An Assessment of Variability in Placement of The Adductor Canal Block Amongst Faculty at a Major Teaching Hospital: An Observational Study
James Cyriac, MD, Mfonobong Essiet, MS, Michael Ma, BS, Joseph Rinehart, MD
Department of Anesthesiology & Perioperative Care, University of California, Irvine, Irvine, CA, USA
The Adductor canal block (ACB) has been shown to both spare quadriceps muscle weakness better and provide equally effective analgesia compared to that of the femoral nerve block1. However, the anatomy, nomenclature, and block technique are highly variable both in literature and in practice. The knowledge of the anatomy and specific block technique are in their relative infancy and there is significant need for standardization of techniques in order to maximize block success rates. The aim of this study was to assess the knowledge of the relevant anatomy and technique of the ACB among regional anesthesia faculty at the University of California, Irvine Medical Center (UCIMC) and to assess the efficacy of a didactic session.
Materials and Methods
Seven UCIMC regional anesthesia faculty members were included. A 14 question pre-test, which assessed the relevant anatomy and landmarks of the ACB, was administered before the didactic session. In addition, the subjects were asked to perform a mock ultrasound-guided ACB on a standardized patient by marking the location of their needle entry site on a 10” x 4” Tegaderm film, which was placed on the medial surface of the proximal right lower extremity. Needle entry sites were recorded as x and y coordinates, with the middle of the Tegaderm film as the origin. Subjects then received a didactic session on the relevant anatomy and technique. After, a post-test was administered and the subjects were asked again to determine and mark their needle entry site under ultrasound guidance.
Faculty members demonstrated a significant increase in test score percentages when comparing pre-test to post-test scores (p<0.05). The variability in needle insertion points after the didactic session was reduced from an interquartile range of 0.84(x-axis) and 1.34(y-axis) to 0.42(x-axis) and 0.71(y-axis), respectively. Furthermore, a more distal approach after receiving the didactic session was shown to be statistically significant (p<0.05). No statistically significant changes in the x-axis (lateral to medial) post-didactic session were detected.
Baseline knowledge level of the adductor canal anatomy was significantly increased after the didactic workshop. The didactic session also resulted in better standardization in regards to block technique. Significant debate still exists as to the “ideal” location to perform an ultrasound-guided ACB.2 We have successfully demonstrated by reviewing the relevant anatomy, significant standardization can be achieved.