Majkowski 1991.

Study characteristics
Methods	Design: RCT, parallel two‐arm, single‐centre study Setting: specialist orthopaedic hospital, Bristol, Avon, UK Recruitment: recruitment and study dates not reported Maximum follow‐up: 48 hours postoperatively
Participants	40 participants undergoing primary unilateral total knee arthroplasty were randomised to one of two groups: Study group (Autotransfusion) (Cell salvage/intervention group): N = 20. M:F 6:14. Mean age 71.3 Control group (Standard drain): N = 20. M:F 6:14. Mean age 70.3 There was no baseline imbalance between groups.
Interventions	Study group (Autotransfusion) (Cell salvage/intervention group): autotransfusion group (Solcotrans orthopaedic reinfusion system) had the two deep intra‐articular drains connected to a Solcotrans reservoir and a suction pressure of 80 mmHg applied for an initial period of 10 minutes, after which the wound was allowed to drain by gravity alone. Two Solcotrans reservoirs were attached sequentially to each participant regardless of the volume drained. Blood was reinfused if a sufficient volume had been collected. Drains were removed at 48 hours. Control group (Standard drain): control group had all drains attached to Redivac bottles. Autotransfusion was not used.
Outcomes	Outcomes reported: amount of blood collected by the cell saver, amount of blood re‐transfused from the cell saver, amount of allogeneic blood transfused, adverse events
Notes	Transfusion protocol: allogeneic blood was given to patients if the haemoglobin level fell below 9.5 g/dL or if indicated haemodynamically. Prospective registration status: the study was published prior to 2010. Ethical approval: it is not clear whether the study was approved by an ethics committee or institutional review board. Language of publication: English Trial funding: not reported Conflicts of interest: not reported
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method used to generate allocation sequences was not described.
Allocation concealment (selection bias)	Unclear risk	Method used to conceal treatment allocation was unclear.
Blinding of participants and personnel (performance bias) Objective outcome: mortality	Low risk	No objective outcomes reported (mortality unlikely to be affected by blinding if reported in future publications)
Blinding of participants and personnel (performance bias) Subjective: transfusion protocol	Low risk	Transfusion protocol: Allogeneic blood was given to patients if the haemoglobin level fell below 9.5 g/dL or if indicated haemodynamically.
Blinding of participants and personnel (performance bias) Subjective: all other outcomes	Low risk	Clear diagnostic guidelines for outcomes, unlikely to be largely affected by blinding
Blinding of outcome assessment (detection bias) Objective outcomes: mortality and transfusions	Low risk	No objective outcomes reported (mortality unlikely to be affected by blinding if reported in future publications)
Blinding of outcome assessment (detection bias) Subjective outcomes	Low risk	Clear diagnostic guidelines for outcomes, unlikely to be largely affected by blinding
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	The number of participants analysed is unclear; no info on participant flow
Selective reporting (reporting bias)	Unclear risk	No trial registration or published protocol is available to compare
Other bias	Unclear risk	No baseline imbalance noted. Funding and conflicts not reported