Osteoarthritis of knee joint in metabolic syndrome

The role of obesity and adipose tissue dysfunction in osteoarthritis pain

Obesity has a pivotal and multifaceted role in pain associated with osteoarthritis (OA), extending beyond the mechanistic influence of BMI. It exerts its effects both directly and indirectly through various modifiable risk factors associated with OA-related pain. Adipose tissue dysfunction is highly involved in OA-related pain through local and systemic inflammation, immune dysfunction, and the production of pro-inflammatory cytokines and adipokines. Adipose tissue dysfunction is intricately connected with metabolic syndrome, which independently exerts specific effects on OA-related pain, distinct from its association with BMI. The interplay among obesity, adipose tissue dysfunction and metabolic syndrome influences OA-related pain through diverse pain mechanisms, including nociceptive pain, peripheral sensitization and central sensitization. These complex interactions contribute to the heightened pain experience observed in individuals with OA and obesity. In addition, pain management strategies are less efficient in individuals with obesity. Importantly, therapeutic interventions targeting obesity and metabolic syndrome hold promise in managing OA-related pain. A deeper understanding of the intricate relationship between obesity, metabolic syndrome and OA-related pain is crucial and could have important implications for improving pain management and developing innovative therapeutic options in OA.

Life's Essential 8 and its association with osteoarthritis and disability: a cross-sectional study based on the NHANES 2005-2018 database

PURPOSE

Osteoarthritis (OA) often coexists with risk factors for cardiovascular disease (CVD), worsening symptoms and functional impairment. This cross-sectional study investigated the association between Life's Essential 8 (LE8) and disability in individuals with OA.

METHODS

Data from 8334 United States adults (aged ≥ 20) who participated in the 2005-2018 National Health and Nutrition Examination Survey (NHANES) with complete data on LE8 components and disability status were analyzed. LE8 components, including diet, physical activity (PA), nicotine exposure, sleep, body mass index (BMI), blood lipids, glucose, and blood pressure (BP), were scored on a 0-100 scale, categorizing cardiovascular health (CVH) as low, moderate, or high. Disability mainly caused by OA was assessed using a standardized physical functioning questionnaire. Association analyses were performed using multivariable logistic regression, adjusting for demographic, socioeconomic, lifestyle, and health-related covariates.

RESULTS

Individuals with CVH scores 10 points higher had a 15% lower prevalence of OA (95% CI 0.81-0.90). Individuals with OA were more than twice as likely to experience disability. High levels of CVH were associated with a lower prevalence of disability in various domains compared to low levels of CVH (all P < 0.05), such as in activities of daily living (OR 0.32, 95% CI 0.18-0.58). Among the LE8 components, BMI, PA, and sleep health were associated with disabilities in all domains, while blood lipid scores were not.

CONCLUSION

A higher adherence to LE8 is associated with a lower prevalence of different types of disability in domains of physical functioning and functional limitations in individuals with OA.

Infrapatellar Fat Pad Modulates Osteoarthritis-Associated Cytokine and MMP Expression in Human Articular Chondrocytes

Osteoarthritis (OA) most frequently affects the knee joint and is associated with an elevated expression of cytokines and extracellular cartilage matrix (ECM), degrading enzymes such as matrix metalloproteinases (MMPs). Differences in gene expression of the intra-articularly located infrapatellar fat pad (IPFP) and other fatty tissue suggest its autonomous function, yet its role in OA pathogenesis remains unknown. Human IPFPs and articular cartilage were collected from OA patients undergoing total knee arthroplasty, and biopsies from the IPFP of healthy patients harvested during knee arthroscopy served as controls (CO). Isolated chondrocytes were co-cultured with either osteoarthritic (OA) or CO-IPFPs in a transwell system. Chondrocyte expression of MMP1, -3, -13, type 1 and 2 collagens, interleukin IL1β, IL6, IL10, and tumor necrosis factor TNFα was analyzed by RTD-PCR at day 0 and day 2, and TNFα secretion was analyzed by ELISA. The cytokine release in IPFPs was assessed by an array. Results: Both IPFPs (CO, OA) significantly reduced the expression of type 2 collagen and TNFα in chondrocytes. On the other hand, only CO-IPFP suppressed the expression of type 1 collagen and significantly induced the MMP13 expression. On the contrary, IL1β and IL6 were significantly induced when exposed to OA-IPFP. Conclusions: The partial loss of the suppressive effect on type 1 collagen gene expression found for OA-IPFP shows the pathological remodeling and dedifferentiation potential of the OA-IPFP on the chondrocytes. However, the significant suppression of TNFα implies that the OA- and CO-IPFP could also exhibit a protective role in the knee joint, preventing the progress of inflammation.

Trajectory of metabolic syndrome and its association with knee pain in middle-aged adults

OBJECTIVE

Metabolic syndrome (MetS) is characterised by the clustering of central obesity with metabolic abnormalities. We aimed to describe the association of MetS and trajectories of MetS over 10-13 years with knee symptoms in general population-based middle-aged adults.

METHODS

Fasting blood biochemistry, waist circumference and blood pressure measures were collected during Childhood Determinants of Adult Health (CDAH)-1 study (year:2004-6; n = 2447; mean age:31.48 ± 2.60) and after 10-13 year at CDAH-3 (year:2014-2019; n = 1549; mean age:44 ± 2.90). Participants were defined as having MetS as per International Diabetes Federation (IDF) definition. Knee symptoms were assessed using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scale at CDAH-3 (mid-adulthood).

RESULTS

The prevalence of MetS increased from 8 % at young adulthood (female:52.06 %) to 13 % in mid-adulthood (female:53.78 %) over 10-13 years. Presence of MetS at mid-adulthood was associated with knee symptoms at mid-adulthood [ratio of means (RoM): 1.33; 95%CI:1.27,1.39]. Four MetS trajectories were identified-'No MetS' (85.01 %); 'Improved MetS' (2.14 %), 'Incident MetS' (8.81 %), and 'Persistent MetS, (4.04 %). Compared to 'No MetS', 'Persistent MetS' [RoM:1.15; 95%CI:1.06,1.25], 'Incident MetS' [RoM:1.56; 95%CI:1.48,1.65], and 'Improved MetS' [RoM:1.22; 95%CI:1.05,1.41] was associated with higher knee symptoms. Notably, 'Incident MetS' was strongly associated with knee symptoms [RoM: 1.56; 95%CI:1.48,1.65] and pain [RoM:1.52; 95%CI:1.37,1.70] at mid-adulthood.

CONCLUSION

In this sample of middle-aged adults, there was a significant positive association between MetS and knee symptoms. Relative to those without MetS at either life stage, the elevation in mean knee pain scores was more pronounced for those who developed MetS after young adulthood than for those who had MetS in young adulthood.

General and central obesity prevalence in young adult: a study based on the Rafsanjan youth cohort study

Growing prevalence of obesity among youth would have adverse consequences and increased risk of developing chronic diseases at older ages. This study explored the prevalence of obesity and its association with relevant risk factors in the Rafsanjan youth cohort population. This cross-sectional study was done on 3006 individuals from the 15-35-year-old population included in the Rafsanjan youth cohort study. The data were extracted from the youth cohort databases, which had been collected through in-person interview and standard questionnaires. Definition of general obesity was considered as body mass index ≤ 30 and that of central obesity as waist to hip ratio (WHR) ≥ 0.9 for men and ≥ 0.85 for women. Multivariate stepwise proportional odds model and multivariable stepwise logistic regression models were done to explore the factors associated with general obesity and central obesity. The mean age was 25.78 ± 6.06 years with 56% (n = 1683) female. The prevalence of general obesity was 15.80% (95% CI 14.50-17.11) and central obesity was 28.41% (95% CI 26.80-30.02). The risk of general obesity increased with increasing age (OR = 1.053, P < 0.0001), being married (OR = 1.658, P < 0.0001), history of diabetes (OR = 1.609, P = 0.0185), history of hypertension (OR = 1.609, P < 0.0001), elevated triglyceride (OR = 1.007, P < 0.0001) and LDL (OR = 1.015, P < 0.0001), while decreasing with being employed (OR = 0.748, P = 0.0002) and elevated HDL (OR = 0.975, P < 0.0001). Prevalence of obesity was high in study population. Marital status, increasing age, and history of chronic diseases were associated with obesity. Preventing programs should be developed against obesity and for promoting healthy habits in young adult especially during education at schools.

Metabolic syndrome and the likelihood of knee pain and functional disability: evidence from a large middle eastern population-based study

OBJECTIVES

Metabolic Syndrome (MetS) has been associated with knee osteoarthritis (KOA) in animal studies, but epidemiologic evidence of the association remains controversial. We investigated the association between MetS and knee pain and functional disability, the hallmarks of KOA, in a Middle Eastern population with high reported MetS rates.

METHODS

A population-based study of adult individuals was conducted between 01/2016 and 03/2019. Data collected included age, sex, blood pressure, body mass index (BMI), waist circumference (WC), and comprehensive metabolic panel blood tests. Knee symptoms were assessed using The Western Ontario and McMaster Arthritis index (WOMAC) The Adult Treatment Panel III criteria was applied to determine if participants had MetS. Multivariable regression was used to determine the association of MetS, and its components, with the WOMAC total and subscale scores.

RESULTS

Of 6,000 participants enrolled, 15.5% had MetS. The multivariate regression demonstrated that participants with MetS had significantly higher WOMAC total and subscale scores after adjusting for demographic variables; however, these associations were not significant after adjusting for BMI. Multivariate regression examining the association between MetS components and the WOMAC scores showed sex-based significant differences with WOMAC scores; however, the differences were not larger than the minimally clinical important differences.

CONCLUSIONS

This study demonstrated that after adjustment for BMI, neither MetS nor its individual parameters were associated with worse knee symptoms. As such, the association between MetS and worse knee symptoms requires further study.

Osteoarthritis and Diabetes: Where Are We and Where Should We Go?

Diabetes mellitus (DM) and osteoarthritis (OA) are chronic noncommunicable diseases that affect millions of people worldwide. OA and DM are prevalent worldwide and associated with chronic pain and disability. Evidence suggests that DM and OA coexist within the same population. The coexistence of DM in patients with OA has been linked to the development and progression of the disease. Furthermore, DM is associated with a greater degree of osteoarthritic pain. Numerous risk factors are common to both DM and OA. Age, sex, race, and metabolic diseases (e.g., obesity, hypertension, and dyslipidemia) have been identified as risk factors. These risk factors (demographics and metabolic disorder) are associated with DM or OA. Other possible factors may include sleep disorders and depression. Medications for metabolic syndromes might be related to the incidence and progression of OA, with conflicting results. Given the growing body of evidence indicating a relationship between DM and OA, it is vital to analyze, interpret, and integrate these findings. Therefore, the purpose of this review was to evaluate the evidence on the prevalence, relationship, pain, and risk factors of both DM and OA. The research was limited to knee, hip, and hand OA.

Excessive sulfur oxidation in endoplasmic reticulum drives an inflammatory reaction of chondrocytes in aging mice

Osteoarthritis, as a common joint disease among middle-aged and elderly people, has many problems, such as diverse pathogenesis, poor prognosis and high recurrence rate, which seriously affects patients’ physical and mental health and reduces their quality of life. At present, the pathogenesis of osteoarthritis is not completely clear, and the treatment plan is mainly to relieve symptoms and ensure basic quality of life. Therefore, it is particularly urgent to explore the pathogenesis of osteoarthritis. Protein, as organic macromolecule which plays a major role in life activities, plays an important role in the development of disease. Through protein omics, this study found that with the increase of age, excessive sulfur oxidation occurred in endoplasmic reticulum of chondrocytes, which then drove the occurrence of inflammatory reaction, and provided a direction for the follow-up molecular targeted.

Metabolic syndrome reduces spinal range of motion: The Yakumo study

BACKGROUND

Excess visceral fat can accumulate owing to lack of exercise. The relationship between metabolic syndrome (MetS) and spinal range of motion (ROM) is not clear. The purpose of this study was to investigate the relationship between MetS and spinal alignment and ROM.

METHODS

Orthopedic evaluation was prospectively performed in 544 participants. The participants were classified into two groups on the basis of the Japanese-specific MetS criteria proposed by the Japanese Committee of the Criteria for MetS (JCCMS). Lower back pain (LBP), knee joint pain with the visual analog scale (VAS), Kellgren-Lawrence (K-L) grade for knee osteoarthritis, body mass index (BMI), and spinal alignment and ROM were evaluated.

RESULTS

Forty-four (8.1%) were diagnosed as having MetS. The prevalence rate of K-L grade 4 in the MetS group was significantly higher than that in the non-MetS group (p < 0.05). When sex, age, and BMI were evaluated as covariates, there were significant differences in the VAS score for knee pain (non-MetS group vs MetS group: 13.7 vs 23.3, p < 0.05), L1-S1 flexion spinal ROM (44.1° vs 38.1°, p < 0.001), flexion spinal inclination angle (SIA) ROM (107.6° vs 99.3°, p < 0.01), and SIA ROM (135.4° vs 124.0°, p < 0.05).

CONCLUSIONS

Knee pain increased and flexion spinal ROM decreased significantly in the MetS group as compared with non-MetS group. Systemic factors associated with MetS may have a specific impact on spinal ROM while promoting knee osteoarthrosis and increased knee pain.

The Impact of Metabolic Syndrome on Quality of Life Among Individuals With Knee Osteoarthritis Living in Egypt

Background:

Several studies have linked metabolic syndrome (MetS) to osteoarthritis (OA), but they have not looked into how MetS can affect the health-related quality of life (HRQOL) of OA individuals.

Objectives:

We aimed to assess the association of MetS and its components, including obesity, hypertension, hyperglycemia, and dyslipidemia, with HRQOL among Egyptians with knee OA.

Methods:

This cross-sectional study comprised 116 adult Egyptian participants with knee OA. They were divided into 2 groups based on whether or not they had the MetS. All participants were subjected to a thorough medical history taking and a detailed medical examination. The Kellgren and Lawrence (K/L) scale evaluated OA in all individuals using anteroposterior knee radiographs. The Health Assessment Questionnaire-Disability Index (HAQ-DI) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used to assess participants’ HRQOL; their higher scores indicate more disability. Spearman rank and Pearson’s correlation analyses were used to assess the association between variables.

Results:

Diabetes, hypertension, dyslipidemia, and obesity were significantly associated with the OA + MetS group with a prevalence of 77.6%, 82.8%, 77.6%, and 50.0%, respectively. According to the K/L scale, 70.7% of the OA + MetS group had grade IV knee affection. The HAQ-DI and WOMAC scores were significantly (P < .001) higher among the OA + MetS individuals compared with the OA individuals. Interleukin (IL)-6 serum levels were also significantly higher in the OA + MetS group (P = .036) and increased significantly with the more serious radiological damage and functional disability. We found significant positive correlations between HAQ-DI and WOMAC with waist circumference (P = .004, .001), as well as triglycerides (P = .006, .008), cholesterol (P = .041, .048), fasting blood sugar (P < .001, < .001) and significant negative correlations with high-density lipoprotein levels (P = .628, .002).

Conclusions:

Individuals with knee OA with MetS showed more significant radiological damage, severe functional disability, and poor HRQOL. They also had higher levels of IL-6, which correlated significantly with the degree of disability, promoting it as a significant therapeutic target.

The role of oxidation of low-density lipids in pathogenesis of osteoarthritis: A narrative review

Osteoarthritis (OA) is a chronic joint disorder that causes degeneration of cartilage, synovial inflammation, and formation of osteophytes. Aging, obesity, and sex are considered the main risk factors of OA. Recent studies have suggested that metabolic syndrome (MetS) disorders, such as hypertension, hyperlipidemia, diabetes mellitus, and obesity, may be involved in the pathogenesis and progression of OA. MetS disorders are common diseases that also result in atherosclerosis. Researchers believe that OA and atherosclerosis have underlying similar molecular mechanisms because the prevalence of both diseases increases with age. Oxidation of low-density lipoprotein (ox-LDL) is believed to play a role in the pathogenesis of atherosclerosis. Recent reports have shown that ox-LDL and low-density lipoprotein receptor 1 (LOX-1) are involved in the pathogenesis of OA. The purpose of this narrative review is to summarize the current understanding of the role of the LOX-1/ox-LDL system in the pathogenesis of OA and to reveal common underlying molecular pathways that are shared by MetS in OA and the LOX-1/ox-LDL system.

Pathogenesis of Osteoarthritis: Risk Factors, Regulatory Pathways in Chondrocytes, and Experimental Models

As the most common chronic degenerative joint disease, osteoarthritis (OA) is the leading cause of pain and physical disability, affecting millions of people worldwide. Mainly characterized by articular cartilage degradation, osteophyte formation, subchondral bone remodeling, and synovial inflammation, OA is a heterogeneous disease that impacts all component tissues of the articular joint organ. Pathological changes, and thus symptoms, vary from person to person, underscoring the critical need of personalized therapies. However, there has only been limited progress towards the prevention and treatment of OA, and there are no approved effective disease-modifying osteoarthritis drugs (DMOADs). Conventional treatments, including non-steroidal anti-inflammatory drugs (NSAIDs) and physical therapy, are still the major remedies to manage the symptoms until the need for total joint replacement. In this review, we provide an update of the known OA risk factors and relevant mechanisms of action. In addition, given that the lack of biologically relevant models to recapitulate human OA pathogenesis represents one of the major roadblocks in developing DMOADs, we discuss current in vivo and in vitro experimental OA models, with special emphasis on recent development and application potential of human cell-derived microphysiological tissue chip platforms.

Metabolic Syndrome and Its Effects on Cartilage Degeneration vs Regeneration: A Pilot Study Using Osteoarthritis Biomarkers

BACKGROUND

Osteoarthritis (OA) of the knee is one of the leading causes of disability characterized by degeneration of hyaline cartilage combined with reparative processes. Its strong association with metabolic syndrome is postulated to be due to both mechanical and biochemical factors. Our study aims to study differential effect of metabolic risk factors on cartilage degeneration and regeneration at biomarker level.

DESIGN

After screening 281 patients presenting with knee pain, 41 patients who met the selection criteria were included and were divided into metabolic (MetS) OA and non-metabolic (Non-MetS) OA phenotypes using National Cholesterol Education Programme-Adult Treatment Panel-III (NCEP-ATP-III) criteria for metabolic syndrome. Serum Cartilage Oligomeric Matrix Protein (COMP) and Procollagen type IIA N terminal Propeptide (PIIANP) levels were used as tools to assess cartilage degeneration and regeneration, respectively.

RESULTS

22 among 41 patients (53.66%) had metabolic syndrome. Covariates like age, gender, Kellgren Lawrence (KL) grades were comparable in both groups. MetS-OA group showed significant increase in serum COMP levels (p = 0.03) with no significant effect on serum PIIANP levels (p = 0.46). Hypertriglyceridemia showed independent association with both cartilage anabolism (p = 0.03) and catabolism (p = 0.03).

CONCLUSION

Metabolic syndrome, though has no effect on cartilage regeneration tends to shift cartilage homeostasis towards degeneration with hypertriglyceridemia showing significant independent effect on cartilage metabolism.

Metabolic syndrome, hypertension, and hyperglycemia were positively associated with knee osteoarthritis, while dyslipidemia showed no association with knee osteoarthritis

OBJECTIVE

Metabolic syndrome (MetS) is a clustering of at least three of the following four medical conditions: obesity, hypertension, dyslipidemia, and hyperglycemia. We aimed to discover the relationships between these diseases and osteoarthritis (OA) of the knee.

METHODS

We searched four databases (EMBASE, PubMed, Cochrane Library, and MEDLINE), as well as articles on websites and conference materials. Study effect estimates and their 95% confidence intervals (CIs) were extracted and calculated. Sensitivity analyses were undertaken to determine inter-study heterogeneity. Finally, we tested for publication bias to determine whether the outcome of the meta-analysis was robust.

RESULTS

A total of 1609 articles were identified, 40 of which were included. In radiological studies, the relationships with OA were increased for people with the following diseases: metabolic syndrome (OR 1.418, 95% CI 1.162 to 1.730), hypertension (OR 1.701, 95% CI 1.411 to 2.052), and hyperglycemia (OR 1.225, 95% CI 1.054 to 1.424). In symptomatic studies, the outcomes were similar in metabolic syndrome (OR 1.174, 95% CI 1.034 to 1.332) and hypertension (OR 1.324, 95% CI 1.186 to 1.478) studies, while there were no associations in hyperglycemia (OR 0.975, 95% CI 0.860 to 1.106) studies. There was no correlation between dyslipidemia and OA, whether in radiological studies (OR 1.216, 95% CI 0.968 to 1.529) or symptomatic studies (OR 1.050, 95% CI 0.961 to 1.146).

CONCLUSIONS

In both studies, metabolic syndrome and hypertension were positively associated with knee OA, and dyslipidemia showed no correlations. Hyperglycemia was associated with OA in radiological studies, while results were reversed in symptomatic studies. Key Points • The hypothesis that metabolic syndrome and its components increase the risk for knee osteoarthritis is attractive; thus, this meta-analysis may help us find out the answer. • There were lots of large-scale studies here, and the total participants were considerable; and this meta-analysis was relatively robust because of reasonable heterogeneity and publication bias. • Targeted education and effective management of risk factors may be helpful for reducing the prevalence of knee osteoarthritis.

Predicting physical activity and cardiovascular risk and quality of life in adults with osteoarthritis at risk for metabolic syndrome: A test of the information-motivation-behavioral skills model

Aim

To examine a hypothetical model of physical activity and health outcomes (cardiovascular risk and quality of life) based on the information-motivation-behavioural skills model in adults.

Design

A cross-sectional survey.

Methods

A total of 165 adults with osteoarthritis at risk for metabolic syndrome were recruited between October 2016 and September 2017 from the outpatient clinic in South Korea. Data were collected on the model constructs such as cognitive function, social support, depressive symptoms, barriers to self-efficacy, physical activity and quality of life. A hypothetical model was tested using the AMOS 25.0 program.

Results

Cognitive function and barriers to self-efficacy had a direct effect on physical activity. Physical activity had a direct effect on cardiovascular risk, while social support and depressive symptoms had a direct effect on quality of life.

Conclusions

The information-motivation-behavioural skills model can predict physical activity and, in turn, cardiovascular risk and quality of life in adults with osteoarthritis at risk for metabolic syndrome.

The associations among RARRES2 rs17173608 gene polymorphism, serum chemerin, and non-traditional lipid profile in patients with metabolic syndrome

Background

The adipokine chemerin retinoic acid receptor responder protein 2 (RARRES2) has been associated with insulin resistance, type II diabetes mellitus (T2DM), obesity, and metabolic syndrome (MetS). The impact of RARRES2 rs17173608 gene polymorphism on MetS and chemerin levels is not completely elucidated. This study included 100 patients with MetS and 68 healthy subjects (non-MetS group). The RARRES2 rs17173608 gene variant was analyzed by tetra amplification refractory mutation system polymerase chain reaction (T-ARMS-PCR). Circulating chemerin levels were determined by ELISA. Serum urea, creatinine, fasting blood glucose, glycated hemoglobin, and traditional lipid profile were measured by colorimetric methods. The estimated glomerular filtration rate (eGFR) and non-traditional lipid parameters were calculated.

Results

Serum chemerin levels were significantly higher in MetS than in non-MetS subjects, type II diabetics (T2DM) than non-diabetics, and overweight compared to lean subjects, but it did not differ significantly between patients with and without hypertension. Strikingly, newly diagnosed diabetic patients had significantly higher serum chermerin levels. Correlation and multiple linear regression analysis showed that serum chemerin levels and non-traditional lipid parameters were correlated significantly with the clinical criteria of MetS. Genotyping and allelic frequency distribution of RARRES2 rs17173608 gene polymorphism showed its significant association with MetS. The TT genotype of RARRES2 rs17173608 SNP was more distributed in T2DM in comparison with non-diabetics, and it was associated significantly with higher serum chemerin and higher glycated hemoglobin levels. RARRES2 rs17173608 GG genotype and G allele frequency were less distributed in T2DM patients than in non-diabetic patients.

Conclusions

The RARRES2 rs17173608 SNP might have an impact on chemerin levels and lipid parameters. The GG genotype and G allele may have a protective role towards the risk of T2DM but not for MetS. Serum chemerin and non-traditional lipid profile are significantly associated with MetS.

An update on the association between metabolic syndrome and osteoarthritis and on the potential role of leptin in osteoarthritis

Metabolic syndrome (MetS) has been associated with osteoarthritis (OA). Leptin, which is one of the markers of MetS, has been associated with OA pathophysiology. This study aimed to provide an update on the association between MetS and OA and on the potential role of leptin in OA. In this review, we summarized the current knowledge of the association between MetS and OA and updated the evidence on the potential role of leptin in OA. Clinical studies have investigated the epidemiologic association between MetS or its components and OA. Results suggested strong epidemiologic associations between MetS and OA, especially in the Asian population. Animal studies also indicated that metabolic dysregulation may lead to OA pathogenesis. The systemic role of MetS in OA pathophysiology is associated with obesity-related inflammation, the beneficial role of n-3 polyunsaturated fatty acids and deleterious role of cholesterol, physical inactivity, hypertension-induced subchondral ischemia, dyslipidemia-induced ectopic lipid deposition in chondrocytes, hyperglycemia-induced local effects of oxidative stress and advanced glycation end-products, low-grade systemic inflammation, and obesity-related adipokines by inducing the expression of proinflammtory factors. Leptin levels in serum/plasma and synovial fluid were associated with joint pain, radiographic progression, bone formation biomarkers, cartilage volume, knee OA incidence, and total joint arthroplasty in OA patients. Elevated leptin expression and increased effect of leptin on infrapatellar fat pad, synovium, articular cartilage, and bone were also involved in the pathogenesis of OA. Current knowledge indicates a convincing epidemiologic association between MetS and OA, especially in the Asian population. Animal studies have also shown that metabolic dysregulation may lead to OA pathogenesis. Accumulating evidence suggests that leptin may play a potential role in OA pathogenesis. Therefore, leptin and its receptor may be an emerging target for intervention in metabolic-associated OA.

Dyslipidemia Might Be Associated with an Increased Risk of Osteoarthritis

Background

According to several studies, the autoimmune response may lead to osteoarthritis and dyslipidemia and may affect the homeostasis of the human body's internal environment and then cause its own immune regulation. Consequently, the risk of osteoarthritis might be increased by dyslipidemia, but this association is not universally acknowledged. Therefore, a systematic review and meta-analysis was conducted to study the relationship between dyslipidemia and the risk of osteoarthritis.

Methods

In this study, PubMed, EMBASE, and the ISI Web of Science were used to identify related studies published before July 2018. The relationship between dyslipidemia and the risk of osteoarthritis was evaluated on the basis of relative risk (RR) values and the corresponding 95% confidence intervals (CIs). To further investigate this relationship, we also employed the random effects model proposed by DerSimonian and Laird.

Results

A total of nine studies were included to study the effect of dyslipidemia on the risk of osteoarthritis, including four cohort, three case-control, and two cross-sectional studies. Among these studies, six stated data for knee osteoarthritis, two reported on hand osteoarthritis, and one reported on hip osteoarthritis. A total of 53,955 participants were included in the meta-analysis, comprising 22,501 patients with OA (19,733 hand OA, 2,679 knee OA, and 89 hip OA). Based on the meta-analysis of case-control and cross-sectional studies, osteoarthritis was clearly higher in those with dyslipidemia compared to those who did not suffer from dyslipidemia (case-control: OR = 1.37; 95%CI = 1.27–1.46; cross-sectional: OR = 1.33; 95%CI = 1.21-1.46). In addition, the meta-analysis of cohort studies did not present any relationship between dyslipidemia and OA (RR = 1.00; 95%CI = 0.85–1.14).

Conclusions

Even though our meta-analysis of case-control and cross-sectional studies suggested a strong relationship between dyslipidemia and osteoarthritis; this relationship was not validated by our meta-analysis of only cohort studies. As a result, further investigation needs to be conducted on the relationship between dyslipidemia and osteoarthritis, considering the significant public health relevance of the topic.

Cigarette smoking and knee osteoarthritis in the elderly: Data from the Korean National Health and Nutritional Examination Survey

BACKGROUND

The relationship between smoking and osteoarthritis (OA) has not been investigated in a large-scale study. The aim of this study was to examine the relationship between smoking and knee OA in the elderly.

METHODS

This study included 5117 subjects aged >60 years who responded to questionnaires on their history of smoking and knee OA diagnosed by a physician taken from the Korean National Health and Nutritional Examination Survey (KNHANES-VI) 2013-2015. We classified all 5117 subjects into 2 groups (the OA group and non-OA group) and compared the demographics and characteristics between the 2 groups. A multivariate logistic regression analysis was conducted to investigate the possible association between knee OA and smoking.

RESULTS

The prevalence of current smoking in the OA group (5.1%) was significantly lower than in the non-OA group (14.6%; p < 0.001). Furthermore, the proportion of moderate smokers who smoked >10 cigarettes per day or heavy smokers who smoked >20 cigarettes per day was significantly higher in the non-OA group. In the multivariate analysis, current smoking history was a preventative factor for the prevalence of OA in a multivariate model that included age, sex, body mass index, waist circumference (OR: 0.752, 95% CI: 0.571-0.989, p = 0.042).

CONCLUSIONS

This large-scale national study highlights an inverse association between smoking and the prevalence of knee OA in the general Korean elder adult population, primarily in males. Further investigation of this relationship between smoking and knee OA is needed to determine smoking's specific mechanism of protection against knee OA.

Metabolic syndrome and trajectory of knee pain in older adults

OBJECTIVES

To examine the association of metabolic syndrome (MetS) and its components with knee pain severity trajectories.

METHODS

Data from a population-based cohort study were utilised. Baseline blood pressure, glucose, triglycerides and high-density lipoprotein (HDL) cholesterol were measured. MetS was defined according to the National Cholesterol Education Program-Adult Treatment Panel III criteria. Radiographic knee osteoarthritis (ROA) was assessed by X-ray. Pain severity was measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain questionnaire at each time-point. Group-based trajectory modelling was used to identify pain trajectories and multi-nominal logistic regression was used for analysis. Mediation analysis was performed to assess whether body mass index (BMI)/central obesity mediated the association between MetS, its components and pain trajectories.

RESULTS

Among 985 participants (Mean ± SD age: 62.9 ± 7.4, 50% female), 32% had MetS and 60% had ROA. Three pain trajectories were identified: 'Minimal pain' (52%), 'Mild pain' (33%) and 'Moderate pain' (15%). After adjustment for potential confounders, central obesity increased risk of belonging to both 'Mild pain' and 'Moderate pain' trajectories as compared to the 'Minimal pain' trajectory group, but MetS [relative risk ratio (RRR): 2.26, 95%CI 1.50-3.39], hypertriglyceridemia (RRR: 1.75, 95%CI 1.16-2.62) and low HDL (RRR: 1.67, 95%CI 1.10-2.52) were only associated with 'Moderate pain' trajectory. BMI/central obesity explained 37-70% of these associations. Results were similar in those with ROA.

CONCLUSION

MetS and its components are predominantly associated with worse pain trajectories through central obesity, suggesting that the development and maintenance of worse pain trajectories may be caused by MetS.

Association between metabolic syndrome and knee structural change on MRI

Objective

To examine the association of metabolic syndrome (MetS) and its components with knee cartilage volume loss and bone marrow lesion (BML) change.

Methods

Longitudinal data on 435 participants from a population-based cohort study were analysed. Blood pressure, glucose, triglycerides and high-density lipoprotein (HDL) were collected. MetS was defined based on the National Cholesterol Education Program–Adult Treatment Panel III criteria. MRI of the right knee was performed to measure cartilage volume and BML. Radiographic knee OA was assessed by X-ray and graded using the Altman atlas for osteophytes and joint space narrowing.

Results

Thirty-two percent of participants had MetS and 60% had radiographic knee OA. In multivariable analysis, the following were independently associated with medial tibial cartilage volume loss: MetS, β = −0.30%; central obesity, β = −0.26%; and low HDL, β = −0.25% per annum. MetS, hypertriglyceridaemia and low HDL were also associated with higher risk of BML size increase in the medial compartment (MetS: relative risk 1.72, 95% CI 1.22, 2.43; hypertriglyceridaemia: relative risk 1.43, 95% CI 1.01, 2.02; low HDL: relative risk 1.67, 95% CI 1.18, 2.36). After further adjustment for central obesity or BMI, MetS and low HDL remained statistically significant for medial tibial cartilage volume loss and BML size increase. The number of components of MetS correlated with greater cartilage volume loss and BML size increase (both P for trend <0.05). There were no statistically significant associations in the lateral compartment.

Conclusion

MetS and low HDL are associated with medial compartment cartilage volume loss and BML size increase, suggesting that targeting these factors has the potential to prevent or slow knee structural change.