Abstract: BACKGROUND: Lower extremity deep vein thrombosis is a common complication after hip and knee arthroplasty. There are many introductions about its influencing factors, but there are few introductions about the thresholds of influencing factors.  
OBJECTIVE: To investigate the diagnostic value of D-dimer, erythrocyte sedimentation rate and C-reactive protein in deep vein thrombosis of lower limbs after hip and knee arthroplasty.
METHODS:  The clinical data of 216 patients who underwent hip and knee arthroplasty in Hebei Provincial People’s Hospital from January 2018 to November 2020 were retrospectively analyzed, including 77 cases of total knee arthroplasty, 31 cases of unicondylar arthroplasty, 35 cases of total hip arthroplasty, and 73 cases of hemiarthroplasty of the hip. Color Doppler ultrasonography of deep veins in both lower extremities was performed on the first day after surgery, and the diagnosis of deep vein thrombosis in lower extremities was confirmed by more than two attending physicians. Among them, there were 86 patients with lower extremity deep vein thrombosis and 130 patients without deep vein thrombosis. The rates of deep vein thrombosis in lower limbs were compared. According to the criteria of age, gender and replacement type, 86 patients without lower extremity deep vein thrombosis after surgery were selected as the control group using PSM propensity score matching method. The levels of plasma D-dimer, albumin and hemoglobin in 172 patients (86 patients in the thrombosis group and 86 patients in the control group) were compared, and the diagnostic efficacy of each index in the diagnosis of lower extremity deep vein thrombosis after hip and knee arthroplasty was analyzed by ROC curve.  
RESULTS AND CONCLUSION: (1) Compared with the control group, the D-dimer level of 172 patients in thrombus group was increased (P < 0.05). (2) The sensitivity and specificity of D-dimer for the diagnosis of deep vein thrombosis of lower extremity after hip arthroplasty were 71.8% and 74.1%. The time sensitivity and specificity of prothrombin were 66.7% and 66.7% respectively. The sensitivity and specificity of erythrocyte sedimentation rate were 61.5% and 70.4%. The sensitivity and specificity of C-reactive protein level were 94.9% and 33.3% respectively. The age sensitivity was 71.8% and the specificity was 100%. (3) The sensitivity and specificity of D-dimer for the diagnosis of deep venous thrombosis of lower extremity after knee arthroplasty were 78.7% and 44.1%, respectively. (4) The above data confirmed that the sensitivity of D-dimer level indicators in the diagnosis of deep vein thrombosis of lower extremities after knee replacement was higher, while the sensitivity and specificity of prothrombin time, erythrocyte sedimentation rate, C-reactive protein level and age in the diagnosis of deep vein thrombosis of lower extremities after hip arthroplasty were higher.

Key words: hip arthroplasty, knee arthroplasty, deep vein thrombosis of lower limbs, D-dimer, erythrocyte sedimentation rate, C-reactive protein, sensitivity, specificity, diagnosis