Objective:To investigate the diagnostic value of erythrocyte sedimentation rate/C-reactive protein (ECR), fibrinogen and D-dimer in periprosthetic infection after artificial knee replacement.Methods:A total of 205 patients, including 62 males and 143 females, aged 66.9±9.5 years (range 26-84 years), who underwent revision of artificial knee joint at Department of Joint Surgery, The First Affiliated Hospital of Xinjiang Medical University from January 2017 to December 2021 were retrospectively collected.122 cases of periprosthetic joint infection (PJI), including 43 cases of acute infection; 79 cases of chronic infection (13 cases of chronic infection combined with rheumatoid arthritis were analyzed separately); there were 83 cases without PJI, including 73 cases of aseptic loosening, 8 cases of prosthesis dislocation and 2 cases of joint stiffness. Erythrocyte sedimentation rate, C-reactive protein, white blood cell count, fibrinogen and D-dimer levels were examined before surgery, and the sensitivity and specificity of the indicators were calculated using the receiver operating characteristic (ROC) curve. The diagnostic value of different inflammatory markers was compared according to the area under curve (AUC).Results:The levels of ECR, erythrocyte sedimentation rate, C-reactive protein, fibrinogen, and D-dimer in acute PJI group were 2.47±2.91, 50 (38, 62) mm/1 h, 31.6 (13.9, 79.3) mg/L, 4.25±0.94 g/L, 763 (453, 1 157) ng/ml, respectively. The chronic PJI group was 3.06±2.95, 50 (34, 64) mm/1 h, 20.4(12.7, 43.3) mg/L, 4.19±0.91 g/L, 586 (317, 1 122) ng/ml, and the non-PJI group was 6.20±4.64, 22 (15, 34) mm/1 h, 4.6 (2.7, 7.74) mg/L, 3.10±0.59 g/L and 363 (181, 591)ng/ml were statistically significant ( P<0.05). The AUC of ECR, erythrocyte sedimentation rate, C-reactive protein, fibrinogen, and D-dimer in the acute PJI group were 0.82, 0.85, 0.90, 0.88, and 0.76, respectively.The optimal critical values were 2.89, 37.00 mm/1 h, 13.6 mg/L, 3.86 g/L, and 443.0 ng/ml, respectively, with sensitivity of 76.7%, 79.1%, 76.7%, 69.8%, and 82.4%, and specificity of 79.5%, 78.3%, 94.0%, 94.0%, 90.4%, and 63.8%, respectively. The AUC of ECR, erythrocyte sedimentation rate, C-reactive protein, fibrinogen, D-dimer, and white blood cell count in the chronic PJI group were 0.77, 0.82, 0.87, 0.85, 0.67, and 0.63, respectively. The optimal critical values are 2.91, 33.00 mm/1 h, 10.9 mg/L, 4.01 g/L, 558.5 ng/ml, and 5.575×10 9 /L, respectively, with sensitivity of 68.2%, 78.8%, 81.8%, 63.6%, 57.9%, and 75.8%, and specificity of 79.5%, 73.5%, 88.0%, 95.2%, 72.5%, and 49.4%, respectively. Conclusion:Fibrinogen has a higher diagnostic value for knee joint PJI, followed by ECR, and D-dimer has the lowest diagnostic value for knee joint PJI.