Method

According to the preliminary performed power analysis we did a prospective controlled study including 151 patients which were randomized in a group A (OrthoPAT® for intra- and postoperative blood salvage and retransfusion, n=76 patients) and a control group B (no retransfusion system was used, n=75 patients). All patients had a primary osteoarthritis of the knee and were operated on without use of a tourniquet. We implanted in all patients a cemented posterior stabilized total knee prosthesis design. In group A the autotransfusion system was used for 6 hours (intra- and postoperatively) and the collected blood was retransfused. The retransfused blood was anticoagulated, filtered and centrifuged to separate waste products. Red cells were washed with saline and reconcentrated to a high hematocrit. The preoperative data for cardiopathy, angiopathy, preoperative anemia or anticoagulant treatment showed no significant differences for group A and B. Because of missing data we finally were able to use the results of 140 patients: 70 group A and 70 in group B. The indications for a blood transfusion were influenced by the clinical symptoms of anemia, the hemoglobin value (hemoglobin < 8.0 g/dl) and the anamnesis of cardiovascular diseases. Evaluation was done with the medical history and the pre-/postoperative hemoglobin values and postoperative need of allogenic blood transfusion.