s / Osteoarthritis and Cartilage 21 (2013) S63–S312 S83 Mice were maintained individually under standardized conditions with open access to food and water and a daily orally dosage of 0.15 mg/g body weight of FORTIGEL or placebo. The development of osteoarthritis in knee joints was scored 0 4 in haematoxylin stainings. Osteoarthritis was assessed as 0 1⁄4 no apparent changes; 1 1⁄4 loss of superficial zone; 2 1⁄4 defects limited above tidemark; 3 1⁄4 defects extending to calcified cartilage and 4 1⁄4 exposure of subchondral bone. Additionally to histochemical classification the plasma adiponectin levels in the STR/ort mice were tested over the time of experimentation. A possible correlation between grade of osteoarthritis and different osteoarthritic risk factors like obesity, aging and moreover, of adiponectin plasma level were assessed. Analysis of variance was performed using the Kruskal-Wallis test. For comparison of collagen hydrolysate and placebo treated animal cohorts the Mann-Whitney U-test was used. Correlations of osteoarthritic changes, weight gain and adiponectin plasma level were analyzed according to Pearson. P values