Comments on: Ultrasound-guided genicular nerve radiofrequency treatment: prospective randomized comparative trial of a 3-nerve protocol versus a 5-nerve protocol

Dear Editor, We want to congratulate Guven et al. for the effort in enhancing the clinical evidence regarding the borderline response of genicular nerve radiofrequency in managing severe osteoarthritic knee pain in their recent publication titled “Ultrasound-guided genicular nerve radiofrequency treatment: Prospective randomized comparative trial of a 3-nerve protocol versus a 5-nerve protocol.”1 However, we have identified several points that the authors should clarify. First, it is imperative to ensure accuracy in the conclusion statements, both within the title, abstract, and the main body of the paper. The procedure carried out on the 2 additional nerves was pulsed radiofrequency and not continuous radiofrequency. It is crucial to rectify this to avoid misleading information and misinterpretation to the reader. While the evidence for continuous radiofrequency of genicular nerves might be deemed marginally conclusive, the evidence for pulsed radiofrequency of genicular nerves is undoubtedly anecdotal.2 Second, in the methods section, the authors detail their ultrasound-guided technique for targeting the additional nerves: the infrapatellar branch of the saphenous nerve and the recurrent fibular nerve of the peroneal nerve. However, the images provided by the authors depict needle trajectories rather than illustrating the nerves themselves. In our extensive experience with this procedure, both by ultrasound and fluoroscopy, it is certainly challenging, if not impossible, to consistently visualize these 2 nerves under ultrasound. Furthermore, notably, in the discussion section the authors mention that their technique was founded on previously described procedures conducted under fluoroscopy, a technique that is based on bony landmarks. Once more, the discrepancy between the technique described in the methods section is misleading to the reader as it does not agree with their explanation in the discussion. More surprising is the authors' description of adjusting the cannula for nerve stimulation using electrical sensory stimulation without providing further information to the readers. This raises the questions: Were the nerves not observed as described in the methods section? Based on our experience, we understand that utilizing sensory stimulation in this procedure is not helpful, given its potential for false positives, such as periosteal stimulation. Furthermore, the technique of sensory stimulation on genicular nerves remains unvalidated and is generally considered impractical by practitioners. Third, it is important to note that the infrapatellar saphenous branch is not a branch that consistently innervates the inferomedial knee quadrant. Moreover, Tran et al described it in only 3 out of 15 specimens, providing articular branches.3 Additionally, recent validated cadaveric studies indicate that solely targeting genicular arteries with the 3 traditional genicular nerves radiofrequency procedures does not accurately correspond to the actual nerve locations. Particularly, the superomedial and superolateral genicular nerves, which are notably present, appear to be situated differently. The former is positioned relative to the adductor tubercle and the latter to the posterosuperior border of the lateral femoral condyle, suggesting that the location should be posterior (deeper) to those described in this article by the author. Finally, the pain outcome results of this study appear to be less effective compared to a recently published randomized control trial (RCT).4 This RCT directly compared the effects of adding steroid to both groups (one receiving sham-cannula insertion but no lesion and the other undergoing bipolar radiofrequency of the traditional genicular nerves). This study demonstrated equally significant relief of pain and functionality objectively evaluated by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores in both groups not only at 6 but 12 months.4 The inclusion of 60 mg of triamcinolone in both groups by Guven et al raises concerns about the ability to draw realistic conclusions regarding the treatment effect of radiofrequency on the geniculate nerves in this study. Recently, we published our retrospective experience adding continuous radiofrequency to three additional nerves—lateral and medial branch of the vastus intermedius and recurrent fibular nerve at the fibular head- under fluoroscopy.5 A RCT on this technique is currently underway. Our study demonstrated significant improvements in pain and functionality at 6 months when compared to the traditional 3 nerves target continuous radiofrequency.5 Based on recent cadaveric studies’ findings and in consideration of the need for prior validation of the nerves suggested for lesioning, we are convinced that enhancing solid evidence on the effectiveness of genicular nerves radiofrequency is imperative. Mauricio Forero, MD, FIPP Hamilton, ON, Canada [email protected] The authors have not declared a specific grant any funding agency in the public commercial or not-for-profit sectors. Conflicts of interest: The authors declare no conflicts of interest.

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