Distribution of sensory nerves supplying the knee joint capsule and implications for genicular blockade and radiofrequency ablation: an anatomical study

Chronic osteoarthritis (OA) pain of the knee is often not effectively managed with current non-pharmacological or pharmacological treatments. Radiofrequency (RF) neurotomy is a therapeutic alternative for chronic pain. We investigated whether RF neurotomy applied to articular nerve branches (genicular nerves) was effective in relieving chronic OA knee joint pain. The study involved 38 elderly patients with (a) severe knee OA pain lasting more than 3 months, (b) positive response to a diagnostic genicular nerve block and (c) no response to conservative treatments. Patients were randomly assigned to receive percutaneous RF genicular neurotomy under fluoroscopic guidance (RF group; n=19) or the same procedure without effective neurotomy (control group; n=19). Visual analogue scale (VAS), Oxford knee scores, and global perceived effect on a 7-point scale were measured at baseline and at 1, 4, and 12weeks post-procedure. VAS scores showed that the RF group had less knee joint pain at 4 (p<0.001) and 12 (p<0.001) weeks compared with the control group. Oxford knee scores showed similar findings (p<0.001). In the RF group, 10/17 (59%), 11/17 (65%) and 10/17 (59%) achieved at least 50% knee pain relief at 1, 4, and 12 weeks, respectively. No patient reported a post-procedure adverse event during the follow-up period. RF neurotomy of genicular nerves leads to significant pain reduction and functional improvement in a subset of elderly chronic knee OA pain, and thus may be an effective treatment in such cases. Further trials with larger sample size and longer follow-up are warranted. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Chronic knee pain is common in all age groups. Some patients who fail conservative therapy benefit from radiofrequency neurotomy. Knowledge of the anatomy is critical to ensure a successful outcome. The purpose of this study was to reanalyze the innervation to the anterior knee capsule from the perspective of the interventional pain practitioner.