For the anterior knee , the proportion of patients reporting moderate-to-severe pain was 6 % :11 % :44 % ( P = 0.02 ) at 2 h , 6 % :6 % :39 % ( P = 0.012 ) at 4 h , and 12 % :6 % :44 % ( P = 0.017 ) at 6 h postoperatively .