To explore the clinical effect of intra-articular injection of platelet-rich plasma （PRP） combined with arthroscopic surgery and its influences on serum Toll-like receptor 4 （TLR-4） and matrix metalloproteinase-3 （MMP-3） in knee osteoarthritis （KOA）.

A total of 100 patients with KOA treated in the Second Department of Orthopedics, the Second Affiliated Hospital of Xingtai Medical College were enrolled as the research objects between January 2024 and January 2025. According to random number table method， they were divided into control group （arthroscopic minimally invasive debridement + injection of hyaluronic acid） and study group （arthroscopic minimally invasive debridement + intra-articular injection of PRP）， 50 cases in each group. The curative effect was compared between the two groups， and evaluation of curative effect was performed at 3 months after treatment. According to 4-level evaluation system， effective rate was calculated. The pain degree was compared between the two groups by numerical rating scale for pain （NRS）, the impairment of knee function was compared by Western Ontario and McMaster universities osteoarthritis index （WOMAC）, the range of motion （ROM）， Lysholm score， levels of serum TLR-4 and MMP-3 7 days after surgery were compared.

The total response rate of study group was higher than that of control group （90.00% vs 70.00%， χ²=6.250， P<0.05）. After treatment， NRS scores were decreased in both groups （t_{study group}=20.944， t_{control group}=17.821； both P<0.001）， which were lower in study group than control group （t=9.909， P<0.001）. After treatment， WOMAC scores were decreased in both groups （t_{study group}=13.900， t_{control group}=9.266； both P<0.001）， which were lower in study group than control group （t=4.416， P<0.05）. After treatment， range of motion and Lysholm score were increased in both groups （range of motion： t_{study group}=22.921， t_{control group}=16.993， both P<0.001； Lysholm score： t_{study group}=14.637， t_{control group}=7.975， both P<0.001）， which were higher in study group than control group （t_{range of motion}=3.273， P=0.002， t_{Lysholm score}=5.718， P<0.001）. After treatment， levels of MMP-3 and TLR-4 were decreased in both groups （MMP-3： t_{study group}=8.063， P<0.001， t_{control group}=3.108， P=0.003； TLR-4： t_{study group}=20.640， t_{control group}=16.492， both P<0.001）， which were lower in study group than control group （t_MMP-3=5.788， t_TLR-4=4.669，both P<0.001）. There was no significant difference in the incidence of complications between the two groups （χ²=0.400， P>0.05）.

Curative effect of intra-articular injection of PRP combined with arthroscopic debridement is significant in KOA patients， which can significantly relieve pain， delay disease progression， improve knee function and has more advantages in reducing TLR-4 level and regulating MMP-3 level.