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Most back pain resolves with conservative treatment, but a significant number of individuals may develop chronic spinal pain. The causes of chronic back or neck pain are obscure, and imaging techniques are not dependable diagnostic tools. Nerve block studies indicate that nonspecific pain is often attributed to disorders of the facet (zygapophyseal) joint; however, nonspecific pain is a condition with no clear pathological etiology. Although no definitive treatment is available, conventional percutaneous radiofrequency (RF) denervation of the facet joint has been advocated and used with increasing frequency.

RF lesioning (also known as RF ablation, RF facet denervation, RF rhizotomy, facet rhizotomy, and percutaneous RF neurotomy) for disorders of the facet joint is performed in an outpatient setting. RF denervation is used to treat back and neck pain originating in the facet joints with degenerative changes. Diagnosis of facet joint pain is confirmed by a positive response from nerve blocks. The goal of RF facet denervation is for long-term pain relief of the facet joint pressure.

The facet joints, also known as apophyseal or zygapophyseal joints, are formed by the superior and inferior articular processes of sequential vertebrae. On the dorsolateral surface of each superior articular facet is a prominence known as the mammillary body or process. The nerves that communicate with these joints sometimes become inflamed or impinged, which leads to pain.

The two most frequently utilized types of RF facet joint denervation used to treat chronic spinal pain are:

• Pulsed radiofrequency (PRF), which consists of short bursts of electrical current of a high voltage, but without heating the tissue enough to cause coagulation.
• Percutaneous or nonpulsed RF, which is performed for a predetermined amount of time with no interruption in the RF flow until the full dosing time is achieved.

PULSED RADIOFREQUENCY (RF)

Pulsed RF, a nonablative alternative to RF, uses short bursts of RF current, rather than a continuous current. The heat from PRF is not enough to cause the tissue to coagulate. PRF denervation causes the transmission across small unmyelinated nerve fibers to be disrupted, but not permanently damaged. This is because the temperatures will not exceed 42°C, versus the 60°C reached in (thermal) percutaneous RF.

Van Zundert et al. (2007) conducted a randomized sham-controlled trial investigating the treatment of PRF for the indication of chronic cervical radicular pain. The study included 23 participants who reported neck pain that radiated over the posterior shoulder to the arm and lasted more than 6 months; these participants had failed conservative therapy. The participants were assessed 3 months following the treatment. Success was defined as at least a 50% pain improvement of the global perceived effect (GPE), at least a 20% reduction in pain on the visual analog scale (VAS), and a reduction in pain medication consumption. Nine of 11 participants in the treatment arm, and four of 12 in the sham group, had at least a 50% pain improvement. Nine of 11 in the treatment group, and three of the 12 in the sham group, achieved at least a 20% reduction in pain on VAS (P=0.2). At 6-month follow-up, there was an increase in participants in the treatment group who reduced their use of pain medication, but the difference was not significant. The authors concluded that PRF may provide cervical pain relief for a limited number of select individuals, but larger studies are needed to validate this conclusion.

Çetin and Yektas (2018) conducted a double-blind RCT comparing PRF to conventional (nonpulsed percutaneous) RF. The PRF group included 75 participants and the conventional RF group had 43 participants with chronic lumbar facet pain. The participants were assessed using the VAS (preoperation and 1, 3, 6, 12, 24 months follow-up) and Odom criteria at 24-month follow up. VAS scores were significantly reduced in both groups at all follow-up times compared to preoperation scores. Only at the 12-month follow-up assessment were the PRF VAS scores significantly reduced compared to the VAS scores of the conventional RF group. At all other times, the PRF VAS scores were significantly greater than the VAS scores of the conventional RF group. At 24-months follow-up, the percentage of positive responders to Odom 1 and 2 criteria was greater in the conventional RF group compared to the PRF group by a statistically significant amount. The authors concluded that pulsed RF is effectively weaker than conventional RF.

Van Eerd et al. (2021) conducted a double-blind sham-controlled trial investigating PRF with bupivacaine injection in participants with chronic cervical facet join pain. The PRF group consisted of 37 participants and the sham group consisted of 39 participants. The primary outcomes were (1) greater than 30% reduction in pain using the Numeric Rating Scale (NRS) at 6 months, (2) Patient Global Impression Change (PGIC) reported as “very much improved" or “much improved," (3) Neck Disability Index (NDI) score, and (4) Medication Quantification Scale III (MQSIII). Both groups reported a clinically significant reduction in NRS score compared to baseline, but there was no difference between the groups at 6 months. Further, there was no difference between groups in PGIC, NDI, or MQSIII scores at 6 months. The authors concluded that there was no difference between the interventions (pulsed RF with bupivacaine vs. sham RF with bupivacaine).

Most studies published on PRF are composed of small case series and reports with limited follow-up. Additional larger RCTs on PRF are needed to establish safety and effectiveness for use in treating chronic facet pain given the (1) high prevalence of chronic back pain, yet low study sample size in sham-controlled trials; (2) established alternatives with long-standing use in routine clinical care; (3) subjectivity of the primary outcome (the perception of pain may be different among different people groups); and ​(4) variability in duration of effect (regeneration of nociceptive nerve tissue).​

NONPULSED (PERCUTANEOUS) RADIOFREQUENCY

Prior to having an RF denervation procedure, a diagnostic paravertebral facet joint nerve block is commonly performed to assess the relative contribution of sympathetic and somatosensory nerves in relation to the pain syndrome. A diagnostic nerve block localizes the nerve(s) responsible for the pain or neuromuscular dysfunction, particularly when multiple sources of pain are potentially present. This procedure is performed under fluoroscopic guidance to ensure accurate placement of the needle in the facet joint or at the medial nerve branch of the facet joint.

Upon needle placement, a long-acting local anesthetic is injected to temporarily numb the facet joint. The individual is then asked to engage in the activities that had previously precipitated pain, and to evaluate the effect of the procedure at 4 to 8 hours postinjection. A temporary or prolonged absence of spinal pain strongly suggests that the facet joint is the source of the symptoms. A repeat injection may be needed to establish consistency of results, particularly if diagnostic nerve blocks are followed by neurolysis.

RF facet joint denervation employs a percutaneously introduced electrode that applies heat from radio waves to selectively destroy sensory afferent nerve fibers, thereby interrupting pain signals from a specific site. A minimum of two levels must be addressed to denervate a single joint; RF lesioning is directed at each of the levels to be lesioned. Destruction of the nerve may be permanent or temporary. In some cases, the treated nerve repairs itself and becomes less irritable, thus resulting in continued resolution of the pain. In cases where the pain returns, the procedure can be repeated in the same joint, following an elapsed time of at least 6 months and a previous positive result from RF denervation, as measured by significant improvement in functional status and reduced facet mediated pain.

PEER-REVIEWED LITERATURE

Lumbar Facet Joint Pain

Several systemic reviews and meta-analyses have been published in recent years (Ambrosio et al., 2023; Li et al., 2022; and Janapala et al., 2021). While these studies include varying study designs, denervation modalities, and outcome measures, all the authors conclude that radiofrequency denervation is a safe and effective procedure for the treatment of individuals with chronic low back pain of facet origin.

A 2015 systematic review by Manchikanti et al. identified nine RCTs or comparative studies on RF denervation of lumbar facet joints. The sample sizes ranged from 31 to 100 subjects. All studies but one showed short- or long-term benefit of facet joint denervation, and the overall body of evidence was rated as level II.

The largest study included in the Manchikanti et al. systematic review compared facet joint injection and facet joint denervation in 100 subjects. There were no sham controls, limiting interpretation of the results. In a 2013 double-blind RCT by Lakemeier et al., RF facet joint denervation was compared with intra-articular steroid injections in 56 subjects. Subjects were selected first on magnetic resonance imaging findings of hypertrophy of the facet joints followed by a positive response to an intra-articular infiltration of the facet joints with anesthetics. A diagnostic double-block of the facet joint was not performed. At 6 months, there was no significant difference between the two groups.

Nath et al. performed an RCT involving 40 individuals, following a screening of 376 individuals, to evaluate short- and intermediate-term effects of RF for lumbar facet pain study data. Individuals who were included in the study complained of pain involving one or more lumbar zygapophysial joints, paravertebral tenderness, and had obtained at least an 80% reduction of pain following controlled medial branch blocks. The 40 participants were randomly assigned to an RF or sham group and were followed for 6 months. Multiple lesions were treated in each participant in the RF group. The GPE and VAS measurements were used to assess outcomes following treatment in both groups. Although back pain was reduced in both groups, the RF participants were significantly more improved on secondary measures of back and hip movement, quality-of-life variables, paravertebral tenderness, and reduction in use of analgesics.

In 2005, van Wijk et al. performed a multicenter RCT. Inclusion criteria were continuous low back pain with or without radiating pain to the upper leg greater than 6 months, as well as tenderness over the facet joints. A total of 226 participants were screened for the study. Of those screened, 81 were randomly assigned to either an RF group (40) or a sham treatment group (41). The primary outcome was determined by defined outcome measures using a VAS scale (a psychometric response scale that can be used to measure subjective characteristics or attitudes), daily physical activities, and individual use of analgesics. Success was defined as 50% reduction of the median VAS-back score without reduction in daily activities and/or increase in analgesic use or reduction of at least 25% in a participant's analgesic use. Participants kept weekly diaries and were followed up at 3 months. Failures at 3 months in the sham group were unblinded and offered RF. Follow-up then continued at 6, 9, and 12 months. At 3 months there was no difference between the two groups. Although some participants were lost to follow-up between 3 months and 12 months, the authors' overall conclusion was that significantly more participants in the RF group than the sham group achieved greater than 50% pain relief on the GPE measure, which used a four-point Lickert scale.

The available peer-reviewed data, including the aforementioned studies, suggest that RFA has improved outcomes related to pain and functional status when used for the treatment of lumbar facet pain in selected individuals.

Cervical Facet Joint Pain

An RCT published in 1995 by Lord et al. utilized RFA to treat chronic cervical pain of the facet joints (individuals with C2-C3 zygapophyseal joint pain were excluded due to the technical difficulty in treating this level of pain.) Of the 54 screened individuals, 24 participants met the inclusion criteria and were randomly assigned to an RFA or sham group. The individuals' perception of pain was confirmed using placebo-controlled blocks. In the RFA group, two or three thermal lesions using RFA were made at each cervical location being treated. Participants were followed for the first few days, then weeks, and then again at 3 months using a VAS measurement and the McGill pain questionnaire, indicating whether activities of daily living had been restored. Those from either group who had no relief of pain or an early return of pain were offered RFA. Those who had pain relief at 3 months were asked to follow up when their pain returned to 50% or more of their pretreatment level. The results were an average return to greater than 50% of pretreatment pain at 263 days in the RFA group versus 8 days in the placebo group.

The data suggest certain selected individuals would benefit from RFA in treating cervical facet joint pain.

Thoracic Facet Joint Pain

There is a current paucity of high-quality data evaluating the safety and effectiveness of treatment with RF denervation in the thoracic facet joints for chronic pain.

Sacroiliac Joint Pain

The literature on RF denervation of the sacroiliac joint (SIJ) is limited. In 2010, Aydin et al. published a meta-analysis of RF ablation (RFA) for sacroiliac pain. Nine studies were reviewed that reported the primary outcome measure of a reduction of pain of 50% or greater, assessed using VAS. This included a randomized placebo-controlled study, three prospective observational studies, and five retrospective studies. All of the studies used injection of local anesthetic to determine if RFA was indicated for the individual. Seven studies reported follow-up treatment to 3 months, and six studies reported follow-up to 6 months. Meta-analysis indicated that at least half of the individuals who received RFA at the SIJ showed a reduction in their pain of 50% or more at 3 and 6 months. The conclusion determined by the meta-analysis review of this literature is limited by the low quality of the studies and lack of RCTs. In addition, the authors concluded, no standards have been established for the specific nerves to ablate or type of technique.

The single RCT included in the meta-analysis by Aydin et al. examined the effect of lateral branch RF denervation in 28 individuals with injection-diagnosed SIJ pain. Two (14%) of 14 participants in the placebo-control group reported pain relief at 1-month follow-up. None reported benefit at 3-month follow-up. Of 14 participants treated with RF denervation, 11 (79%) reported pain relief at 1 month, nine (64%) at 3 months, and eight (57%) at 6 months.

In 2012, Patel et al. published results from a double-blind placebo-controlled trial designed to compare the efficacy of lateral branch neurotomy using cooled RF to a sham intervention for the treatment of SIJ pain. The authors randomly assigned individuals (N=51) who had a positive response to two lateral branch blocks to lateral branch RF or sham treatment at a 2:1 ratio. The primary outcomes were pain, physical function, disability, quality of life, and treatment success. Significant improvements in pain (–2.4 vs –0.8), physical function (14 vs 3), disability (–11 vs 2), and quality of life (0.09 vs 0.02) were observed for radiofrequency treatment compared with controls at the 3-month follow-up point. Treatment success was defined as a 50% or greater reduction in the numeric rating scale (NRS). Using this definition, 47% of radiofrequency-treated participants and 12% of sham participants achieved treatment success.

In a subsequent publication, Patel reported that the treatment response was maintained out to 12 months in among the 25 of 34 participants who completed all follow-up visits. Of the nine individuals who terminated study participation, four were considered treatment failures (12% of 34).

In 2014, Zheng et al. reported a RCT of palisade sacroiliac RFA in 155 subjects with ankylosing spondylitis. Palisade RFA uses a row of RF cannulae perpendicular to the dorsal sacrum. Study participants were randomly assigned to either palisade RFA or celecoxib. Blinded evaluation found that RFA resulted in lower global VAS scores compared with celecoxib (2.8 vs 5.0, respectively; P<0.001), as well improved scores for secondary outcome measures. This study is limited by the lack of a sham control.

Cohen et al. (2024) conducted a multicentered RCT comparing cooled RF to standard medical management in participants with chronic SIJ pain. Standard medical management consisted of pharmacotherapy, physical therapy, lifestyle adjustments, and therapeutic injections among others. Both groups each had 105 participants in this intent-to-treat analysis, although several were excluded prior to completion of follow up. The primary outcome was a mean reduction in NRS pain score at 3 months. The cooled RF group had a significantly greater reduction in pain compared to the standard medical management group at 3 months. The authors conclude that cooled RF is superior to standard medical management, but that more research is needed to improve the technique.

Additional larger well-designed trials are needed for comparing specific procedures in defined populations for use in sacroiliac pain given the (1) high prevalence of SIJ pain, yet low study sample size in sham-controlled trials; (2) established alternatives with longstanding use in routine clinical care; (3) subjectivity of the primary outcome (the perception of pain may be different among different people groups); and (4) variability in duration of effect (regeneration of nociceptive nerve tissue).

Repeat Procedures

Two retrospective small series studies (Schofferman and Kine, 2004; Husted et al., 2008) were found (20 and 24 participants, respectively) involving the use of repeat RF procedures. In both studies, over 80% of participants had greater than 50% relief from repeat RF treatment. The duration of pain relief following the repeat RF was comparable to the duration of relief from the initial RF treatment. Since then, similar outcomes using repeat RF have been observed.

A 2012 systematic review of 16 studies of repeated medial branch neurotomy for facet joint pain found that repeated RF denervation was successful 33% to 85% of the time when the first procedure was successful. The average duration of pain relief was estimated to be 7 to 9 months after the first treatment and 11.6 months after a repeated lumbar procedure.

Alternate Methods of Denervation

Other methods with denervation include cooled RF, laser denervation, cryodenervation, and chemodenervation.

Cooled RF involves the use of an electrode similar to that of nonpulsed RF, but also includes a continuous flow of water, keeping the tissue temperature from reaching temperatures observed when using nonpulsed RF (e.g., Coolief). This lower temperature still creates a lesion, while allowing for increased dosing (in procedure duration and lesion size) without uncontrolled damage to surrounding tissues. There are several RCTs investigating the use of cooled RF in addition to ones referenced previously (Patel et al., 2012; Patel, 2016; Cohen et al., 2024). However, these other studies (Cohen et al., 2008; McCormick et al., 2019; McCormick et al., 2023) fail to corroborate the safety and effectiveness found in the highest quality study, Patel et al., 2012. The RCTs lack at least one crucial component of the 2012 study (e.g., lack of blinding, not sham-controlled, different spine region), thus, not demonstrating safety and effectiveness in the same manner in a different setting. Replication of study results is essential to establish medical necessity given the (1) high prevalence of chronic back pain (sacroiliac or otherwise), yet low study sample size; (2) established alternatives with longstanding use in routine clinical care; (3) subjectivity of the primary outcome (the perception of pain may be different among different people groups); and (4) variability in duration of effect (regeneration of nociceptive nerve tissue).

Laser denervation involves the use of a laser to denervate or destroy the nerves for facet joint pain. Iwatsuki et al. in 2007 reported laser denervation to the dorsal surface of the facet capsule in 21 participants who had a positive response to a diagnostic medical branch block. One year following laser denervation, 17 (81%) of the participants had greater than 70% pain reduction. In four participants (19%) who previously had spinal surgery, the response to laser denervation was not successful. Additional controlled trials are needed to evaluate this technique.

Cryodenervation involves inserting a slim, luminated, double-walled cryodenervation probe under local anesthesia. The cryodenervation probe has been cooled to –70°C by carbon dioxide, thereby freezing the pain-causing nerves.

Chemodenervation involves injections with diluted phenol solution, a chemical ablating agent that is injected into the facet joint nerve. There is a paucity of literature on laser denervation, cryodenervation, and chemodenervation. Long-term controlled studies are lacking. Additional literature is needed to establish safety and long-term efficacy to support the use of these methods in the treatment of facet joint pain.

PROFESSIONAL SOCIETIES

Updated guidelines on interventional techniques in the management of chronic spinal pain from the American Society of Interventional Pain Physicians (ASIPP) were published in 2020. ASIPP provides the following guidelines:

• The level of evidence is II (second highest of five) with moderate (middle of three) strength of recommendation for lumbar RF ablation with inclusion of 11 relevant RCTs with two negative studies and four studies with long-term improvement.
• The level of evidence is II with moderate strength of recommendation for cervical RF ablation with inclusion of one RCT with positive results and two observational studies with long-term improvement.
• The level of evidence is III with weak to moderate strength of recommendation with emerging evidence for thoracic RF ablation with inclusion of one relevant RCT and three observational studies.

In 2020, the North American Spine Society (NASS) published clinical guidelines for multidisciplinary spine care. NASS indicated that thermal RF ablation is suggested as a treatment for individuals with low back pain from the zygapophyseal joints. The outcomes of this procedure become more reliable when more stringent diagnostic criteria are used. The relief from these ablations is durable for at least 6 months following the procedure (Grade B; scale of A, B, C, or Insufficient). Additionally, NASS grades cooled radiofrequency for SIJ pain as grade C, and cryodenervation for zygapophyseal joint pain as grade I.

In 2021, the American Society for Pain and Neuroscience (ASPN) published guidelines for RF neurotomy. ASPN provide the statements below based on spinal segment.

• Cervical
• While the use of PRF on the cervical medial branches has been reported, further studies are necessary.
• Cervical medial branch RF neurotomy may be used for the treatment of axial neck pain when facet joints have been identified as the etiology of pain via diagnostic blocks. GRADE I A (highest of five).​​
• Thoracic
• Overall, there is a paucity of quality research and publications addressing thoracic medial branch RFN. Thoracic facet-related back pain would benefit from high-quality research addressing basic questions, including comparison of different RFN modalities to conventional medical management and to each other in a prospective, long-term manner.
• Thoracic medial branch RF neurotomy may be used for the treatment of thoracic/midback pain when facet joints have been identified as the etiology of pain via diagnostic blocks. GRADE II-3 C (middle of five).
• Lumbar
  
• ​While the use of PRF on the lumbar medial branches has been reported, further studies are necessary.
  
• ​Lumbar medial branch RF neurotomy may be used for the treatment of axial low back pain when facet joints have been identified as the etiology of pain via diagnostic blocks, GRADE I A (highest of five).
• ​Sacroiliac joint:
• ​Studies used conventional RF, PRF, and cooled RF, with variable parameters and procedural times. The present literature suggests the clinical efficacy of unipolar, bipolar, cooled and PRF; however, studies are limited and are of fair quality at best.
• ​Lateral sacral branch RF neurotomy may be used for the treatment of posterior sacral ligament and joint pain following positive response to appropriately placed diagnostic blocks. GRADE II-1 B (second of five).
  

In 2014, the American Association of Neurological Surgeons (AANS) and the Congress of Neurological Surgeons (CNS) published updated guidelines on the treatment of degenerative disease of the lumbar spine. AANS/CNS indicated that lumbar medial nerve ablation is suggested for the short-term (3- to 6-month) relief of facet-mediated pain in individuals who have chronic lower back pain without radiculopathy from degenerative disease of the lumbar spine (Grade B).

The American Society of Anesthesiologists Task Force on Chronic Pain Management and the American Society of Regional Anesthesia and Pain Medicine published guidelines for chronic pain management in 2010. The guidelines stated that conventional (e.g., 80°C) or thermal (e.g., 67°C) RF ablation of the medial branch nerves to the facet joint should be performed for low back (medial branch) pain when previous diagnostic or therapeutic injections of the joint or medial branch nerve have provided temporary relief.

SUMMARY

Percutaneous RF facet denervation is used to treat neck and back pain originating in facet joints with degenerative changes. Diagnosis of facet joint pain is confirmed by response to nerve blocks. The goal of facet denervation is long-term pain relief. However, the nerves regenerate and, therefore, repeat procedures may be required.

For individuals who have suspected facet joint pain who receive diagnostic medial branch blocks, the evidence includes varying study designs across a large body of literature. Relevant outcomes are other test performance measures, symptoms, and functional outcomes. There is considerable controversy about the role of these blocks, the number of positive blocks required, and the extent of pain relief obtained. Studies have reported the use of single or double blocks and at least 50% or 80% improvement in pain and function. This evidence has suggested that there are relatively few study participants who exhibit pain relief following two nerve blocks, but that these select participants may have pain relief for several months following RF denervation. Other large series have reported the prevalence and false-positive rates following controlled diagnostic blocks, although there are issues with the reference standards used in these studies because there is no criterion standard for the diagnosis of facet joint pain. There is level I evidence for the use of medial branch blocks for diagnosing chronic lumbar facet joint pain and level II evidence for diagnosing cervical and thoracic facet joint pain. The evidence available supports a threshold of at least 75% to 80% pain relief to reduce the false-positive rate.

For individuals who have facet joint pain who receive RF ablation, the evidence includes varying study designs across a large body of literature. Relevant outcomes are symptoms, functional outcomes, quality of life, and medication use. While evidence is limited to a few RCTs with small sample sizes, RF facet denervation appears to provide at least 50% pain relief in carefully selected individuals. Diagnosis of facet joint pain is difficult. However, response to controlled medial branch blocks and the presence of tenderness over the facet joint appears to be reliable predictors of success. When RF facet denervation is successful, repeat treatments appear to have similar success rates and duration of pain relief. Thus, the data indicate that, in carefully selected individuals with lumbar or cervical facet joint pain, RF treatments can improve outcomes. 

PRF does not appear to be as effective as conventional RF denervation when the relevant outcomes of symptomology, functionality, quality of life, and medication use are studied. Additionally, there is insufficient evidence to evaluate the efficacy of other methods of denervation (e.g., cooled RF, alcohol, laser, cryodenervation) for facet joint pain.

For individuals who have SIJ pain who receive RFA, the evidence is limited. Relevant outcomes are symptoms, functional outcomes, quality of life, medication use, and treatment-related morbidity. Further high-quality controlled trials are needed to compare this procedure in defined populations with sham control and alternative treatments.