The influence of immediate knee flexion on blood loss and other parameters following total knee replacement

420 patients scheduled for total knee arthroplasty were randomized to either positioning of the knee in 120 deg passive flexion for 3 hours postoperatively, the same flexion for 6 hours postoperatively, or in full passive extension postoperatively. The objective was to determine the effect of each protocol on postoperative blood loss, transfusion requirements, and pain within the first 12 postoperative hours. The results indicated that blood loss was significantly lower with the 6h flexion protocol compared to extension, although no significant difference among groups was identified for transfusion requirement. Additionally, pain and discomfort was highest with 6h flexion, with 2 cases of transient lower limb sensory nerve palsy recorded.