Ultrasound standard for popliteal sciatic block: circular expansion of the paraneural sheath with the needle in-plane from lateral-to-medial in the ‘reverse Sim’s position’  J.-A. Lin, Y.-J. Lee, H.-T. Lu, Y.-T. Lin  British Journal of Anaesthesia  Volume 115, Issue 6, Pages 938-940 (December 2015) DOI: 10.1093/bja/aev388 Copyright © 2015 The Author(s) Terms and Conditions

Fig 1 Popliteal sciatic block in the ‘reverse Sim’s position’. The leg to be blocked is placed over the dependent leg in the lateral decubitus position. Contrary to the Sim’s position for posterior Labat approach, the patient is asked to extend the knee and flex the hip of the leg to be blocked, with the knee of dependent leg flexed to serve as a stable base. The leg to be blocked is placed on a pillow based on the dependent leg to suspend the foot in the air, so that the seesaw sign can be applied in addition to the traceback approach and distal squeeze technique. The inset shows the simulated needle trajectory (white solid line) toward the septum in case of typical postero-lateral position of the common peroneal division (yellow dotted circle) in relation to the tibial division (white dotted circle). The needle insertion point to easily make the needle in-plane through the desired trajectory could be inferred from the ultrasound images (about 2 cm below the posterior skin surface in this case), which is usually above the probe in the reverse Sim’s position with the biceps tendon as the natural barrier to avoid gravity-dependent gel contamination. British Journal of Anaesthesia 2015 115, 938-940DOI: (10.1093/bja/aev388) Copyright © 2015 The Author(s) Terms and Conditions