We describe a modification of the sciatic nerve (SN) block in the popliteal fossa through the lateral approach. After a brief anatomic study using previously reported landmarks, we propose a new needle orientation associated with a double injection technique after identification of the tibial and the common peroneal nerve. Thirty-four patients undergoing ankle or foot surgery were enrolled in this study. With patients in the supine position, the upper edge of the patella and the groove between the posterior border of the vastus lateralis and the anterior border of the tendon of the biceps femoris were identified. The needle was directed posteriorly with a 20-30 degrees angle relative to the horizontal plane and slightly caudal. Both nerves were individually located with a nerve stimulator and blocked with a mixture of lidocaine-bupivacaine and clonidine. In all but one case, the two nerves were easily located, and no vascular puncture was evident. Effective analgesia was obtained for a minimum of 15 h (first analgesic demand). We conclude that this technique, with a modified direction of the needle and a double stimulation, provides a very high rate of success for SN blockade in the popliteal fossa.
Implications: We describe a new lateral approach to the sciatic nerve in the popliteal fossa. The needle was directed caudad and posteriorly while seeking with a nerve stimulator for the tibial and the peroneal nerves, which were blocked separately. This technique was very successful.