Does smoking protect against osteoarthritis?

Lifestyle behaviour changes associated with osteoarthritis: a prospective cohort study

The aim of this prospective cohort study was to compare changes in lifestyle behaviours over nine years in women who were and were not diagnosed with osteoarthritis (OA). Data were from the 1945-51 cohort of the Australian Longitudinal Study on Women's Health (aged 50-55 in 2001) who completed written surveys in 2001, 2004, 2007 and 2010. The sample included 610 women who were, and 3810 women who were not diagnosed with OA between 2004 and 2007. Descriptive statistics were used to assess changes in lifestyle behaviours (weight, sitting time, physical activity, alcohol and smoking) in the two groups, over three survey intervals: from 2001-2004 (prior to diagnosis); from 2004-2007 (around diagnosis); and from 2007-2010 (following diagnosis). Compared with women without OA (28%), a greater proportion of women with OA (38%) made at least one positive lifestyle change (p < 0.001). These included losing > 5 kg (9.8% vs. 14.4%, p < 0.001), and reducing sitting time by an hour (29.5% vs. 39.1%, p < 0.001) following diagnosis. However, women with OA also made negative lifestyle changes (35% vs. 29%, p < 0.001), for example, gaining > 5 kg around the time of diagnosis (21.4% vs. 14.5%, p < 0.001) and increasing sitting time by an hour following diagnosis (38.4% vs. 32.3%, p = 0.003). More women with OA also started smoking following diagnosis (8.9% vs. 0.8%, p < 0.001). While some women made positive changes in lifestyle behaviours during and following OA diagnosis, others made negative changes. Consistent support from clinicians for managing OA symptoms may enable patients to make more positive changes in lifestyle behaviours.

Association of smoking with cartilage loss of knee osteoarthritis: data from two longitudinal cohorts

BACKGROUND

Previous studies have been inconsistent concerning the association between smoking and risk of osteoarthritis (OA). This study aimed to explore the associations of smoking status and change in cartilage volume of OA in two longitudinal cohorts.

METHODS

Subjects from the Osteoarthritis Initiative cohort (OAI, n = 593) and the Tasmanian Older Adult Cohort (TASOAC, n = 394) were included in this study. For both cohorts, participants were classified into three groups based on their smoking status, namely 'never', 'former', and 'current' smokers. The outcome measures were the annual rate of change of tibiofemoral cartilage volume over 2 years in OAI and of tibial cartilage volume over 2.6 years in TASOAC. Potential confounders were balanced using the inverse probability of treatment weighting (IPTW) method.

RESULTS

Overall, 42.3% and 37.4% of participants were former smokers, and 5.7% and 9.3% were current smokers in the OAI and TASOAC cohorts, respectively. Compared to never smokers, neither former nor current smoking was associated with risk of the annual rate of change of tibiofemoral cartilage volume in OAI (former smoker: β=-0.068%/year, 95% confidence interval [CI] -0.824 to 0.688, p = 0.860; current smoker: β=-0.222%/year, 95% CI -0.565 to 0.120, p = 0.204) and tibial cartilage volume in TASOAC (former smoker: β = 0.001%/year, 95% CI -0.986 to 0.989, p = 0.998; current smoker: β=-0.839%/year, 95% CI -2.520 to 0.844, p = 0.329).

CONCLUSIONS

Our findings from two independent cohorts consistently showed that smoking was not associated with knee cartilage loss in older adults.

The associations of implant and patient factors with migration of the tibial component differ by sex : a radiostereometric study on more than 400 total knee arthroplasties

AIMS

Thresholds of acceptable early migration of the components in total knee arthroplasty (TKA) have traditionally ignored the effects of patient and implant factors that may influence migration. The aim of this study was to determine which of these factors are associated with overall longitudinal migration of well-fixed tibial components following TKA.

METHODS

Radiostereometric analysis (RSA) data over a two-year period were available for 419 successful primary TKAs (267 cemented and 152 uncemented in 257 female and 162 male patients). Longitudinal analysis of data using marginal models was performed to examine the associations of patient factors (age, sex, BMI, smoking status) and implant factors (cemented or uncemented, the size of the implant) with maximum total point motion (MTPM) migration. Analyses were also performed on subgroups based on sex and fixation.

RESULTS

In the overall group, only fixation was significantly associated with migration (p < 0.001). For uncemented tibial components in males, smoking was significantly associated with lower migration (p = 0.030) and BMI approached significance (p = 0.061). For females with uncemented components, smoking (p = 0.081) and age (p = 0.063) approached significance and were both associated with increased migration. The small number of self-reported smokers in this study warrants cautious interpretation and further investigation. For cemented components in females, larger sizes of tibial component were significantly associated with increased migration (p = 0.004). No factors were significant for cemented components in males.

CONCLUSION

The migration of uncemented tibial components was more sensitive to patient factors than cemented implants. These differences were not consistent by sex, suggesting that it may be of value to evaluate female and male patients separately following TKA. Cite this article: Bone Joint J 2022;104-B(4):444-451.

Does smoking cessation increase risk of knee replacement? a general population-based cohort study

OBJECTIVE

Smoking represents a major issue for global public health. Owing to methodologic challenges, findings of an association between smoking and risk of knee osteoarthritis (OA) are inconsistent. We sought to assess the relation of onset of smoking cessation to the risk of OA sequelae, i.e., knee replacement, and to perform sub-cohort analysis according to weight change after smoking cessation.

DESIGN

Using The Health Improvement Network, we conducted a cohort study to examine the association between smoking cessation and risk of knee replacement among patients with knee OA. Participants who stopped smoking were further grouped into three sub-cohorts: weight gain (body mass index [BMI] increased>1.14 kg/m²), no substantial weight change (absolute value of BMI change<1.14 kg/m²), and weight loss (BMI loss>1.14 kg/m²) after smoking cessation.

RESULTS

We identified 108 cases of knee replacement among 1,054 recent quitters (26.7/1,000 person-years) and 1,108 cases among 15,765 current smokers (17.4/1,000 person-years). The rate difference of knee replacement in recent quitter cohort vs current smoker cohort was 10.4 (95% confidence interval [CI]:5.3-15.6)/1,000 person-years and the adjusted hazard ratio (HR) was 1.30 (95%CI:1.05-1.59). Compared with current smokers, risk of knee replacement was higher among quitters with weight gain (HR = 1.42,95%CI:1.01-1.98), but not among those with no substantial weight change (HR = 1.29,95%CI:0.90-1.83) or those with weight loss (HR = 1.11,95%CI:0.71-1.75).

CONCLUSIONS

Our large population-based cohort study provides the first evidence that smoking cessation was associated with a higher risk of knee replacement among individuals with knee OA, and such an association was due to weight gain after smoking cessation.

Towards sex-specific osteoarthritis risk models: evaluation of risk factors for knee osteoarthritis in males and females

Objectives

The aim of this study was to identify sex-specific prevalence and strength of risk factors for the incidence of radiographic knee OA (incRKOA).

Methods

Our study population consisted of 10 958 Rotterdam Study participants free of knee OA in one or both knees at baseline. One thousand and sixty-four participants developed RKOA after a median follow-up time of 9.6 years. We estimated the association between each available risk factor and incRKOA using sex stratified multivariate regression models with generalized estimating equations. Subsequently, we statistically tested sex differences between risk estimates and calculated the population attributable fractions (PAFs) for modifiable risk factors.

Results

The prevalence of the investigated risk factors was, in general, higher in women compared with men, except that alcohol intake and smoking were higher in men and high BMI showed equal prevalence. We found significantly different risk estimates between men and women: high level of physical activity [relative risk (RR) 1.76 (95% CI: 1.29–2.40)] or a Kellgren and Lawrence score 1 at baseline [RR 5.48 (95% CI: 4.51–6.65)] was higher in men. Among borderline significantly different risk estimates was BMI ≥27, associated with higher risk for incRKOA in women [RR 2.00 (95% CI: 1.74–2.31)]. The PAF for higher BMI was 25.6% in women and 19.3% in men.

Conclusion

We found sex-specific differences in both presence and relative risk of several risk factors for incRKOA. Especially BMI, a modifiable risk factor, impacts women more strongly than men. These risk factors can be used in the development of personalized prevention strategies and in building sex-specific prediction tools to identify high risk profile patients.

Exposure to second-hand cigarette smoke exacerbates the progression of osteoarthritis in a surgical induced murine model

Osteoarthritis (OA), formerly understood to be a result of passive wear, is now known to be associated with chronic inflammation. Cigarette smoking promotes systemic inflammation and has been implicated in increased joint OA incidence in some studies, though the recent observational data on the association are contradictory. We hypothesize that second-hand smoke (SHS) treatment will increase the incidence of OA in a mouse model that has been subjected to a surgical destabilization of the medial meniscus (DMM). To test this hypothesis, we applied either SHS treatment or room air (RA) to mice for 28 days post-DMM surgery. Histopathology findings indicated that the knees of SHS mice exhibited more severe OA than their control counterparts. Increased expression of matrix metalloprotease-13 (MMP-13), an important extracellular protease known to degrade articular cartilage, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), an intracellular effector of inflammatory pathways, were observed in the SHS group. These findings provide greater understanding and evidence for a detrimental role of cigarette smoke on OA progression and systemic inflammation.

A comparison of risk factors for osteo- and rheumatoid arthritis using NHANES data

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Both osteo- and rheumatoid arthritis increase with age.

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Osteoarthritis is more common in whites, but rheumatoid arthritis is in blacks.

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Obesity and female sex increase risk of risk of both osteo- and rheumatoid arthritis.

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Smoking increases risk of both forms of arthritis in women.

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These two forms of arthritis have many common risk factors.

Osteoarthritis and rheumatoid arthritis are both diseases of joints, but they have very different etiologies. Osteoarthritis is a disease assumed to result from wear and tear over time, whereas rheumatoid arthritis is an autoimmune disease where the body’s immune system attacks joint tissues. Using NHANES data (1999–2015), we have compared the influence of age, sex, ethnicity, body mass index and smoking on these two very different forms of arthritis. Incidence of both increases with age and are more frequent in females than males. There is little apparent difference between osteoarthritis and rheumatoid arthritis in women of normal as comparted to overweight, but both are more frequent in obese women, especially those over the age of 60. While osteoarthritis is more frequent in whites, blacks have more rheumatoid arthritis, and Hispanics show an intermediate prevalence. Smoking significantly increased the incidence of both osteoarthritis and rheumatoid arthritis in women, but increased prevalence of only RA in men. There was no effect of smoking on OA prevalence in males. It is remarkable that two diseases of joints, which have quite different causes, should have so many commonalities. The differences that exist appear to be due to a combination of inflammatory markers and access to health care.

Thumb Carpometacarpal Arthritis: Prognostic Indicators and Timing of Further Intervention Following Corticosteroid Injection

PURPOSE

Corticosteroid injections are commonly used to treat thumb carpometacarpal arthritis in adults. We aimed to define the timing of surgery following an initial corticosteroid injection and identify patient-specific factors that influence the likelihood of repeat injection or surgery.

METHODS

We performed a retrospective analysis of all patients who underwent a first-time corticosteroid injection for carpometacarpal arthritis between 2009 and 2017. Demographic information, radiographic classification, additional nonsurgical therapies, complications, and outcomes were collected. Primary outcomes were repeat injection and surgical reconstruction. Kaplan-Meier survival analysis was used to characterize the timing of surgical intervention and Cox regression modeling was used to identify predictors of subsequent intervention.

RESULTS

Two-hundred thirty-nine patients (average age, 62.9 years) were identified, of which 141 (59.0%) had a repeat injection and 90 (37.6%) underwent surgery. There were no patient-specific characteristics associated with repeat injection. Eaton stage III/IV arthritis at initial presentation, current smoking status, and prior ipsilateral hand surgery were associated with an increased likelihood of surgery. By Kaplan-Meier analyses, 87.7% of patients who presented with Eaton III/IV arthritis did not have surgery within a year and 66.7% of these patients did not have surgery within 5 years.

CONCLUSIONS

In this retrospective observational cohort study with 10-year follow-up from a 4-surgeon practice, advanced radiographic arthritis, current smoking status, and a history of ipsilateral hand surgery were patient-specific factors that predicted progression to surgery following injection. Of patients who presented with advanced radiographic arthritis, one-third underwent surgery within 5 years of initial injection. Although injection efficacy and causality cannot be inferred based on an observational longitudinal analysis, these data identify patient-specific factors that may have an impact on surgical decision-making and a potential timeframe for future intervention.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

AMPK controls the axonal regenerative ability of dorsal root ganglia sensory neurons after spinal cord injury

Regeneration after injury occurs in axons that lie in the peripheral nervous system but fails in the central nervous system, thereby limiting functional recovery. Differences in axonal signalling in response to injury that might underpin this differential regenerative ability are poorly characterized. Combining axoplasmic proteomics from peripheral sciatic or central projecting dorsal root ganglion (DRG) axons with cell body RNA-seq, we uncover injury-dependent signalling pathways that are uniquely represented in peripheral versus central projecting sciatic DRG axons. We identify AMPK as a crucial regulator of axonal regenerative signalling that is specifically downregulated in injured peripheral, but not central, axons. We find that AMPK in DRG interacts with the 26S proteasome and its CaMKIIα-dependent regulatory subunit PSMC5 to promote AMPKα proteasomal degradation following sciatic axotomy. Conditional deletion of AMPKα1 promotes multiple regenerative signalling pathways after central axonal injury and stimulates robust axonal growth across the spinal cord injury site, suggesting inhibition of AMPK as a therapeutic strategy to enhance regeneration following spinal cord injury.

Household air pollution and arthritis in low-and middle-income countries: Cross-sectional evidence from the World Health Organization's study on Global Ageing and Adult Health

Background

Evidence points to a clear link between air pollution exposure and several chronic diseases though investigations regarding arthritis are still lacking. Emerging evidence suggests an association between ambient air pollution and rheumatoid arthritis. Household air pollution exposure, conversely, is largely unstudied but may be an important consideration for arthritis, particularly in low- and middle-income countries (LMICs), where cooking and heating activities can generate high indoor air pollutant levels.

Methods

We investigated the association of household air pollution (electricity vs. gas; kerosene/paraffin; coal/charcoal; wood; or agriculture/crop/animal dung/shrubs/grass as the main fuel used for cooking) and arthritis in six LMICs (China, Ghana, India, Mexico, the Russian Federation, South Africa) using data from Wave I of the World Health Organization Study on Global AGEing and Adult Health (SAGE) (2007–2010). Multivariable analyses were adjusted for sociodemographic, household and lifestyle characteristics and several comorbidities.

Results

The use of gas (aOR = 1.76, 95%CI: 1.40–2.21); coal (aOR = 1.74, 95%CI: 1.22–2.47); wood (aOR = 1.69, 95%CI: 1.30–2.19); or agriculture/crop/animal dung/shrubs/grass: aOR = 1.95 (1.46–2.61) fuels for cooking were strongly associated with an increased odds of arthritis, compared to electricity in cluster and stratified adjusted analyses. Gender (female), age (≥50 years), overweight (25.0 ≤BMI<30.0 kg/m²), obesity (BMI ≥30.0 kg/m²), former and current alcohol consumption, and the comorbidities angina pectoris, diabetes, chronic lung disease, depression and hypertension were also associated with a higher odds of arthritis. Underweight (BMI<18.5 kg/m²) and higher education levels (college/university completed/post-graduate studies) were associated with a lower odds of arthritis.

Conclusions

These findings suggest that exposure to household air pollution from cook fuels is associated with an increased odds of arthritis in these regions, which warrants further investigation.

Causal association between smoking behavior and the decreased risk of osteoarthritis: a Mendelian randomization

OBJECTIVE

This study aimed to examine whether smoking behavior is causally associated with osteoarthritis.

METHODS

A two-sample Mendelian randomization (MR) analysis using the inverse-variance weighted (IVW), weighted median, and MR-Egger regression methods was performed. We used the publicly available summary statistics datasets of smoking behavior genome-wide association studies (GWASs; n = 85,997) as an exposure, and a GWAS in 7410 patients with osteoarthritis in the arcOGEN study and 11,009 controls of European ancestry as an outcome.

RESULTS

We selected four single nucleotide polymorphisms (SNPs) from GWASs of smoking behavior as instrumental variables (IVs) to improve inference. These SNPs were located at CHRNA3 (rs1051730), SLC25A5P5A9 (rs215614), CHRNB3 (rs6474412), and CYP2B6 (rs7260329). The IVW method showed evidence to support an inverse causal association between smoking behavior and osteoarthritis in the knee and hip (beta = -0.056, standard error [SE] = 0.027, p = 0.035). MR-Egger regression revealed that directional pleiotropy was unlikely to be biasing the result (intercept = -0.005; p = 0.848), but showed no causal association between smoking behavior and osteoarthritis (beta = -0.048, SE = 0.048, p = 0.427). However, the weighted median approach yielded evidence of a negative causal association between smoking behavior and osteoarthritis (beta = -0.056, SE = 0.028, p = 0.046). Cochran's Q test and the funnel plot indicated no evidence of heterogeneity between IV estimates based on the individual variants.

CONCLUSION

The results of MR analysis support that smoking behavior was causally associated with a reduced risk of osteoarthritis.

Quadriceps muscle weakness is related to increased risk of radiographic knee OA but not its progression in both women and men: the Matsudai Knee Osteoarthritis Survey

PURPOSE

The purpose of this study was to investigate the causal relationship between quadriceps muscle strength and radiographic knee osteoarthritis (OA) in a longitudinal study.

METHODS

The present study included 976 knees from 488 subjects who participated in both the 5th (2007) and 7th (2013) surveys of the Matsudai Knee Osteoarthritis Survey. Bilateral quadriceps strengths of each subject were measured using the quadriceps training machine (QTM-05F, Alcare Co., Ltd., Tokyo, Japan). Additionally, weight-bearing standing knee radiographs were obtained, and knee OA was graded according to the Kellgren-Lawrence classification system. The relationships between quadriceps strength and the incidence and progression of radiographic knee OA were assessed using multiple logistic regression analysis.

RESULTS

After adjusting for age and body mass index (BMI), both female and male knees in the lowest quantile of quadriceps strength had higher risk of the incidence of radiographic knee OA compared with the highest quantile of quadriceps strength (women: OR 2.414, 95% CI 1.098-5.311; men: OR 2.774, 95% CI 1.053-7.309). In contrast, after adjusting for age, BMI and femorotibial angle, both female and male knees in the lowest quantile compared with the highest quantile of quadriceps strength did not differ in risk of the progression of radiographic knee OA (women: OR 1.040, 95% CI 0.386-2.802; men: OR 2.814, 95% CI 0.532-14.898).

CONCLUSION

Quadriceps muscle weakness was related to increased risk of the incidence of radiographic knee OA, but not its progression, in both women and men. Therefore, the clinically important finding of this study is that, in both women and men, maintaining higher quadriceps muscle strength may be one of the most effective prevention methods for incident radiographic knee OA.

LEVEL OF EVIDENCE

II.

The mediating effect of body mass index on the relationship between smoking and hip or knee replacement due to primary osteoarthritis. A population-based cohort study (the HUNT Study)

To investigate the total effect of smoking on total hip or knee replacement (THR/TKR) due to primary osteoarthritis (OA) and to quantify the indirect effect of smoking through body mass index (BMI). Participants from the Nord-Trøndelag Health Study (the HUNT Study) were linked to the Norwegian Arthroplasty Register to detect the first THR or TKR due to primary OA. A mediation analysis was used to decompose the total effect of smoking into a direct and indirect effect. BMI was considered a mediator in the analysis. All effects were estimated as hazard ratios (HRs) with 95% confidence intervals (CIs). The indirect effect of smoking mediated through BMI was expressed as a percentage (proportion*100). In total 55 188 participants were followed up during 17.2 years (median). We identified 1322 THRs and 754 TKRs. For men, the total effect of current vs. never smoking revealed a decreased risk of THR (HR 0.59, 95% CI 0.46-0.76) and TKR (HR 0.47, 95% CI 0.32-0.66). For women, current smoking increased the risk of THR (HR 1.34, 95% CI 1.11-1.60). For men, 6% and 7% of the risk reduction for THR and TKR, respectively, was mediated by BMI. We found a negative association between smoking and THR or TKR for men. On the contrary, smoking was associated with increased risk of THR for women. Most of the effect of smoking on joint replacement risk remained unexplained by BMI.

Association between smoking and risk of knee osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

To investigate the association between smoking and the risk for knee osteoarthritis (OA).

DESIGN

Cohort, case-control, and cross-sectional studies were obtained from the Medline, Embase, and Web of Science databases. Estimates were calculated using a random-effects model. Subgroup analyses and meta-regression models were performed to investigate potential sources of heterogeneity. We further analyzed the dose-response relationship between cigarette consumption and risk of knee OA.

RESULTS

Thirty-eight independent observational studies that included 481,744 participants were analyzed. Those who had ever smoked had a significantly decreased risk of developing knee OA relative to those who had never smoked (RR = 0.80; 95% CI 0.73-0.88). This was unaffected by study design, and the pooled relative risks (RRs) were 0.79 (95% CI, 0.65-0.96), 0.71 (95% CI, 0.61-0.84) and 0.83 (95% CI, 0.73-0.94) for cohort, case-control, and cross-sectional studies, respectively. Analysis of subgroups stratified by gender reduced the heterogeneity from moderate to low in both males and females. The lower risk for developing knee OA was more apparent in male smokers (RR = 0.69; 95% CI 0.58-0.80) than female smokers (RR = 0.89; 95% CI 0.77-1.02) and dose-response analysis showed a linear decrease in knee OA with increased cigarette consumption.

CONCLUSIONS

We found an inverse association between cigarette smoking and risk of knee OA, irrespective of study design. This association was more apparent in males. However, we have not demonstrated a causal relationship between smoking and OA, and further investigations are needed.

The causal role of smoking on the risk of hip or knee replacement due to primary osteoarthritis: a Mendelian randomisation analysis of the HUNT study

OBJECTIVE

Smoking has been associated with a reduced risk of hip and knee osteoarthritis (OA) and subsequent joint replacement. The aim of the present study was to assess whether the observed association is likely to be causal.

METHOD

55,745 participants of a population-based cohort were genotyped for the rs1051730 C > T single-nucleotide polymorphism (SNP), a proxy for smoking quantity among smokers. A Mendelian randomization analysis was performed using rs1051730 as an instrument to evaluate the causal role of smoking on the risk of hip or knee replacement (combined as total joint replacement (TJR)). Association between rs1051730 T alleles and TJR was estimated by hazard ratios (HRs) and 95% confidence intervals (CIs). All analyses were adjusted for age and sex.

RESULTS

Smoking quantity (no. of cigarettes) was inversely associated with TJR (HR 0.97, 95% CI 0.97-0.98). In the Mendelian randomization analysis, rs1051730 T alleles were associated with reduced risk of TJR among current smokers (HR 0.84, 95% CI 0.76-0.98, per T allele), however we found no evidence of association among former (HR 0.97, 95% CI 0.88-1.07) and never smokers (HR 0.97, 95% CI 0.89-1.06). Neither adjusting for body mass index (BMI), cardiovascular disease (CVD) nor accounting for the competing risk of mortality substantially changed the results.

CONCLUSION

This study suggests that smoking may be causally associated with the reduced risk of TJR. Our findings add support to the inverse association found in previous observational studies. More research is needed to further elucidate the underlying mechanisms of this causal association.

Plausible Roles for RAGE in Conditions Exacerbated by Direct and Indirect (Secondhand) Smoke Exposure

Approximately 1 billion people smoke worldwide, and the burden placed on society by primary and secondhand smokers is expected to increase. Smoking is the leading risk factor for myriad health complications stemming from diverse pathogenic programs. First- and second-hand cigarette smoke contains thousands of constituents, including several carcinogens and cytotoxic chemicals that orchestrate chronic inflammatory responses and destructive remodeling events. In the current review, we outline details related to compromised pulmonary and systemic conditions related to smoke exposure. Specifically, data are discussed relative to impaired lung physiology, cancer mechanisms, maternal-fetal complications, cardiometabolic, and joint disorders in the context of smoke exposure exacerbations. As a general unifying mechanism, the receptor for advanced glycation end-products (RAGE) and its signaling axis is increasingly considered central to smoke-related pathogenesis. RAGE is a multi-ligand cell surface receptor whose expression increases following cigarette smoke exposure. RAGE signaling participates in the underpinning of inflammatory mechanisms mediated by requisite cytokines, chemokines, and remodeling enzymes. Understanding the biological contributions of RAGE during cigarette smoke-induced inflammation may provide critically important insight into the pathology of lung disease and systemic complications that combine during the demise of those exposed.

Relationship between decreased lower extremity muscle mass and knee pain severity in both the general population and patients with knee osteoarthritis: Findings from the KNHANES V 1-2

Objective

To identify the prevalence of and risk factors for knee pain and radiographic knee osteoarthritis (RKOA) and to investigate the relationship between decreased lower extremity muscle mass (DLEM) and knee pain severity.

Methods

Using data from the Korea National Health and Nutrition Examination Survey, 3,278 participants who were ≥50 years old and who underwent dual x-ray absorptiometry, plain knee radiographs and completed a knee pain questionnaire were enrolled. Lower extremity muscle mass (LEM) was defined as the sum of the fat-free soft tissue mass of the legs, and lower extremity muscle mass index (LMI) was calculated as LEM/body weight (%). DLEM was defined as an LMI more than two standard deviations below the mean of a gender-matched young reference group. Categorical variables were presented as numbers (weighted %).

Results

The prevalence of knee pain and RKOA were 22% (n = 721) and 34.7% (n = 1,234), respectively. Multivariate logistic regression analysis showed being female (OR 2.15, 95% CI 1.67–2.79), older (OR 1.03, 95% CI 1.01–1.04), less educated (OR 1.72, 95% CI 1.09–2.71), stiffness (OR 16.15, 95% CI 12.04–21.66), bed rest (OR 2.49, 95% CI 1.81–3.43), RKOA (OR 2.20, 95% CI 1.78–2.74) and DLEM (OR 1.54, 95% CI 1.09–2.17) were associated with knee pain. Participants with simultaneous RKOA and DLEM complained of more severe pain (pain score 7.18 ± 2.48) than those with knee pain without RKOA or DLEM (5.02 ± 2.44), those with only RKOA (6.29 ± 2.50), or those with only DLEM (6.78 ± 2.18) (P<0.001). These results remained after multivariate analyses of variance (MANOVAs).

Conclusion

The prevalence of knee pain and RKOA were 22% and 34.7%, respectively, in the general Korean population. DLEM was an independent risk factor for knee pain and it was associated with increased pain severity, regardless of RKOA.

What is the effect of nicotinic acetylcholine receptor stimulation on osteoarthritis in a rodent animal model?

OBJECTIVES

Despite the rising number of patients with osteoarthritis, no sufficient chondroprotective and prophylactic therapy for osteoarthritis has been established yet. The purpose of this study was to verify whether stimulation of the nicotinic acetylcholine receptor via nicotine has a beneficial effect on cartilage degeneration in the development of osteoarthritis and is capable of reducing the expression of proinflammatory cytokines and cartilage degrading enzymes in synovial membranes after osteoarthritis induction.

METHODS

Experimental osteoarthritis was induced in Lewis rats using a standardized osteoarthritis model with monoiodoacetate. A total of 16 Lewis rats were randomized into four groups: control, sham + nicotine application, osteoarthritis, and osteoarthritis + nicotine application. Nicotine (0.625 mg/kg twice daily) was administered intraperitoneally for 42 days. We analyzed histological sections, radiological images and the expression of the proinflammatory cytokines, such as interleukin-1β, tumor necrosis factor-α and interleukin-6, and of matrix metalloproteases 3, 9 and 13 and tissue inhibitors of metalloprotease-1 in synovial membranes via quantitative polymerase chain reaction.

RESULTS

Histological and x-ray examination revealed cartilage degeneration in the osteoarthritis group compared to control or sham + nicotine groups (histological control vs osteoarthritis: p = 0.002 and x-ray control vs osteoarthritis: p = 0.004). Nicotine treatment reduced the cartilage degeneration without significant differences. Osteoarthritis induction led to a higher expression of proinflammatory cytokines and matrix metalloproteases as compared to control groups. This effect was attenuated after nicotine administration. The differences of proinflammatory cytokines and matrix metalloproteases did not reach statistical significance.

CONCLUSION

With the present small-scale study, we could not prove a positive effect of nicotinic acetylcholine receptor stimulation on osteoarthritis due to a conservative statistical analysis and the consecutive lack of significant differences. Nevertheless, we found promising tendencies of relevant parameters that might prompt further experiments designed to evaluate the potency of stimulation of this receptor system as an additional treatment approach for osteoarthritis.

Association between direct and indirect smoking and osteoarthritis prevalence in Koreans: a cross-sectional study

OBJECTIVES

To assess the association between smoking patterns and knee and hip joint osteoarthritis (OA) prevalence in Koreans aged 50 years or older with focus on knee OA.

DESIGN

Cross-sectional study using nationally representative data.

SETTING

Data were collected at portable Health Examination Centres in Korea.

PARTICIPANTS

Data of 9064 participants of the 5th Korean National Health and Nutrition Examination Survey (2010-2012) aged 50 years or older who received knee or hip joint X-rays out of 31,596 total surveyees were analysed.

PRIMARY OUTCOME MEASURES

OA prevalence by smoking behaviour (current smoking, past smoking, indirect smoking and non-smoking).

SECONDARY OUTCOME MEASURES

Estimated risk of OA by smoking amount, period, pack-years and indirect smoking exposure time to assess the association between smoking-related factors and knee OA by calculating ORs and adjusting for covariates in a complex sampling design. A multinomial logistic regression analysis and backward elimination method was used.

RESULTS

OA prevalence in Koreans aged 50 years or older was 13.9%, with prevalence about 3.5 times higher in women (men 5.7%, women 20.1%). ORs for knee and hip joint OA prevalence by smoking behaviour in male indirect-smokers were lower than those in non-smokers in age and sex (OR 0.271; 95% CI 0.088 to 0.828), and selective adjustments (OR 0.314; 95% CI 0.102 to 0.966). All other analyses for smoking behaviour and total OA prevalence, and knee OA prevalence were not significantly different. Associations between smoking amount, period, pack-years and knee OA prevalence were non-significant in ever-smokers. Associations between indirect smoking exposure time and knee OA prevalence were also non-significant.

CONCLUSIONS

This study found that though direct and previous smoking and OA prevalence were not associated, there was a weak relationship between indirect smoking and OA.

Current evidence on risk factors for knee osteoarthritis in older adults: a systematic review and meta-analysis

Osteoarthritis (OA) is a leading cause of pain and disability and leads to a reduced quality of life. The aim was to determine the current evidence on risk factors for onset of knee pain/OA in those aged 50 and over. A systematic review and meta-analysis was conducted of cohort studies for risk factors for the onset of knee pain. Two authors screened abstracts and papers and completed data extraction. Where possible, pooled odds ratios (OR) were calculated via random effects meta-analysis and population attributable fractions (PAFs) derived. 6554 papers were identified and after screening 46 studies were included. The main factors associated with onset of knee pain were being overweight (pooled OR 1.98, 95% confidence intervals (CI) 1.57-2.20), obesity (pooled OR 2.66 95% CI 2.15-3.28), female gender (pooled OR 1.68, 95% CI 1.37-2.07), previous knee injury (pooled OR 2.83, 95% CI 1.91-4.19). Hand OA (pooled OR 1.30, 95% CI 0.90-1.87) was found to be non-significant. Smoking was found not to be a statistically significant risk or protective factor (pooled OR 0.92, 95% CI 0.83-1.01). PAFs indicated that in patients with new onset of knee pain 5.1% of cases were due to previous knee injury and 24.6% related to being overweight or obese. Clinicians can use the identified risk factors to identify and manage patients at risk of developing or increasing knee pain. Obesity in particular needs to be a major target for prevention of development of knee pain. More research is needed into a number of potential risk factors.

Smoking and osteoarthritis: a review of the evidence and its implications

A number of reports including a recent publication in Osteoarthritis and Cartilage have suggested that smokers have a lower than expected prevalence of osteoarthritis (OA) than nonsmokers. We review the evidence linking smoking with OA, suggest approaches whereby the direct and indirect effects of smoking on OA might be distinguished, highlight two diseases, ulcerative colitis and Parkinson's disease, where smoking is protective, discuss mechanisms by which nicotine might act and lastly explore the association of smoking with enhanced musculoskeletal pain.

Total hip replacement due to primary osteoarthritis in relation to cumulative occupational exposures and lifestyle factors: a nationwide nested case-control study

OBJECTIVE

To investigate the risk of total hip replacement (THR) due to primary osteoarthritis in relation to cumulative occupational mechanical exposures and lifestyle factors.

METHODS

Using register information, we identified first-time THR cases within the Danish working population in 2005-2006. For each case, 2 age- and sex-matched controls were drawn. Persons within 2,500 randomly selected case-control sets received a questionnaire about job history, weight at age 25 years, present weight and height, smoking, and sports activities at age 25 years. The job history was combined with a job exposure matrix. Cumulative exposure estimates were expressed according to the pack-year concept of smoking (e.g., cumulative lifting was expressed as ton-years). We used conditional logistic regression for statistical analyses.

RESULTS

In total, 1,776 case-control sets (71%) were available for analysis. The adjusted odds ratio (OR) for exposure to ≥20 ton-years was 1.35 (95% confidence interval [95% CI] 1.05-1.74) for men and 1.00 (95% CI 0.73-1.41) for women. Standing/walking and whole body vibration showed no associations. The adjusted OR for body mass index (BMI) ≥30 kg/m(2) at age 25 years was 2.44 (95% CI 1.38-4.32) for men and 5.12 (95% CI 2.30-11.39) for women. The corresponding adjusted ORs for an increase in BMI of ≥10 kg/m(2) since age 25 years were 2.16 (95% CI 1.25-3.70) and 2.46 (95% CI 1.47-4.13). Sports participation showed weak positive associations, while pack-years of smoking showed no associations.

CONCLUSION

The results indicated a modest increase in risk of THR in relation to cumulative lifting among men and an increased risk in relation to a high BMI at age 25 years and to a gain in BMI in both sexes.

Relationship between cigarette smoking and radiographic knee osteoarthritis in Chinese population: a cross-sectional study

The purpose of this paper was to estimate the cross-sectional association between cigarette smoking and radiographic knee Osteoarthritis (OA) in Chinese population. A total of 3,789 subjects (1,796 females and 1,993 males) participated in this study. A subject was diagnosed with radiographic knee OA if Kellgren-Lawrence (K-L) grade ≥2 in at least one leg. The smoking status was classified into four levels based on the daily smoking habit: (1) 0/day; (2) 1-10/day; (3) 11-20/day; and (4) >20/day. Linear trend and multivariable logistic regression were conducted for statistical analysis. The prevalence of radiographic knee OA was 28.4 % among the subjects of this study. An inverse association was observed between cigarette smoking and radiographic knee OA in the linear trend test. Such association remained valid after adjusting the factors of age, gender, body mass index, betel quilt chewing status, physical activity, alcohol drinking status, mean total energy intake and educational level in the multivariable logistic regression. This study suggested a negative association between cigarette smoking and radiographic knee OA in the Chinese population. The findings of this study need to be confirmed by further prospective research.

Cigarette smoking and risk of total knee replacement for severe osteoarthritis among Chinese in Singapore--the Singapore Chinese health study

PURPOSE

Data on the effects of cigarette smoking with osteoarthritis (OA) are inconsistent and no study has examined the effect of smoking cessation. We examined smoking status, duration, dosage and cessation in association with risk of total knee replacement (TKR) for severe knee OA among elderly Chinese in Singapore.

METHODS

We used data from the Singapore Chinese Health Study, a population-based prospective cohort of 63,257 Chinese men and women aged 45-74 years during enrollment between 1993 and 1998. Detailed information on smoking, current diet and lifestyle factors were obtained through in person interviews. As of 31 December 2011, 1,973 incident TKR cases for severe knee OA had been identified via linkage with nationwide hospital discharge database. We used Cox regression methods to examine smoking in relation to TKR risk with adjustment for age, gender, education, body mass index (BMI), comorbidities and physical activity level.

RESULTS

Compared to never smokers, current smokers had a 51% decrease in risk of TKR [Hazards ratio (HR) = 0.49; 95% confidence interval (CI) = 0.40-0.60]. Among current smokers, there was a very strong dose-dependent association between increasing duration and dosage of smoking with decreasing risk of TKR (P for trend <0.0001). Among former smokers, there was a dose-dependent response between decrease in duration of smoking cessation and reduction in TKR risk (P for trend = 0.034).

CONCLUSION

Our findings strongly implicate smoking as a protective factor for TKR indicated for severe knee OA. This concurs with experimental data that nicotine promotes proliferation and collagen synthesis in chondrocytes.

Osteoarthritis of the hand I: aetiology and pathogenesis, risk factors, investigation and diagnosis

Objective

Osteoarthritis (OA) of the hand can be a debilitating condition that hinders an individual's quality of life. With multiple joints within the hand that are commonly affected OA, an individual's ability to use their hand in everyday movements become more limited. The article aims to review literature on the aetiology and pathogenesis of OA, risk factors, characteristics of hand OA and the steps of diagnosis.

Key findings

The aetiology and pathogenesis of OA, in particular hand OA, is not fully understood. However, it is known that several factors play a role. Environmental factors, such as stress from mechanical loading, especially to vulnerable joints predispose individuals to developing OA. Extracellular matrix changes in protein levels have also been noted in individuals with OA. Linked to hand OA development are boney enlargements (Herbeden's and Bouchard's nodes). Several risk factors for OA include: age, obesity, gender, smoking, genetics, diet and occupation. Various diagnostic methods include a combination of using radiographic methods, clinical presentation, a number of developed measurements and scales.

Summary

With OA having several risk factors and various causes and contributing elements, it is important to elucidate the pathogenesis of OA and determine exactly how risk factors play a role in its development. Because of the contributions from several elements, diagnosis is best when it uses multiple methods. In turn, understanding OA and making better diagnoses could lead to improved management of the condition through both pharmacological and non-pharmacological interventions.

Knee pain and its severity in elderly Koreans: prevalence, risk factors and impact on quality of life

This study investigated the epidemiology (prevalence, risk factors, and impact on quality of life) of knee pain and its severity in elderly Koreans. The subjects (n=3,054) were participants aged ≥50 yr from the fifth Korea National Health and Nutrition Examination Survey, conducted in 2010. Knee pain was defined as pain in the knee lasting ≥30 days during the most recent 3 months; severity was categorized as mild, moderate, or severe. EQ-5D was used to measure quality of life. The prevalence of knee pain was 23.1% (11.7% in men, 31.9% in women). The prevalences of mild, moderate, and severe knee pain were 4.3%, 9.1%, and 9.7%, respectively (2.8%, 5.4%, and 3.5% in men and 5.4%, 12.0%, and 14.4% in women). Old age, female gender, a low level of education, a manual occupation, obesity, and radiographic osteoarthritis were risk factors for knee pain, and were associated with increased severity of knee pain. Excluding men with mild knee pain, people with knee pain had significantly lower quality of life than those without knee pain. Early interventional approaches are needed to reduce the medical, social, and economic burden of knee pain in elderly Koreans.

Cigarette smoking and musculoskeletal disorders

Cigarette smoking has deleterious effects on the musculo-skeletal system. The loss of bone mineral content and increased incidence of fractures are the best known negative consequences. The pathogenesis is complex, due to direct toxic effects on osteoblasts/osteoclasts activity of nicotine, and indirect actions on sex and adrenocortical hormones, vitamin D, intestinal calcium absorption, vessels and oxygen supply. Smoking may favour the onset or aggravate the progression of rheumatoid arthritis and back pain. Negative influences have been observed on muscle and on tendons. Moreover, smoking habit is associated to a number of short term post-operative complications and higher resource consumption. Smoking cessation is highly advisable with positive effects on the bone metabolism on the long term. More positive and immediate results can be obtained in patients submitted to orthopedic surgery: the healing process is improved, the frequency of complications is reduced, and the length of hospital stay is shortened.

Quadriceps muscle strength and its relationship to radiographic knee osteoarthritis in Japanese elderly

BACKGROUND

Knee osteoarthritis (OA) is a multifactorial disease and strongly affected by mechanical factors. The aims of the present study were to assess validity and reliability of a new muscle strength measuring device, the Quadriceps Training Machine (QTM) and evaluate the relationship between quadriceps strength measured by QTM and radiographic knee OA by epidemiological survey.

METHODS

The isometric knee extension muscle strength of QTM was compared with BIODEX in 24 healthy adults. Then, the relationship between radiographic knee OA and quadriceps strength using QTM was investigated with 2,032 knees in 1,016 subjects by an epidemiological survey (Matsudai Knee Osteoarthritis Survey).

RESULTS

Significant correlation was observed between QTM and BIODEX (r = 0.69, 0.82). In the Matsudai Knee Osteoarthritis Survey, the prevalence of radiographic OA (grade II or higher upon Kellgren-Lawrence classification) was: 13, 36.9, 67.8, and 86.5 %, regarding women in their fifties, sixties, seventies, and eighties, respectively, and was 1.7, 13.4, 33.5, and 66.2 % regarding men, respectively. Quadriceps muscle strength declined following 50 years of age, and significant decline was observed in the their sixties and seventies. Quadriceps muscle strength of the OA group (grades II, III and IV) was significantly declined compared with that of the Non-OA group (grade-0 and I). Furthermore, the tendency of the muscle strength level to decline with the progression of knee OA grade was particularly observed between grade 0 and grade I in both men and women and between grade I and grade II in men.

CONCLUSION

The relationship between radiographic knee OA and quadriceps strength was quantitatively evaluated by an epidemiological survey, and we found a correlation between knee OA and the decline in quadriceps strength. Furthermore, it was suggested that the decline in quadriceps muscle strength may be more strongly related to the incidence of knee OA than to its progression.

The musculoskeletal effects of cigarette smoking

➤ Cigarette smoking decreases bone mineral density and increases the risk of sustaining a fracture or tendon injury, with partial reversibility of these risks with long-term cessation of smoking. ➤ Cigarette smoking increases the risk for perioperative complications, nonunion and delayed union of fractures, infection, and soft-tissue and wound-healing complications. ➤ Brief preoperative cessation of smoking may mitigate these perioperative risks. ➤ Informed-consent discussions should include notification of the higher risk of perioperative complications with cigarette smoking and the benefits of temporary cessation of smoking.

Social determinants and osteoarthritis outcomes

Osteoarthritis (OA) is one of the most frequently occurring musculoskeletal diseases, posing a significant public health problem due to its impact on pain and disability. Traditional risk factors fail to account for all of the risk observed for OA outcomes. In recent years, our view of disease causation has broadened to include health risks that are created by an individual's socioeconomic circumstances. Early research into social determinants has focused on social position and explored factors related to the individual such as education, income and occupation. Results from these investigations suggest that low education attainment and nonprofessional occupation are associated with poorer arthritis outcomes. More recently, research has expanded to examine how one's neighborhood socioeconomic environment may be relevant to OA outcomes. This narrative review proposes a framework to help guide our understanding of how social context may interact with pathophysiological processes and individual-level variables to influence health outcomes in those living with OA.

Prevalence and associated factors of knee osteoarthritis in a community-based population in Heilongjiang, Northeast China

Few data exist concerning the prevalence of knee OA and associated factors in Northeast China. This study was undertaken to estimate the prevalence of radiographic and symptomatic knee OA among community residents and to elucidate relevant risk factors. Unmatched case-control study was adopted to study risk factors of knee OA. Radiographic OA was evaluated according to the Kellgren and Lawrence grading scheme. Statistical analyses included tests and logistic model regressions. A total of 1,196 people aged 40-84 years participated in the community-based health survey in Northeast China in 2005. Survey participants completed an interviewer-based questionnaire. The standardized prevalence of symptomatic knee OA was 16.05% and it was significantly higher in women than in men (19.87% vs. 11.91%, = 13.76, P < 0.001). There was also an increased tendency with age in both sex (men: x (2) = 29.67, P (trend) < 0.001; women: x (2) = 40.26, P (trend) < 0.001). The prevalence of symptomatic knee OA was significantly higher than that in Beijing and Shantou, while lower than that in Wuchuan county of inner Mongolia with nonsignificant difference. Logistic regressions revealed that age, sex, BMI, and work status might be risk factors for knee OA in urban residents, whereas age, BMI, and smoking habits might be risk factors in rural dwellers. Symptomatic knee OA is extremely common with preponderance for elderly women and constitutes a major public health problem. The findings will be useful to guide the distribution of future health care resources and preventive strategies.

The relationship between body mass index and hip osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

Body mass index, a measure of relative weight, is increasingly recognized as an important risk factor for osteoarthritis, especially in weight bearing joints. The objective was to assess the association between body mass index and hip osteoarthritis susceptibility and investigate the difference between sex, study type and osteoarthritis definition.

METHODS

We did electronic searches of Medline, Embase and Cochrane library from the commencement to December 2009. A meta-analysis and meta-regression was executed to quantitatively assess the strength of associations between body mass index and hip osteoarthritis risk. Study-specific incremental estimates were standardized to determine the risk associated with a 5 kg/m(2) increase in body mass index.

RESULTS

Fourteen epidemiological studies were included. Our study showed that body mass index was significantly positive associated with hip osteoarthritis risk. A 5-unit increase in body mass index was related to an increased risk of hip osteoarthritis (RR: 1.11; 95%CI: 1.07, 1.16). The magnitudes of associations were similar in women as compared with men (women, RR: 1.10; 95%CI: 1.05, 1.15; men, RR: 1.08; 95%CI: 1.04, 1.12; p > 0.05). The summary estimates were 1.12 (95%CI: 1.02, 1.24) in case-control studies and 1.11 (95%CI: 1.06, 1.16) in cohort studies (p > 0.05). Body mass index was positively associated with hip osteoarthritis defined by radiography and/or clinical symptom (RR: 1.04; 95%CI: 1.00, 1.07) and clinical surgery (RR: 1.16; 95%CI: 1.11, 1.22) with no significant difference (p > 0.05).

CONCLUSION

Increased body mass index contributes to a positive effect on susceptibility to hip osteoarthritis. Associations between body mass index and hip osteoarthritis risk do not vary by sex, study design or osteoarthritis definition.

Individual and occupational risk factors for knee osteoarthritis: results of a case-control study in Germany

INTRODUCTION

A number of occupational risk factors are discussed in relation to the development and progress of knee joint diseases (for example, working in a kneeling or squatting posture, lifting and carrying heavy weights). Besides the occupational factors, a number of individual risk factors are important. The distinction between work-related and other factors is crucial in assessing the risk and in deriving preventive measures in occupational health.

METHODS

In a case-control study, patients with and without symptomatic knee osteoarthritis (OA) were questioned by means of a standardised questionnaire complemented by a semi-standardised interview. Controls were matched and assigned to the cases by gender and age. Conditional logistic regression was used in analysing data.

RESULTS

In total, 739 cases and 571 controls were included in the study. In women and men, several individual and occupational predictors for knee OA could be described: obesity (odds ratio (OR) up to 17.65 in women and up to 12.56 in men); kneeling/squatting (women, OR 2.52 (>8,934 hours/life); men, 2.16 (574 to 12,244 hours/life), 2.47 (>12,244 hours/life)); genetic predisposition (women, OR 2.17; men, OR 2.37); and sports with a risk of unapparent trauma (women, OR 2.47 (>or=1,440 hours/life); men, 2.58 (>or=3,232 hours/life)). In women, malalignment of the knee (OR 11.54), pain in the knee already in childhood (OR 2.08), and the daily lifting and carrying of loads (>or=1,088 tons/life, OR 2.13) were related to an increased OR; sitting and smoking led to a reduced OR.

CONCLUSIONS

The results support a dose-response relationship between kneeling/squatting and symptomatic knee OA in men and, for the first time, in women. The results concerning general and occupational predictors for knee OA reflect the findings from the literature quite well. Yet occupational risks such as jumping or climbing stairs/ladders, as discussed in the literature, did not correlate with symptomatic knee OA in the present study. With regards to occupational health, prevention measures should focus on the reduction of kneeling activities and the lifting and carrying of loads as well as general risk factors, most notably the reduction of obesity. More intervention studies of the effectiveness of tools and working methods for reducing knee straining activities are needed.

Case-control study of knee osteoarthritis and lifestyle factors considering their interaction with physical workload

AIMS

The aim of this study is to examine the dose-response relationships between age, "lifestyle factors" (body mass index, tobacco smoking, sports), and symptomatic knee osteoarthritis in a population-based case-control study. Additionally, the study aims to investigate the mode of interaction between body mass index (BMI) and physical workload (occupational kneeling/squatting and lifting/carrying of loads) with respect to the risk of symptomatic knee osteoarthritis.

METHODS

In five orthopedic clinics and five practices, 295 male patients aged 25-70 with radiographically confirmed knee osteoarthritis associated with chronic complaints were recruited. The control group comprised 327 male control subjects. In a structured personal interview, body weight at different ages, body height, cumulative amount of smoking, and cumulative duration of different sports activities until the date of first diagnosis of knee osteoarthritis were elicited. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis. An interaction analysis for the parameters BMI and kneeling/squatting respective lifting/carrying of loads was performed. Population attributable risks (PAR) for knee osteoarthritis were determined for BMI solely and for the combination of BMI with occupational kneeling/squatting and lifting/carrying of loads, respectively.

RESULTS

Age and overweight were strongly associated with the diagnosis of knee osteoarthritis. Compared with persons less than 35 years old, persons who were at least 65 years old had an odds ratio (OR) of 19.0 (95% CI 6.1-58.7) for knee osteoarthritis. Persons with a BMI > or = 28.41 kg/m2 had a strongly elevated risk of knee osteoarthritis (OR 10.8; 95% CI 4.8-24.3) compared to persons with a BMI < 22.86 kg/m2. Heavy tobacco smoking (> or = 55.5 pack years) was associated with a decreased knee osteoarthritis risk in comparison with never-smoking (OR 0.2; 95% CI 0.1-0.5). Ball games (handball, volleyball, basketball) and cycling were associated with symptomatic knee osteoarthritis (OR 4.0; 95% CI 1.8-8.9 and OR 3.7; 95% CI 1.7-7.8 in the highest category of cumulative duration, respectively); to a weaker degree jogging, swimming, and soccer also were positively related to symptomatic knee osteoarthritis. Combining the two parameters, BMI and kneeling/squatting into one variable led to a multiplicative interaction mode for symptomatic knee osteoarthritis. For persons with elevated BMI in combination with moderate to high exposure to occupational kneeling/squatting, the population attributable risk (PAR) was 4%. The PAR for elevated BMI in combination with moderate to high exposure to occupational lifting/carrying of loads was 7%.

CONCLUSIONS

In accordance with the literature, we find a strong association between BMI and knee osteoarthritis risk. Considering the relatively high prevalence of occupational manual materials handling, prevention of knee osteoarthritis should not only focus on body weight reduction, but should also take into account work organizational measures particularly aiming to reduce occupational lifting and carrying of loads.

Risk factors for onset of osteoarthritis of the knee in older adults: a systematic review and meta-analysis

OBJECTIVE

Knee osteoarthritis (OA) is common in older adults. Determination of risk factors for onset of knee OA may help in its prevention. The objective of this systematic review, and meta-analysis, was to determine the current evidence on risk factors for knee OA.

DESIGN

A systematic literature search was carried out for cohort and case-control studies evaluating the association of demographic, comorbid, and other patient-determined factors with onset of knee OA. A scoring tool was developed to assess the quality of studies. Heterogeneity of studies was examined. Where possible studies were pooled to give an overall estimate of the association of factors with onset of knee OA.

RESULTS

Of the 2233 studies screened, 85 were eventually included in the review. Study quality tended to be moderate. The main factors consistently associated with knee OA were obesity (pooled OR 2.63, 95% CI 2.28-3.05), previous knee trauma (pooled OR 3.86, 95% CI 2.61-5.70), hand OA (pooled OR 1.49, 95% CI 1.05-2.10), female gender (pooled OR 1.84 95% CI 1.32-2.55) and older age. Smoking appeared to have a moderate protective effect, however this was not evident once the analysis was restricted to cohort studies only.

CONCLUSIONS

Whilst certain factors have been extensively reviewed (for example, body mass index), more longitudinal studies are needed to investigate the association of physical occupational and other patient-determined factors with future knee OA. The quality of such studies also needs to be improved. However, there are identifiable factors which can be targeted for prevention of disabling knee pain.

Smoking is associated with increased cartilage loss and persistence of bone marrow lesions over 2 years in community-based individuals

OBJECTIVE

To determine whether smoking is related to change in tibial and patella cartilage, and the development or persistence of bone marrow lesions (BMLs) over 2 years in a cohort of middle-aged adults.

METHODS

Two hundred and seventy-one adult subjects recruited from the Melbourne Collaborative Cohort Study underwent an MRI of their dominant knee at baseline and approximately 2 years later. Cartilage volume and BMLs were determined for both time points. At baseline, subjects also completed a questionnaire about current and past cigarette smoking.

RESULTS

Being a 'smoker' (former or current) was associated with increased annual loss of medial but not lateral or patella cartilage volume (medial: difference = 13.4 microl, P = 0.03; lateral difference = 4.86 microl, P = 0.45, patella difference = -2.57 microl, P = 0.79). A relationship between increasing pack-years smoked and increased medial cartilage volume loss was also observed (P = 0.04). Amongst people who had a BML at baseline, BMLs present in 'ever smokers' were 11.4 [95% confidence interval (CI) 1.54, 89.9; P = 0.02] times more likely to persist over 2 years than those present in 'never smokers'. In addition, the relationship between smoking and increased medial cartilage loss for subjects with a BML present at baseline was partially mediated by the persistence of the BMLs over 2 years.

CONCLUSION

This study contributes to the evidence of a detrimental effect of smoking on joint cartilage. Furthermore, it provides a possible mechanism that the association smoking shares with increased cartilage loss may be mediated via smoking impairing the ability for BMLs to resolve.

The inflammatory reflex and the role of complementary and alternative medical therapies

The body's first defense against invading pathogens or tissue injury is the innate immune system. Since excessive immune responses can be damaging, anti-inflammatory mechanisms function to control the pro-inflammatory response and prevent injury. The cholinergic anti-inflammatory pathway is a neural mechanism that suppresses the innate inflammatory response. Knowledge concerning innervation of the immune system offers a unique opportunity to explore previously unrecognized techniques to treat disease. It also enables consideration of the neurological basis of complementary and alternative medical therapies, such as meditation and acupuncture. This evolving area of research has implications for the pathogenesis of chronic inflammatory conditions including inflammatory bowel disease, rheumatoid arthritis, type 2 diabetes, and other conditions of excessive cytokine release.

Risk factors for knee osteoarthritis in Morocco. A case control study

Osteoarthritis (OA) of the knee is the most common form of arthritis. A positive association between obesity and several occupational factors and knee OA has been observed in previous studies in populations of different ethnicity. The aim of this study was to examine the relation between knee OA and body weight and occupational factors in a Moroccan sample of patients with knee OA. Our cases were consecutive patients diagnosed in our department with knee OA utilizing radiography in a 1-year period. No cases displayed established causes of secondary OA. Controls were selected randomly from the general population and were individually matched to each case for age and sex. Interviews were obtained from 95 cases and controls. Detailed information on general health status, height, weight, smoking habits, specific physical loads from occupation and housework, and sports activities was collected. The risk of knee OA increased with higher body mass index, odds ratio (OR) = 3.12 (95% confidence interval [CI] = 1.67-5.81; p < 0.0001). Sitting more than 3 h/day and climbing stairs more than 50 steps/day were associated with decreased risk of knee OA, OR = 0.29 (95% CI = 0.15-0.56; p = 0.02) and 0.48 (95% CI = 0.26-0.91; p < 0.0001), respectively. Overweight is a risk factor for knee OA, whereas sitting and climbing stairs are inversely associated with knee OA.

Hip osteoarthritis in a rural male population: A prospective population-based register study

OBJECTIVES

A cohort of rural men with urban referents was followed over 13 years to study the risk of developing osteoarthritis of the hip joint.

METHODS

A group of 1,220 farmers, 1,130 matched rural non-farming men, and 1,087 urban men were identified in 1989 and followed over time. Information on hospital care and surgery was obtained from the national Swedish register of hospital care and surgery.

RESULTS

More farmers than referents had been hospitalized for osteoarthritis and had undergone surgery for osteoarthritis of the hip joint. Hazard ratio for osteoarthritis of the hip joint was 3.0 (95% CI: 1.7-5.3) for farmers versus urban controls. Non-farming rural men had no increased risk as compared with urban referents.

CONCLUSION

Farmers but not non-farming rural men had a significantly increased risk of developing osteoarthritis of the hip joint as compared with urban referents.

Cigarette smoking and radiographic progression in rheumatoid arthritis

BACKGROUND

Smoking is a well-established environmental risk factor for the development of rheumatoid arthritis (RA). However, it remains unclear whether smoking influences RA disease progression and whether smokers have more radiographic damage progression than non-smokers over time.

OBJECTIVE

To compare the rates of radiographic damage progression in current smokers and non-smokers in a large prospective RA cohort.

METHODS

The SCQM-RA is a population-based registry monitoring disease activity, radiographic damage and symptoms at regular intervals. All patients in the SCQM-RA database with sequential plain radiographs were included. Joint erosions were assessed in 38 hand and foot joints with a validated scoring method. The rate of erosion progression was analysed using multivariate longitudinal regression models and adjusted for potential confounders.

RESULTS

2004 RA patients with a mean of 3.6 sequential radiographs and 3.1 years of follow-up were included. The 545 (27%) current smokers smoked on average 16 cigarettes per day and had a mean past smoking exposure of 20.6 pack-years. Radiographic joint damage progressed at a similar rate in current smokers and non-smokers (p = 0.26). However, smoking intensity was associated with a significant inverse dose-response; heavy smokers (>1 pack-day) progressed significantly less than non-smokers or moderate smokers (p<0.001).

CONCLUSION

Radiographic joint damage progressed at an equivalent rate in smokers and non-smokers. Furthermore, a significant trend was observed for reduced radiographic progression and generally more favourable functional scores among heavy smokers, suggesting that cigarette smoke does not accelerate RA disease progression.

Factors associated with pain and functional limitation in Japanese male patients with knee osteoarthritis

The present study investigated factors associated with knee pain and functional limitation in knee OA patients. Subjects were 109 Japanese males who were newly diagnosed with knee OA at three university hospitals over a 1-year period. Knee pain and functional limitation in walking and climbing and/or descending stairs were selected as outcome measures. To assess factors associated with outcomes, we calculated odds ratios (OR) using logistic regression analysis. Taller height (> or =163 vs. <163 cm) showed a negative association with knee pain, "Pain on walking": OR = 0.08, 95% confidence interval = 0.01-0.79; "Pain on stairs": 0.25, 0.08-0.82. A significant characteristic related to a lesser degree of functional disability was alcohol consumption ("Waking distance": 0.34, 0.14-0.84; "Help on stairs": 0.21, 0.09-0.51). In the present study, knee pain was associated with shorter height in male Japanese patients with knee OA. Functional limitation was associated with no consumption of alcohol.

A positive association of smoking and articular knee joint cartilage in healthy people

OBJECTIVE

To determine whether smoking affects knee cartilage in healthy adults by examining the association of tobacco use with tibial cartilage volume and tibiofemoral cartilage defects.

METHODS

Two hundred and ninety-seven healthy adult subjects were recruited from an existing cohort examining healthy aging, the Melbourne Collaborative Cohort Study (MCCS). Questionnaire data were obtained at recruitment to the MCCS in 1990-1994 and at magnetic resonance imaging to determine cartilage outcomes in 2003.

RESULTS

Tibial cartilage volume was positively associated with subjects who ever smoked as well as pack-years smoked, suggesting a dose-response. There was no association between smoking and presence of tibiofemoral cartilage defects.

CONCLUSION

Our findings demonstrate that smoking is associated with increased tibial cartilage volume but not presence of tibiofemoral cartilage defects, providing further support for a beneficial effect on articular knee cartilage.

Physiology and immunology of the cholinergic antiinflammatory pathway

Cytokine production by the immune system contributes importantly to both health and disease. The nervous system, via an inflammatory reflex of the vagus nerve, can inhibit cytokine release and thereby prevent tissue injury and death. The efferent neural signaling pathway is termed the cholinergic antiinflammatory pathway. Cholinergic agonists inhibit cytokine synthesis and protect against cytokine-mediated diseases. Stimulation of the vagus nerve prevents the damaging effects of cytokine release in experimental sepsis, endotoxemia, ischemia/reperfusion injury, hemorrhagic shock, arthritis, and other inflammatory syndromes. Herein is a review of this physiological, functional anatomical mechanism for neurological regulation of cytokine-dependent disease that begins to define an immunological homunculus.