Does temporary clamping of drains following knee arthroplasty reduce blood loss? A randomised controlled trial

In a randomised, blinded study 76 patients undergoing primary total knee arthroplasty were assigned to either immediate drain opening (n=45) or drains opened at 2 h (n=31). No significant differences were found between the groups for the volume of drained blood, transfusion requirements, knee motion or wound status. The authors conclude that the practice of clamping drains has no benefit in routine knee arthroplasty. However, when faced with immediate brisk blood loss, the results suggest that drains can be clamped without any excess morbidity.