6 randomized control trials containing patients undergoing primary TKA were analyzed to determine the effectiveness of drainage-clamping methods in the reduction of blood loss following TKA. Results indicated that there was no significant difference between clamping and non-clamping techniques in terms of postoperative haemoglobin levels (p= 0.45), blood transfusion rates (p= 0.14), symptomatic thromboembolic events (p= 0.17), and wound complications. There was, however, a significant difference in terms of drainage volume between the groups, with the clamping group showing significantly lower drainage volumes than the non-clamping group (p=0.0001). Sub group analysis between 3 studies also showed higher postoperative hemoglobin levels in patients with clamping for 4 hours or more (p= 0.002).