The exercise intervention group had significantly improved P4 scores ( mean difference , -6 ; 95 % CI : -8 , -3 ) , KOOS pain scores ( mean difference , 9 ; 95 % CI : 5 , 13 ) , and KOOS function scores ( mean difference , 11 ; 95 % CI : 7 , 15 ) compared to those of the control group at 2 weeks .