The Effect of Postoperative Knee Position on Blood Loss and Fuction

Abstract：Objective The purpose of this study was to assess the effect of postoperative knee position on blood loss and clinical function during primary total knee arthroplasty(TKA). Methods 100 consecutive patients undergoing primary TKA for degenerative osteoarthritis were prospectively included and allocated into two treatment groups:flexion and extension group. 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. The primary outcomes included total blood loss,hidden blood loss and range of motion at six weeks;and secondary outcomes were postoperative hemoglobin level,drainage,transfusion requirement,knee circumference,length of hospital stay,and complications. Results There were 50 patients in flexion group,with 34 females and 16 males. The mean age was 63. 1 years. 50 patients(32 females and 18 males)were included in extension group,with mean age of 62. 4 years. Total blood loss(821. 4 ±114. 3 mL Vs 1008. 4. 0 ±102. 6 mL)and hidden blood loss(637. 5 ±173. 3 mL Vs 763. 1 ± 103. 5 mL)were lower in flexion group when compared with extension group,and the differences were significant(P <0. 001). The drainage in flexion group was(195. 2 ± 64. 8)mL,which was significantly lower than that in extension group (258. 1 ± 78. 3,P ﹦ 0. 001). Patients in flexion group gained higher hemoglobin level and less knee circumference,with statis-tical significance. The range of motion was similar when follow up at 6 weeks postoperatively(P > 0. 05). 3 patients in flexion group and 9 in extension group required transfusion. Superficial wound infection occurred in 3 patients in flexion group and 2 in extension group. None of them developed DVT. Conclusion Postoperative extation of the hip by 45°with 45°knee flexion,is an effective and simple method to reduce blood loss and knee swelling following primary TKA.