Osteoarthritis represents the most common form of arthritis with symptomatic knee OA occurring in 10% of men and 13% of women aged 60 years or older. A double-blinded randomized controlled trial published in 2010 found that radiofrequency ablation (RFA) of genicular nerves for chronic knee pain resulted in statistically significant less visual analogue scale (VAS) pain scores at 1, 4 and 12 weeks compared with baseline.
We performed a retrospective study of patients who underwent RFA of the genicular nerves to analyze the length of pain relief beyond three months, culminating at six months. We propose that using a stimulating threshold of 0.15 V before nerve ablation better localizes the RFA electrode to the genicular nerves. Ablations were performed at 60°C for 120 seconds, minimal temperature required for protein denaturation and coagulation necrosis.
Retrospective chart review was performed on patients status-post RFA since May of 2014. Follow-up phone interviews at 3 and 6-months post treatment were conducted. Statistical analysis was performed in order to calculate average degree pain relief (0-100%) and percentage of those describing pain relief at 3-months and 6-months post RFA. We also attempted to quantify patient satisfaction with RFA by calculating response percentage to procedure length, anxiety, pain and if they would recommend this intervention to others.
We have established the following exclusion criteria: the patient is too debilitated secondary to systemic disease or dementia and unable to participate in accurate follow-up or the patient was found to be suffering from a chronic rheumatologic disease.
Since beginning chart review in February 2015 we have pulled 30 patient’s charts that underwent RFA of the genicular nerves. The average age of our patient population was roughly 65 years old and average BMI was roughly 28.
Out of 30 patients, 21 were ready for their 3-month follow-up during our data-sampling period. We were able to follow-up with 14, 3 of which met exclusion criteria. At 3 months 73% of patients described pain relief. Their average percent pain relief was 55%.
Out of 30 patients, 18 were ready for their 6-month follow-up during our data-sampling period. We were able to follow-up with all 18 patients, 3 of which met exclusion criteria. At 6 months 67% of patients described pain relief. Their average percent pain relief was 51%.
Of note, 5 patients found themselves 7 or more months since RFA when finally contacted. Of these 5 patients, 3 still described pain relief. Their average percent pain relief was 62%. The longest duration noted being roughly 12 months with roughly 60% pain relief.
We did not observe any complications such as neuralgia, parasthesias or motor weakness secondary to RFA; and only 1 patient described transient numbness of the knee.
All patients described no to mild anxiety associated with the procedure and all felt the procedure was short or appropriate length. Of 25 patients polled, 68% would recommend this procedure to a family member or loved one.
Thus far, RFA of the genicular nerves appears to be an efficacious treatment option for patients suffering from chronic knee pain secondary to OA. Genicular nerve RFA is a minimally invasive procedure with minimal side effects or risks that may allow a patient extended pain relief without the need of pharmacologic agents or invasive knee surgery.