To determine if needle insertion at the inguinal crease with stimulation of sartorius muscle (anterior branch) causes an equivalent block to the classical method with stimulation of the quadriceps femoris muscle (posterior branch), for femoral nerve blockade. To test this hypothesis, we plan to conduct a randomised controlled double-blind study comparing success of femoral never block (motor and sensory) using sartorius twitch versus quadriceps femoris twitch as an end point.