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Abstract Background Obesity influences the development of osteoarthritis via low-grade inflammation. Progression of local inflammation (= synovitis) increased with weight gain in overweight and obese women compared to stable weight. Synovitis could be associated with subcutaneous fat (SCF) around the knee. Purpose of the study was to investigate the effect of weight loss on synovitis progression and to assess whether SCF around the knee mediates the relationship between weight loss and synovitis progression. Methods We included 234 overweight and obese participants (body mass index [BMI] ≥ 25 kg/m2) from the Osteoarthritis Initiative (OAI) with > 10% weight loss (n = 117) or stable overweight (

Summary: Objective: With adults working to older ages, occupation is an important, yet less modifiable domain of physical activity to consider in the risk of knee osteoarthritis (OA). This study aimed to investigate the association between predominant lifetime occupation and prevalent knee OA. Design: Participant-level data were used from five international community-based cohorts: Johnston County Osteoarthritis Project, the Hertfordshire Cohort Study, the Multicenter Osteoarthritis Study, the Tasmanian Cohort Study and Framingham Osteoarthritis Study. Self-reported predominant occupation was categorized into sedentary, light, light manual and heavy manual levels. Cross-sectional associations between predominant lifetime occupation and knee OA outcomes including prevalence of radiographic knee OA (RKOA), symptomatic RKOA and knee pain, were assessed using logistic regression, accounting for cohort clustering. Results: Data for 7391 participants were included. 24.7% reported sedentary lifetime occupation, 30.0% light, 35.9% light manual and 9.4% heavy manual. 43.3% presented with RKOA, 52.1% with knee pain and 29.0% with symptomatic RKOA. There was over a two-fold increase in the odds of having RKOA, knee pain and symptomatic RKOA in those whose with heavy manual compared to sedentary occupations ((odds ratio (OR): 2.14; 95% confidence interval (CI): 1.79, 2.58), (OR: 2.19; 95% CI: 1.78, 2.70), (OR: 2.41; 95% CI: 1.94, 2.99) respectively). Conclusion: This large international multi-cohort study demonstrated an association of heavy manual work with RKOA, symptomatic RKOA and knee pain. Measures that protect workers and are designed to reduce heavy manual related activities remain a priority to reduce the risk of knee OA.

Weakness has been documented as a feature of tibiofemoral knee osteoarthritis (OA) and may cause disease in this compartment by shock absorption during impulse loading at heel strike, when the patellofemoral joint is not engaged. Our objective was to determine the association of muscle weakness with compartment‐specific knee OA, to evaluate sex‐specific differences in this relationship, and to determine, by evaluating asymptomatic individuals with OA, whether symptoms may produce the weakness seen in OA.This cross‐sectional study involved 2,472 subjects (1,475 women and 997 men) ages 60 years or older from 4 central districts of Beijing, China. For all subjects, a skyline view of each knee and an anteroposterior (AP) or posteroanterior (PA) radiograph of both knees were obtained during weight bearing. Radiographs were read by one reader for Kellgren/Lawrence (K/L) grade, joint space narrowing (JSN), and osteophytes. We defined a subject as having tibiofemoral OA when the K/L grade was ≥2 on AP/PA view, patellofemoral OA on skyline view when the osteophyte score was ≥2 (or when the JSN score was ≥2 and the osteophyte score was ≥1), and mixed OA when the knee had both patellofemoral and tibiofemoral radiographic OA. Strength was measured isometrically for each leg separately, and knee pain was evaluated by questionnaire.In women, quadriceps weakness was associated with tibiofemoral OA (odds ratio [OR] 0.7, 95% confidence interval [95% CI] 0.4–1.0), patellofemoral OA (OR 0.6, 95% CI 0.4–0.9), and mixed OA (OR 0.4, 95% CI 0.3–0.6). In men, weakness was associated with mixed OA (OR 0.5, 95% CI 0.3–0.8), and the ORs suggesting an association of patellofemoral OA with weakness were the same as those in women, although in men this trend did not reach statistical significance (P = 0.12). In men, isolated tibiofemoral disease was not associated with weakness; however, the sample size in this analysis was limited. When subjects with knee symptoms were excluded, the relationship of quadriceps weakness to OA was attenuated, with only the relationship between muscle weakness and mixed OA remaining significant.There is a relationship between quadriceps weakness and knee OA in all compartments, with the strongest association in mixed disease. Pain may contribute to some of this weakness. [ABSTRACT FROM AUTHOR]