Aim: Allogenic blood transfusion rate and related factors, in a cohort of 78 consecutive primary total knee replacements without patellar substitution (TKR) between January 2007 and December 2008 in the Hospital Axarquía (Málaga; Spain).

Patients and Methods: All patients were diagnosed of primary knee osteoarthritis. Along 2007 (group I) they were admitted in the previous day to a TKR and discharged following surgeon criteria. In 2008 (group II), patients were admitted on the day surgery, underwent a cemented TKR and were discharged following an objective clinical pathway. Variables: age, sex, comorbidities, previous surgery, length of stay (LOS), Ahlbäck classification, prosthesis fixation, surgery time, pre- and postoperative Hb, blood transfusion, readmission at the first 30-days and complications in the first postoperative year. Statistical analysis were carried out by the software SPSS 11.0.

Results: Group I: Mean age 69 yrs (52–80), gender 1:2,4. 89,7% Ahlbäck 3 and 4. 44% hybrid implants. Mean surgery time 100 minutes. LOS 13,3 days (7–28). Mean preop Hb 12,9 g/dl (10–16,5) and Hb at discharge 10,27 g/dl (8,4–13,1). Transfusion rate 14,63%. There were a 25% of complications in the first year. Group II: Mean age 69,7 yrs (54–84), gender 1:1,3. 94,2% Ahlbäck 3 and 4. 8 % of hybrid implants. Mean surgery time 112 minutes. LOS 3,78 days (2–8). Mean preop Hb 13,24 g/dl (11–15,8) and Hb level at discharge 10,15 g/dl (8–13,5). Transfusion rate was 10,8%. There were a 8,1% of complications in the first year. None of complications was related with a tisular oxigenation deficit, nor there were readmissions within the first postoperative month. Transfusion rates difference were not statistically significative. Statistically associated variables were preoperative Hb level < 12,5 g/dl (p=0,001), and postoperative Hb level at 24 hr. < 9,5 g/dl (p=0,017).

Discussion: Allogenic transfusion rates reported in our country without specific blood saving measures ranged from 30% to 46%. Several strategies have been developed to reduce blood transfusions and its complications. The golden rule is the appropriateness of the transfusion, attending clinical and analytical parameters based on guidelines. Our study suggest the best strategy is an appropriate transfusion indication, thus obtaining a transfusion rate low enough to made expensive pre-operative autologous blood predonation and peri-operative blood salvage programs unnecessary. Postoperative hemoglobin level predictive blood transfusion enables a safe and saving time hospital discharge.

Conclusions: The main factors predicting the need for postoperative blood transfusion after TKA are preoperative hemoglobin levels and postoperative hemoglobin levels at 24 hr. Short time results are improved when surgeons use transfusion guidelines with less transfusional morbidity and cost-saving without compromising patients’ safe and outcomes.