Background: Genicular nerve block has recently emerged as a novel alternative treatment in
chronic knee pain. The needle placement for genicular nerve injection is made under fluoroscopic
guidance with reference to bony landmarks.
Objective: To investigate the anatomic landmarks for medial genicular nerve branches and to
determine the accuracy of ultrasound-guided genicular nerve block in a cadaveric model.
Study Design: Cadaveric accuracy study.
Setting: University hospital anatomy laboratory.
Methods: Ten cadaveric knee specimens without surgery or major procedures were used in the
study. The anatomic location of the superior medial genicular nerve (SMGN) and the inferior medial
genicular nerve (IMGN) was examined using 4 knee dissections. The determined anatomical sites of
the genicular nerves in the remaining 6 knee specimens were injected with 0.5 mL red ink under
ultrasound guidance. The knee specimens were subsequently dissected to assess for accuracy. If
the nerve was dyed with red ink, it was considered accurate placement. All other locations were
considered inaccurate.
Results: The course of the SMGN is that it curves around the femur shaft and passes between the
adductor magnus tendon and the femoral medial epicondyle, then descends approximately one
cm anterior to the adductor tubercle. The IMGN is situated horizontally around the tibial medial
epicondyle and passes beneath the medial collateral ligament at the midpoint between the tibial
medial epicondyle and the tibial insertion of the medial collateral ligament. The adductor tubercle
for the SMGN and the medial collateral ligament for the IMGN were determined as anatomic
landmarks for ultrasound. The bony cortex one cm anterior to the peak of the adductor tubercle
and the bony cortex at the midpoint between the peak of the tibial medial epicondyle and the initial
fibers inserting on the tibia of the medial collateral ligament were the target points for the injections
of SMGN and IMGN, respectively. In the cadaver dissections both genicular nerves were seen to be
dyed with red ink in all the injections of the 6 knees.
Limitations: The small number of cadavers might have led to some anatomic variations of
genicular nerves being overlooked.
Conclusions: The result of this cadaveric study suggests that ultrasound-guided medial genicular
nerve branch block can be performed accurately using the above-stated anatomic landmarks.
Key words: Knee pain, genicular nerve, nerve block, osteoarthritis, ultrasonography, cadaver
study, injection, accuracy
Ultrasound-guided genicular nerve block in chronic knee pain
