Effects of Catheter Location on Postoperative Analgesia for Continuous Adductor Canal and Popliteal-Sciatic Nerve Blocks

Adductor canal catheters: Inserted as described by Jæger et al., 2013: "…we performed an ultrasound survey at the medial part of the thigh, halfway between the superior anterior iliac spine and the \[superior border of the\] patella. In a short axis view, we identified the femoral artery underneath the sartorius muscle, with the vein just inferior and the saphenous nerve just lateral to the artery." Popliteal catheters: Using an ultrasound, the bifurcation of the sciatic nerve will be identified in short axis and marked at a point immediately distal at which point the two main branches of the sciatic nerve are separate and a hypoechoic area can be viewed between the two. This level will be marked on the skin. The needle will be inserted to intersect the sciatic nerve 6-7 cm proximal to the mark on the skin (therefore, proximal to the sciatic bifurcation) and injection with saline used to ensure subepimyseal spread.

Adductor canal catheters: Inserted as described by Manickam et al. 2009 Popliteal catheters: Using an ultrasound, the bifurcation of the sciatic nerve will be identified in short axis and marked at a point immediately distal at which point the two main branches of the sciatic nerve are separate and a hypoechoic area can be viewed between the two. This level will be marked on the skin. The needle tip will be inserted into the hypoechoic area between the two branches of the sciatic nerve immediately distal to the sciatic nerve bifurcation between the paraneurium and epineurium (the subparaneural space/compartment). As described by Tran et al, "An adequate position was defined as the presence of circular expansion of the paraneural sheath... Once circular expansion was obtained, we injected."