Chronic Joint Pain & Sensory Signaling
Damaged joints send constant pain signals through specific sensory nerve branches.
- ~51 M: US adults with chronic pain (CDC estimate)
- ~14 M: Knee OA pain prevalence (US adults affected)
- Millions/yr: Opioid prescriptions for joint pain (driving the search for alternatives)
- 3 main: Genicular nerve branches (knee) (superior/inferior medial, superior lateral)
How joints generate pain signals
Inflamed joint tissue fires nociceptors that reach the brain via named nerve branches.
Why opioids fall short here
Opioids dull perception everywhere but don't fix the local signaling pathway.
Targeting the messenger, not the brain
RFA interrupts the specific nerve carrying pain, sparing motor and other function.
Diagnostic Nerve Block
A local anesthetic injection confirms the identified nerve truly carries the pain.
- Lidocaine/bupivacaine: Anesthetic used (short-acting local)
- ≥50%: Pain relief threshold (needed to proceed to RFA)
- Hours: Block duration (temporary, diagnostic only)
- 1–2: Typical confirmatory blocks (done before ablation)
Why a test block comes first
It proves the chosen nerve, not another source, is driving the pain.
Reading the response
Significant temporary pain relief predicts a good ablation outcome.
Guarding against false positives
Some clinics repeat the block to rule out placebo response.
RF Probe Placement
A thin insulated needle is guided next to the confirmed nerve.
- Fluoroscopy/ultrasound: Guidance method (real-time imaging)
- ~5–10 mm: Needle exposed tip (active heating surface)
- <5 mm: Placement accuracy target (from nerve course)
- Outpatient: Procedure setting (local anesthesia only)
Positioning the active tip
The exposed electrode is placed parallel to the nerve's path.
Confirming placement
Sensory and motor stimulation tests verify correct probe position.
Minimizing collateral tissue effects
Careful placement avoids nearby motor nerves and vessels.
Thermal Radiofrequency Ablation
Alternating current at the tip heats tissue enough to disrupt nerve fibers.
- 60–90°C: Typical temperature (at electrode tip)
- 60–90 sec: Lesion duration (per ablation cycle)
- Coagulative necrosis: Mechanism (of nerve fiber tissue)
- Larger lesion: Cooled-RF option (via internally cooled probes)
How RF energy makes heat
Ionic agitation from alternating current heats tissue around the tip.
Disrupting nerve conduction
Heat denatures axonal structures, halting electrical signal transmission.
Dose matters
Higher temperature and longer duration create a larger, longer-lasting lesion.
Sustained, Non-Opioid Pain Relief
The ablated nerve stays silent for months while it slowly regenerates.
- 6–12 mo: Typical relief duration (before regrowth)
- ~50–70%: Reported pain reduction (in responders)
- Often reduced: Opioid use after RFA (per clinical studies)
- Possible: Repeat treatment (once nerve regenerates)
Why relief isn't permanent
Peripheral nerves slowly regrow, eventually restoring signal transmission.
A repeatable, drug-free option
Ablation can be redone safely once symptoms return.
Fitting into pain management
RFA reduces reliance on systemic opioids for joint pain control.