CAPS (Crosswise Approach to Popliteal Sciatic) block: an alternative ultrasound-guided technique for supine popliteal fossa block

Editor—The ultrasound-guided popliteal sciatic nerve block (PSNB) is the most commonly performed lower extremity block for below-knee surgeries. The distal-most part of the sciatic nerve is targeted at or just above the point of its divergence into tibial and common peroneal nerves. The ultrasound-guided PSNB can be performed in the prone, lateral, or supine position.1–3 Amongst these three approaches, the supine position offers greatest patient comfort but has a few technical challenges in accessing the nerve.