Comparison of Bleeding Following Two Different Systems of Total Knee Arthroplasty: Medial Pivot Versus Posterior Stabilizer

Bleeding is the most common post-operative complication of knee arthroplasty. Arthroplasty systems with posterior cruciate ligaments potentially affected the amount of postoperative bleeding due to a lower need for bone cutting. In this study, two types of prosthesis, including preserving and not preserving posterior cruciate ligament (PCL), were compared in terms of post-operative bleeding. In the current cohort study, 100 patients participated in this study and were divided to two groups: 50 patients were treated by using posterior stabilized (PS) system and 50 patients were treated through the Wright cruciate retaining (CR) system with a medial pivot mechanism. Blood loss during surgery and hemoglobin and hematocrit levels were measured for three days after surgery. In the first group, the amount of collected blood through the drainage tube in first group was 261.87 cc and in the second group this was 225.86 cc, (P = 0.42). After three days the mean drop in hemoglobin in PS group was 2.69 g/dL and in the CR group, this was 2.77 g/dL (P = 0.741). Hemoglobin declined on the second day after surgery, to approximately 3.5 g/dL and 2.74 g/dL for the PS and CR group, respectively, and was significantly higher in the PS group (P = 0.003), and the blood loss in the two groups of nPS and CR were 92 cc and 71 cc, respectively (P = 0.003). The mean blood transfusion per patient in the PS group was 1.2 unit, which was significantly higher than the CR group with mean of 0.78 unit per patient (P = 0.012). The PS system (Zimmer company product) leads to greater bleeding during the three days, which increased the need for blood transfusion. Consequently, the type of implanted prosthesis could influence the amount of bleeding. In certain circumstances, prevention of postoperative bleeding is crucial, and prostheses can be most beneficial to reduce the amount of acute bleeding in the patient.