Knee flexion significantly reduces blood loss and transfusion rate after uncemented total knee arthroplasty

摘要

Our aim was to evaluate post-operative knee flexion at 90° on a CPM machine as an effective, reliable and easily accessible means of reducing blood loss after knee arthroplasty. We performed a case-control study on 100 patients undergoing uncemented posterior cruciate retaining total knee arthroplasty. Two groups of 50 patients each were treated in a standard fashion, except for the use of the CPM machine to flex the knee at 90° and without using suction drains in one group. This set up was arranged in theatre and was in situ for 24 hours after surgery. For first two hours the knee was maintained at 90° flexion on a static CPM machine followed by dynamic CPM to allow 30° to 60° flexion for next 22 hours. We measured postoperative change in haemoglobin, haematocrit, and blood drained in first 24 hours. Range of motion was assessed, as were any complications. We found a statistically significant reduction in blood loss without compromising range of motion and without an increase in complications. We recommend the use of CPM machine as a safe and reliable means of significantly reducing blood loss by flexing the knee after total knee arthroplasties. Introduction Blood loss following total knee replacement (TKR) can be substantial. The total mean blood loss has been described in the literature to be up to 1474ml, of which up to 735ml can be hidden loss into the tissues [4].Since knee arthroplasties are generally performed under tourniquet control, most blood loss occurs in the postoperative period. There are increased concerns regarding transfusion-associated infections and reactions and the cost of blood transfusions. A review of literature demonstrates a wide range of transfusion requirement in up to 45% to 80% of patients undergoing TKR [1]. Problems with suction drains include blood loss, obstruction and increased infection [10,11]. A variety of strategies to reduce blood loss following TKR have been described in the literature. These include the use of procoagulant drugs [7], clamping the suction drains, elevating the leg at 35 degree without flexing the knee [5] or flexing the knee on a special 90/90 pillow [9]. Flexing the knee at after 90 ° TKR significantly reduces blood loss probably by increasing the tension of the soft tissues and thereby decreasing the dead space available for bleeding [8]. The most probable reason for lack of popularity of pillows appears to be practical difficulties in finding and using these specially designed pillows. There is also a theoretical risk of compression of the popliteal vein, leading to an increased risk of DVT with this method[5]. We devised a novel method of maintaining the knee at 90 ° flexion after the operation by using the familiar and readily available CPM machine. The aim of our study was to evaluate the effectiveness of the CPM machine in substantially reducing blood loss after knee arthroplasty and thereby reducing the requirement for allogenic blood transfusion. Material and methods A retrospective case-control study was performed over 6 months (May 2004 to October 2004). Inclusion criteria were patients admitted in the department undergoing elective uncemented TKR for painful osteoarthritis of the knee. Patients with bleeding disorders, peripheral vascular disease, or anticoagulant medications were excluded from the study.A total of one hundred patients identified for the study were split into a control group (knee in extension with post-operative suction drain) and the treatment group (knee at 90 ° flexion after the operation on the CPM machine). There were fifty patients in each group.All patients underwent standard surgery performed with a tourniquet using a medial parapatellar approach. All the patients had standard uncemented TKR (Profix Total Knee System, Smith & Nephew). The knees were all closed in flexion with two layers of continuous vicryl and clips to skin. The tourniquet was released after the wound closure, over a suction drain with the knee in extension in th