Abstract: Objective　To explore the serum expression of thrombospondin-1 (TSP-1) and clinical significance in patients with knee osteoarthritis. Methods　A total of 186 patients with knee osteoarthritis were selected. According to KL classification, the patients were divided into KL 0 group (n= 44), KLⅠgroup (n= 52), KLⅡgroup (n=39), KL Ⅲ group (n= 28) and KL Ⅳ group (n=23). The control group were included 170 healthy people in our hospital. The serum level of TSP-1 was detected by enzyme-linked immunosorbent assay (ELISA), and the correlation between TSP-1 and the severity and clinical indicators of osteoarthritis was analyzed. The subject performance characteristic curve (ROC) was drawn to obtain the optimal threshold value of TSP-1 to predict osteoarthritis. Results　The serum level of TSP-1 was significantly higher in osteoarthritis group than that in control group (P＜0.05). Compared with patients of KL 0 group, the serum TSP-1 levels were significantly higher in KLⅠ, KL Ⅱ, KL Ⅲ and KL Ⅳ groups (P＜0.05). Compared with patients of KLⅠgroup, the serum TSP-1 levels were significantly higher in patients of KL Ⅲ and KL Ⅳ groups (P＜0.05). Compared with patients of KLⅡ and KLⅢgroups, the serum TSP-1 levels were significantly higher in patients of KLⅣgroup (P＜0.05). The serum TSP-1 level was positively correlated with erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), cartilage oligomeric matrix protein (COMP), matrix metalloproteinase-13 (MMP-13) and transforming growth factor-β1 (TGF-β1) levels. The ROC results showed that the optimal threshold of serum TSP-1 for the diagnosis of osteoarthritis was 250.9 μg/L (sensitivity=81.1%, specificity=81.9%). Conclusion　The serum level of TSP-1 is abnormally high in patients with osteoarthritis, which is closely related to the severity of osteoarthritis.

Key words: osteoarthritis, knee, transforming growth factor beta, KL classification, thrombospondin-1