Fig. 1

A, C After perineural catheter placement, ultrasound images displaying bifurcation of the sciatic nerve into tibial and common peroneal branches. Note, the catheter is not seen. B Doppler ultrasound image demonstrating complete sciatic nerve coverage, ≥ 50% of tibial and common peroneal branches are covered by the agitation solution. D Doppler ultrasound image demonstrating partial coverage of the sciatic nerve, < 50% of the tibial and common peroneal branches are covered by the agitation solution. T, tibial branch; CP, common peroneal branch