Blinding Method
Experienced anesthesiologists who had performed at least 100
ultrasound-guided femoral nerve block combined with sciatic nerve block
using a high-frequency (6 to 13 MHz) ultrasound probe (Sonosite, Inc.,
USA) were responsible for performing all blocks. The procedural data was
recorded by an independent investigator. The performers and the
investigator did not further participate in the study. An independent
observer evaluating the sensory and motor block was absent in the
operating room during block placement and was blinded to the
concentration of local anesthetic injected. The same observer followed
up the patients postoperatively within the first 24hs.