A stimulation current of 1 mA at 2 Hz is selected, with a stimulus duration of 0.1 ms. After the needle is advanced further, at a depth of about 7-9 cm, there is plantar and dorsal flexion of the foot as a response to the stimulus from the tibial or peroneal part of the sciatic nerve. Do not advance the needle any further. Perform an aspiration test; ensure no blood is withdrawn. Test doses of 3-5 ml local anaesthetic. During the injection, the twitching should slowly disappear/decrease in magnitude.