Total knee arthroplasty (TKA) is a common, effective operation but postoperative infection has devastating consequences. Several papers have associated perioperative autologous transfusion with reduced infection rates. Salvaged blood may augment the inflammatory response and central within it is polymorphonuclear leukocyte (PMN). Our hypothesis was that autologous transfusion enhances PMN activity by: increased PMN transmigration to potential infection site, enhanced phagocytosis, augmented respiratory burst activity.

Our randomised controlled prospective study showed a significant increase in superoxide production by PMN of patients who received unwashed autologous transfusion supporting the clinical studies where infection rates following autologous transfusion were reduced.

Objective: It has been observed in previous studies of autologous blood transfusion in total knee arthroplasty, that this technique is associated with a lower infection rate, though studies have not been sufficiently large to demonstrate a significant difference. We hypothesised that autologous salvage blood contained high levels of pro-inflammatory mediators which may prime or augment the patients’ inflammatory response, and, in particular, the function of the polymorphonuclear leukocyte (PMN).

Methods: Patients were randomised after consent to those receiving autologous transfusion and those having conventional treatment which was homologous transfusion only if clinically indicated. PMN were then isolated from the patients pre-admission immediately after the operation and 24 hours post-total knee arthroplasty. Three different aspects of PMN activity were measured: 1) The respiratory burst activity; 2) the ability to phagocytose microbes using radiolabelled staphylococcus epidermis; 3) and the ability to migrate across a collagen coated porous inserts.

Results: 80 patients were studied, of whom 43 were in the autologous transfusion group and 37 in the first group. Of these 37, 6 had homologous transfusion. The study showed no significant difference between the phagocytic ability of the PMN from both groups. The main stimulus to transmigration is surgery itself. There was a significant increase in the production of reactive oxygen species by the PMN of those patients who received an autologous transfusion post-operatively.

Conclusions: Using molecular biology techniques to study the PMN directly, our study indicates that autologous transfusion alters the activity of PMN and this indicates a possible mechanism whereby the immune response to infection could be enhanced. This, in turn, would explain the observed differences in infection rate in previous studies.