Background Although being overweight or obese is an important risk factor for the development of knee osteoarthritis (OA), the complex interplay between weight and genetic factors on the early-onset knee OA is still unclear.
Objectives To determine the effects of weight on knee cartilage volume, defects and knee pain over 10 years in offspring having at least one parent with a total knee replacement for severe primary knee OA and in controls with no family history of knee OA.
Methods 372 participants (186 offspring and 186 controls) aged from 26–61 years were recruited at baseline, and followed at 2.3 (Phase 2) and 10.2 (Phase 3) years later. T1-weighted magnetic resonance imaging (MRI) of the right knee was used to measure cartilage volume and defects at each time-point. Knee pain was only assessed at Phase 2 and Phase 3 using Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Data were analysed using mixed-effects model with adjustment for potential confounders.
Results Study participants were middle-age adults (mean age 45 years and mean weight of 77.5 kg) at baseline. In multivariable analysis, increasing body weight was negatively associated with medial tibiofemoral cartilage volume (β=-0.28 ml, per 1 SD increase, 95% CI -0.49 to -0.07) and the presence of medial tibiofemoral cartilage defects (OR=1.70, per 1 SD increase, 95% CI 1.20 to 2.33) in offspring over 10.2 years. Similar associations were observed for lateral tibiofemoral cartilage volume (β=-0.19 ml, P=0.059), and defects (OR=1.56, P=0.050). Over 7.9 years, body weight was positively associated with total knee pain (β=1.78, per 1 SD increase, 95% CI 0.49 to 3.06) and all pain subscales (β=0.36 to 0.58, all P<0.05) apart from sitting and standing in offspring while adjusting for potential confounders and knee structural factors. There were no statistically significant associations between weight, and cartilage volume or defects or pain in controls (all P>0.05).
Conclusions Body weight is associated with knee cartilage volume, defects and pain in offspring of parent with primary knee OA but not in controls, suggesting an interplay between genetic factors and overweight/obesity in the pathogenesis of early knee OA.
Disclosure of Interest None declared
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