46 patients undergoing total knee replacement with an autotransfusion drain were randomized to receive either intra-operative peri-articular infiltration of local anaesthetic or a femoral nerve block to determine if the drain concentrations of levobupivacaine posed health and safety concerns during re-transfusion. Levobupivacaine levels were measured from blood serum samples taken pre-transfusion, from the re-transfusion drain, and post-transfusion. Concentrations of anaesthetic were found to be statistically higher in the drain samples of the peri-articular injection group, but were concluded as being non-toxic.