To investigate the correlation between the pathological characteristics of knee osteoarthritis under arthroscope and the levels of serum microRNA-27a (miRNA-27a) and toll-like receptor 4 (TLR4).

From April 2019 to October 2020, 170 patients with knee osteoarthritis who underwent arthroscopic surgery in the Central Hospital of Enshi Tujia and Miao Autonomous Prefecture and treated under arthroscope were selected as the knee osteoarthritis group, and 170 healthy people at the same time were selected as the control group. Those with incomplete clinical data were excluded. The serum levels of miRNA-27a and TLR4 were detected by real-time fluorescence quantitative PCR and enzyme linked immunosorbent assay, the pathological characteristics of the patients were observed under arthroscopy, including the degree of cartilage injury, meniscus injury, synovial changes, free body and bone hyperplasia, the differences of serum levels of miRNA-27a and TLR4 in the patients with knee osteoarthritis with different pathological features were analyzed by one way ANOVA. The relationship between serum miRNA-27a and TLR4 levels in the patients with knee osteoarthritis was analyzed by Pearson test.

The level of serum miRNA-27a in the knee osteoarthritis group was significantly lower than that in the control group (t=53.706, P <0.05), and the level of serum TLR4 was significantly higher than that in the control group (t=47.037, P<0.05), and there was a negative correlation between them (r=-0.462, P<0.05). The levels of serum miRNA-27a in patients with different degrees of cartilage injury and meniscus injury were grade I, II, III and IV from high to low, and the levels of serum TLR4 were grade IV, III, II and I from high to low; the total differences among the groups were statistically significant(F=88.792, 76.093, 81.652, all P<0.05); the levels of serum miRNA-27a in patients with different synovial change grades were grade I, II and III from high to low, and the levels of serum TLR4 were grade III, II and I from high to low, total differences among the groups were statistically significant (F=25.581, 24.999, 12.426, all P<0.05). There were statistically significant differences between the different grades (all P<0.05). The level of serum miRNA-27a in the patients with loose body and hyperosteogeny grade I was significantly lower than the patients with grade zero (t=7.280, 6.756, both P <0.05), and the level of serum TLR4 in the patients with loose body and hyperosteogeny grade I was significantly higher than the patients with grade zero (t=5.511, 5.128, both P<0.05).

The level of serum miRNA-27a is decreased and the level of serum TLR4 is increased in patients with knee osteoarthritis. The changes of both levels are related to the characteristics of arthroscopic lesions.