Comparison of Blood Loss between Open‐Box Prosthesis and Closed‐Box Prosthesis after Primary Total Knee Arthroplasty

OBJECTIVE: To compare the blood loss after procedures of primary unilateral or one‐stage bilateral total knee arthroplasty (TKA) caused by open‐box prosthesis and closed‐box prosthesis. METHODS: This was a retrospective study. Patients undergoing procedures of primary TKA between January 2017 and July 2020 in our institution were assessed for eligibility for this study. Those who were diagnosed with knee osteoarthritis and underwent primary unilateral or one‐stage bilateral TKA by using PFC Sigma PS150 (closed‐box prosthesis) or Vanguard (open‐box prosthesis) knee systems and had complete data of laboratory indexes on postoperative day (POD) 1, POD 3, and POD 5 were the interested population. At last 243 patients were enrolled, among which 88 patients were classified into the unilateral closed‐box group, 66 patients into the unilateral open‐box group, 47 patients into the one‐stage bilateral closed‐box group, and 42 patients into the one‐stage bilateral open‐box group. The perioperative management and operative techniques were almost the same for each patient, except the selection of prosthesis, which was decided according to surgeon's preference. The baseline information, postoperative laboratory indexes tested on POD 1, POD 3, and POD 5 including hemoglobin, hematocrit, platelet, thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (APTT), and international normalized ratio (INR), the primary outcome measurements including the maximum decreased value of hemoglobin and the volume of total blood loss, and the secondary outcome measurements including the transfusion rate and the average transfused red blood cell (RBC) units were well compared between the open‐box group and the closed‐box group. RESULTS: The baseline was comparable between groups, except higher preoperative levels of hemoglobin (134.43 g/L vs 126.51 g/L, P = 0.003) and hematocrit (39.92% vs 37.37%, P = 0.000) observed in the one‐stage bilateral open‐box group. The differences of postoperative coagulation function monitored by TT, PT, APTT, and INR were clinically irrelevant between groups. For patients receiving unilateral TKA, significantly higher value of decreased hemoglobin (26.06 g/L vs 21.05 g/L, P = 0.025) and significantly larger amount of total blood loss (920.34 mL vs 723.19 mL, P = 0.013) were observed in the open‐box group. For patients receiving one‐stage bilateral TKA, the open‐box prosthesis was observed to cause more hemoglobin drop (37.81 g/L vs 32.02 g/L, P = 0.071) and total blood loss (1327.26 mL vs 1177.42 mL, P = 0.247) compared to the closed‐box prosthesis, though the differences were not significant. The transfusion rate and the average transfused RBC units were not significantly different between the open‐box group and the closed‐box group no matte whether the patients were from the unilateral TKA group or from one‐stage bilateral TKA group. CONCLUSION: The use of open‐box prosthesis caused more hemoglobin drop and total blood loss than closed‐box prosthesis after primary unilateral or one‐stage bilateral TKA, resulting in comparable transfusion rate and average transfused RBC units between groups.