Abbreviations

ACLR=anterior cruciate ligament reconstruction

Cont=continuous

IP=in-plane

IV=intravenous

GA=general anesthesia

LA=local anesthetic

OOP=out-of-plane

RA=regional anesthesia

SS=single shot (single injection)

THJR= total hip joint replacement

TKJR=total knee joint replacement

US=ultrasound

UGRA=ultrasound-guided regional anesthesia

Definitions

Out-of-plane: Block needle orientation perpendicular to the long axis (or "plane") of the ultrasound beam. Needle tip approximation is through observation of tissue displacement and/or injectate spread.

In-plane:  Block needle orientation parallel to the long axis (or "plane") of the ultrasound beam. The entire needle shaft and tip may be visualised with this orientation.

Short axis imaging: Orientation of the ultrasound beam perpendicular to the long axis of the nerve. Most ultrasound guided regional anesthesia is conducted using this approach.

Long axis imaging: Orientation of the ultrasound beam parallel to the long axis of the nerve. Nerve imaging can be challenging using this approach, and therefore, it is rarely used.