Effect of Preemptive Multimodal Analgesia for Arthroscopic Knee Ligament Repair

tified by external palpation: the posterior superior iliac spine and the sacral hiatus. Anatomic references. The sciatic nerve leaves the pelvis through the greater sciatic foramen, at the level of the lower border of the piriformis muscle, and then crosses the ischial spine (“Labat’s Landmark”). The piriformis muscle is posterior to the nerve at the parasacral level1 and continues its course, perpendicular to the border of the sacral. This close anatomic relation to the piriformis muscle and the sciatic nerve was used as a reference in the new surface markings for our posterior sciatic nerve block. Technique of sciatic nerve block. The patients are positioned as for classic posterior sciatic nerve block: on their side with the leg to be blocked uppermost and flexed at the hip (“Sim’s position”). A line is drawn from the posterior superior iliac spine (PSIS) to the sacral hiatus (SH). From the midpoint of that line, a second line of equal length, perpendicular to the first and directed laterally, is then drawn. The end of that line is the point of puncture (Fig 1). After the routine antiseptic skin preparation, a 21-gauge, 100-mm insulated stimulating needle is inserted slowly in a sagittal plane (Stimuplex; B. Braun, Melsungen, Germany) connected to a peripheral nerve stimulator, while a motor response is sought. After verifying a blood negative aspiration, an injection of 0.3 mL/kg mepivacaine 1.5% without epinephrine solution is injected. This block has been used on 40 adult patients (American Society of Anesthesiologists [ASA] physical status I-III) undergoing lower extremity surgery.2 Successful block of the nerve was achieved after 1 (90%) or 2 (10%) attempts. The block failed in 1 patient. Complications were transitory in 1 patient with mild paresthesia in the tibial nerve distribution. No vascular punctures occurred in 40 patients. The sciatic nerve approach we describe shows an anatomic landmark of block of sciatic nerve at the gluteal zone. This landmark is based on the nerve course at the inferior border of the piriformis muscle in the parasacral region (Fig 1).