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Objective:
To determine the therapeutic effect of geniculate nerve radiofrequency for chronic knee pain by image-guided procedures performed on an outpatient basis by an interventional musculoskeletal radiologist.

Materials and Methods:
This study was approved by the hospital ethics committee. A total of 21 patients (age 60 +/- 10 years) suffering from moderate to severe osteoarthritis of the knee (Kellgren-Lawrence classification grade 2 to 4) were included. All 21 patients consented to undergo image-guided radiofrequency ablation of the geniculate nerves. Visual analogue scale (VAS) was measured at baseline and at 1, 4, and 12 weeks after the procedure. Radiofrequency ablation was performed for each knee targeting the superior medial genicular nerve, superior lateral geniculate nerve and inferior medial genicular nerve. The procedure was done under local anesthesia and conscious sedation utilizing C arm image intensifier for image guidance. Siemens Cios Spin (Munich, Germany). Following proper localization of each geniculate nerve by a 17 G needle under image guidance, an electrode probe was inserted coaxially into the needle at the proper site. The probes were then connected to an AVANOS radiofrequency machine generator (Windward Parkway Alpharetta, GA) utilizing the cold leaf-tip radiofrequency ablation technique. Testing for sensory stimulation at 50 Hz, 1.2 and 1.6 volts. Any heat sensation by the patient at the stimulus meant proper localization. Then, motor stimulation was performed at 2 Hz for 0.5 volt intervals until 3 volts. If there was any muscle shivering or reticulation, the probe was relocalized either medially or laterally to avoid ablation of the motor nerve. One radiofrequency lesion was made for each geniculate nerve. The electrode tip temperature was raised to 60° for 180 seconds, then all probes and needles were withdrawn. The patient was kept for observation for at least 4 hours and then discharged home with pain medications and instructions to place ice at the sites of needles.

Results:
Patient age range from 50 - 70 years. Baseline score for pain before the procedure on a visual analog scale ranged from 8/10 to10/10 with an average of 8.9/10. Patient pain score 1 week after the procedure ranged from 4/10 to 6/10 with an average of 4.6/10 on the visual analog scale. Patient pain score 4 weeks after the procedure ranged from 3/10 to 5/10 with an average of 3.3/10 on the visual analog scale. Patient pain score 12 weeks after the procedure ranged from 1/10 to 4/10 with an average of 2.3/10 on a visual analog scale. There was a significant reduction of pain between the baseline and 12 weeks with a p value measuring less than 0.05.

Conclusion:
Radiofrequency ablation of the geniculate nerves of the knee has significant pain reduction and functional improvement in elderly patients with chronic osteoarthritis of the knee. Therefore, it is an effective treatment in such cases.