The effect of knee position on blood loss and range of motion following total knee arthroplasty

Purpose: This study prospectively assessed the effects of knee position on blood loss and range of motion after primary total knee arthroplasty (TKA). Methods: One hundred and ten consecutive TKA patients were randomized into flexion group and extension group. Both groups had the leg elevated 30° at the hip over an inactive CPM for 72 h postoperatively. The flexion group had the knee flexed to 30° during this period. The extension group had the knee extended fully. Perioperative blood loss, hidden blood loss, knee swelling, ecchymosis, analgesia requirements, range of motion (ROM), fixed flexion deformity (FFD), straight-leg raising action, and postoperative complications within 6 weeks of surgery were measured for evaluation and comparison. Results: The postoperative hidden blood loss, knee swelling, and scope of ecchymosis were significantly lower in the flexion group than in the extension group, and ROM and straight-leg raising action were significantly higher during the early period after operation. No significant difference was observed in perioperative blood loss, the amount of morphine used, or FFD in the early postoperative period or in ROM and FFD at 6 weeks postoperatively. Conclusions: The findings of this study indicate that flexion of the knee to 30° with the leg elevated 30° at the hip after total knee arthroplasty may mitigate knee swelling and provide other beneficial results during the early rehabilitation following TKA. Level of evidence: Prospective comparative study, Level I. © 2011 Springer-Verlag.