Comparative evaluation of monopolar and bipolar radiofrequency ablation of genicular nerves in chronic knee pain due to osteoarthritis

BACKGROUND AND AIMS: Monopolar radiofrequency ablation (MRFA) of the genicular nerve is effective in managing chronic knee pain from osteoarthritis (OA); however, the procedure itself is associated with significant pain due to manipulation of electrode to localise tiny genicular nerves. We hypothesised that inserting two electrodes to target the genicular nerves [bipolar radiofrequency ablation (BRFA)] without sensory localisation can decrease the procedural pain with equal analgesic efficacy in treating knee pain. METHODS: Thirty patients with chronic knee pain due to OA were randomised to receive either MRFA (n = 15) or BRFA (n = 15), after having 50% pain relief with diagnostic genicular nerve block. Pain during the procedure (assessed by the Numeric Rating Scale [NRS]), time taken to do the procedure and complications were recorded. Knee pain was assessed by the Oxford Knee Score at baseline, 1 week, 1 month, 3 months and 6 months following the procedure. RESULTS: Patients in both groups had good pain relief, and no difference in pain relief and the duration of pain relief was seen between the two groups. The median (range) NRS for procedural pain was significantly lower in the bipolar group [3 (3–5)] than in the monopolar group [5 (3–7), P = 0.013]. There was no significant difference in procedure time and no complications were seen in either group. CONCLUSION: BRFA is an effective alternative for ablation of genicular nerves in patients with knee pain due to OA. It causes less procedural pain compared with MRFA.