There was no significant difference in mean WOSI scores between the groups ; the mean WOSI score ( and standard deviation ) for the open group was 85.2 20.4 ( 95 % confidence interval [ CI ] = 80.5 to 89.8 ) , and for the arthroscopic group , 81.9 19.8 ( 95 % CI = 77.4 to 86.4 ) ; p = 0.31 .