Martin 2009.

Methods	Participants undergoing total knee arthroplasty (TKA) were divided into one of three groups. It is unclear whether the study used randomisation. The method of allocation concealment is not clear. The blinding status of study participants, personnel, and outcome assessors is not described.
Participants	150 participants undergoing TKA were divided into one of three groups: Group A: three wound drainages with an autotransfusion system and suction. N = 50 Group B: no wound drainage. N = 50 Group C: one intra‐articular wound drainage without suction. N = 50 There was between‐group baseline imbalance for age, weight, body surface area, haemoglobin concentration, and red cell mass.
Interventions	Group A: three wound drainages with an autotransfusion system and suction Group B: no wound drainage Group C: one intra‐articular wound drainage without suction All participants were treated with tourniquets intraoperatively.
Outcomes	Outcomes reported: haemoglobin values, blood transfusion requirements, blood loss, postoperative range of motion, knee society score, rate of complications
Notes	Transfusion protocol: a transfusion protocol is not described. Prospective registration status: it is unclear whether the study was prospectively registered. Ethical approval: it is unclear whether the study was approved by an ethics committee or institutional review board. Language: the available abstract is published in English. Reason for awaiting classification status: the study is published as a conference abstract only. Further details regarding the study design are not clear. The abstract does not mention randomisation. More information is required to assess for inclusion.