Serum uric acid and patterns of radiographic osteoarthritis--the Ulm Osteoarthritis Study

Crystal arthropathies and osteoarthritis-where is the link?

Osteoarthritis (OA) is one of the leading causes of disability worldwide. As our understanding of OA progressively has moved from a purely mechanical "wear and tear" concept toward a complex multi-tissue condition in which inflammation plays a central role, the possible role of crystal-induced inflammation in OA incidence and progression may be relevant. In addition to gout, which affects 4% of the US population, basic calcium phosphate and calcium pyrophosphate deposition both may induce joint inflammation and may play a role in pain in OA. This narrative review article discusses the possible mechanisms underlying the associations between crystal-induced arthropathies and OA, and the important implications of these for clinical practice and future research.

Hip and Knee Osteoarthritis in Patients with Chronic Myeloproliferative Neoplasms: A Cross-Sectional Study

BACKGROUND

Osteoarthritis (OA) is a progressive degenerative disease with an inflammatory background. Chronic myeloproliferative neoplasms (MPN) are clonal hematopoietic disorders characterized by chronic inflammation and a tendency for connective tissue remodeling.

AIM

This study aimed to investigate the prevalence and associated risk factors of symptomatic OA (sOA) in MPN patients.

PATIENTS AND METHODS

A total of 100 consecutive MPN (39 essential-thrombocythemia, 34 polycythemia-vera, 27 myelofibrosis) patients treated in two community hematologic centers were cross-sectionally evaluated. Patients were required to have both symptoms attributable to hip and/or knee OA and radiographic confirmation to be considered as having sOA.

RESULTS

The prevalence of hip and/or knee sOA was significantly higher among MPN patients than the previously reported prevalence in the general population of similar age (61% vs. 22%, p < 0.001). Hip sOA was present in 50%, knee sOA in 51% and sOA of both localizations in 41% of patients. A high proportion of MPN patients had radiographic signs of hip OA (94%) and knee OA (98%) in the presence of attributable symptoms. Among the other factors, sOA was univariately associated with the presence of JAK2 mutation, myelofibrosis phenotype, older age, higher body weight, and higher MPN-SAF score (p < 0.050 for all analyses). In the multivariate analysis, older age (odds ratio = 1.19, 95% confidence interval-CI 1.06-1.33) and higher body weight (OR = 1.15, 95% CI 1.06-1.25) were recognized as independent risk factors for sOA. On the other hand, cytoreductive treatment was a protective factor for sOA (OR = 0.07, 95% CI 0.006-0.86).

CONCLUSIONS

The prevalence of sOA in MPN patients was higher than that in the general population and seems to correlate with older age, increased myeloproliferation and a higher inflammatory state. Whether cytoreductive treatment may postpone OA development in MPN patients warrants additional confirmation.

Hyperuricemia and gout: effects on bone and articular cartilage (literature review)

Gout is a disease characterized by deposition of sodium monourate crystals in tissues which is the reason of inflammation among persons with hyperuricemia (HU). The prevalence of HU, which can be considered the first stage of gout formation, varies in different countries. Despite this, only a small number of persons with HU have been shown to develop symptoms of gout. Recent data suggest that HU is an independent risk factor for cartilage and bone damage. UA, both in the form of crystals and in a dissolved form, activates damage and potentiates cell death by releasing reactive oxygen species, activating the necroptosis pathway, neutrophil traps, synthesis of pro-inflammatory cytokines, and other pathogenetic mechanisms that cause the negative effects of HU and gout on articular cartilage and subchondral bone. The association of HU and osteoarthritis (OA) is well known and based on the common pathogenesis, but the direction of this relationship is still a debatable issue. The accumulated data suggest the need for a deeper study of the relationship of gout and asymptomatic HU with pathological processes leading to the development and progression of OA and disorders of bone metabolism.

Serum uric acid and knee osteoarthritis in community residents without gout: a longitudinal study

OBJECTIVES

Emerging evidence suggests a potential link between OA and gout; however, the association between serum uric acid (UA) itself and knee OA remains uncertain due to a lack of longitudinal studies. Here, we investigated the association between serum UA and knee OA according to cartilage status in elderly community residents without gout.

METHODS

In this longitudinal study, participants without a history of gout were recruited from among the Korean cohort of the Hallym Aging Study (n = 296 for radiography study and n = 223 for MRI study). Weight-bearing knee radiographs and 1.5-T MRI scans, along with blood collection for analysis of serum UA, were performed at baseline and after 3 years. The severity and structural progression of knee OA were evaluated using the Kellgren-Lawrence grading system and the Whole-Organ MRI Score (WORMS) cartilage scoring method. Multivariable logistic regression analysis was conducted using generalized estimating equation (GEE) models.

RESULTS

Serum UA levels were not associated with radiographic progression after adjusting for age, sex and BMI. There was no significant association between serum UA and tibiofemoral cartilage loss on MRI. However, baseline serum UA levels were negatively associated with patellofemoral cartilage loss over 3 years (adjusted odd ratio 0.70 per 1 mg/dl increase, 95% CI: 0.49, 0.98).

CONCLUSION

In this population-based cohort, serum UA was not a risk factor for knee OA progression. Further large-scale longitudinal studies in other populations are needed to validate the effects of UA on cartilage damage.

Association of serum uric acid with clinical and radiological severity of knee osteoarthritis in non-gouty patients

Background

A growing body of evidence suggested that uric acid (UA) may contribute in the pathways underlying osteoarthritis (OA) pathogenesis; however, studies that investigated the relationship between UA and OA emerged inconclusive results. The purpose of the study was to explore the association of serum uric acid (sUA) levels with clinical severity, radiological severity of knee osteoarthritis (KOA) based on Kellgren-Lawrence (KL) grading system, and MRI changes in non-gouty patients.

Results

WOMAC scores: pain, stiffness, function, and total score are significantly higher in H-sUA group than L-sUA group (p = 0.004, p = 0.019, p = 0.018, p = 0.008 respectively). Joint space width (JSW) is significantly narrower in H-sUA group than L-sUA group (p = 0.013). H-sUA group had more frequent KL grade 4 (p < 0.001), osteophytes grade 4 (p < 0.001), focal bone erosion (p < 0.001), bone marrow lesions (p = 0.023), and synovitis (p = 0.011) than L-sUA group. Female KOA patients in H-sUA group had significantly higher pain, stiffness, and function and total WOMAC scores than L-sUA group (p = 0.003, p = 0.015, p = 0.008, p = 0.004), more frequently had KL grade 4 and osteophytes grade 4 (p = 0.003, p < 0.001), significantly narrower JSW (p = 0.016), more frequently show focal bone erosion (p = 0.002), bone marrow lesions (p = 0.019), and synovitis (p = 0.004) than L-sUA group. In regression analysis, female sex (p = 0.035), duration of KOA (p = 0.031), and sUA level (p = 0.025) were associated with KL severity. For female patients with KOA, KL severity is associated with duration of KOA (p = 0.045) and sUA (p = 0.009).

Conclusion

Higher sUA level is associated with higher clinical severity, higher radiographic KL grades, and more frequent MRI findings in patients with primary KOA patients. Our results also indicated that sUA level was significantly associated with KOA severity in female patients, but not in male patients. More studies are warranted to explore whether the two conditions exist simultaneously or there is a direct causal relationship between the two conditions.

Elevation of Urate in Saliva and Serum of Patients with Knee Osteoarthritis

BACKGROUND

Knee osteoarthritis (knee OA) is the most common joint disease and the leading cause of disability and has a considerable financial burden on the healthcare system.

OBJECTIVE

The aim of the present study was to evaluate urate in saliva and serum of knee OA.

METHODS

Serum and saliva urate levels of 30 knee OA and 30 healthy controls were evaluated in a cross-sectional study. Data were analysed by Student's t test, Pearson correlation test, and receiver operating characteristic.

RESULTS

The mean serum and both stimulated and unstimulated saliva urate levels were higher in the knee OA than that of the healthy group. WOMAC score positively correlated with serum (r = 0.485; p = 0.004), unstimulated saliva (r = 0.575; p = 0.001) and stimulated saliva (r = 0.453; p = 0.009) levels of urate. The serum level of urate significantly correlated with unstimulated (r = 0.442; p < 0.001) and stimulated (r = 0.563; p < 0.001) saliva urate levels. Serum and saliva urate had significant cutoff values (6.4, 4.9, and 3.3 mg/dL in serum, stimulated, and unstimulated saliva, respectively).

CONCLUSION

In this study, urate in serum and saliva was increased in patients with knee OA and positively correlated with WOMAC.

Relationship between cardiac biomarker concentrations and long-term mortality in subjects with osteoarthritis

Osteoarthritis (OA) is associated with adverse cardio-metabolic features. N-terminal pro-B-type natriuretic peptide (NT-proBNP) and high-sensitivity troponins T and I (hs-cTnT and hs-cTnI) are well-characterized cardiac markers and provide prognostic information. The objective was to assess the association of cardiac biomarker concentrations with long-term mortality in subjects with OA. In a cohort of 679 OA subjects, undergoing hip or knee replacement during 1995/1996, cardiac biomarkers were measured and subjects were followed over 20 years. During a median follow-up of 18.4 years, 332 (48.9%) subjects died. Median of hs-cTnT, hs-cTnI, and NT-proBNP at baseline was 3.2 ng/L, 3.9 ng/L, and 96.8 ng/L. The top quartile of NT-proBNP was associated with increased risk of mortality (Hazard Ratio (HR) 1.79, 95% confidence interval (CI) 1.17–2.73) after adjustment for covariates including troponins (hs-cTnT HR 1.30 (95% CI 0.90–1.89), hs-cTnI HR 1.32 (95% CI 0.87–2.00) for top category). When biomarker associations were evaluated as continuous variables, only NT-proBNP (HR per log-unit increment 1.34, 95% CI 1.16–1.54) and hs-cTnI (HR 1.38, 95% CI 1.11–1.72) showed robust results. Elevated cardiac biomarker concentrations predicted an increased risk of long-term mortality and strongest for NT-proBNP and hs-cTnI. These results might help to identify subjects at risk and target preventive efforts early.

Five years' trajectories of functionality and pain in patients after hip or knee replacement and association with long-term patient survival

To describe the 5 years’ trajectories in functionality and pain of patients with hip or knee osteoarthritis and arthroplasty and analyze the association of these with long-term patients survival. Patients with OA receiving total hip or knee arthroplasty were recruited and completed two sets of standardized questionnaires for functionality and pain 6, 12, and 60 months postoperatively. Multivariate mixed models were conducted to assess trajectories over time and the resulting improvement per month during the last time period was included in a landmark-model to estimate adjusted hazard ratios for mortality. In total 809 patients with joint replacement were included (mean age 65.0 years, 62.2% female), 407 patients died (median follow-up 18.4 years). Both instruments of functionality and pain showed extensive improvement during the first 6 months. Baseline and change in functionality (both p < 0.001) and pain (p = 0.02) during the first 6 months were associated with mortality. Better values in functionality corresponded with improved survival whereas the association with the pain scores was inverse. In patients with hip and knee OA, an explicit improvement in function is seen within the first 6 months after arthroplasty. In addition, especially the functionality scores at baseline as well as their improvement showed an association with long-term patient survival.

Serum Cartilage Oligomeric Matrix Protein in Late-Stage Osteoarthritis: Association with Clinical Features, Renal Function, and Cardiovascular Biomarkers

This study aimed to assess associations between serum cartilage oligomeric matrix protein (sCOMP) and phenotypic characteristics in late-stage hip and knee Osteoarthritis (OA) as well as its correlation with further serum markers of possible comorbidities in the Ulm Osteoarthritis Study. Moreover, the prognostic relevance of preoperative sCOMP concentrations for short-term functionality and pain outcomes after hip or knee joint replacement was explored. Preoperative serum samples and detailed information about the health status (i.e., WOMAC scores, Hannover Functionality Status (FFbH)) of 754 OA patients undergoing total joint replacement were included. Spearman rank-correlation coefficients and multiple linear regression models were used to evaluate the relationships between sCOMP, other serum markers, and health outcomes. There was a significant positive association between sCOMP and markers of renal (cystatin C, creatinine, and eGFR) and cardiac (e.g., NT-proBNP) impairment. Since renal failure might cause accumulation of sCOMP, additional adjustment with eGFR was performed. Preoperative sCOMP levels in knee OA but not hip OA patients were positively associated with FFbH, WOMAC function sub-scale and total WOMAC scale as well as the post-operative WOMAC stiffness sub-scale six months after surgery. Our data clearly demonstrate an association between sCOMP and renal function as well as other confounding factors, which should be considered in future biomarker studies.

The association between serum uric acid level and changes of MRI findings in knee osteoarthritis: A retrospective study (A STROBE-compliant article)

The objective of this study was to examine whether Magnetic resonance imaging (MRI) features of knee osteoarthritis (OA) had an association with the level of serum uric acid (SUA). The MRI of the OA patients from June 2015 to July 2017 were studied. The patients fulfilled the following inclusion criteria: 1) meet American College of Rheumatology (ACR) radiological and clinical criteria for OA of the knee, 2) age ≤ 65years old, 3) Body mass index (BMI) < 25 kg/m. Patients with OA were categorized into two groups based on the level of SUA. Patients with SUA level lower than 360 umol/L were recruited into the first group and the others were the second group. Odds ratios (OR) and 95% confidence intervals (CI) for SUA level and different MRI patterns were estimated with multivariable logistic regression.71 patients were included in this research. The mean age of the first group was 54.5 ± 8.4 and the second group was 55.6 ± 6.4. The Body Mass Index (BMI) of two groups was 22.7 ± 1.3 and 23.23 ± 1.9 separately. The mean SUA and creatinine (CR) level of the second group were 433.8 ± 70.6 umol/L and 80.1 ± 23.9 umol/L. There were statistically more focal erosions, osteophytes, bone marrow lesions and synovitis in the MRIs of the second group. A positive association between SUA level and synovitis as well as soft tissue swelling in MRIs was observed in patients with knee OA (OR = 1.017; 1.008, 95% CI: 1.007-1.028; 1.000-1.016). In conclusion, subjects with higher SUA level were more likely to have MRI abnormalities. OA patients need to lower their SUA level in order to keep the disease from progressing.

Effects of ChondroT on potassium Oxonate-induced Hyperuricemic mice: downregulation of xanthine oxidase and urate transporter 1

Background

ChondroT, a new herbal medication, consists of the water extracts of Osterici Radix, Lonicerae Folium, Angelicae Gigantis Radix, Clematidis Radix, and Phellodendri Cortex (6:4:4:4:3). We previously reported that ChondroT showed significant anti-arthritis and anti-inflammatory effects.

Methods

This study was designed to evaluate the effect of ChondroT on hyperuricemia. First, the effect of ChondroT was evaluated on xanthine oxidase (XOD) activity in vitro. The anti-hyperuricemic effect of ChondroT was also studied in potassium oxonate (PO)-induced hyperuricemic model mice. Uric acid (UA) and XOD were evaluated in the serum, urine, and liver of the mice. In addition, we measured serum creatinine (Cr) and blood urea nitrogen (BUN) levels as well as mRNA expression of the mouse urate transporter 1 (mURAT1) to evaluate kidney function and urate excretion in hyperuricemic mice.

Results

ChondroT showed in vitro XOD inhibitory activity in a dose-dependent manner (P < 0.05). We demonstrated that ChondroT (37.5, 75 and 150 mg/kg) significantly reduced serum UA (P < 0.01 and P < 0.001, respectively), and upregulated urinary UA (P < 0.001, respectively) in PO-induced hyperuricemic mice. In addition, ChondroT (75 and 150 mg/kg) significantly reduced Cr (P < 0.05 and P < 0.01, respectively), BUN (P < 0.05 and P < 0.001, respectively), GOT (P < 0.05 and P < 0.01, respectively), and GPT (P > 0.05 and P < 0.05, respectively) levels in PO-induced hyperuricemic mice. ChondroT (75 and 150 mg/kg) also significantly downregulated serum (P < 0.05) and liver (P < 0.05) XOD activity. Compared to the hyperuricemic mice, the ChondroT (37.5, 75, and 150 mg/kg)-treated mice showed decreased mURAT1 protein expression level.

Conclusion

ChondroT displayed anti-hyperuricemic effects by regulating XOD activity and kidney mURAT1.

Proteoglycans isolated from the bramble shark cartilage show potential anti-osteoarthritic properties

Osteoarthritis (OA) causes articular cartilage destruction, initiating pain and inflammation in the joints, resulting in joint disability. Medications are available to manage these symptoms; however, their effects on the disease progression are limited. Loss of proteoglycans (PGs) was reported to contribute articular cartilage destruction in OA. Therapeutics approaches were previously studied in the animal models of OA. In the present study, we investigated the oral efficacy of four dosages of PGs (25 mg/kg, 50 mg/kg, 100 mg/kg and 200 mg/kg), isolated from the bramble shark cartilage, in an animal model of OA. Indomethacin was used as a bioequivalent formulation. Primarily, the mass spectrum analysis of the purified PGs obtained from bramble shark cartilage revealed the presence of two unique peptides including AGWLSDGSVR and LDGNPINLSK, that showed sequence similarity with aggrecan core-protein and epiphycan, respectively. The levels of C-reactive protein and uric acid in the OA rats were reduced when treated with PGs. Histopathology analysis displayed less cartilage erosion and neovascularization in OA rats treated with PGs. The X-ray imaging presented higher bone density with 200 mg/kg dosage of PG treatment in OA rats. The expressions of the inflammatory modulators including TNF-α, IL-1β, MMP13, NOS2, IL-10 and COX-2 were found to be moderated with PG treatment. In addition, PG treatment maintained the activities of antioxidant enzymes, including SOD and catalase in the joint tissues with a higher GSH content, in a dose-dependent manner. Taken together, our preliminary findings report the anti-osteoarthritic properties of PGs and recommend to evaluate its efficacy and safety in randomized trials.

Osteoarthritis-patterns, cardio-metabolic risk factors and risk of all-cause mortality: 20 years follow-up in patients after hip or knee replacement

Osteoarthritis (OA) is a common musculoskeletal disorder and occur in different patterns. However, its impact on long-term all-cause-mortality is inconclusive. Study aims: Investigate 20-year all-cause-mortality in patients with hip/knee arthroplasty (recruited 1995/1996, N = 809) from the Ulm Osteoarthritis Study-cohort, in comparison to general population. Furthermore, to enlighten the triangle between baseline life-style and cardio-metabolic risk factors, phenotypic OA-patterns (laterality, generalization, cause) and all-cause-mortality. Mortality was assessed during 20 years follow-up. Standardized mortality ratios (SMR), adjusted odds ratios and hazard ratios (aHR) were calculated. After five years cohort-mortality was reduced compared to the general population, however 20 years later assimilated (SMR = 1.11; 95%-CI 0.73-1.49). OA-patterns were associated with age, cholesterol, and overweight/obesity. In comparison to primary OA decreased mortality was observed for patients with secondary OA (aHR = 0.76; 95%-CI 0.61-0.95) adjusted for age, smoking, overweight/obesity, diabetes, hypertension, cardiac insufficiency, uric acid, and lower cholesterol. There was no increased mortality in patients after 20 years follow-up compared to general population. Significantly decreased mortality in secondary compared to primary OA suggests a subtype-specific involvement of systemic co-factors in determination of all-cause-mortality. Because cardio-metabolic risk factors were associated with increased risk of bilateral OA and lower long-term survival, those risk factors should be consequently targeted in OA-patients.

Exploring the Link between Uric Acid and Osteoarthritis

Both gout and osteoarthritis (OA) are common forms of arthritis that inflict a huge burden to an aging population with the increasing prevalence of obesity. Clinicians have long observed the link between these two conditions. In this review, we summarize the evidence from epidemiologic and immunological studies that described the possible relationship between the two conditions. The recent new understanding on monosodium uric acid crystal-induced inflammation has given insight into probable shared pathogenesis pathways for both conditions. We describe the potential therapeutic implications, particularly regarding the possibility of repurposing traditional gout medications for use in OA.

Gout and Osteoarthritis: Associations, Pathophysiology, and Therapeutic Implications

Osteoarthritis (OA), the most common type of arthritis worldwide, is a degenerative disease of diarthrodial joints resulting in pain, reduced quality of life, and socioeconomic burden. Gout, the most common form of inflammatory arthritis, is a consequence of persistently elevated levels of urate and the formation of proinflammatory monosodium urate crystals in joints. Clinicians have long noted a predilection for both diseases to occur in the same joints. In this review, we provide an overview into research elucidating possible biochemical, mechanical, and immunological relationships between gout and OA. We additionally consider the potential implications of these relationships for OA treatment.

Presence of gout is associated with increased prevalence and severity of knee osteoarthritis among older men: results of a pilot study

BACKGROUND

Gout and osteoarthritis (OA) are the most prevalent arthritides, but their relationship is neither well established nor well understood.

OBJECTIVES

We assessed whether a diagnosis of gout or asymptomatic hyperuricemia (AH) is associated with increased prevalence/severity of knee OA.

METHODS

One hundred nineteen male patients aged 55 to 85 years were sequentially enrolled from the primary care clinics of an urban Veterans Affairs hospital, assessed and categorized into 3 groups: gout (American College of Rheumatology Classification Criteria), AH (serum urate ≥6.8 mg/dL, no gout), and control (serum urate <6.8 mg/dL, no gout). Twenty-five patients from each group subsequently underwent formal assessment of knee OA presence and severity (American College of Rheumatology Clinical/Radiographic Criteria, Kellgren-Lawrence grade). Musculoskeletal ultrasound was used to detect monosodium urate deposition at the knees and first metatarsophalangeal joints.

RESULTS

The study showed 68.0% of gout, 52.0% of AH, and 28.0% of age-matched control subjects had knee OA (gout vs control, P = 0.017). Odds ratio for knee OA in gout versus control subjects was 5.46 prior to and 3.80 after adjusting for body mass index. Gout subjects also had higher Kellgren-Lawrence grades than did the control subjects (P = 0.001). Subjects with sonographically detected monosodium urate crystal deposition on cartilage were more likely to have OA than those without (60.0 vs 27.5%, P = 0.037), with crystal deposition at the first metatarsophalangeal joints correlating most closely with OA knee involvement.

CONCLUSIONS

Knee OA was more prevalent in gout patients versus control subjects and intermediate in AH. Knee OA was more severe in gout patients versus control subjects.

The associations of serum uric acid level and hyperuricemia with knee osteoarthritis

To examine the cross-sectional associations of the serum uric acid level and hyperuricemia (HU) with the radiographic features of osteoarthritis (OA), including osteophytes (OST) and joint space narrowing (JSN), a total of 4685 subjects were included in this study. Blood samples were drawn from all subjects. Serum uric acid and some other indexes were detected. OST and JSN were assessed for each subject according to the Osteoarthritis Research Society International (OARSI) atlas. A multivariable logistic analysis model was applied to test the target associations after adjusting a number of potential confounding factors. The prevalence of OST was increased in the highest tertile of uric acid compared to the lowest in female subjects (OR 1.46, 95 % CI 1.07-1.99, P for trend = 0.02). Meanwhile, a positive association between OST and HU was observed in female subjects (OR 1.43, 95 % CI 1.01-2.03, P = 0.05). However, serum uric acid and HU were not significantly associated with JSN in male subjects. The findings of this study indicated that the serum uric acid concentration and prevalence of HU are positively associated with OST of the knee in the female population. Level of evidence Cross-sectional study, Level III.

Colchicine--Update on mechanisms of action and therapeutic uses

OBJECTIVES

To review the literature and provide an update on the mechanisms of action and therapeutic uses of oral colchicine in arthritis and inflammatory conditions.

METHODS

We performed PubMed database searches through June 2014 for relevant studies in the English literature published since the last update of colchicine in 2008. Searches encompassed colchicine mechanisms of action and clinical applications in medical conditions. A total of 381 articles were reviewed.

RESULTS

The primary mechanism of action of colchicine is tubulin disruption. This leads to subsequent down regulation of multiple inflammatory pathways and modulation of innate immunity. Newly described mechanisms include various inhibitory effects on macrophages including the inhibition of the NACHT-LRRPYD-containing protein 3 (NALP3) inflammasome, inhibition of pore formation activated by purinergic receptors P2X7 and P2X2, and stimulation of dendritic cell maturation and antigen presentation. Colchicine also has anti-fibrotic activities and various effects on endothelial function. The therapeutic use of colchicine has extended beyond gouty arthritis and familial Mediterranean fever, to osteoarthritis, pericarditis, and atherosclerosis.

CONCLUSION

Further understanding of the mechanisms of action underlying the therapeutic efficacy of colchicine will lead to its potential use in a variety of conditions.

"Generalized osteoarthritis": a systematic review

OBJECTIVES

Given the conflicting definitions of "generalized osteoarthritis" (GOA) in the literature, we performed a systematic review of GOA definitions, risk factors, and outcomes.

METHODS

We searched the MEDLINE literature with the terms osteoarthritis, generalized, polyarticular, multiple joint, and multi-joint to obtain articles related to GOA, following evidence-based guidelines. Titles and abstracts of 948 articles were reviewed, with full-text review of 108. Data were extracted based on pre-specified criteria for 74 articles plus 24 identified through bibliographic review (n = 98).

RESULTS

Twenty-four large cohorts (n ~ 30,000) were represented along with numerous clinical series (n ~ 9000), across 22 countries and 60 years (1952-2012). No less than 15 definitions of GOA were given in 30 studies with a stated GOA definition; at least 6 groups used a summed score of joints or radiographic grades. Prevalence estimates based on these GOA definitions were 1-80%, although most were 5-25%. Increased risk and progression of GOA was associated with age, female sex, and genetic/familial factors. Associations with increased body mass index or bone mineral density were not consistent. A study estimated the heritability of GOA at 42%. Collagen biomarker levels increased with the number of involved joints. Increased OA burden was associated with increased mortality and disability, poorer health, and function.

CONCLUSION

While there remains no standard definition of GOA, this term is commonly used. The impact on health may be greater when OA is in more than one joint. A descriptive term, such as multi-joint or polyarticular OA, designating OA of multiple joints or joint groups is recommended.

Review of hyperuricemia as new marker for metabolic syndrome

Hyperuricemia has long been established as the major etiologic factor in gout. In recent years, a large body of evidence has accumulated that suggests that hyperuricemia may play a role in the development and pathogenesis of a number of metabolic, hemodynamic, and systemic pathologic diseases, including metabolic syndrome, hypertension, stroke, and atherosclerosis. A number of epidemiologic studies have linked hyperuricemia with each of these disorders. In some studies, therapies that lower uric acid may prevent or improve certain components of the metabolic syndrome. There is an association between uric acid and the development of systemic lupus erythematosus; the connection between other rheumatic diseases such as rheumatoid arthritis and osteoarthritis is less clear. The mechanism for the role of uric acid in disorders other than gout is not well established but recent investigations point towards systemic inflammation induced by urate, as the major pathophysiological event common to systemic diseases, including atherosclerosis.

Epidemiological evidence for work load as a risk factor for osteoarthritis of the hip: a systematic review

Objective

Osteoarthritis of the hip (OA) is a common degenerative disorder of the joint cartilage that presents a major public health problem worldwide. While intrinsic risk factors (e.g, body mass and morphology) have been identified, external risk factors are not well understood. In this systematic review, the evidence for workload as a risk factor for hip OA is summarized and used to derive recommendations for prevention and further research.

Methods

Epidemiological studies on workload or occupation and osteoarthritis of the hip were identified through database and bibliography searches. Using pre-defined quality criteria, 30 studies were selected for critical evaluation; six of these provided quantitative exposure data.

Results

Study results were too heterogeneous to develop pooled risk estimates by specific work activities. The weight of evidence favors a graded association between long-term exposure to heavy lifting and risk of hip OA. Long-term exposure to standing at work might also increase the risk of hip OA.

Conclusions

It is not possible to estimate a quantitative dose-response relationship between workload and hip OA using existing data, but there is enough evidence available to identify job-related heavy lifting and standing as hazards, and thus to begin developing recommendations for preventing hip OA by limiting the amount and duration of these activities. Future research to identify specific risk factors for work-related hip OA should focus on implementing rigorous study methods with quantitative exposure measures and objective diagnostic criteria.

Uric acid is a danger signal of increasing risk for osteoarthritis through inflammasome activation

Uric acid (UA) is known to activate the NLRP3 (Nacht, leucine-rich repeat and pyrin domain containing protein 3) inflammasome. When activated, the NLRP3 (also known as NALP3) inflammasome leads to the production of IL-18 and IL-1β. In this cohort of subjects with knee osteoarthritis (OA), synovial fluid uric acid was strongly correlated with synovial fluid IL-18 and IL-1β. Synovial fluid uric acid and IL-18 were strongly and positively associated with OA severity as measured by both radiograph and bone scintigraphy, and synovial fluid IL-1β was associated with OA severity but only by radiograph. Furthermore, synovial fluid IL-18 was associated with a 3-y change in OA severity, on the basis of the radiograph. We conclude that synovial fluid uric acid is a marker of knee OA severity. The correlation of synovial fluid uric acid with the two cytokines (IL-18 and IL-1β) known to be produced by uric acid-activated inflammasomes and the association of synovial fluid IL-18 with OA progression, lend strong support to the potential involvement of the innate immune system in OA pathology and OA progression.

The role of uric acid and other crystals in osteoarthritis

Clinicians have long assumed that an association exists between crystal arthropathies and the presence of osteoarthritis (OA). However, studies establishing an independent association between calcium pyrophosphate or uric acid crystal disease and OA are sparse. Even less is known about a possible pathogenic relationship. Whereas some studies suggest that the relationships between crystals and OA may not be incidental and that crystal deposition may contribute to the onset and/or acceleration of OA joint damage, other authors have challenged this assertion. In this review, we provide an overview of past and current research elucidating the role of crystal deposition, including monosodium urate, calcium pyrophosphate, and other crystals, in OA. Given the clinical frequency of gout and that agents exist to modulate serum UA levels, special attention is given to the role of monosodium urate crystals.

Übergewicht und Arthrose

An increasing prevalence and incidence of osteoarthritis especially in aging populations results in different socioeconomic problems. Recent studies have shown an association between osteoarthritis and overweight especially for knee and hip joints. The mechanisms responsible for the destruction of joints are still unknown, however. Obesity and overweight can lead to higher force transmission on joints at least in lower extremities, but mechanical factors hardly explain the association between overweight and hand osteoarthritis shown in different studies. There may be additional metabolic effects responsible for cartilage destruction, but distinct mechanisms have not been demonstrated up to now. They would, however, support preventive measures as well as therapeutic approaches.