Anatomic basis to the ultrasound-guided approach for saphenous nerve blockade.
OBJECTIVE
Successful blockade of the saphenous nerve using surface landmarks can be challenging. We evaluated the anatomic basis of performing a saphenous nerve block with ultrasound (US) using its relationship to the saphenous branch of descending genicular artery, sartorius muscle, and the adductor hiatus as defined by cadaveric measurements.


METHODS
Using a total of 9 cadaveric knee dissections, the saphenous nerve and its relationship to the saphenous branch of the descending genicular artery (SBDGA) were examined. The distances from the patella to the distal end of the adductor canal and the bifurcation of the saphenous nerve were recorded. US images of an above-the-knee, subsartorial saphenous nerve block were reviewed.


RESULTS
The saphenous nerve coursed with the SBDGA. It exited the adductor canal at a median of 10.25 cm (range, 7.0-11.5 cm) cephalad to the proximal patellar border and traveled closely with the SBDGA. At its bifurcation into the infrapatellar branch and sartorial branch, the saphenous nerve was at its closest approximation to the SBDGA. This point was found to be at a median of 2.7 cm (range, 2.1-3.4 cm) cephalad and a median of 6.6 cm (range, 5.0-9.0 cm) posterior to the proximal and posterior patellar border, respectively.


CONCLUSIONS
The US-guided approach for saphenous nerve blockade using its close anatomic relationship to the SBDGA is a feasible alternative to previously described surface landmark-based or US-guided paravenous approaches.
Horn
Jean-Louis
JL
Department of Anesthesiology and Perioperative Medicine, Oregon Health and Science University, Portland, OR 97239-0884, USA. hornj@ohsu.edu
Pitsch
Trevor
T
Salinas
Francis
F
Benninger
Brion
B
D000328:Adult; D001158:Arteries / Q000000981:diagnostic imaging; D002102:Cadaver; D005267:Femoral Nerve / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D006801:Humans; D007719:Knee Joint / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000294:innervation*; D008297:Male; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000294:innervation; D009407:Nerve Block / Q000379:methods*; D012189:Retrospective Studies; D018615:Ultrasonography, Doppler, Color; D018084:Ultrasonography, Interventional