Which knee pain treatment is more effective?
Knee pain is one the most common pain conditions, affecting 25% of adults and accounting for an estimated 4 million primary care visits each year. Knee pain is caused by a wide range of problems, from sports injuries to overuse and degenerative conditions, like osteoarthritis. As such, treatment options for knee pain are specific to the pathology (i.e. source of pain) and can vary depending on the severity of symptoms. Among knee interventions, the genicular nerve block and genicular nerve radiofrequency ablation (RFA) are two of the most common surgical alternatives for persistent pain.
What causes genicular nerve pain?
The genicular nerve refers to a network of nerves that feed into your knee and are responsible for submitting sensory information, like pain signals, from the knee joint to the brain.
Genicular nerve pain is caused by a wide range of issues, including:
- Sports injury—Sprains, fractures, and tears across knee tissue can irritate the surrounding nerves.
- Osteoarthritis—As the cartilage in the knee joint wears down due to osteoarthritis, the bones rub against each other, causing inflammation and compression of the genicular nerves around the knee.
- Knee surgery—Some patients may experience chronic knee pain after undergoing invasive knee surgery due to nerve irritation or damage during the procedure.
- Overuse—Activities that involve repetitive stress or overuse of the knee joint, such as running, jumping, or squatting, can lead to inflammation and irritation of the genicular nerves over time.
What are genicular nerve blocks?
Genicular nerve blocks are minimally invasive solution and especially effective for genicular nerve pain induced by osteoarthritis.
Nerve blocks effectively disrupt the transmission of pain signals from the affected knee joint to the brain. A block procedure consists of local anesthetic and a steroid medication, injected directly into the genicular nerves under x-ray guidance.
Patients with knee osteoarthritis may experience significant relief from their chronic pain. However, nerve blocks are not designed to be long-lasting pain management solutions.
Patients who respond well to two genicular nerve block treatments may qualify for a longer-lasting ablation treatment.
What is a genicular nerve ablation?
Genicular Radiofrequency Ablation (RFA)
Radiofrequency Ablations are also minimally invasive, though they may provider longer lasting relief than their nerve block counterparts. Radiofrequency ablations disrupt pain signals using heat. Using x-ray guidance your doctor administers electrodes directly on the irritated genicular nerve. Then, a high voltage current passes through the electrode to create a precise heat lesion on the nerve, effectively stopping pain signal transmission.
Genicular Cryoablation
Similar to a RFA, a cryoablation interrupts pain signals transmitted by nerves in the knee. Whereas RFAs use heat to target the affected nerve, a cryoablation uses extreme cold.
During cryoablation, your doctor employs X-ray guidance to place thin needles called cryoprobes into the irritated genicular nerve. Once the cryoprobes are in place, your doctor administers CO2 gas to freeze the tips of the needles down to -80℃. The extreme cold damages the irritated nerve to effectively stop the pain signals. Like a RFA, nerve regeneration may occur after 6-9 months.
Nerve block vs. ablation?
If you’re looking for an alternative to total knee arthroscopy, both nerve blocks and ablations can provide pain relief. But the two are not necessarily equal treatments.
Nerve blocks are effective early treatments—not only do they alleviate pain, but they also indicate whether or not a longer-lasting treatment like an ablation will effectively reduce pain. While a radiofrequency ablation and cryoablation can provide relief for up to 9 months. In other words, a nerve block is a necessary stepping stone on the path to an ablation.
When it comes to mitigating pain there is no single solution. Certain pain interventions effectively target certain conditions. The only way to really know which surgery alternative is best for you, is to consult with a pain management specialist.
References
Bunt, Christopher W et al. “Knee Pain in Adults and Adolescents: The Initial Evaluation.” American family physician vol. 98,9 (2018): 576-585.
Iannaccone, Ferdinand et al. “A Review of Long-Term Pain Relief after Genicular Nerve Radiofrequency Ablation in Chronic Knee Osteoarthritis.” Pain physician vol. 20,3 (2017): E437-E444.
Conger, Aaron et al. “Genicular Nerve Radiofrequency Ablation for the Treatment of Painful Knee Osteoarthritis: Current Evidence and Future Directions.” Pain medicine (Malden, Mass.) vol. 22,Suppl 1 (2021): S20-S23. doi:10.1093/pm/pnab129
Chang, Yi-Wei et al. “Functional outcomes and physical performance of knee osteoarthritis patients after ultrasound-guided genicular nerve radiofrequency ablation.” Pain medicine (Malden, Mass.), pnab280. 17 Sep. 2021, doi:10.1093/pm/pnab280