Block onset time was shorter in the subparaneural group than in the extraneural group ( 11 [ 3-21 ] minutes ; mean [ 95 % confidence interval ] , 11 [ 8.97-13 .02 ] minutes and 17 [ 6-30 ] minutes ; mean [ 95 % confidence interval ] 18.37 [ 14.17-22 .57 ] minutes , respectively ; P = 0.002 ) .