Methods	A prospective, randomised controlled trial of consecutive osteoarthritic patients undergoing unilateral total knee replacement was conducted. Randomisation was by random number tables. Method of allocation concealment was not described
Participants	70 consecutive patients undergoing unilateral total knee replacement with a cruciate-sparing Kinemax Plus prosthesis were randomly allocated to one of two groups: Group 1 (Autotransfusion group): n=35 Group 2 (Control group): n=35 NB: Mean age of patients enrolled in study was 72 years. Demographic data were not reported
Interventions	Group 1: Autotransfusion group (Dideco 797 reinfusion system) had deep and superficial drains inserted before skin closure and connected to the Dideco 797 reinfusion system which maintains a constant suction of −25mmHg. The drainage collected was mixed with citrate in a ratio of 12:1, filtered during collection and again during reinfusion through a 40um filter. No washing took place. Drainage was collected for 6 hours or until 500mls had accumulated, at which point reinfusion of the unwashed salvaged blood took place. Group 2: Control group had deep and superficial drains inserted before skin closure and connected to a standard Haemovac system which maintains a constant suction of −25mmHg. Autotransfusion was not available to this group.
Outcomes	Outcomes reported: amount of blood re-transfused from cell saver, amount of allogenic blood transfused, number of patients transfused allogeneic blood, adverse events, hospital length of stay
Notes	Transfusion threshold: transfusion protocol was not reported.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Method used to generate allocation sequences was adequate.
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was unclear.
Blinding (performance bias and detection bias) All outcomes	High risk