Background Obesity is the strongest modifiable risk factor for development and progression of knee osteoarthritis (OA). There is emerging evidence for a beneficial effect of weight loss on knee structure. The amount of weight loss necessary for any knee structural benefits is not known.
Objectives The aim of this longitudinal study was to examine the effect of weight loss on change in knee cartilage volume in an obese cohort.
Methods 250 subjects were recruited from various community sources targeting weight loss. Of these subjects, 67 obese subjects (BMI ≥ 30 kg m-2) achieved weight loss (> 0kg) over the study period. Anthropometric (weight and height) and knee cartilage volume (determined by magnetic resonance imaging) measures were assessed at baseline and an average of 2.4 years (range 1.7 – 3.9 years) later.
Results Weight loss was associated with a non-linear reduction in the rate of medial knee cartilage loss. For weight loss between 0 to 7.5% of initial body weight, there was a progressive reduction in cartilage loss (β = 0.64% (95% CI -1.2 - -0.08%; p = 0.03). However, when greater weight loss (> 7.5%) was achieved, there was no additional beneficial effect on cartilage change (β = -0.03% (95% CI -0.17 - 0.20%; p = 0.79). There were no significant relationships between weight loss and change in cartilage volumes at either the lateral tibia or patella.
Conclusions The relationship between weight loss and medial knee cartilage volume loss is non-linear with even as little as 1% weight loss slowing the progression toward clinical knee OA. Weight loss of up to 7.5% of body weight virtually stops cartilage loss over a period of just over 2 years. Whether the rate of loss of articular cartilage remains static over a longer time-frame in a population who on average, still remains obese, requires further investigation. Nonetheless these results infer that modest weight loss may help to prevent or at least retard the progression of obesity related knee OA.
Disclosure of Interest None Declared
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