Echogenic Versus Stimulating Needle and Catheter for Sciatic Blocks

Patients scheduled for total knee replacements and suitable for sciatic nerve block will be randomized to one of 2 groups. Group 1 will have the nerve block performed using a standard Pajunk block needle under ultrasound guidance and with electrical nerve stimulation (ENS), and have catheter placement also guided by electrical nerve stimulation. Group 2 will have the block performed using a Sonoplex echogenic block needle and have an echogenic catheter sited, all under ultrasound (US) guidance. Group 2 will have needle location aided by ENS, but ENS will not be used for catheter location. An observer blinded to the needle type will assess the quality of needle visualisation on a recording of the US image taken during the procedure, along with adequacy of spread of local anesthetic. The primary outcome will be needle visibility, and secondary outcomes will be block success rate, block performance time, complication rate, number of needle passes per block, and adequacy of spread of local anesthetic.