Lower blood loss after unicompartmental than total knee arthroplasty

Purpose It is intuitive that blood loss is lower after unicompartmental knee arthroplasty (UKA), but the difference in potential blood loss between UKA and total knee arthroplasty (TKA) has not yet been studied extensively. The hypothesis of this study was that blood loss is less important in UKA and that it can be performed without transfusion risk, even in preoperative anaemic patients. Methods A comparative matched retrospective study on 105 (57F/48M) UKA patients with a mean (SD) age of 64 (10) years, a mean (SD) BMI of 29.5 (5) kg/m 2 and a mean (SD) preoperative haemoglobin (Hb) level of 13.7 (1.5) g/dl was matched with 105 TKA patients for age, BMI, gender, ASA score and preoperative alignment. Blood loss was measured peroperatively and as a substitute for blood loss by mean Hb and haematocrit drop at day 2 and 4 postoperatively. Results Mean (SD) visible blood loss was lower for UKA [20 (10) cc vs. 110 (10) cc; P