) and control (n=40) groups. All participants underwent their usual physiotherapy care weekly for eight weeks. The experimental group received a structured HBE+EDU program to their usual care, while the control group performed home stretching exercises to equate treatment time. The Knee Injury and Osteoarthritis Outcome Score (KOOS) for the disability level, visual analogue scale (VAS) for pain, and timed up-and-go test (TUG) for mobility were measured pre-post intervention.

RESULTS

After eight weeks, the experimental group demonstrated significant improvements in the KOOS (all subscales), pain VAS, and TUG scores compared to baseline (P<0.001); meanwhile, only KOOS (activities of daily living and sports subscales) was significant in the control group. Relative to the control, the experimental group presented higher improvements (P<0.001) by 22.2%, 44.1%, and 15.7% for KOOS, pain VAS, and TUG, respectively.

CONCLUSION

Integrating the HBE+EDU program into usual KOA rehabilitation could reduce pain and disability, while it improved functional mobility. The finding of this study suggests a combination of a structured HBE and EDU program to be considered as part of mainstream KOA management.

Loss of Productivity-Adjusted Life-Years in Working-Age Australians Due to Knee Osteoarthritis: A Life-Table Modeling Approach

OBJECTIVE

Productivity-adjusted life-years (PALYs) offers a novel approach for quantifying the productivity burden of chronic conditions at the population level over the working lifespan. This study was undertaken to estimate the productivity burden of knee osteoarthritis (KOA) among working-age Australians, defined as lost PALYs and lost gross domestic product (GDP).

METHODS

A static life-table model was constructed to simulate the experiences of working Australians (between the ages of 15-64 years) with KOA and those without KOA, with follow-up to 65 years (retirement age), a 1-year cycle length, and an annual discount rate of 5%. KOA prevalence data were obtained from the 2019 Global Burden of Diseases, Injuries, and Risk Factors study. Demographic and mortality data were sourced from the Australian Bureau of Statistics. Health utilities and productivity indices were derived from published sources. Population-level losses in years of life, quality-adjusted life-years (QALYs), and PALYs attributable to KOA were estimated by comparing estimates in the KOA cohort to the no KOA cohort.

RESULTS

In 2019, a total of 913,539 working-age Australians were estimated to have KOA, with an overall prevalence of 5.5% (4.5% in men and 6.5% in women). By retirement age, KOA was associated with 39,602 excess deaths, 125,651 years of life lost, 1,938,059 QALYs lost, and 1,943,287 PALYs lost. The economic impact of lost productivity due to KOA amounted to 424 billion Australian dollars in lost GDP.

CONCLUSION

Our modeling demonstrates a significant economic burden of KOA among the working Australian population, with marked productivity loss. Our findings highlight the need for public health funding and scalable population-level strategies for effective KOA prevention and support to maintain productive working.

Association of Pre-operative Arthritis with Long-Term Mortality Following Bariatric Surgery

BACKGROUND

Metabolic and bariatric surgery (MBS) is an effective treatment for obesity and may reduce mortality. Several factors are associated with higher mortality following MBS. The purpose of this study was to examine whether pre-operative arthritis was associated with long-term mortality following MBS.

METHODS

Using a retrospective cohort design, subjects who underwent MBS were identified from the Utah Bariatric Surgery Registry. These subjects were linked to the Utah Population Database. State death records from 1998 through 2021 were used to identify deaths following MBS. ICD-9/10 diagnosis codes were used to identify a pre-operative diagnosis of arthritis and to classify the cause of death. All causes of death, internal cause of death (e.g., diabetes, heart disease), and external cause of death (e.g., suicide) were defined as outcomes. Entropy balancing (EB) was applied to create weights to balance the baseline characteristics of the two groups. Weighted Cox proportional hazards regression was used to evaluate the association of pre-operative arthritis with long-term mortality following MBS.

RESULTS

The final sample included 15,112 patients. Among them, 36% had a pre-operative arthritis diagnosis. Average (SD) age was 48(12) years old at surgery, and 75% were female. Patients with pre-operative arthritis had 25% (p < 0.01) and 26% (p < 0.01) higher risk of all cause of death and internal cause of death, respectively, compared to patients without pre-operative arthritis.

CONCLUSION

Individuals with arthritis prior to MBS may have higher hazard of long-term mortality than those without pre-operative arthritis.

Exercise & Sports Science Australia (ESSA) updated Position Statement on exercise and physical activity for people with hip/knee osteoarthritis

This Position Statement is an update to the existing statement. It is intended for all health practitioners who manage people with hip/knee osteoarthritis. It synthesises the most recent evidence (with a focus on clinical guidelines and systematic reviews) for exercise in people with hip/knee osteoarthritis, and provides guidance to practitioners about how best to implement exercise in clinical practice. Clinical practice guidelines for hip/knee osteoarthritis advocate physical activity and exercise as fundamental core components of evidence-based management. Research evidence indicates that exercise can reduce joint pain, increase physical function, and improve quality of life in hip/knee osteoarthritis, and that a range of exercise types (both supervised and unsupervised) may be beneficial. Exercise dosage should be guided by the principles of the American College of Sports Medicine. As people with osteoarthritis experience many barriers to exercise, practitioners should take an active role in monitoring and promoting adherence to exercise in order to optimise therapeutic benefits.

Anatomical Imaging Study on Uneven Settlement of the Proximal Tibia

OBJECTIVE

Uneven settlement of the proximal tibia significantly contributes to the onset and progression of medial compartment knee OA; however, the specific location and variations of proximal tibial deformity remain unclear. Therefore, this study aimed to explore the effects of the anatomic morphology of different tibial regions on proximal tibial vara and proximal tibial microstructural changes with age in both sexes to reveal the pattern of uneven settlement of the proximal tibia.

METHODS

In this retrospective study, we reviewed the radiographs of 414 patients (789 legs) between May and September 2021. The medial proximal tibial angle (MPTA) and four anatomic angles of the tibia (i.e., the tibial plateau-epiphyseal line [PT-EL] angle, epiphyseal line-tibial platform [EL-PF] angle, epiphyseal axis inclination angle [EAIA], and subepiphyseal axis inclination angle [SAIA]) were measured. The effect of each angle on MPTA and their changes with age in both sexes were investigated using Pearson's correlation coefficient and multiple linear regression.

RESULTS

In females, PT-EL angle, EL-PF angle, and SAIA negatively correlated with MPTA (r = -0.325, -0.246, and -0.502; p < 0.05), and EAIA positively correlated with MPTA (r = 0.099, p < 0.05). Regression analysis showed that the correlations between MPTA and PT-EL angle, EL-PF angle, and SAIA were significant (β = -1.003, -0.013, and -0.971; adjusted R²  = 0.979). Furthermore, MPTA negatively correlated with age (r = -0.202, p < 0.05); PT-EL angle and EAIA positively correlated with age (r = 0.237 and 0.142, p < 0.05). Regression analysis showed that only the correlation between PT-EL angle and age was significant (β = 5.635, p < 0.05). In males, PT-EL angle, EL-PF angle, and SAIA negatively correlated with MPTA (r = -0.270, -0.267, and -0.533; p < 0.05), and EAIA positively correlated with MPTA (r = 0.135, p < 0.05). Regression analysis showed that the correlations between MPTA and PT-EL angle, EL-PF angle, and SAIA were significant (β = -0.992, -0.017, and -0.958; adjusted R²  = 0.970). However, there was no significant correlation between age and any of the measured angles (p > 0.05).

CONCLUSIONS

Proximal tibial vara is affected by the anatomic morphology of the epiphyseal and subepiphyseal regions. In females, the uneven settlement of the epiphysis progresses with age and may be responsible for dynamic varus deformity of the proximal tibia.

The therapeutic effect and mechanism of melatonin on osteoarthritis: From the perspective of non-coding RNAs

Osteoarthritis (OA) is a slowly progressing and irreversible joint disease. The existing non-surgical treatment can only delay its progress, making the early treatment of OA a research hotspot in recent years. Melatonin, a neurohormone mainly secreted by the pineal gland, has a variety of regulatory functions in different organs, and numerous studies have confirmed its therapeutic effect on OA. Non-coding RNAs (ncRNAs) constitute the majority of the human transcribed genome. Various ncRNAs show significant differentially expressed between healthy people and OA patients. ncRNAs play diverse roles in many cellular processes and have been implicated in many pathological conditions, especially OA. Interestingly, the latest research found a close interaction between ncRNAs and melatonin in regulating the pathogenesis of OA. This review discusses the current understanding of the melatonin-mediated modulation of ncRNAs in the early stage of OA. We also delineate the potential link between rhythm genes and ncRNAs in chondrocytes. This review will serve as a solid foundation to formulate ideas for future mechanistic studies on the therapeutic potential of melatonin and ncRNAs in OA and better explore the emerging functions of the ncRNAs.

Progress in osteoarthritis research by the National Natural Science Foundation of China

Osteoarthritis (OA) in China is gradually becoming an important scientific research area that has had a significant impact on research and development (R&D) activities in the OA field worldwide. This article summarizes the R&D progress related to OA in China in recent years. The National Natural Science Foundation of China (NSFC) is a national funding institution for basic research and plays a critical role in promoting and supporting Chinese scholars' R&D activities. We collected and analyzed information on NSFC funding in the field of OA from 2010 to 2019, including the amount, the level and the program categories of the funded projects. The data fully demonstrate the important and positive role of the NSFC in supporting free exploration, cultivating research teams and young talent, and boosting OA R&D. In this article, we outline and discuss hot topics in focused areas, key advances in this field and the prospects for progress in OA research in China.

Progression of Knee Osteoarthritis With Use of Intraarticular Glucocorticoids Versus Hyaluronic Acid

OBJECTIVE

To determine whether intraarticular glucocorticoid (GC) injections are associated with increased knee osteoarthritis (OA) progression compared to hyaluronic acid (HA) injections, which have been reported to delay OA progression and knee replacement.

METHODS

We identified participants from 2 large cohort studies, the Osteoarthritis Initiative (OAI) and the Multicenter Osteoarthritis Study. Study visits were performed at regular intervals and included questionnaires about intraarticular GC or HA injection use in the previous 6 months and incident total knee replacement (TKR). Knee radiographs were obtained at each study visit and interpreted in a similar manner. Outcome measures were radiographic progression based on Kellgren/Lawrence (K/L) grade and joint space narrowing (JSN) for both cohorts and based on medial joint space width for OAI participants, and incident TKR. We compared preinjection and postinjection radiographs to generate rate ratios of progression comparing GC injection with HA injection. A Cox proportional hazards model was used to estimate the rate of TKR for both groups.

RESULTS

We studied 791 participants (980 knees) with knee OA, of whom 629 reported GC injection use and 162 HA injection use. Rate ratios of progression were similar between those receiving GCs and those receiving HA for JSN (1.00 [95% confidence interval (95% CI) 0.83-1.21]), K/L grade (1.03 [95% CI 0.83-1.29]), and medial joint space width (1.03 [95% CI 0.72-1.48]). Hazard of TKR was slightly lower for those receiving intraarticular GC compared to those receiving HA (hazard ratio 0.75 [95% CI 0.51-1.09]).

CONCLUSION

Intraarticular GC injections are not associated with an increased risk of knee OA progression compared to HA.

Association between sleep disorders and osteoarthritis: A case-control study of 351,932 adults in the UK

This study aimed to analyse the association between sleep disorders and osteoarthritis in adults in the UK. This case-control study included patients aged ≥ 18 years who were diagnosed with osteoarthritis for the first time in one of 256 general practices in the UK between 1997 and 2016 (index date). Patients without osteoarthritis were matched (1:1) to those with osteoarthritis by sex, age, index year, general practice, observation time prior to index date (in years), obesity, injuries, and other types of arthritis. For patients without osteoarthritis, the index date was a randomly selected visit date between 1997 and 2016. The presence of sleep disorders prior to index date was assessed in the two groups. Finally, conditional logistic regression analyses were conducted to investigate the association between sleep disorders and osteoarthritis. This case-control study included 351,932 adults (61.5% women; mean [SD] age 64.9 [14.2] years). Overall, there was a significant association between sleep disorders and osteoarthritis (odds ratio = 1.25, 95% confidence interval = 1.22-1.29). This finding was corroborated in all sex and age subgroups, except in patients aged > 80 years. In terms of the type of sleep disorder, non-organic sleep disorders, hypersomnia and sleep apnea were associated to a significant extent with higher odds of developing osteoarthritis. Finally, the relationship between sleep disorders and osteoarthritis was significant in all osteoarthritis subgroups, except in that of patients with knee osteoarthritis. Based on these results, it can be concluded that sleep disorders may play a role in the development of osteoarthritis.

Risk of venous thromboembolism in knee, hip and hand osteoarthritis: a general population-based cohort study

OBJECTIVES

Osteoarthritis is a leading cause of immobility and joint replacement, two strong risk factors for venous thromboembolism (VTE). We aimed to examine the relation of knee, hip and hand osteoarthritis to the risk of VTE and investigate joint replacement as a potential mediator.

METHODS

We conducted three cohort studies using data from The Health Improvement Network. Up to five individuals without osteoarthritis were matched to each case of incident knee (n=20 696), hip (n=10 411) or hand (n=6329) osteoarthritis by age, sex, entry time and body mass index. We examined the relation of osteoarthritis to VTE (pulmonary embolism and deep vein thrombosis) using a multivariable Cox proportional hazard model.

RESULTS

VTE developed in 327 individuals with knee osteoarthritis and 951 individuals without osteoarthritis (2.7 vs 2.0 per 1000 person-years), with multivariable-adjusted HR being 1.38 (95% CI 1.23 to 1.56). The indirect effect (HR) of knee osteoarthritis on VTE through knee replacement was 1.07 (95% CI 1.01 to 1.15), explaining 24.8% of its total effect on VTE. Risk of VTE was higher in hip osteoarthritis than non-osteoarthritis (3.3 vs 1.8 per 1000 person-years; multivariable-adjusted HR=1.83, 95% CI 1.56 to 2.13). The indirect effect through hip replacement yielded an HR of 1.14 (95% CI 1.04 to 1.25), explaining 28.1% of the total effect. No statistically significant difference in VTE risk was observed between hand osteoarthritis and non-osteoarthritis (1.5 vs 1.6 per 1000 person-years; multivariable-adjusted HR=0.88, 95% CI 0.67 to 1.16).

CONCLUSION

Our large population-based cohort study provides the first evidence that knee or hip osteoarthritis, but not hand osteoarthritis, was associated with an increased risk of VTE, and such an association was partially mediated through knee or hip replacement.

The association between walking speed from short- and standard-distance tests with the risk of all-cause mortality among adults with radiographic knee osteoarthritis: data from three large United States cohort studies

OBJECTIVE

Adults with radiographic knee OA (rKOA) are at increased risk of mortality and walking difficulty may modify this relation. Little is known about specific aspects of walking difficulty that increase mortality risk. We investigated the association of walking speed (objective measure of walking difficulty) with mortality and examined the threshold that best discriminated this risk in adults with rKOA.

METHODS

Participants with rKOA from the Johnston County Osteoarthritis Project (JoCoOA, longitudinal population-based cohort), Osteoarthritis Initiative and Multicenter Osteoarthritis Study (OAI and MOST, cohorts of individuals with or at high risk of knee OA) were included. Baseline speed was measured via 2.4-meter (m) walk test (short-distance) in JoCoOA and 20-m walk test (standard-distance) in OAI and MOST. To examine the association of walking speed with mortality risk over 9 years, hazard ratios (HR) and 95% confidence intervals (CI) were calculated from Cox regression models adjusted for potential confounders. A Maximal Likelihood Ratio Chi-square Approach was utilized to identify an optimal threshold of walking speed predictive of mortality.

RESULTS

Deaths after 9 years of follow-up occurred in 23.3% (290/1244) of JoCoOA and 5.9% (249/4215) of OAI + MOST. Walking 0.2 m/s slower during short- and standard-distance walk tests was associated with 23% (aHR [95%CI]; 1.23 [1.10, 1.39]) and 25% (1.25 [1.09, 1.43]) higher mortality risk, respectively. Walking <0.5 m/s on short-distance and <1.2 m/s standard-distance walk tests, best discriminated those with and without mortality risk.

CONCLUSION

Slower walking speed measured via short- and standard-distance walk tests was associated with increased mortality risk in adults with rKOA.

Behavioral Graded Activity+ (BGA+) for Osteoarthritis: A Paradigm Shift from Disease-Based Treatment to Personalized Activity Self-Management

Three promising directions for improving care for osteoarthritis (OA) include novel education strategies to target unhelpful illness and treatment beliefs; methods to enhance the efficacy of exercise interventions; and innovative, brain-directed treatments. Here we explain that each of those three promising directions can be combined through a paradigm-shift from disease-based treatments to personalized activity self-management for patients with OA. Behavioral graded activity (BGA) accounts for the current understanding of OA and OA pain and allows a paradigm shift from a disease-based treatment to personalized activity self-management for patients with OA. To account for the implementation barriers of BGA, we propose adding pain neuroscience education to BGA (referred to as BGA⁺). Rather than focusing on the biomedical (and biomechanical) disease characteristics of OA, pain neuroscience education implies teaching people about the underlying biopsychosocial mechanisms of pain. To account for the lack of studies showing that BGA is “safe” with respect to disease activity and the inflammatory nature of OA patients, a trial exploring the effects of BGA⁺ on the markers of inflammation is needed. Such a trial could clear the path for the required paradigm shift in the management of OA (pain) and would allow workforce capacity building that de-emphasizes biomedical management for OA.

Proteoglycan-4 regulates fibroblast to myofibroblast transition and expression of fibrotic genes in the synovium

Background

Synovial tissue fibrosis is common in advanced OA with features including the presence of stress fiber-positive myofibroblasts and deposition of cross-linked collagen type-I. Proteoglycan-4 (PRG4) is a mucinous glycoprotein secreted by synovial fibroblasts and is a major component of synovial fluid. PRG4 is a ligand of the CD44 receptor. Our objective was to examine the role of PRG4-CD44 interaction in regulating synovial tissue fibrosis in vitro and in vivo.

Methods

OA synoviocytes were treated with TGF-β ± PRG4 for 24 h and α-SMA content was determined using immunofluorescence. Rhodamine-labeled rhPRG4 was incubated with OA synoviocytes ± anti-CD44 or isotype control antibodies and cellular uptake of rhPRG4 was determined following a 30-min incubation and α-SMA expression following a 24-h incubation. HEK-TGF-β cells were treated with TGF-β ± rhPRG4 and Smad3 phosphorylation was determined using immunofluorescence and TGF-β/Smad pathway activation was determined colorimetrically. We probed for stress fibers and focal adhesions (FAs) in TGF-β-treated murine fibroblasts and fibroblast migration was quantified ± rhPRG4. Synovial expression of fibrotic markers: α-SMA, collagen type-I, and PLOD2 in Prg4 gene-trap (Prg4^GT) and recombined Prg4^GTR animals were studied at 2 and 9 months of age. Synovial expression of α-SMA and PLOD2 was determined in 2-month-old Prg4^GT/GT&Cd44^−/− and Prg4^GTR/GTR&Cd44^−/− animals.

Results

PRG4 reduced α-SMA content in OA synoviocytes (p < 0.001). rhPRG4 was internalized by OA synoviocytes via CD44 and CD44 neutralization attenuated rhPRG4’s antifibrotic effect (p < 0.05). rhPRG4 reduced pSmad3 signal in HEK-TGF-β cells (p < 0.001) and TGF-β/Smad pathway activation (p < 0.001). rhPRG4 reduced the number of stress fiber-positive myofibroblasts, FAs mean size, and cell migration in TGF-β-treated NIH3T3 fibroblasts (p < 0.05). rhPRG4 inhibited fibroblast migration in a macrophage and fibroblast co-culture model without altering active or total TGF-β levels. Synovial tissues of 9-month-old Prg4^GT/GT animals had higher α-SMA, collagen type-I, and PLOD2 (p < 0.001) content and Prg4 re-expression reduced these markers (p < 0.01). Prg4 re-expression also reduced α-SMA and PLOD2 staining in CD44-deficient mice.

Conclusion

PRG4 is an endogenous antifibrotic modulator in the joint and its effect on myofibroblast formation is partially mediated by CD44, but CD44 is not required to demonstrate an antifibrotic effect in vivo.