Abstract
The use of re-infusion drains on 99 consecutive patients undergoing total knee arthroplasty surgery at a large hospital was analysed. As a control group the records of 99 patients treated without re-infusion were analysed retrospectively. The primary aim was to ascertain the cost effectiveness of the drains. Secondary aims were to assess safety of the drains, whether or not they reduced the need for allogeneic blood transfusion and whether they decreased the length of stay in hospital. The direct cost of consumables increased for the evaluation period. There was a smaller proportion of allogeneic blood transfusion (27% vs 38%) and a smaller mean number of units transfused (0.92 vs 0.54) in the re-infusion group compared to the control group. Patients benefited directly in that the mean length of stay was also significantly shorter in the re-infusion group. We anticipate more direct cost saving with experience and best practice and conclude that the use of re-infusion drains is a cost effective blood saving method in total knee joint arthroplasty.

Keywords
Allogeneic blood, re-infused blood, total knee joint arthroplasty

Introduction
Allogeneic blood transfusion (ABT) is the most common and accepted method of blood transfusion. While effective in replacing the volume of blood loss, the procedure introduces several risk factors  including transmission of viralagents, specifically human immunodeficiency virus (HIV) and hepatitis, insufficient platelet count, isoimmunisation, and possible transfusion reactions (Spain, Miller, Bergamini, Montgomery, & Richardson, 1997). Re-infusion of wound drainage has been considered a safe procedure for patients having elective surgery since the 1970s, but despite its potential to reduce the above risks, has not been widely practiced. In recent years however, due to increased public concern regarding the safety of blood transfusions, including transfusion related diseases such as HIV, hepatitis B and C and immuno-suppression, various pre, intra and postoperative techniques have been used with the goal of minimising exposure to ABT. There has been renewed interest for the use of autologous transfusion in elective orthopaedic surgery (Feagan, Wong, Johnston, & Arellano, 2002; Martin, Whiteside, Milliano, & Reedy, 1992; Munoz, Ariza, Garceran, Gomez, & Campos, 2005; Pertl & Kaltenecker, 2001; Sinardi, et al., 2005; Steinberg, Ben-Galim, Yanic, Dekel, & Menahem, 2004; Strumper, et al., 2004).