Effects of knee position on blood loss following total knee arthroplasty: a randomized, controlled study

OBJECTIVE: Blood loss following total knee arthroplasty is a serious side-effect of surgery and impacts on patient recovery and quality of life. The aim of this study was to assess the effect of postoperative knee position during recovery on blood loss and range of motion. METHODS: One hundred consecutive patients, with stage III or IV degenerative osteoarthritis, were enrolled in the study and randomized equally between two treatment groups: flexion and extension. In the flexion group, the affected leg was elevated postoperatively by 45° at the hip, with 45° flexion at the knee, while patients in the extension group had the knee extended fully. Blood loss, pre- and postoperative hemoglobin levels, and range of motion were recorded together with duration of hospital stay and complications. RESULTS: Calculated blood loss, hidden blood loss, and postoperative hemoglobin levels between the two groups were significantly different, with patients in the flexion group experiencing lower blood loss than those in the extension group (P < 0.05). After 6-week rehabilitation, patients from both groups attained a similar range of motion in the joint. Duration of hospital stay was shorter in the flexion group by 1.6 days. Wound infection rates were similar in both groups, and we observed no proven deep vein thrombosis. CONCLUSIONS: Postoperative elevation of the hip by 45°, with 45° knee flexion, is an effective and simple method of reducing blood loss and hospital stay following unilateral primary total knee arthroplasty.