total joint replacement usually represents the final route for treatment of degenerative disease of the knee . joint replacements are more and more frequent and routine these days thanks to , for example , the consequent aging of the general population , increased functional requirements , and the development and use of new materials and more sophisticated surgical techniques . in this context , there is a need to develop new protocols for management and use of transfusion therapies in the field of orthopedic surgery . transfusion of homologous blood are frequent and costly and expose patients to potential risks of infection [ 1 , 2 ] ; hence several methods have been proposed to avoid them [ 3 , 4 ] . preoperative blood donation and intra- and postoperative blood collection and administration of pharmaceutical agents to either reduce blood loss ( e.g. , tranexamic acid ) or stimulate the production of erythrocytes ( e.g. , erythropoietin ) have been proposed as alternative techniques to transfusion of homologous blood in various studies [ 3 , 4 ] . in the scientific literature , there are several reports of studies where reinfusion of blood collection in postoperative orthopedic surgery , especially in prosthesis surgery [ 514 ] , is analyzed . the aim of the present study was to verify the safety , the clinical efficacy , and the possible benefits of reinfusion of postoperatively collected autologous blood in total knee replacement procedures , with special emphasis on cost - benefit and reinfusion procedure , by comparing autologous blood transfusion with nonautologous blood transfusion . between 2011 and 2012 , one hundred twenty - four patients with a mean age of 71.2  6.8 years and a range between 50 and 84 years were included in the study . the first group consisted of a series of sixty - four consecutive patients ( male to female ratio 1  :  5 , range of age between 62 and 84 years ) , who underwent one stage unilateral total knee arthroplasty using a blood reinfusion device in 2012 . fifty - eight of these patients received autologous transfusion and six patients were excluded , five due to systemic pathologies . the control group consisted of sixty consecutive patients ( male to female ratio 1  :  3 , age ranging from 50 to 79 years ) . this population was operated on consecutively in 2011 but is not subjected to autologous blood reinfusion because we have been using this device since january 1 , 2012 . before any study - related measures were taken all patients read and signed informed consent for any possible transfusion of homologous red blood cell and a specific consent for reinfusion , after adequate information on possible risks and benefits of both methods . the manuscript was performed in accordance with the ethical standards of the 1964 declaration of helsinki as revised in 2000 ; for this type of study formal consent is not required . antibiotic prophylaxis was obtained by administration of ceftriaxone 1  g intramuscular injection once daily and teicoplanin 800  mg intravenous injection once daily , 30 minutes before inducing anaesthesia . antithrombotic prophylaxis was obtained by administration of enoxaparin sodium 4,000 i.u . once daily by subcutaneous injection for 35 days , 12 hours before surgery ; two patients had an urticarial reaction and therefore it has been replaced with fondaparinux sodium 2.5  mg once daily by subcutaneous injection for 35 days . patients were subjected to surgical intervention for unilateral primary arthroplasty knee , by implanting a zimmer 's nexgen cemented prosthesis or how medical 's triathlon prosthesis . surgery was carried out by the same surgeon on all patients ; a standard surgical procedure was performed including a longitudinal medial skin incision and median parapatellar quadriceps splitting approach . limb ischemia was achieved through temporary leg loop tire located at the root of the limb and the tourniquet was deflated after the step of cementing . postoperative pain was controlled with paracetamol 100  ml/10  mg endovenous with a 4-hour minimum interval between each administration . bellovac abt is a drainage system for postoperative collection , filtration , and reinfusion of shed autologous blood . it consists of all components required for collection and reinfusion of one unit of shed autologous blood . the initial negative suction pressure is 90  mmhg ( 12  kpa ) , generating safe and efficient drainage . once the recovery of shed blood is completed ( within < 6 hours ) the transfusion bag can be replaced with a collection bag for evacuation only , thus serving as a simple wound drainage ( card system technical bellovac abt for drainage and the recovery of the blood postoperative manufacturer : astra tech ab , via cristoni , casalecchio di reno ( bo ) ) . for all patients , we decided that a homologous transfusion therapy was only indicated for haemoglobin values below 8  g / dl . the study group consisted of a series of sixty - four consecutive patients with mean age 73.3  5.7 years ( 14 males and 50 females ) , while the control group consisted of sixty consecutive patients with mean age 69  7.2 years ( 18 males and 42 females ) . we excluded patients with systemic pathologies such as uncompensated diabetes mellitus , cancer , severe cardiovascular pathologies , immunodepression , anticoagulating or antiaggregating therapy , coagulation disorders including deep venous thrombosis , and ongoing infections . we considered as discriminating factors hemoglobin values < 12  g / dl for women and < 14  g / dl for men . length of surgery was 2.24  0.38 hours in the study group versus 2.06  0.32 hours ( p = 0.17 ) . hemoglobin values ( hb ; g / dl ) were checked preoperatively , immediately after surgery , on the first day and the second day after the operation , and on discharge . they were later compared between groups . in the study group , patients were subjected to a microbiological culture of a blood sample ( 20  ml ) from the bag of postoperative recovery , at the end of the procedure of reinfusion . in our hospital , the transfusion medicine unite has provided the following expense items : the cost of an autologous blood retransfusion system is around  68,00 , while the costs of an allogenic blood transfusion , including cross - matching , delivery , and refrigerated storage , are stated to be  270 . added costs of the postoperative drain and the abt system are  20 and  68 , respectively . all data are presented as mean  sd or median ( iqr ) as appropriate . groups were compared using the one - way anova or t - test for normally distributed data and the nonparametric kruskal - wallis or mann - whitney u test for non - normally distributed variables . the study group consisted of a series of sixty - four consecutive patients with mean age 73.3  5.7 years , 14 male and 50 female , while the control group consisted of sixty consecutive patients with mean age 69  7.2 years , 18 male and 42 female ( p < 0.05 ) . the average body weight of the study group was 70.8  8.8  kg and 73.1  8.0  kg ( p = 0.43 ) . in the study group , all the patients received autologous blood transfusion . in the first six hours 400  122.4 ml ( min . 600 ) was collected and retransfused ; within 24 hours there was 198.5  142.4  ml of blood drained in the drainage . in the control group , because of the intraoperative use of a tourniquet , intraoperative blood loss was negligible in both groups . we noticed a reduction rate of allogeneic blood transfusion between the study and the control group ( 10.3% versus 30% ; p = 0.08 ) . six patients in the study group , four women and two men , were subjected to allogeneic transfusion , five patients received one unit of homologous blood between the second and fourth days postoperatively , and one patient received two units of homologous blood . , we registered 18 patients who received homologous blood transfusion ; each one had received a bag of homologous whole blood . the transfusion trigger in the abt group ( n = 6 ) was 7.5  0.1  g / dl , whereas that in the control group ( n = 18 ) was 7.3  0.2  g / dl ( p = 0.09 ) . one unit of red blood cells can be expected to result in a hemoglobin increase of 1  g / dl in a typical adult . in the abt group we recorded an increase in hemoglobin equal to 0.7  0.3 ( g / dl ) , after autologous transfusion . in this group we recorded an increase in hemoglobin equal to 1.3  0.2 ( g / dl ) ( n = 7 bags ) versus 0.9  0.1 ( g / dl ) ( n = 18 bags ) in the control group after homologous transfusion ( p < 0.01 ) . therefore , we noticed a greater rise in hemoglobin after homologous transfusion in the group given reinfusion ( figure 1 ) . the tourniquet time was 1.13  0.27 hours in study group versus 1.04  0.27 hours in control group ( p = 0.36 ) . in the study group the mean length of stay at the hospital ( los ) was 7.88  0.7 days , while it was 8.96  2.47 days for the control group ( p = 0.03 ) . really , we did not find any significant difference for hemoglobin count between groups from admission to hospital discharge ( table 1 and figure 2 ) ; as expected , we did not find any difference between groups considering the reduction in hemoglobin for study 's time points ( table 2 and figure 3 ) . 
 the results of microbiological cultures performed on blood samples taken from the postoperative blood bag at the end of the procedure of reinfusion were negative in all cases . in our study a total knee replacement surgical procedure , along with the complementary use of a device for postoperative collection and reinfusion of shed blood resulted in an average reduction of the length of hospital stay equal to 1.08  0.76 days ( p = 0.03 versus control ) . the cost of an autologous blood retransfusion system is around  68,00 , while the costs of a allogeneic blood transfusion are stated to be  270 , including cross - matching , delivery , and refrigerated storage . in the present study , 18 allogeneic transfusions were given in the no - drainage group , while 7 allogeneic transfusions were given in the abt group , at a cost of  4.860,00 and  1.890,00 , respectively . the additional costs of the postoperative drain and the abt system were  20 and  68 , respectively , in either group at a cost of  1.160,00 ( n = 58 ) and  4.352,00 ( n = 64 ) . the average cost per patient turned out to be lower in the group receiving reinfusion (  97.53 versus  103.79 ; p < 0.01 ) . primarily , autologous blood reduces the need for allogeneic blood transfusion ; furthermore , it prevents the transmission of viral diseases ( hepatitis c virus , hepatitis b virus , human immunodeficiency virus , and creutzfeldt - jacob virus ) , transfusion reactions , and transfusion errors [ 16 , 17 ] . the main advantage of postoperative collection and reinfusion of shed blood is this method 's simplicity ; hence it finds its application in traumatized patients . however , its main disadvantage is the risk of contamination during blood collection [ 8 , 18 ] . identify some possible complications of collection of red blood cells , such as nonimmunologic haemolysis , gas embolism , nonhaemolytic transfusion reaction , coagulopathies , contamination with drugs , the intraoperative use of washing solutions in the surgical site and infectious agents , cytokines , and other microaggregates . the risk of complications decreased due to improvement of techniques and practices as well as increased experience with autologous blood collection systems . cleveland clinic has performed a five - year retrospective study of complications , with both homologous and collected shed blood , noting that the incidence of complications with collected blood was around 0.027% compared to 0.14% of homologous blood . in our study the results of microbiological cultures performed on blood samples taken from the postoperative blood bag at the end of the reinfusion were negative in all cases . the purpose of collection of shed blood is to reduce or eliminate the need for homologous blood transfusion and the associated risk of infectious and noninfectious complications . during 2006 , a meta - analysis of the recovery of red blood cells in adult elective surgery showed that recovery of blood could reduce the need for homologous blood transfusion . the use of recovered red blood cells has reduced the exposure to allogeneic blood by 39% with an average saving of 0.67 units per patient . in 2013 a meta - analysis proved that the use of a postoperative autotransfusion reinfusion system reduced significantly the demand for allogeneic blood transfusions . it also cut the number of patients who needed allogeneic blood transfusions and the cost of hospitalization after total knee arthroplasty . collection of blood in orthopedic surgery results in greater safety and efficacy [ 2426 ] . 94 cases have been studied but a power analysis of the study was not performed ; however , we argue that the use of a device for autologous blood collection and washing results in an average reduction of 4 units of allogeneic blood and cost savings of an average of 406.84 dollars per patient . in the literature these authors suggest that autologous blood transfusion drains have no effect on the proportion of transfused patients in primary total knee arthroplasty [ 2834 ] . the postoperative hemoglobin levels , the length of hospital stay , and the adverse events are also comparable between groups . in our opinion autologous blood collection and reinfusion , by the use of postoperative systems , is a procedure that allows limiting the transfusion of homologous blood to patients undergoing tkr , improving the postoperative course from a psychophysical point of view and allowing an early transfer to rehabilitation unit . we noticed a reduction in allogenic blood transfusion between the study and the control group ( 10.3% versus 30% ; p = 0.08 ) . reinfusion group patients also displayed a reduction in the length of stay in hospital by 1.08  0.76 days ( p = 0.03 versus control ) . concerning costs , the question is whether savings derived from the reduction in allogeneic blood transfusion requirements outweighed the extra costs of the abt system . zacharopoulos et al .   stated that use of the postoperative blood reinfusion systems is highly effective in reducing the demand for homologous blood transfusion for patients undergoing total knee replacement surgery , resulting in important cost savings in the management of these patients . a previous study observing patients undergoing tka found net savings in different cost scenarios of  5 to  106 per patient with the same abt system as used in this study and  52 to  50 per patient with another abt system . a review of cost - effectiveness on blood - saving measures stated that cell salvage had lower costs compared with all of the alternative blood - saving strategies except acute normovolemic dilution and concluded that autotransfusion may be a cost - effective method to reduce allogeneic transfusions [ 37 , 38 ] . the evidence that supports the use of red blood cell recovery in knee prosthesis is stronger and comprises randomized studies and one large retrospective review [ 39 , 40 ] . the average cost per patient was found to be lower in the group receiving reinfusion (  97.53 versus  103.79 ; p < 0.01 ) . this work presents a lot of strengths such as the same characteristics of the sample , the surgical technique performed by the same surgeon , and the rigorous cost analysis ; on the contrary we are aware of some weaknesses such as the retrospective design . this study has confirmed the absolute safety of the device and the absence of bacteria in examined samples . our results emphasize the effectiveness of this procedure and have the characteristics of simplicity , low cost , easy reproducibility , and safety . in addition , this recovery system replaces the simple postoperative surgical drainage , representing a further saving of economic resources . finally we conclude that the use of the shed blood recovery system bellovac abt constitutes a valid device , which can find wide application in orthopedics , especially in the context of total knee replacement surgery .
surgeries for total knee replacement ( tkr ) are increasing and in this context there is a need to develop new protocols for management and use of blood transfusion therapy . 
 autologous blood reduces the need for allogeneic blood transfusion and the aim of the present study was to verify the safety and the clinical efficacy . 
 an observational retrospective study has been conducted on 124 patients , undergoing cemented total knee prosthesis replacement . 
 observed population was stratified into two groups : the first group received reinfusion of autologous blood collected in the postoperative surgery and the second group did not receive autologous blood reinfusion . 
 analysis of data shows that patients undergoing autologous blood reinfusion received less homologous blood bags ( 10.6% versus 30% ; p = 0.08 ) and reduced days of hospitalization ( 7.88  0.7 days versus 8.96  2.47 days for the control group ; p = 0.03 ) . 
 microbiological tests were negative in all postoperatively salvaged and reinfused units . 
 our results emphasize the effectiveness of this procedure and have the characteristics of simplicity , low cost (  97.53 versus  103.79 ; p < 0.01 ) , and easy reproducibility . 
 use of autologous drainage system postoperatively is a procedure that allows reducing transfusion of homologous blood bags in patients undergoing tkr .