Background We previously showed that middle-aged women free of clinical knee osteoarthritis (OA), but at high-risk for future OA development due to a BMI ≥27 kg/m2, had a high prevalence of OA features on MRI . Subjects with a steadily decrease in body weight over 30 months (-9.0±7.2 kg), did not show a significantly different progression of these features, compared to those without loss in body weight .
Objectives To explore the effects of differences in body weight in the years prior to inclusion on the prevalence of knee OA on MRI at baseline, to discuss the optimal timing for preventive weight loss strategies for OA development.
Methods Data from the PROOF study (ISRCTN 42823086) were used . At baseline, women aged 50–60, with a BMI ≥27 kg/m2 were recruited. At inclusion, the women were free of clinical knee OA. At baseline, all participants filled-in a questionnaire for demographic data, including body weight at age 40, and body weight and height were measured. BMI at 40 years and at baseline was calculated and classified into normal weight (BMI <25 kg/m2), overweight (BMI ≥25 and <30 kg/m2) and obesity (BMI ≥30 kg/m2). MRI scans of both knees was made on a 1.5 Tesla scanner. All MRIs were scored using the semi-quantitative MRI Osteoarthritis Knee Score (MOAKS) and MRI OA was defined in all knees was defined using published definitions . Using logistic regression, the percentages of women with MRI OA, with unilateral MRI OA, bilateral MRI OA, and with ≥2 affected compartments were compared, using the normal/overweight group as reference.
Results 374 women had all baseline measurements available and were selected. At baseline, 127 women were overweight and 248 were obese. Mean age was 55.7±3.2 years. Of the baseline obese women, 11% (26 women) reported normal weight, 52% (130 women) overweight and 37% (92 women) obesity at 40 years. Of the baseline overweight women, 39% (49 women) reported normal weight, 61% (77 women) overweight and 1 woman reported obesity at 40 years (see figure).
Baseline prevalence of MRI OA, of unilateral/bilateral MRI OA, and the percentage of women with ≥2 affected compartments, out of both TF and both PF compartments, are presented in the table.
Conclusions Women with higher body weight at 40 years showed higher prevalence of knee OA on MRI at the age of 56. It is highly questionable whether OA related structural abnormalities seen on MRI are reversible. It is suggested that body weight reduction around the age of 40 might be much more effective for the prevention of future knee OA development than it would be at the age range of 50 to 60 years, where radiographic and clinical knee OA usually develops.
Landsmeer M, Runhaar J, et al. Reducing progression of knee OA features assessed by MRI in overweight and obese women: secondary outcomes of a preventive RCT. OA&C, 2016;24:982–90.
Landsmeer M, de Vos B, et al. Effect of weight change on progression of knee OA features assessed by MRI in high-risk overweight and obese women. OA&C, 2016;24:S263–S264.
Runhaar J, van Middelkoop M, et al. Prevention of knee osteoarthritis in overweight females: the first preventive randomized controlled trial in osteoarthritis. Am J Med. 2015;128(8):888–895.e4.
Hunter D, Arden N, et al. Definition of osteoarthritis on MRI: results of a Delphi exercise. OA&C, 2011;19(8):963–9.
Disclosure of Interest None declared