Chronic pain is an insidious and complex disease with considerable personal and economic impacts . Although it is typically considered a presentation secondary to an ongoing disease, such as cancer, or the result of a work- or life-related trauma , it is also a disease state in and of itself with its own pathology, genetic factors, and medical definition [3, 4].
“The Global Burden of Disease Study 2016 reaffirmed that the high prominence of pain and pain-related diseases is the leading cause of disability and disease burden globally .” “Measuring years lived with disability; low back and neck pain have consistently been the leading causes of disability internationally, with other chronic pain conditions featuring prominently in the top 10 causes of disability .”
Back pain is one of the most frequent reasons for visiting a physician in the United States and is the most common type of pain reported by Americans. “More than $100 billion  is spent annually in the United States on low back pain, which is the leading cause of work-related disability and economic burden in the United States [7, 8]." Simply put, chronic pain has a significant effect on the economy and on the quality of life of those afflicted with it.
One of the most common causes of pain is facet joint degeneration [9,10,11,12,13]. “Radiofrequency neurotomy/ablation (RFN/RFA) of the medial branch nerves, the nerves which supply the facet joints, is a commonly used procedure and is one of the only proven efficacious interventional modalities for treating facet joint pain [14,15,16].” In a systematic review of randomized controlled trials (RCT) of RFA for chronic low back pain evidence was found to support RFA as an efficacious therapy for lumbar facet joint pain in five of six RCT analyzed . In another meta-analysis looking at RFA in patients with chronic pain originating from the facet joints, RFA was found to be more efficacious than corticosteroid injections and found to result in better pain improvement for an entire year . Specifically, "RFA is a procedure that may offer pain relief for patients without a known pathology .”
RFA is often a treatment modality that is considered after surgical procedures that involved the placement of metallic hardware . This is because patients who have undergone surgery often suffer from further joint degeneration secondary to the surgery itself , which leads to additional, subsequent pain that is best treated with RFA . Unfortunately, "there is a theoretical risk involved with treating patients with existing spinal hardware with RFA, as the needle tip used for the procedure ends up in close proximity to this metal hardware ." The ultimate concern is that the metal hardware will serve as a heat sink, increasing the risk of thermal energy damage in the tissues surrounding it as well as drawing heat energy away from the intended site and thus reducing overall efficacy .
These risks remain theoretical due to a paucity of high-quality studies that directly explore the possibility that heat transfer does occur and that this occurrence, if it exists, has any impact on the safety and efficacy of the procedure.
At this time, the limited research that has been done has focused on the transfer of heat versus the efficacy of the procedure in these types of patients. Gazelka et al. , in a cadaver study, found that regardless if the RFA cannula was placed on or near the pedicle hardware, there was a significant increase in temperature of the hardware and that these "results suggested that pedicle screws could serve as a possible source of tissue heating and thermal injury during RFA "; therefore, further precautions should be taken when performing this procedure on patients who had existing hardware at the site of the RFA procedure . Lamer et al.  looked directly at patients who had existing spinal hardware. The results of their study aligned with those found by Gazelka et al. That is, temperature increases were seen in 60% of pedicle screws  with warnings that "a practitioner should weigh the risks and benefits of lesioning the medial branch nerve at a level adjacent to a pedicle screw to minimize the risk of heat energy transfer to the hardware and the surrounding tissue ." Klessinger  was one of the few to look at safety and efficacy of lumbar RFN in the presence of pedicle screws via a retrospective practice audit, which ultimately included 38 patients. Although they found strong evidence that the pedicle screws did ‘sustain significantly increased temperatures,’ no effect from heated metal devices was detected . Even more, “patients reported no adverse effects or worsening pain. Therefore, despite the potential risk, RFA in the presence of pedicle screws appears to be a safe procedure .”
The purpose of our study was to specifically explore the efficacy of patients receiving RFA who also have existing hardware at the same site. We started at a place of accepting and anticipating that the hardware would be subjected to temperature increases, as this has now been validated by a minimum of three studies [19, 22, 23]. What we sought to elucidate was if this temperature increase had, in turn, any negative consequences on the outcomes of the procedure from an efficacy standpoint as there is continued theoretical concern that the dissipation of heat into the hardware can lead to a smaller lesion, which can reduce efficacy.