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

Abstract

Osteoarthritis (OA) of the knee is one of the most common joint diseases affecting adults in the United States. For elderly patients with multiple medical comorbidities who do not wish to undergo total knee arthroplasty (TKA), lifestyle modification, pharmacologic management, and injections are the mainstay of therapy. Previously, pain management interventions were limited to intra-articular joint injections and viscosupplementation with hyaluronic acid. Fluoroscopic-guided techniques for radiofrequency ablation (RFA) of the genicular nerves have been previously described and a recent cadaveric study suggests that ultrasound-guided genicular nerve blocks can be performed accurately. We performed an ultrasound-guided radiofrequency ablation of the genicular nerves in 88-year-old woman who had deferred surgical management given her age. Following successful ultrasound guided diagnostic genicular nerve blocks, she proceeded to RFA using the same ultrasound guided technique. The procedure resulted in significant pain relief and improvement in overall function for greater than 6 months. The use of ultrasound provides a relatively rapid and noninvasive method to directly visualize genicular nerves and surrounding vasculature. Our case suggests that, for genicular nerve blockade and RFA, ultrasound may be a useful alternative to fluoroscopy. Not only did the procedure result in significant pain relief that has persisted for greater than 6 months but also more importantly her function status and quality of life were improved.

Figures

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.