The duration of motor block for the combination group ( 11.5 4.7 hours ) was between that of the bupivacaine ( 16.4 9.4 hours ) and mepivacaine ( 6.0 4.2 hours ) groups ( P = 0.03 between bupivacaine and combination groups ; P = 0.01 between mepivacaine and combination groups ) .
