SIR 2024
Pain Management/MSK
Aazrin Mir, MS (she/her/hers)
Medical Student
Georgetown University School of Medicine
Financial relationships: Full list of relationships is listed on the CME information page.
Neil K. Jain, DO (he/him/his)
Integrated Interventional Radiology Resident
Medstar Georgetown University Hospital
Financial relationships: Full list of relationships is listed on the CME information page.
Thomas Stirrat, BS, BA
Medical Student
Georgetown University School of Medicine
Disclosure information not submitted.
John B. Smirniotopoulos, MD
Assistant Professor of Radiology
MedStar Georgetown University Hospital
Financial relationships: Full list of relationships is listed on the CME information page.
Knee osteoarthritis (OA) is one of the leading causes of pain and disability. The Kellgren and Lawrence systems are used to diagnose severity of disease on x-ray, and MRI can be utilized to evaluate changes in cartilage. Genicular nerve ablation (GNA) is an emerging procedure that has shown to relieve OA pain that is unresponsive to medical or surgical treatment. According to a cadaveric study published in 2023, there is significant variability in the location of the superomedial and superolateral genicular nerves in knee dissections. The novel “pull-back” technique has established a safe and efficacious profile for management of anatomic heterogeneity.
Clinical Findings/Procedure Details:
Patient selection for ablation involves evaluation of the Visual Analog Scale (VAS) for pain and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score for function. The genicular nerves (GN), a group of six nociceptive carriers, are targeted. First, patients receive a diagnostic block of 1mL lidocaine around the superior lateral (SL), superior medial (SM), and inferior medial (IM) GN. A >50% reduction in VAS after a block qualifies a patient for GNA. GNA is performed under ultrasound or fluoroscopic guidance, using thermal or cooled techniques. With probes in position, motor function is tested using 2Hz and 2V stimulation to ensure no gross fasciculations. Radiofrequency GNA heats the nerves to 80 to 90 degrees Celsius, creating an elliptical area of tissue destruction. Cooled GNA uses saline to cool the probe to 60 degrees Celsius with a spherical shape of destruction. An initial ablation at ⅔ shaft depth is performed for the SM and SL locations, after which those trocars are retracted to ⅓ shaft depth for a second ablation. This "pull-back" technique was developed due to anatomic heterogeneity to ensure the maximum zone of nerve ablation. The IM and optional suprapatellar ablations are performed in a single location per standard protocol. The total procedural time is around 15-30 minutes under local anesthesia. Genicular nerve ablation is a minimally invasive treatment option that has been shown to provide relief to patients whose knee OA pain has not improved, and does not negatively impact future procedures or surgery. The novel pull-back technique allows for management of anatomic heterogeneity of the superomedial and superolateral genicular nerves, maximizing the probability of complete sensory denervation.
Conclusion and/or Teaching Points: