Pain Physician, cilt.18, sa.5, 2015 (SCI-Expanded)
Background: Genicular nerve block has recently emerged as a novel alternative treatment inchronic knee pain. The needle placement for genicular nerve injection is made under fluoroscopicguidance with reference to bony landmarks.Objective: To investigate the anatomic landmarks for medial genicular nerve branches and todetermine 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 thestudy. The anatomic location of the superior medial genicular nerve (SMGN) and the inferior medialgenicular nerve (IMGN) was examined using 4 knee dissections. The determined anatomical sites ofthe genicular nerves in the remaining 6 knee specimens were injected with 0.5 mL red ink underultrasound guidance. The knee specimens were subsequently dissected to assess for accuracy. Ifthe nerve was dyed with red ink, it was considered accurate placement. All other locations wereconsidered inaccurate.Results: The course of the SMGN is that it curves around the femur shaft and passes between theadductor magnus tendon and the femoral medial epicondyle, then descends approximately onecm anterior to the adductor tubercle. The IMGN is situated horizontally around the tibial medialepicondyle and passes beneath the medial collateral ligament at the midpoint between the tibialmedial epicondyle and the tibial insertion of the medial collateral ligament. The adductor tuberclefor the SMGN and the medial collateral ligament for the IMGN were determined as anatomiclandmarks for ultrasound. The bony cortex one cm anterior to the peak of the adductor tubercleand the bony cortex at the midpoint between the peak of the tibial medial epicondyle and the initialfibers inserting on the tibia of the medial collateral ligament were the target points for the injectionsof SMGN and IMGN, respectively. In the cadaver dissections both genicular nerves were seen to bedyed with red ink in all the injections of the 6 knees.Limitations: The small number of cadavers might have led to some anatomic variations ofgenicular nerves being overlooked.Conclusions: The result of this cadaveric study suggests that ultrasound-guided medial genicularnerve branch block can be performed accurately using the above-stated anatomic landmarks.