To explore the influence of postoperative pain of discoid meniscus under arthroscopy on knee function and cartilage metabolism in the short term and to analyze its risk factors.

From January 2017 to December 2018, 152 patients with lateral discoid meniscus of knee joint admitted to the Department of Sports Medicine, Qilu Hospital, Shandong University were all treated with arthroscopic meniscus suture. Those with VAS pain score ≥1 three months after operation were included in pain group (n=43), and the rest were included in painless group (n=109). The Lysholm knee score scale (LKSS) and Hospital of Special Surgery (HSS) knee score were used to evaluate the knee function of the two groups before and after treatment. Enzyme-linked immunosorbent assay (ELISA) was used to detect and compare cartilage metabolism indexes in joint fluid of the two groups, and multivariate logistic regression analysis was conducted to analyze the risk factors of postoperative pain.

LKSS and HSS scores of both groups were significantly higher in three months after the surgery than those before the surgery(all P<0.01), and the pain group were significantly lower than the painless group (t=12.217, 5.928, both P<0.01). Serum metalloproteinase (MMP) -1, MMP-3 and tissue inhibitor of metalloproteinase-1 (TIMP-1) levels in the two groups of joint fluid were significantly lower than those before surgery (all P<0.01), and the levels of the painless group were significantly lower than those of the pain group (t=7.230, 12.411, 11.504, all P<0.01). Multivariate logistic regression analysis showed that age, articular cartilage injury and loading time ≥one week were independent risk factors for postoperative pain (OR=5.068, 7.893, 8.142, P<0.05), postoperative cold compress as a protective factor (OR=0.150, P<0.05).

The treatment of discoid meniscus by arthroscopic meniscus suture and plasty can achieve better knee function and improve the intra-articular environment in the short term. Postoperative pain will have a negative impact and there are many risk factors, which should be paid attention to and prevented in clinical practice.