Methods	Patients were randomised to receive an autologous reinfusion drain or a standard suction drain using the computer program MINIM. The method used to conceal treatment allocation was not described
Participants	104 consecutive patients undergoing primary cemented total knee arthroplasty were randomised to one of two groups: Group 1 (Autotransfusion group): n=52 Group 2 (Control group): n=52 NB: Of the 104 randomised patients 43 were male and 61 were female. The mean age of randomised subjects was 68.5 years
Interventions	Group 1: Autotransfusion group (Bellovac autotransfusion system) had one deep drain inserted at the end of the operation. The drain was opened in the recovery room 20 minutes after the tourniquet was released. If blood collected in the reinfusion drain was more than 150mls it was transfused back into the patient unwashed and a new bag was then attached to the drain. The process was repeated if the amount of blood collected again exceeded 150mls. Group 2: Control group (Redivac standard suction drain) had their collected blood discarded.
Outcomes	Outcomes reported: number of patients transfused allogeneic blood, amount of allogeneic blood transfused, blood loss, hospital length of stay, Hb & Hct levels, wound problems, knee range of motion
Notes	Transfusion threshold: allogeneic blood transfusion was given if the haemoglobin level was less than 9.0g/dL
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The software program MINIM was used to randomise patients to intervention or control
Allocation concealment (selection bias)	Unclear risk	The method used to conceal treatment allocation was not described
Blinding (performance bias and detection bias) All outcomes	High risk