Knee Genicular Nerve Rhizotomy: A Candidate Evaluation Guide
For patients living with chronic knee pain that has not responded to conservative care, genicular nerve radiofrequency rhizotomy is one option providers may discuss. Before the procedure is considered, candidates go through a structured evaluation that includes imaging review, a diagnostic nerve block, and a conversation about goals and expectations.
Genicular nerve rhizotomy, sometimes called genicular radiofrequency ablation, is a minimally invasive procedure that targets small sensory nerves around the knee joint. These genicular nerves carry pain signals from the joint to the brain. When the nerves are interrupted using controlled heat from a radiofrequency probe, many patients experience a meaningful reduction in pain that can last from several months to roughly a year. The procedure does not repair the joint itself; it changes how pain signals travel from the joint to the central nervous system.
The clinical team typically considers rhizotomy for patients with persistent knee pain related to osteoarthritis, post-surgical pain after total knee replacement, or chronic joint pain that has not improved with physical therapy, oral medications, bracing, or injection-based treatments. Candidates are usually adults whose imaging confirms a structural source of pain and whose daily function is meaningfully limited by their symptoms. Patients who are not surgical candidates, or who want to delay a knee replacement, may also be evaluated.
The diagnostic genicular nerve block: the gating step
The single most important step in candidate evaluation is the diagnostic genicular nerve block. Before any rhizotomy is scheduled, providers perform a test block in which a small volume of local anesthetic is delivered, under image guidance, to the same nerves that would later be targeted by the radiofrequency probe. The patient then tracks pain levels during the hours that follow, often using a simple diary or scale provided by the clinic.
A diagnostic block is considered positive when the patient reports a clear, time-limited reduction in their typical knee pain during the window when the anesthetic is active. Many programs use a threshold around fifty percent improvement, though the exact criteria are set by the treating physician. A positive block suggests that the genicular nerves are a meaningful contributor to the pain pattern, which in turn suggests that interrupting those nerves with radiofrequency energy is more likely to help. A negative or equivocal block is also informative: it tells the team that another pain generator is likely involved, and that rhizotomy is unlikely to be the right next step.
Some practices use a single diagnostic block; others use two blocks performed on separate days to reduce the chance of a false positive. The approach depends on clinical judgment, payer requirements, and patient circumstances.
What the consultation conversation typically covers
The consultation visit is a working conversation. Providers review the patient's pain history, prior treatments, imaging, and any relevant surgical records. Patients can expect questions about which activities are limited, how sleep is affected, what makes the pain better or worse, and what a meaningful improvement would look like in daily life. The goal of these questions is to build a realistic picture of what success would mean for this specific patient.
The clinical team also discusses the expected scope of benefit. Rhizotomy is a pain-management procedure, not a structural fix. Patients who respond well typically describe reduced pain with walking, stairs, or prolonged standing, and a lower reliance on oral pain medication. The team also explains that the nerves can regenerate over time, which is why the effect is time-limited and why some patients return for a repeat procedure if their initial result was positive.
Risks and contraindications are reviewed in plain language. Common considerations include active infection, certain bleeding disorders or anticoagulant use that has not been managed in coordination with the prescribing physician, pregnancy, and implanted devices that may interact with radiofrequency equipment. Patients are asked to share a complete medication list, including supplements, and to disclose any prior reactions to local anesthetics or contrast agents.
The consultation also covers logistics: what to expect on the day of the procedure, how long the appointment usually takes, whether a driver is needed, and how recovery is structured in the days that follow. Patients receive written instructions and a point of contact for questions that come up between visits.
A strong candidate, in short, is a patient with confirmed knee-related pain, a positive diagnostic block, realistic expectations, and a treatment history that shows conservative options have been given a fair trial. Patients who do not meet all of these criteria are not turned away; they are redirected toward the next appropriate evaluation, which may include additional imaging, a different injection-based treatment, or a referral back to an orthopedic surgeon for surgical reassessment.
This article is informational and is not medical advice. Treatment options should always be discussed in consultation with a qualified physician.