Ultrasound-Guided Genicular Nerve Thermal Radiofrequency Ablation for Chronic Knee Pain

Figure 1

For all procedures, 22 G, 5 mm active tip, 50 mm long RF needle was advanced to the target area under continuous ultrasound guidance. Impedance was between 400 and 500 ohms. Sensory testing was positive up to 0.40 mV, 50 Hz, described as a pressure-like sensation which was concordant with the patient’s usual distribution of pain. Motor testing up to 3 mV at 2 Hz was negative. After stimulation and negative aspiration, 2.0 cc of 2% Lidocaine was injected. At this point, continuous radiofrequency lesioning was started at 80°C for 90 sec. The needle was then removed and the area dressed. (a) Superomedial genicular nerve (SMGN): a high frequency, linear ultrasound (Sonosite, Bethel, WA, USA) transducer was placed in the sagittal orientation over the right femoral medial epicondyle and translated proximally to the level of the adductor tubercle and the insertion of the adductor magnus tendon. The bony cortex one cm anterior to the peak of the adductor tubercle was targeted for the injection. The presence of the SMGN’s corresponding artery confirmed the target area. Using an in-plane technique, the needle was inserted in a cephalad to caudad direction. The solid white arrow delineates the needle trajectory. (b) Superior lateral genicular nerve (SLGN): a high frequency, linear ultrasound (Sonosite, Bethel, WA, USA) transducer was placed in the sagittal orientation over the right femoral lateral epicondyle and translated proximally to the level of the insertion of the biceps femoris tendon. The bony cortex was targeted near the SLGN’s corresponding artery. Using an in-plane technique, the needle was inserted in a cephalad to caudad direction. Solid white arrow delineates the needle path. (c) Inferior medial genicular nerve (IMGN): a high frequency, linear ultrasound (Sonosite, Bethel, WA, USA) transducer was placed in the sagittal orientation over the right tibial medial epicondyle. The medial collateral ligament was visualized. The transducer was then translated distally to the level of the tibial insertion site of the medial collateral ligament below the tibial medial epicondyle. The point of 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 was targeted for the injection to the IMGN. The presence of the IMGN’s corresponding artery confirmed the target area. Using an in-plane technique, the needle was inserted in a cephalad to caudad direction. The solid white arrow delineates the needle path.

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