Factors That Affect Radiofrequency Heat Lesion Size

MRI genicular nerve mapping: a novel approach to sagittal genicular nerve localization

BACKGROUND AND OBJECTIVES

Chronic knee pain, including postarthroplasty knee pain, is a major cause of morbidity. Radiofrequency ablation of genicular nerve branches is a treatment option. The literature to date has demonstrated and recommended consistent rhizotomy targets in the coronal and axial position of the three primary genicular nerve branches (superomedial genicular nerve, superolateral genicular nerve, inferomedial genicular nerve). The debate on genicular nerve positions focuses on the anterior-posterior courses of the nerve branches.

METHODS

The sagittal positions of the three primary genicular neurovascular bundles were measured in 28 consecutive knee MRI and described relative to the total anterior-posterior depth of the bony cortex. Standard radiofrequency capture radius at the classic rhizotomy targets sites was compared with identified nerve position to report proportion of observed nerves within the capture radius.

RESULTS

The genicular neurovascular bundles were found further posterior than classic landmark targets. Proportion of visualized nerve branches captured by classic rhizotomy target radius varied by genicular nerve branch.

CONCLUSIONS

This study supports updated guidance on genicular rhizotomy targets. Nerve localization studies using MRI data may be a promising avenue in future nerve localization research pertinent to rhizotomy.

Current opinion: optimize radiofrequency ablation through electrophysiological principles, modeling, and clinical recommendations

PURPOSE OF REVIEW

This article aims to empower the interventional pain physician to utilize RFA effectively by explaining the technical and electrophysiological features of monopolar, bipolar, and internally cooled RFA. Scientific data are used to provide advice on the effective, well tolerated, and rational application of these techniques. Moreover, physicians need to know how to analyze and generalize ex-vivo and in-vivo models to the clinical setting to optimize clinical outcomes.

RECENT FINDINGS

Recent studies suggest that there are many ways to enhance the technical effectiveness of interventional pain medicine RFA through adjustments in the equipment selection and settings and the local tissue conditions specific to the targeted anatomical area. These modifications could assist in improving clinical and safety outcomes.

SUMMARY

To optimize both the efficacy and safety of RFA, physicians must understand, conceptualize, interpret, and clinically translate the basic science of RFA. This knowledge is crucial for optimizing equipment selection and settings based on target location to enhance clinical outcomes and limit technical failures.

Genicular nerve radiofrequency ablation practice patterns: A survey study of the International Pain and Spine Interventional Society

Introduction

Chronic knee pain often results from degenerative conditions such as knee osteoarthritis (OA) and can worsen after surgical interventions like total knee arthroplasty (TKA). Knee OA affects approximately 86 million individuals globally, leading to decreased function, mobility limitations, and disability. While TKA is a common surgical treatment for refractory knee OA, though up to 20 % of patients experience chronic post-operative knee pain worse than their pre-operative pain. Genicular nerve radiofrequency ablation (GnRFA) has emerged as a promising intervention for knee OA pain unresponsive to conservative management and for chronic post-TKA pain. GnRFA is an evidence-based technique supported by multiple prospective cohort studies and randomized controlled trials (RCTs). However, practice patterns and GnRFA techniques vary, and no peer-reviewed publication has yet quantified these variations in real-world clinical practice.

Objective

This study aims to understand the practice patterns of interventional pain physicians regarding patient selection, use of prognostic blocks, imaging, nerve targets, GnRFA types, and GnRFA techniques in treating knee pain secondary to OA or persistent post-TKA pain.

Methods

An anonymous 29-question survey was distributed via electronic mail to members of the International Pain and Spine Intervention Society (IPSIS) from January 16, 2024, to February 29, 2024. The survey assessed practice patterns related to patient selection, prognostic block use, and GnRFA techniques. Data were collected and stored using REDCap software, with descriptive statistics calculated.

Results

A total of 150 completed surveys were analyzed, representing a completion rate of 2.0 % of surveys sent, 3.5 % of emails opened, and 56.8 % of those who clicked on the survey link. Respondents generally use common selection protocols regarding OA grade (Kelgren-Lawrence 3 and 4), duration of failed conservative care (3-6 months), a single anesthetic block paradigm, and use of fluoroscopic guidance for the GnRFA procedure. More variability was reported between respondents regarding the volume of anesthetic used during prognostic blocks, the threshold to consider a prognostic block "positive," the technology used, and nerves targeted during the GnRFA procedure.

Conclusion

The study provides valuable insights into the current practice patterns of GnRFA among interventional pain physicians. While there is consensus on some aspects of patient selection and procedural techniques, significant variability exists in prognostic block protocols and nerve targets for GnRFA. These findings highlight the need for further research to explore the long-term efficacy and safety of GnRFA and to standardize techniques and protocols across different practice settings, ultimately improving patient outcomes and quality of life. The low response rate may limit generalizability, and the survey did not include data on active tip sizes used for ablation or whether other procedures should be exhausted before resorting to GnRFA. Additionally, a survey to IPSIS membership only may not fully represent a diverse cohort of pain management specialists, potentially introducing sampling bias. Future studies should include members from a broader range of professional organizations to enhance representativeness.

Safety assessment of electrosurgical electrodes by using mini pig tissue

Electrosurgical electrodes are the main dissecting devices widely used for surgeries throughout the world. The present study aimed to evaluate the thermal injury and safety within animals' organs following a minimally invasive electrosurgery technique with electrosurgical electrode AE40-300 (LIPO) and AE20-80 (LIFT). To ensure the effective application of electrosurgery in a clinical environment, it is crucial to minimize heat-induced injury to nearby tissues. In this study, the skin, liver, kidney, and femoral muscle dissected from 9 minipigs were used in tissue thermal spread experiments. Thermal imaging area analysis, maximum temperature, and time to reach basal temperature were evaluated. Thermography results revealed that the surgical temperature was significantly lower in the minimally invasive electrosurgery with AE40-300 (LIPO) and AE20-80 (LIFT) compared to the predicate device. In addition, AE40-300 (LIPO) and AE20-80 (LIFT) created a relatively small thermal injury area and thermal diffusion. Our results indicated that the tested devices named AE40-300 (LIPO) and AE20-80 (LIFT) reduced excessive thermal injury and could be applied to clinical use safely.

Parasagittal needle placement approach for lumbar medial branch denervation: a brief technical report

Radiofrequency denervation of lumbar medial branches is a viable treatment option to manage chronic facetogenic low back pain. Traditionally, lumbar medial branch denervation involves placement of the electrode's active tip at a 20-degree angulation away from the parasagittal plane. However, more recent anatomical studies have provided evidence supporting the feasibility of an alternative parasagittal approach targeting the posterior half of the lateral neck of the superior articular process to capture the lumbar medial branches. Currently, there is a lack of clinical data on the effectiveness of the alternative parasagittal needle placement technique. Therefore, in this brief technical report, the parasagittal needle placement technique and the pain relief outcomes in four consecutive patients following treatment with the parasagittal approach are described.

Comparison of the Efficacy of Different Radiofrequency Techniques for the Treatment of Lumbar Facet Joint Pain: Combined with Anatomy

PURPOSE OF REVIEW

Lumbar facet pain is generally considered to be one of the major causes of chronic low back pain. Each lumbar facet joint is innervated by the medial branch of the posterior spinal nerve from its own level and above. Radiofrequency (RF) of the medial branch of the posterior branch of the spinal nerve is an effective method for the treatment of lumbar facet pain. RF technology is diverse, including traditional radiofrequency (TRF), pulsed radiofrequency (PRF), cooled radiofrequency (CRF), low-temperature plasma radiofrequency ablation (CA), and other treatment methods. The purpose of this paper is to compare the efficacy of different radiofrequency techniques and to analyze the reasons for this in the context of anatomy.

RECENT FINDINGS

There have been studies confirming the differences in efficacy of different RF techniques. However, most of the studies only compared two RF techniques, not four techniques, TRF, CRF, PRF, and CA, and did not analyze the reasons for the differences in efficacy. This article reviews the differences in the efficacy of the above four RF techniques, clarifies that the differences are mainly due to the inability to precisely localize the medial branch of the posterior branch of the spinal nerve, analyzes the reasons for the inability to precisely localize the posterior branch of the spinal nerve in conjunction with anatomy, and proposes that the development of RF technology for lumbar facet pain requires more in-depth anatomical, imaging, and clinical studies.

Water-circulating probes significantly modify lesion length and axon damage in cooled radiofrequency ablations when compared with similar-sized standard radiofrequency probes in rats

INTRODUCTION

Preclinical research demonstrated water-cooled radiofrequency (CRF) ablations have a significant impact on structural and functional changes compared to standard radiofrequency (SRF) ablations. Clinical procedures utilizing RF to treat chronic pain conditions also show sustained functional outcomes. We hypothesize that the design of the RF probes plays an important role in interventional procedure success, but it remains unclear which specific design features.

METHODS

RF ablations were performed in male Lewis rats (n=51) using multiple-sized probes for CRF (17 Ga/2 mm and 17Ga/4 mm) and SRF (22Ga/5 mm, 18Ga/10 mm and 16Ga/10 mm) to evaluate generator energy output, lesion length, axon damage by histology and nerve function analysis via electromyography. To exclude probe design variables beyond size and remain objective, we tested cooled probes with and without water circulation, which resulted in the CRF probe performing like an SRF probe.

RESULTS

Consistent with our previous findings in smaller probes, CRF large probes delivered more energy (p<0.01) and generated multiple zones of thermal damage in sciatic nerves. When the water-circulating feature was turned off, however, energy output (p<0.001) and lesion length (p<0.05) was significantly reduced. CRF probes with the water circulation also featured significantly more axonal disruption, than larger sized SRF probes (p<0.0001).

CONCLUSIONS

Overall, this data confirms that CRF's water-circulating technology has a greater impact on energy deposition, lesion length and axon damage compared with SRF ablations. Moreover, results suggest that the structural differences between RF modalities cannot be solely attributed to probe size, and it may shed light on its differences in clinical outcomes.

True lateral imaging during lumbar medial branch radiofrequency neurotomy: Interobserver reliability

Background

True lateral imaging (TLI), obtained by superimposing bilateral lumbar spine structures and aligning superior endplate cortical bone, requires deliberate rotational adjustments of the laterally positioned fluoroscope in both the axial and longitudinal planes. True lateral segmental imaging is necessary to depict true and accurate radiofrequency (RF) cannula positioning relative to bony anatomy during lumbar medial branch radiofrequency neurotomy (LMBRFN).

Objective

To determine the interobserver reliability of TLI during LMBRFN.

Methods

This was a retrospective review of a prospectively generated collection of lateral fluoroscopic images to determine the interobserver reliability of TLI during LMBRFN. Lateral fluoroscopic images were prospectively collected from 34 consecutive L4-5 and L5-S1 LMBRFN procedures during routine clinical practice. Employing International Pain and Spine Intervention Society (IPSIS) LMBRFN and TLI techniques, an RF cannula was positioned parallel to the L3 and L4 medial branches and the L5 dorsal rami. During the normal course of TLI, untrue and final true lateral segmental images were obtained and saved. An original data set of 100 pairs of true and untrue lateral images was reviewed to verify true laterality using established criteria; disagreement was resolved by consensus or discarding ambiguous cases. To measure interobserver reliability (Cohen's Kappa), two blinded expert reviewers independently reviewed the image set, identifying the true lateral image and the plane requiring correction.

Results

The observers agreed upon 98/98 true lateral RF-segment images (Kappa score 1.0 [1.00,1.00]). The observers agreed upon 86/98 maneuvers to correct the untrue RF-segment image. The Kappa score for determining the most appropriate corrective maneuver was 0.76 (0.63,0.89), showing substantial interobserver agreement.

Conclusions

The true lateral image of the targeted RF segment during LMBRFN was reliably determined with perfect interobserver agreement. Interobserver agreement was substantial regarding the maneuver to achieve TLI.

3D nerve proximity mapping of the medial branch of lumbar dorsal ramus: An anatomical study

Objective

Lumbar medial branch (MB) radiofrequency ablation is a common intervention to treat facetogenic low back pain. Consensus among spine pain interventionalists is that the cannula tip should be placed adjacent to the periosteum of the lateral neck of the superior articular process (SAP) to ensure maximum contact with the MB. The spatial relationship of the nerve to the periosteum of the lateral neck of the SAP has not been quantified in 3D. The objectives of the current study were to: 1) use 3D modelling technology to quantify the location along the lateral neck of the SAP where the MB is in direct contact with the periosteum; and 2) identify target site(s) to optimize lumbar MB denervation.

Design

Seventy lumbar dorsal rami in 14 formalin-embalmed specimens were dissected, digitized, and modeled in 3D. The 3D positional data of the MB were used to generate a novel nerve proximity map which provided a method to quantify and visualize the 3D course of the MB in relation to the periosteum of the lateral neck of SAP. The percent of the lateral neck of SAP in contact with the MB was quantified and consistent target site(s) identified.

Results

There was variability in the percentage of the lateral neck of SAP in contact with the MB. The mean percentage of the lateral neck of SAP in contact with the MB for the L1-L5 levels ranged between 57.39 ± 10.72 % (for L1) to 81.54 ± 10.48 % (for L5). The nerve proximity map showed consistent course of the MB along the posterior portion of the lateral neck of SAP and at a novel target site distal to the mamillo-accessory notch (i.e. sub-mammillary landmark).

Conclusion

The percent of the lateral neck that was in contact with the MB was quantified and visualized using a novel nerve proximity mapping methodology which may be used to inform cannula tip depth placement. Further, the nerve proximity maps were used to identify an alternative landmark to extend the length of the MB captured. The proposed sub-mammillary landmark may be a viable target site pending future anatomical and clinical investigations.

Investigation of Optimal Needle Position for Radiofrequency Ablation-Based Blockade of Interspace between the Popliteal Artery and the Posterior Capsule of the Knee: A Cadaveric Study

Background and Objectives: The interspace between the popliteal artery and the posterior capsule of the knee (iPACK) block has been widely used in perioperative settings to control posterior knee pain and can additionally be used for chronic knee pain. In this cadaveric study, we aimed to investigate the needle tip position and its proximity to the articular branch of the tibial nerve (ABTN) during an iPACK-targeted radiofrequency procedure. Materials and Methods: An ultrasound-guided iPACK block was performed on 20 knees of 10 cadavers. We injected 0.1 mL each of blue and green gelatinous dye near the tibial artery (point A) and posterior knee capsule (point B), respectively, and evaluated the spread of both around the ABTN. For a hypothetical conventional radiofrequency ablation (RFA) lesion (diameter, 2.95 mm) and cooled RFA lesion (diameter, 4.9 mm), we counted the number of specimens in which the ABTNs would be captured. Results: The percentage of specimens in which the ABTN would be captured by a cooled RFA lesion was 64.71% at point A and 43.75% at point B (p = 0.334). Meanwhile, the percentage of specimens in which the ABTN would be captured by a conventional RFA lesion was 58.82% from point A and 25% from point B (p = 0.065). Conclusions: When performing an RFA-based iPACK block, the needle tip may be positioned either lateral to the tibial artery or in the space between the posterior knee capsule and the tibial artery. However, more studies with larger samples are needed to verify these results before the clinical use of this procedure can be recommended.

Fractional-Order Electrical Modeling of Aluminum Coated via Plasma Electro-Oxidation and Thermal Spray Methods to Optimize Radiofrequency Medical Devices

Active medical devices rely on a source of energy that is applied to the human body for specific purposes such as electrosurgery, ultrasounds for breaking up kidney stones (lithotripsy), laser irradiation, and other medical techniques and procedures that are extensively used. These systems must provide adequate working power with a commitment not to produce side effects on patients. Therefore, the materials used in these devices must effectively transmit energy, allow for security control, sense real-time variations in case of any issues, and ensure the implementation of closed-loop systems for control. This work extends to the experimental data adjustment of some different coating techniques based on plasma electro-oxidation (PEO) and thermal spray (TS) using fractional-order models. According to the physical structure of the coating in different coating techniques, Cole family models were selected. The experimental data were obtained by means of a vector network analyzer (VNA) in the frequency spectrum from 0.3 MHz to 5 MHz. The results show that some models from the Cole family (the single-dispersion model and inductive model) offered a goodness of fit to the experimental impedance in terms of RMSE error and a squared error R2 close to unity. The use of this type of fractional-order electrical model allows an adjustment with a very small number of elements compared to integer-order models, facilitating its use and a consequent reduction in instrumentation cost and the development of control devices that are more robust and easily miniaturized for embedded applications. Additionally, fractional-order models allow for more accurate assessment in industrial and medical applications.

Sacroiliac Joint Denervation-A Novel Approach to Target Sacral Lateral Branches: A Practical Approach

INTRODUCTION

Sacroiliac joint (SIJ) pain is a relatively common cause of low back pain. Percutaneous radiofrequency (RF) techniques for SIJ are limited to ablation of the posterior SIJ innervation. Different techniques have been described for SIJ radiofrequency ablation, including conventional thermal, cooled RF, pulsed RF, bipolar RF, and specialized tip RF needle (i.e., multi-tined); however, additional costs may limit these applications.

METHODS

This new technique for SIJ denervation uses anatomical landmarks and a single RF cannula. Two spinal needles are placed lateral to the posterior S1 and S2 sacral foramina; then, with caudal tilt we get a coaxial view of the sacral bone, we advance an 18-G curved 15-mm active tip RF cannula just lateral to the aligned finder needles. Ablation is performed, and then the RF cannula is retracted 2 cm and ablation is repeated for a total of four lesions.

RESULTS

The two spinal needles placed lateral to the posterior sacral foramina S1 and S2 guide the final needle in the posterior aspect of the sacrum, lateral to the sacral foramina, where the lateral sacral branches are located.

CONCLUSION

We introduce a cost and time efficient technique to perform radiofrequency ablation of the sacral lateral branches using a single RF needle. This technique utilizes the sacrum's reliable anatomy and angulation and maximizes the surface area of the active tip lesioning. This technique creates a strip lesion lateral to the sacral foramina and reduces time and cost efficacy compared to several of the other techniques and/or commercially available special devices designed for sacroiliac denervation.

Bipolar radiofrequency ablation lesion areas and confluence: An ex vivo study and technical report

INTRODUCTION

Radiofrequency ablation (RFA) has been used for nearly 100 years, treating an array of medical conditions including chronic pain. Radiofrequency (RF) energy depolarizes and repolarizes tissues adjacent to a probe producing heat and causing direct thermal injury. When positioned adjacent to neural structures, it leads to neural tissue injury and cell death interrupting pain signaling with the ultimate goal of providing lasting pain relief. Today, RFA is commonly used to treat cervical, thoracic, and lumbar zygapophyseal joints, sacroiliac joint, and more recently large peripheral joint-mediated pain. There are several applications of RFA systems, including bipolar, conventional thermal, cooled, protruding, and pulsed. As yet, no study has determined the best technical practice for bipolar RFA.

OBJECTIVE

This ex vivo study examines RFA lesion midpoint (LMP) area and lesion confluence comparing three different commonly used gauge (g) probes (18-g, 20-g, and 22-g) with 10-mm active tips at various interprobe distances (IPD) to guide best technical practices for its clinical application.

METHODS

Bipolar RFA lesions were generated in preservative-free chicken breast specimens using three different gauge probes (18-g, 20-g, and 22-g) with 10-mm active tips at various IPD (6, 8, 10, 12, 14, 16, and 18 mm). RF was applied for 105 s (15-s ramp time) at 80°C for each lesion at both room and human physiological temperature. The specimen tissues were dissected through the lesion to obtain a length, width, and depth, which were used to calculate the LMP area (mm2 ). The LMP areas of each thermal ablation were investigated using visualization and descriptive analysis. The Kruskal-Wallis test was performed to compare LMP areas between the two temperature groups and the three different gauge probe subgroups at the various IPDs.

RESULTS

Of the 36 RF lesions (14: 18-g, 12: 20-g, and 10: 22-g) performed, 24 demonstrated lesion confluence. The average time to reach 80°C was 16-17 s; therefore, the average time of RF-energy delivery (at goal temperature) was 88-89 s despite varying needle size or IPD. Comparing the 25 and 37°C groups, 18-g probes produced mean LMP areas of 73.7 and 79.2 mm2 , respectively; 20-g probes produced mean LMP areas of 66 and 66.8 mm2 , respectively; 22-g probes produced mean LMP areas of 56.6 and 59.7 mm2 , respectively. There was no statistical evidence to state a difference regarding LMP area between temperature groups; however, the 18-g probes produced consistently larger LMP areas in the 37°C compared to 25°C specimen groups at each IPD. Lesion confluence was lost for 18-g, 20-g, and 22-g probes at IPD of 14, 12, and 10 mm, respectively, in both 25 and 37°C groups. LMP area was similar between 6 and 8 mm IPD in all of the three-gauge groups; however, there was a significant drop in LMP area from 8 mm IPD to 10 mm and greater. The 18-g, 20-g, and 22-g probes all demonstrated a sharp decline in LMP area when increasing the IPD from 8 to 10 mm.

CONCLUSION

This ex vivo technical study evaluated bipolar RFA LMP areas and lesion confluence, and determined the recommended IPD of 18-g, 20-g, and 22-g probes to be less than 12, 10, and 8 mm, respectively, for best clinical practice. Placing bipolar probes at an IPD greater than 14, 12, and 10 mm, respectively, risks the loss of lesion confluence and failure to produce a clinically significant treatment response due to lack of nerve capture. In clinical practice, the use of injectate may produce larger lesions than demonstrated in this study. Additionally, in vivo factors may impact ablation zone size and ablation patterns. As there are a paucity of studies comparing various RFA applications and conventional RFA needles are least expensive, it is possible that bipolar conventional RFA is more cost-effective than other techniques.

Impact of temperature on the magnitude and duration of relief after lumbar facets medial branch nerves radiofrequency ablation: a randomized double-blinded study

INTRODUCTION

There are numerous studies appraising the variables that may influence the clinical outcomes after lumbar thermal radiofrequency ablation (RFA). Expanding the lesion size may increase the likelihood of capturing the target nerves in the lesion, thereby increasing the technical success rate of RFA. However, our literature search has failed to identify a consensus on the optimal target temperature. A retrospective study demonstrated that there seems to be significant functional improvement associated with the temperature of 90°C compared with 80°C. The authors prospectively studied the subject in a double-blinded randomized fashion.

METHODS

Patients undergoing RFA for lumbar facetogenic pain were randomized in two cohorts (80°C and 90°C). Physicians and patients were blinded to the temperature used. The primary outcome was self-reported pain scores up to 12 months. Secondary outcomes included: self-reported functional improvement, duration of relief as measured by the time before repeat ablation of the same medial branches nerves, opioids' consumption, and patient satisfaction.

RESULTS

Both groups reported pain improvement in all follow-up time points. Overall, both groups achieved statistically significant pain reduction (p<0.05). The median time to repeat RFA in the 80°C group was 112 (49-252) days, while it was 217 (198-348) days in the 90°C group (p<0.04). The univariate analysis emphasized that the RFA temperature is a statistically significant factor for pain improvement of more than 50%, OR 2.7 (1.1 to 6.6) p value=0.031.

CONCLUSION

RFA has been demonstrated as an effective therapeutic modality for lumbar facetogenic back pain. Yet, the several factors involved in determining a favorable outcome of this procedure require further research and optimization. This prospective double-blinded randomized trial demonstrated that RFA at both temperatures (80°C, 90°C) provided significance at all the time periods examined. However, RFA at 90°C was superior to 80°C in regard to the duration of relief.

Percutaneous radiofrequency ablation and endoscopic neurotomy for lumbar facet joint syndrome: are they good enough?

OBJECTIVE

Lumbar facet joint (LFJ) syndrome is one of the common causes of low back pain (LBP). There are different views on percutaneous and endoscopic radiofrequency. The purpose of this systematic review and meta-analysis is to explore the therapeutic effect of radiofrequency ablation on LBP originating from LFJ and compare the therapeutic effect of percutaneous radiofrequency ablation and endoscopic neurotomy.

METHODS

We included randomized controlled trials which compared the efficiency of percutaneous radiofrequency ablation and conservative treatment (sham procedures, facet joint injection, physiotherapy, exercise, or oral medication) or compared the efficiency of percutaneous radiofrequency ablation and endoscopic neurotomy for LFJ syndrome. We searched in PubMed and Web of Science from inception to March 27, 2023. Meta-analysis was performed using RevMan 5.4 software.

RESULTS

A total of 11 randomized controlled trials were included. Among them, nine studies were used for evaluating efficiency of percutaneous radiofrequency ablation, and two studies were used for evaluating efficiency of endoscopic neurotomy. Pooled data from two studies reporting outcomes at 1 year did not show a benefit from facet joint denervation by comparing the percutaneous radiofrequency ablation and conservative treatment (standardized mean difference (SMD) = -0.87, 95% confidence interval (CI) [-2.10, 0.37], P = 0.17). There was no significant difference between percutaneous radiofrequency ablation and endoscopic neurotomy at 1-month follow-up (mean difference (MD) = -0.13, 95%CI [-0.18, -0.44], P = 0.41). At 12-month follow-up the pain relief in the endoscopic neurotomy was significantly better than that in the percutaneous radiofrequency ablation group (MD = 1.98, 95%CI [1.60, 2.36], P < 0 .0001).

CONCLUSION

The LBP was significantly relieved shortly after percutaneous radiofrequency ablation. Compared with percutaneous radiofrequency ablation, endoscopic neurotomy seems to have a longer effect. A longer follow-up period is needed to confirm its effectiveness.

Predicting spatio-temporal radiofrequency ablation temperature using deep neural networks

Radiofrequency ablation (RFA) of the medial branch nerve is a widely used therapeutic intervention for facet joint pain. However, denervation of the multifidus muscle is an inevitable consequence of RFA. New ablation techniques with the potential to prevent muscle denervation can be designed using computational simulations. However, depending on the complexity of the model, they could be computationally expensive. As an alternative approach, deep neural networks (DNNs) can be used to predict tissue temperature during RFA procedure. The objective of this paper is to predict the tissue spatial and temporal temperature distributions during RFA using DNNs. First, finite element (FE) models with a range of distances between the probes were run to obtain the temperature readings. The measured temperatures were then used to train the DNNs that predict the spatio-temporal temperature distribution within the tissue. Finally, a separate data obtained from FE simulations were used to test the efficacy of the network. The results presented in this paper demonstrate that the network can achieve an error rate as low as 0.05%, accompanied by a 92% reduction in time compared to FE simulations. The approach proposed in this study will play a major role in the design of new RFA treatments for facet joint pain.

Bipolar radiofrequency ablation for cancer pain in the trigeminal distribution

Tumours in patients with head and neck cancer (HNC) are associated with a more significant decrease in quality of life compared with the rest of patients with cancer. We present a patient with pain due to HNC successfully treated with bipolar radiofrequency ablation. A man in his 70s presented with a tumour in the left V2 and V3 region, with disabling pain, Visual Analogue Scale (VAS) score of 10/10, pain on swallowing, chewing and speaking, 3 months of evolution. The patient was evaluated in the pain management department, and the interventional treatment proposed consisted of bipolar pulsed radiofrequency, followed by bipolar thermal radiofrequency of the left V2 and V3 branches with fluoroscopic guidance to achieve better control and coverage of the affected trigeminal branches. Immediately after the procedure, the patient reported a significant improvement in pain with a 0-10 VAS; hypoesthesia in the affected V2 and V3 territory was identified, but no motor weakness. The improvement in pain was maintained for 6 months with a significant improvement in quality of life and pain, which allowed him to speak, chew and swallow without pain. Later, the patient died from complications associated with the disease. The treatment approach in these patients is both pain treatment and achieving independence by allowing better speech ability and improving eating, the above as a pillar of treatment focused on improving the patient's quality of life. This approach is a potential tool in the early stage of the disease in patients with pain due to HNC.

Bipolar radiofrequency ablation of genicular nerves in chronic knee pain: A novel technique for more complete sensory denervation

BACKGROUND

Monopolar radiofrequency ablation (MRFA) of the genicular nerves has been considered the main interventional treatment for chronic knee pain. However, the variable locations of these nerves could suggest that traditional MRFA of genicular nerves may be insufficient to cover the area needed to provide complete sensory denervation. For these reasons, some alternatives have been proposed to achieve an increase in the lesion area that offers better outcomes such a bipolar radiofrequency ablation (BRFA).

OBJECTIVE

To describe the efficacy and safety of the bipolar radiofrequency ablation (BRFA) of the genicular nerves in the patients with chronic knee pain.

METHODS

A retrospective study was conducted in the Pain Medicine Department. Institutional review board approval from the Hospital Ethical Committee and informed consent were obtained. We reviewed our database for BRFA of genicular nerves from January 2018 to December 2021 for patients with chronic knee pain. The cannulas were placed using ultrasound guidance (10 cm, 22-gauge and 10 mm active curved tip), and each pair of cannulas were subjected to BRFA for 90 seconds at 80∘C. Data analysis was conducted using T-test for paired variables (Visual analogue scale and EuroQol, an instrument intended to complement other forms of quality-of-life measures).

RESULTS

Twenty-five patients met inclusion criteria after excluding 7 based on the study design. The mean improvement of our patients according to the VAS was -3.98 (95%CI: -4.37 to -3.59) p< 0.0001 and EuroQol +0.416 (95%CI: 0.364 to 0.468) p< 0.0001. The mean duration of improvement was 8 (6-11) months after BRFA. There were no reported serious adverse events related to the procedure, only local pain for 24 to 48 hours in 3 patients.

CONCLUSIONS

We can conclude that BRFA reduces procedural pain and increases the treatment area, providing more complete sensory denervation and improved clinical outcomes.

IonicRF™: a novel step in technology for radiofrequency ablation treatments

Radiofrequency ablation (RFA) has been utilized since the 1970s to treat various painful conditions. The technology has evolved from its initial use to treat lumbar facet mediated pain with monopolar lesioning to now treat a plethora of chronic pain conditions. This article reviews Abbott Corporation's (IL, USA) IonicRF™ generator. The IonicRF generator utilizes an intelligent power algorithm that improves efficiency and reduces procedure time. The generator also carries a wide range of RFA therapies such as monopolar, bipolar, pulsed or pulsed dose radiofrequency. Additionally, the IonicRF RFA generator is compatible with the Simplicity™ RF probe (Abbott) which allows for efficient and effective denervation of the sacroiliac joint.

3. Pain originating from the lumbar facet joints

INTRODUCTION

Pain originating from the lumbar facets can be defined as pain that arises from the innervated structures comprising the joint: the subchondral bone, synovium, synovial folds, and joint capsule. Reported prevalence rates range from 4.8% to over 50% among patients with mechanical low back pain, with diagnosis heavily dependent on the criteria employed. In well-designed studies, the prevalence is generally between 10% and 20%, increasing with age.

METHODS

The literature on the diagnosis and treatment of lumbar facet joint pain was retrieved and summarized.

RESULTS

There are no pathognomic signs or symptoms of pain originating from the lumbar facet joints. The most common reported symptom is uni- or bilateral (in more advanced cases) axial low back pain, which often radiates into the upper legs in a non-dermatomal distribution. Most patients report an aching type of pain exacerbated by activity, sometimes with morning stiffness. The diagnostic value of abnormal radiologic findings is poor owing to the low specificity. SPECT can accurately identify joint inflammation and has a predictive value for diagnostic lumbar facet injections. After "red flags" are ruled out, conservatives should be considered. In those unresponsive to conservative therapy with symptoms and physical examination suggesting lumbar facet joint pain, a diagnostic/prognostic medial branch block can be performed which remains the most reliable way to select patients for radiofrequency ablation.

CONCLUSIONS

Well-selected individuals with chronic low back originating from the facet joints may benefit from lumbar medial branch radiofrequency ablation.

Navigated Radiofrequency Ablation Peripheral Rhizotomy for Lumbosacral Hypertonia in a Nonambulatory Patient With Spinal Fusion: Indications, Surgical Techniques, and Lessons Learned

BACKGROUND AND OBJECTIVES

Radiofrequency ablation (RFA) is a destructive therapy which causes target tissue destruction by application of a thermal dose. Neurosurgical applications of RFA are well-described for myriad chronic pain and movement disorder diagnoses. In fact, RFA pallidotomy and thalamotomy are the initial procedures from which the field of neurosurgical management for movement disorders emerged. RFA rhizotomy for post-traumatic spasms was popular in the 1970s and 1980s, although it was largely abandoned after the invention and Food and Drug Administration approval of intrathecal baclofen therapy. RFA has not been described as a primary treatment of hypertonia in nonambulatory children.

METHODS

We report a case of computer-navigated, nonselective RFA peripheral rhizotomy for a nonambulatory child with a history of severe scoliosis and spinal fusion, where an open rhizotomy was technically impractical.

RESULTS

Navigation to and ablation of the bilateral L1-L5 peripheral nerves with this approach was successful, and the patient experienced bilateral lower extremity tone improvement.

CONCLUSION

We use this case to highlight considerations in indications, our applied operative technique, and lessons learned from this novel application of RFA peripheral rhizotomy in children.

Comparison of the efficacy of genicular nerve phenol neurolysis and radiofrequency ablation for pain management in patients with knee osteoarthritis

Background

: Genicular nerve neurolysis with phenol and radiofrequency ablation (RFA) are two interventional techniques for treating chronic refractory knee osteoarthritis (KOA) pain. This study aimed to compare the efficacy and adverse effects of both techniques.

Methods

: Sixty-four patients responding to diagnostic blockade of the superior medial, superior lateral, and inferior medial genicular nerve under ultrasound guidance were randomly divided into two groups: Group P (2 mL phenol for each genicular nerve) and Group R (RFA 80°C for 60 seconds for each genicular nerve). The numeric rating scale (NRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were used to evaluate the effectiveness of the interventions.

Results

: RFA and phenol neurolysis of the genicular nerves provided effective analgesia within groups at 1 week, 1 month, and 3 months compared to baseline. There was no significant difference between the groups in terms of NRS and WOMAC scores at all measurement times. At the 3rd month follow-up, 50% or more pain relief was observed in 53.1% of patients in Group P and 50% of patients in Group R. The rate of transient paresthesia was 34.4% in Group P and 6.3% in Group R, and this was significantly higher in Group P.

Conclusions

: Neurolysis of the genicular nerves with both RFA and phenol is effective in the management of KOA pain. Phenol may be a good alternative to RFA. Further studies are needed on issues such as dose adjustment to prevent transient paresthesia response.

A randomized controlled study of the long-term efficacy of cooled and monopolar radiofrequency ablation for the treatment of chronic pain related to knee osteoarthritis

Background

Chronic knee pain due to osteoarthritis (OA) is expected to become more prevalent. Although conventional therapies may provide relief they are not long-lasting. Persistent pain may lead to total knee replacement, which is not free of adverse outcomes. Monopolar and cooled radiofrequency ablation (RFA) of genicular nerves is an effective option. However, either method may provide distinctive results depending on expected lesion size, a key aspect considering the anatomical variability of knee innervations. This prospective, double-blind, randomized controlled trial evaluated the efficacy and durability of knee RFA using a cooled probe or a monopolar probe of comparable diameter.

Methods

This investigator-initiated, post-market, double-blinded, prospective, randomized controlled trial was approved by the Western IRB. 79 subjects with chronic knee pain due to knee OA were enrolled in multiple locations of a single center. 75 subjects were randomized (1:1) into RFA treatment with either a 4 ​mm/17G cooled active tip (CRFA) or a 10 ​mm/16G monopolar active tip (MRFA) using conventional procedures. Primary endpoint was change in knee pain level (100 ​mm VAS score) from baseline at 24-week post-treatment. Other endpoints include change in functionality, global perceived effect, and frequency of adverse events. Evaluation spanned to 52-week post-treatment. Significance of results (p ​< ​0.05) was calculated using standard statistical analyses.

Results

Both CRFA and MRFA provided significant reduction (41 ​mm and 39 ​mm, respectively) of chronic knee pain at 24-week. At the 52-week visit, reduction in pain level was sustained for CRFA (42 ​mm) but seems to decrease for MRFA (31 ​mm). Improvements in functionality were also significant and sustained with both treatments, although tend to decrease with MRFA at 52-week. Most patients also perceived a very good/good effect of treatments along the duration of the study.

Conclusion

RFA of knee genicular nerves for the treatment of OA chronic pain is effective for 52 weeks post-ablation when using a CRFA (4 ​mm/17G active tip) or MRFA (10 ​mm/16G active tip). The benefits of CRFA seems to be better sustained beyond 24 weeks than the ones of MRFA, although no significant differences were observed at 52 weeks.

Radiofrequency Ablation of the Infrapatellar Branch of the Saphenous Nerve for the Treatment of Chronic Anterior Inferomedial Knee Pain

INTRO

Genicular nerve radiofrequency ablation (GNRFA) is an effective treatment for chronic knee pain related to osteoarthritis. It is often utilized when conservative management has failed and patients wish to avoid arthroplasty, are poor surgical candidates due to comorbid medical conditions, or in those suffering from persistent pain after arthroplasty. The classic targets for GNRFA include the superior lateral genicular nerve, superior medial genicular nerve, and inferior medial genicular nerve but multiple anatomic studies have demonstrated additional sensory innervation to the knee.

OBJECTIVE

In this research article, we propose an image-guided technique that can safely target the infrapatellar branch of the saphenous nerve which also provides sensory innervation to the anterior capsule.

PROPOSAL

The proposed technique includes variations for conventional bipolar radiofrequency ablation, cooled radiofrequency ablation, dual-tined bipolar radiofrequency ablation, and monopolar radiofrequency ablation using a long axis approach. The described technique is based on updated anatomic studies and takes into account safety concerns such as thermal risk to the skin and/or pes anserine tendons and breaching of the synovial cavity.

CONCLUSION

Future clinical research should be performed to confirm the safety and effectiveness of this specific approach.

Prognostic factors of unilateral prelemniscal radiations radiofrequency lesions: A surgical technique for the treatment of Parkinson's disease motor symptoms

OBJECTIVE

A group of patients with Parkinson's disease (PD) were managed with unilateral prelemniscal radiation radiofrequency lesions (U-Raprl). The current study aims to evaluate prognostic factors that could influence clinical response.

METHODS

Patients previously diagnosed with PD managed with U-Raprl were included in the study, classifying them into two groups according to their percentage of clinical response (</≥ 50%) at 5 years of follow-up in relation to the part III of the Unified Parkinson's Disease Rating Scale (UPDRS-III), analyzing the possible factors associated with their response (age, evolution of PD, Hoehn and Yahr scale (HYS), and levodopa dose). To show differences between groups before and after the intervention, a T-test was performed, and a Mann-Whitney U test was carried out to determine differences between the response groups, added to an effect size calculation using a Cohen's d (α = 0.05, and β = 0.20).

RESULTS

Thirty-four patients were included, where the most prevalent symptoms were tremor and rigidity, with 52.9% percentage of males, 59.3 ± 6.4 mean age, and 7.4 ± 2.1 of mean evolution of PD. Analysis shows differences between groups (p < 0.05) according to the HYS, UPDRS, and levodopa intake, after the intervention. The analysis of the groups according to their response showed differences between the HYS (p < 0.01, ∆ > 1.5), Age (p < 0.0001, ∆ = 2.38), Evolution (p < 0.0001, ∆ = 2.38), and post-operative UPDRS (p < 0.01, ∆ = 1.38). The qualitative analysis of the distribution regarding the responder group shows that those patients with an age under 58 years, an evolution fewer than 7 years, and a preoperative HYS score smaller than 2, showed a response ≥ 50% according to the UPDRS-III in all cases.

CONCLUSION

U-Raprl is a highly effective procedure with a 5-year persistence of improvement. The most relevant prognostic factors to consider for a clinical response according to UPDRS-III greater than 50% are age under 58 years, less than 7 years of PD evolution, and HYS less or equal to 3.

Neurosurgical Ablation for Pain: A Technology Review

Neurosurgical ablative procedures for pain have dramatically transformed over the years. Compared to their precursors, present day techniques are less invasive and more precise as a result of advances in both device engineering and imaging technology. From a clinical perspective, understanding the strengths and drawbacks of modern techniques is necessary to optimize patient outcomes. In this review, we provide an overview of the major contemporary neuroablative modalities/technologies used for treating pain. We will compare and contrast these modalities from one another with respect to their intraoperative monitoring needs, invasiveness, range of access, and lesion generation. Finally, we will provide a brief commentary on the future of neuroablation given the advent of neuromodulation options for pain control.

Radiofrequency Neurotomy Does Not Cause Fatty Degeneration of the Lumbar Paraspinal Musculature in Patients with Chronic Lumbar Pain-A Retrospective 3D-Computer-Assisted MRI Analysis Using iSix Software

OBJECTIVE

The present study aimed (1) to analyze the relative paraspinal autochthonous intramuscular fat volume before and after radiofrequency neurotomy (RFN) and (2) to compare it to the contralateral non-treated side.

DESIGN

Retrospective cohort study.

SETTING

Inselspital, University Hospital Bern, University of Bern.

SUBJECTS

Twenty patients (59.60 ± 8.49 years; 55% female) with chronic low back pain, treated with RFN (L2/3-L5/S1) due to symptomatic facet joint syndrome (FCS) between 2008 and 2017 were included.

METHODS

All patients received a magnetic resonance imaging (MRI) of the lumbar spine before and at a minimum of 6 months after RFN. The absolute (cm3) and relative (%) paraspinal muscle and fat volume was analyzed three-dimensionally on standard T2-MRI sequences using a newly developed software (iSix, Osiris plugin). Both sides were examined and allocated as treated or non-treated side.

RESULTS

A total of 31 treated and 9 non-treated sides (Level L2/3-L5/S1) were examined. There were no differences in the relative paraspinal intramuscular fat volume before and at a median of 1.4 [0.9 - 2.6] years after RFN (P = .726). We found no differences in the relative fat volume between the treated and non-treated side before (P = .481) and after (P = .578) RFN.

CONCLUSIONS

Our study shows that there are no differences in the paraspinal muscle/fat distribution after RFN. RFN of the medial branches for FCS does not seem to cause fatty degeneration of the lumbar paraspinal muscles as a sign of iatrogenic muscle denervation.

Computed Tomography-Guided Percutaneous T4 Thoracic Sympathetic Radiofrequency Thermocoagulation for Primary Palmar Hyperhidrosis: A Retrospective Observational Trial

PURPOSE

To evaluate the efficacy, safety, and patient satisfaction of computed tomography (CT)-guided percutaneous T4 thoracic sympathetic radiofrequency thermocoagulation (RFT) for the treatment of primary palmar hyperhidrosis (PPHH).

MATERIALS AND METHODS

A total of 158 patients who underwent bilateral thoracic sympathetic RFT at the T4 level were analysed. Hyperhidrosis Severity Scale (HDSS), Dermatologic Quality of Life Index (DLQI), patient satisfaction, and adverse events were evaluated within 12 months after RFT.

RESULTS

The mean age of the patients was 25.27 years, and 95 (60.1%) were females. The technical success, defined as planned needle placement and completion of RFT, was 99.4%. After the procedure, 243 hands (77.4%) were completely dry; and 58 hands (18.4%) were partially dry. From before RFT to 12 months after RFT, the proportion of hands with the HDSS grades 3 and 4 from 100% decreased to 31.9%; and that with the DLQI scores D and E from 100% decreased to 4.0% (P < .001). The clinical success rate was 76.6%, and the patient satisfaction rate was 80.8% at 12 months after RFT. During the procedures, there was unilateral local bleeding in two patients (0.6%) and bradycardia in five patients (3.2%); after the procedures, unilateral pneumothorax occurred in 15 patients (4.7%) and closed thoracic drainage was performed in two patients (0.6%); thoracic neuralgia occurred in 24 patients (15.2%). The incidence of compensatory hyperhidrosis (CH) 12 months after RFT was 15.2%.

CONCLUSIONS

CT-guided percutaneous T4 thoracic sympathetic RFT is safe, effective, and minimally invasive for the treatment of PPHH.

LEVEL OF EVIDENCE

Level 2 observational study with dramatic effect.

Radiofrequency Ablation for Chronic Lumbar Zygapophyseal Joint Pain Using a V-Shaped Active Tip Needle: An Observational Retrospective Study

Background

Lumbar zygapophyseal joint dysfunction represents one of the major sources of chronic low back pain. Radiofrequency ablation (RFA) using a V-shaped active tip needle may offer a larger lesion of the medial branch nerves, improving clinical outcome. The aim of our study is to evaluate the efficacy and the feasibility of RFA using V-shaped active tip needles.

Methods

This is a single-center observational retrospective study. Clinical records were screened and analyzed if they met the following inclusion criteria: adult patients (>18 years), diagnosis of chronic lumbar zygapophyseal joint pain, failure of conservative treatments, ability to provide informed consent for data analysis and publication. Exclusion criteria: lumbar pain not related to zygapophyseal joints, previous spinal/lumbar surgery, incomplete data, absence or withdrawal of informed consent. The primary outcome of the study was a change in pain intensity at follow-up. The secondary outcomes were the evaluation of quality-of-life improvement, the occurrence of adverse events and the impact on post-procedural analgesic consumption. For these purposes, pre- and post-treatment numeric rating scale (NRS), neuropathic pain 4 questions (DN4), EuroQoL - EQ-5D-3L, EQ-VAS, EQ-index and North American Spine Society (NASS) index were retrieved and analysed.

Results

Sixty-four patients were included. 7.8% of patients at 1-month (CI95% 0.026, 0.173), 37.5% at 3-month (CI95% 0.257, 0.505), 40.6% at 6-month (CI95% 0.285, 0.536) and 35.9% at 9-month (CI95% 0.243, 0.489) follow-up reported a reduction of more than 80% in NRS Statistical analysis indicated a significant change in NRS, DN4, EQ-index and EQ-5D-VAS (p-value <0.001) at the different time-points.

Conclusion

RFA using a V-shaped active tip needle might be a feasible and effective treatment for chronic lumbar zygapophyseal joint pain.

Bipolar radiofrequency ablation of the superomedial (SM), superolateral (SL) and inferomedial (IM) genicular nerves for chronic osteoarthritis knee pain: a randomized double-blind placebo-controlled trial with 12-month follow-up

BACKGROUND

Variability in anatomy in the knees supports the use of aggressive lesioning techniques such as bipolar-radiofrequency ablation (RFA) to treat knee osteoarthritis (KOA). There are no randomized controlled trials evaluating the efficacy of bipolar-RFA.

METHODS

Sixty-four patients with KOA who experienced >50% pain relief from prognostic superomedial, superolateral and inferomedial genicular nerve blocks were randomly assigned to receive either genicular nerve local anesthetic and steroid injections with sham-RFA or local anesthetic and steroid plus bipolar-RFA. Participants and outcome adjudicators were blinded to allocation. The primary outcome was Visual Analog Scale pain score 12 months postprocedure. Secondary outcome measures included Western Ontario and McMaster Universities Arthritis (WOMAC) and Patient Global Improvement-Indexes (PGI-I).

RESULTS

Both groups experienced significant reductions in pain, with no significant differences observed at 12 months (reduction from 5.7±1.9 to 3.2±2.6 in the RFA-group vs from 5.0±1.4 to 2.6±2.4 in the control-group (p=0.40)) or any other time point. No significant changes were observed between groups for WOMAC and PGI-I at the primary endpoint, with only the control group experiencing a significant improvement in function at 12-month follow-up (mean reduction from 91.2±38.2 to 67.1±51.9 in the RFA-group (p=0.06) vs from 95.8±41.1 to 60.6±42.8 in the control group (p=0.001); p=0.85 between groups).

CONCLUSION

Our failure to find efficacy for genicular nerve RFA, coupled with evidence showing that a plenitude of nerves supply the knee joint and preliminary studies indicating superiority of lesioning strategies targeting more than three nerves, suggest controlled trials using more aggressive lesioning strategies are warranted.

TRIAL REGISTRATION NUMBER

TCTR20170130003.

Facet Joint Syndrome: Pathophysiology, Diagnosis, and Treatment

Facet joint osteoarthritis (OA) is the most frequent form of facet joint syndrome. Medical history, referred pain patterns, physical examination, and diagnostic imaging studies (standard radiographs, magnetic resonance imaging, computed tomography and single-photon emission computed tomography) may suggest but not confirm lumbar facet joint (LFJ) syndrome as a source of low back pain (LBP). However, the diagnosis and treatment of facet joint syndrome is still controversial and needs further study. It is widely acknowledged that block with local anesthetic is perhaps the most effective method to establish a diagnosis of pain from LFJ. Particularly, there are different rates of success among different populations selected for diagnostic block with various positive criteria. Currently, in addition to conservative treatments for pain such as painkillers, functional exercises, and massage, there are many other methods, including block, denervation of the nerves that innervate the joints by radiofrequency, freezing or endoscopy, and injections. Due to the limited duration of pain relief from neurolysis of medial branch, many scholars have recently turned their targets to dorsal roots and LFJ capsules. Therefore, we reviewed the latest research progress of facet joint syndrome from diagnosis to treatment.

Review of Opioid Sparing Interventional Pain Management Options and Techniques for Radiofrequency Ablations for Sacroiliac Joint Pain

PURPOSE OF REVIEW

The goal of this clinical review was to provide an update about the existing treatment options and associated evidence for various radiofrequency ablation techniques for sacroiliac joint pain. An electronic literature search on radiofrequency for the treatment of sacroiliac joint pain was conducted using PubMed, NCBI and Google Scholar. The following search keywords were used: radiofrequency ablation (cooled, pulsed, conventional, bipolar, intra-articular), sacroiliac joint and sacroiliac pain. The search was limited to human subjects, English language and articles with available full text. The bibliographic sections of all manuscripts were further searched for additional relevant citations. The full text of the relevant articles was reviewed by all the authors.

RECENT FINDINGS

Our study showed that radiofrequency ablation is a safe and effective treatment option that can be utilized to manage sacroiliac joint pain. It offers accessibility to the primary care physician, reduces office visits with "pain" as the primary complaint and provides the added benefit of acting as a non-opioid sparing means of analgesia.

Cooled and traditional thermal radiofrequency ablation of genicular nerves in patients with chronic knee pain: a comparative outcomes analysis

INTRODUCTION

Genicular nerve radiofrequency ablation (GNRFA) is a minimally invasive intervention for patients with chronic knee pain (CKP) not responding to conservative treatments. Few investigations have compared treatment outcomes of cooled-RFA (c-RFA) and thermal-RFA (t-RFA), two common approaches of GNRFA. This study aims to investigate and compare outcomes, including probability of treatment success, between c-RFA and t-RFA in patients with CKP.

METHODS

This retrospective cohort study analyzed a total of 208 propensity score matched patients, including 104 patients who received c-RFA and 104 patients who received t-RFA. The primary outcome was probability of pain relief after the procedure, defined as reduction in Numeric Rating Scale (NRS) pain score of 2 or greater. The secondary outcomes were degree of NRS pain score reductions, duration of relief, and the probability of patients receiving TKA within 1 year of treatment.

RESULTS

T-RFA was associated with a higher probability of pain relief within 1, 3, and 6 months after procedure when compared with c-RFA. Probabilities of pain relief from t-RFA and c-RFA were 62% (95% CI 51% to 71%) and 43% (95% CI 34% to 53%; p=0.01) within 1 month, 78% (95% CI 68% to 85%) and 55% (95% CI 45% to 64%; p<0.001) within 3 months, and 79% (95% CI 70% to 86%) and 59% (95% CI 49% to 68%; p<0.01) within 6 months, respectively. t-RFA was also associated with greater mean NRS pain score reduction at 1 month after procedure: -4.71 (95% CI -5.3 to -4.1) when compared with -3.59 (95% CI -4.3 to -2.9; p=0.02) from c-RFA. T-RFA and c-RFA were comparable in pain score reduction at 3, 6, 9 and 12 months after procedure. Both groups demonstrated comparable duration of relief and probability of patients receiving TKA within 1 year.

DISCUSSION

Both t-RFA and c-RFA effectively reduced NRS pain scores in most patients with CKP within the 1 year follow-up period. Genicular nerve t-RFA was associated with a higher probability of treatment success and a greater degree of pain relief at 1 month after the procedure when compared with c-RFA in propensity score matched patients with CKP.

Cooled Radiofrequency Ablation Provides Prolonged Pain Relief Compared to Traditional Radiofrequency Ablation: A Real-World, Large Retrospective Clinical Comparison from a Single Practice

Background

Genicular radiofrequency ablation is an established therapy for chronic knee pain. An analysis comparing different probe sizes and technologies has not yet been undertaken for this indication. This large retrospective, comparison study from a single-center comprehensive pain management practice aims to do that.

Methods

Outcomes of 170 patients who underwent traditional radiofrequency ablation (tRFA) for chronic knee pain were compared to 170 consecutive patients who received cooled radiofrequency ablation (CRFA) with similar (p=0.5) pre-procedural pain scores.

Results

The VAS pain score at the first post-procedure visit at 4–6 weeks decreased to 5.07±2.8 cm for tRFA and to 4.26 ± 3.2 cm for CRFA (p<0.001 for both from baseline). The difference was profound and significantly better in the favor of CRFA (p<0.001) as the duration of reduction of pain scores by greater than 50% was 2.6 months for tRFA and 11.1 months for CRFA. There were only 15 patients (8.8%) who continued to receive >50% of pain relief in tRFA at 12 months, as opposed to 78 (46%) at 12 months for CRFA. We compared the initial outcomes and long-term pain relief. Long-term outcomes were better for the bigger lesion size treatment group patients.

Conclusion

We conclude that the duration and intensity of pain relief were of a greater magnitude after the larger diameter probe cooled RFA.

Comparison of two needle versus one needle lesioning techniques for thoracic medial branch neurotomy

Background and objectives

No prior studies have investigated an assumed advantage of creating a radiofrequency strip lesion for posterior element spinal axial pain using a two-needle technique (TNT) compared to a one-needle technique (ONT) that creates a single ovoid lesion. We explore the relationship of TNT compared to ONT on the magnitude and duration of pain relief following thoracic medial branch neurotomy (TMBN).

Methods

This study is a retrospective audit of consecutive patients treated with TMBN at a single site and interventionalist over ten years (2007-2017). All patients had undergone TMBN after failed conservative care and, with few exceptions, patient-reported ≥ 70% pain relief after thoracic medial branch block (TMBB). All patients had TMBN performed with a medial to lateral (MLA) radiofrequency cannula approach using either an ONT or TNT technique. We used parametric and nonparametric statistics and three levels of case analysis to assess for intergroup differences.

Results

Thirty-five consecutive patients underwent their primary TMBN, and two underwent both on a subsequent repeat using the MLA approach, 19 using the ONT, 18 using the TNT. The TNT group had clinically and statistically greater pain relief magnitude and duration than the ONT subgroup. The difference resulted in non-overlapping 95% confidence intervals for both percent pain relief and duration of pain relief using three levels of case analysis.

Conclusion

The comparison of TMBN techniques demonstrates a statistically significant separation of TNT to ONT sample mean values for magnitude and duration of pain relief when using TNT compared to ONT for TMBN using an MLA.

A comparison of the effectiveness of cervical medial branch radiofrequency ablation for chronic facet joint syndrome in patients selected by two common medial branch block paradigms

Background

Cervical medial branch radiofrequency ablation (CMBRFA) is effective when patients are selected by dual medial branch blocks (MBBs). SIS guidelines recommend 100% pain improvement after dual comparative MBBs before CMBRFA; however, our prior investigation showed similar outcomes in those selected by a lesser strict paradigm.

Objective

Compare pain and patient impression of improvement after CMBRFA in individuals stratified by a less stringent (80-99%) dual MBB response than those selected by the 100% criteria.

Design

Cross-sectional study.

Methods

Follow-up was conducted via standardized telephone survey at ≥6 months post-CMBRFA to obtain Numerical Rating Scale (NRS) pain and Patient Global Impression of Change (PGIC) scores. Primary and secondary outcomes were within-group and between-group differences in the proportions of patients reporting ≥50% NRS score reduction and PGIC scores.

Results

Medical records of 195 consecutive patients were reviewed; 100 individuals were analyzed. 48% (95% CI 35-61%) and 52% (95% CI 37-67%) of the 80-99% and 100% MBB groups, reported ≥50% pain reduction at ≥6 months post-CMBRFA. 74% (95% CI 63-85%) and 67% (95% CI 52-81%) of the 80-99% and 100% MBB groups reported a PGIC score consistent with "improved" or "very much improved." There were no significant between-group differences in any outcome at any time point.

Conclusions

We observed similar rates of pain relief and global improvement after CMBRFA in patients selected by dual MBBs with ≥80% symptom relief versus 100% relief. This provides evidence that a more practical criteria, compared to a more strict selection paradigm, may result in similar clinical outcomes.

Anatomical study of the medial branches of the lumbar dorsal rami: implications for image-guided intervention

INTRODUCTION

Fluoroscopic-guided radiofrequency ablation of the lumbar medial branches is commonly performed to manage chronic low back pain originating from the facet joints. A detailed understanding of the course of medial branches in relation to bony and soft tissue landmarks is paramount to optimizing lumbar denervation procedures, particularly parallel placement of the radiofrequency electrode. The objectives of this study were to investigate the relationship of medial branches to anatomical landmarks and discuss the implications for lumbar denervation.

METHODS

Ten cadaveric specimens were meticulously dissected. The origin, course, and relationship of lumbar medial branches to bony and soft tissue landmarks were documented.

RESULTS

The medial branches followed the lateral neck of superior articular process deep to the intertransversarii mediales muscle at each lumbar vertebral level. In all specimens, the medial branches coursed laterally on the anterior half of the neck and transitioned from parasagittal-to-medial on the posterior half to reach the mamillo-accessory notch. The mamillo-accessory ligament was found to not occlude the nerve on the posterior quarter of the lateral neck but rather at the mamillo-accessory notch located at the posterior margin of the superior articular process.

DISCUSSION

A detailed understanding of the relationship of medial branches to anatomical landmarks is essential to optimizing needle placement for lumbar denervation procedures. The current study suggests that a parasagittal placement, with increased cranial-to-caudal angulation of the electrode, may improve parallel tip alignment with the targeted medial branch and represent a potential alternative to the traditional technique.

Bipolar Radiofrequency Neurotomy of the Genicular Nerves for Chronic Pain Due to Knee Osteoarthritis

Background: The current treatments for chronic knee osteoarthritis (OA), a disabling and costly healthcare condition in the United States, vary in their level of supporting evidence. Although total knee replacement is one of the best-supported interventions, its associated risks should not be taken lightly, especially in older patients with comorbidities. Genicular nerve block with subsequent genicular nerve radiofrequency neurotomy (GN-RFN) has emerged as a promising intervention for refractory pain in knee OA. Purposes/Questions: We sought to assess the pain and functional outcomes of genicular nerve bipolar radiofrequency neurotomy (B-RFN) for the treatment of chronic pain due to knee OA. Methods: A total of 21 patients who underwent unilateral genicular nerve B-RFN after positive diagnostic genicular nerve block (50% or greater pain relief) treated between July 2018 to December 2018 were included. Pain numeric rating scale (NRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores were collected at baseline, 3 months, and 6 months post-B-RFN. Changes at each time point were compared to baseline scores using paired sample t tests. Results: At 3 months, 62% of patients had a greater than 50% improvement in NRS scores and 57% of patients had a greater than 50% improvement in WOMAC scores. At 6 months, 81% of patients had a greater than 50% improvement in NRS scores and 67% had a greater than 50% improvement in WOMAC scores. The absolute change in mean NRS (± standard deviation) at 6 months went from 7.5 ± 1.9 to 2.5 ± 1.2. The absolute change in mean WOMAC scores at 6 months went from 46.9 ± 8.0 to 19.0 ± 6.2. Conclusion: Of 21 patients, 14 (67%) saw greater than 50% improvements in both NRS and WOMAC scores at 6 months after genicular nerve B-RFN. Further prospective studies are needed to determine the selection criteria of patients most likely to benefit from this procedure.

The Effectiveness of Fluoroscopically Guided Genicular Nerve Radiofrequency Ablation for the Treatment of Chronic Knee Pain Due to Osteoarthritis: A Systematic Review

ABSTRACT

The objective was to determine the effectiveness of fluoroscopically guided genicular nerve radiofrequency ablation for painful knee osteoarthritis. Primary outcome measure was improvement in pain after 6 mos. Secondary outcomes included the Oxford Knee Score and Western Ontario and McMaster Universities Osteoarthritis Index. Two reviewers independently assessed publications before October 10, 2020. The Cochrane Risk of Bias Tool and Grades of Recommendation, Assessment, Development, and Evaluation system were used. One hundred ninety-nine publications were screened, and nine were included. Six-month success rates for 50% or greater pain relief after radiofrequency ablation ranged from 49% to 74%. When compared with intra-articular steroid injection, the probability of success was 4.5 times higher for radiofrequency ablation (relative risk = 4.58 [95% confidence interval = 2.61-8.04]). When radiofrequency ablation was compared with hyaluronic acid injection, the probability of treatment success was 1.8 times higher (relative risk = 1.88, 95% confidence interval = 1.38-2.57). The group mean Oxford Knee Score and Western Ontario and McMaster Universities Osteoarthritis Index scores improved in participants receiving genicular radiofrequency ablation compared with intra-articular steroid injection and hyaluronic acid injection. According to Grades of Recommendation, Assessment, Development, and Evaluation, there is moderate-quality evidence that fluoroscopically guided genicular radiofrequency ablation is effective for reducing pain associated with knee osteoarthritis at minimum of 6 mos. Further research is likely to have an important impact on the current understanding of the long-term effectiveness of this treatment.

Alternative treatment of hip pain from advanced hip osteoarthritis utilizing cooled radiofrequency ablation: single institution pilot study

OBJECTIVE

To establish the effectiveness of cooled radiofrequency ablation in managing hip pain from osteoarthritis at 6 months after receiving treatment in patients who failed conservative treatments and are not surgical candidates due to comorbidities or unwillingness to undergo arthroplasty surgery by targeting the femoral and obturator branches and assessing the degree of hip pain relief and change of function.

MATERIALS AND METHODS

This prospective pilot study includes a total of 11 consecutive patients experiencing persistent chronic hip pain in the setting of advanced osteoarthritis. Patients initially underwent anesthetic blocks of the obturator and femoral nerve branches to determine cooled radiofrequency ablation candidacy. After adequate response to the anesthetic blocks (> 50% immediate pain relief), patients were subjected to the procedures 2-3 weeks later. Treatment response was evaluated utilizing clinically validated questionnaires and visual analog score in order to assess impact on pain severity, stiffness, and functional activities of daily living. Follow-up outcome scores were collected up to 6 months after cooled radiofrequency ablation procedure.

RESULTS

A total of 11 hips were treated consecutively between August 2019 and March 2020 (mean patient age 61.4 years; 8 M:3F). The mean total HOOS score improved significantly from baseline at 17.0 ± 6.0 to 52.9 ± 5.4 at a mean of 6.2 months after treatment (p < 0.0001), with significant improvement in mean pain score from 16.1 ± 6.6 to 53.4 ± 7.4 (p < 0.0001) and mean stiffness score from 15.0 ± 8.1 to 53.6 ± 11.0 (p < 0.0001). No major complications were encountered. No patients went on to re-treatment, surgery, or other intervention.

CONCLUSION

Image-guided obturator and femoral nerve cooled radiofrequency ablation is effective and safe in treating chronic hip pain/stiffness in the setting of advanced osteoarthritis.

Ultrasound-guided monopolar versus bipolar radiofrequency ablation for genicular nerves in chronic knee osteoarthritis pain: A randomized controlled study

Background

This study compared between monopolar and bipolar radiofrequency (RF) ablation of the genicular nerves using ultrasound guidance (USG) in chronic knee osteoarthritis pain.

Material and methods

This was a prospective, randomized, double-blind study. Fifty patients with knee osteoarthritis pain were equally randomized to either monopolar or bipolar groups. The primary outcome was visual analogue score (VAS). The secondary outcomes were the proportion of successful responders with a reduction of 50% of VAS score at 12 and 24 weeks, the procedure time and pain and oxford knee score (OKS).VAS and OKS were recorded at 1, 4, 12, 24 weeks after intervention. Any complications were reported.

Results

Mean VAS score in bipolar group was (p < 0.05) lower than monopolar group at 12 weeks [4.84 ± 0.62 Vs. 3.56 ± 0.71] and 24 weeks [5.44 ± 0.82 Vs. 3.96 ± 0.79]. The Proportion of successful responders with a reduction of at least 50% of VAS score were more in bipolar group than monopolar group at 12 weeks (80% Vs. 12%) and 24 weeks (44% Vs. 4%). Mean OKS score in bipolar group was (p < 0.05) lower than monopolar group at 12 weeks [26 ± 3 Vs. 34 ± 3] and 24 weeks [27 ± 3 Vs. 35 ± 3].The procedure time and pain were (p < 0.05) lower in monopolar than bipolar group. The complications were similar in both groups.

Conclusion

USG bipolar RF ablation is more effective than monopolar RF ablation in controlling knee osteoarthritis pain as for the duration and severity of pain without fluoroscopic confirmation.

•

A study on 50 patient undergoing USG RFA of genicular nerves of 2 groups; Monopolar or bipolar RFA.

•

Bipolar RFA is more effective than Monopolar RFA.

•

USG radiofrequency ablation is alternative to fluoroscopic RFA.

•

No significant difference between the two groups according to complications.

Radiofrequency Ablation for the Knee Joint: A Survey by the American Society of Pain and Neuroscience

Background

Genicular nerve radiofrequency ablation (RFA) is an effective, minimally invasive procedure often used to treat patients with intractable knee pain secondary to knee osteoarthritis and failed knee replacements. The prevalence of knee pain in adults has been estimated to be as high as 40% and is continuously increasing with an aging population. Over the past two decades, proceduralists have adopted variations in patient preparation, procedural steps, and post-operative care for genicular nerve RFA procedures. A survey was dispensed via the American Society of Pain and Neuroscience (ASPN) to gain a popular assessment of common practices for genicular nerve RFA.

Methods

A 29 question survey was dispensed via SurveyMonkey to all members of ASPN. Members were able to respond to the survey a single time and were unable to make changes to their responses once the survey was submitted. After responses were compiled, each question was assessed in order to determine common practices for genicular nerve RFA.

Results

A total of 378 proceduralists responded to the survey. There was high consensus with the three most commonly targeted nerves. The inferomedial, superomedial, and superolateral genicular branches were treated by 95–96% of respondents, while other targets were less commonly treated. There remains some debate among proceduralists regarding the need for a second diagnostic nerve block and the type of steroid used for diagnostic nerve blocks.

Conclusion

Pain physicians use a wide variety of methods to perform genicular nerve ablations. The data offered by the survey show that there is no standardized protocol when it comes to treating knee pain via genicular nerve block and ablation and highlights controversies among proceduralists that ought to serve as the targets of future clinical research aimed at establishing a standardized protocol.

Cooled Radiofrequency Ablation for Chronic Joint Pain Secondary to Hip and Shoulder Osteoarthritis

Osteoarthritis (OA) of the shoulder and hip is a leading cause of physical disability and mental distress. Traditional nonsurgical management alone is often unable to completely address the associated chronic joint pain. Moreover, a large number of patients are not eligible for joint replacement surgery owing to comorbidities or cost. Radiofrequency ablation (RFA) of articular sensory nerve fibers can disrupt the transmission of nociceptive signals by neurolysis, thereby providing long-term pain relief. A subtype of RFA, cooled RFA (CRFA), utilizes internally cooled electrodes to generate larger ablative zones compared with standard RFA techniques. Given the complex variable innervation of large joints such as the glenohumeral and hip joints, a larger ablative treatment zone, such as that provided by CRFA, is desired to capture a greater number of afferent nociceptive fibers. The suprascapular, axillary, and lateral pectoral nerve articular sensory branches are targeted during CRFA of the glenohumeral joint. The obturator and femoral nerve articular sensory branches are targeted during CRFA of the hip. CRFA is a promising tool in the interventionalist's arsenal for management of OA-related pain and symptoms, particularly in patients who cannot undergo, have long wait times until, or have persistent pain following joint replacement surgery. An invited commentary by Tomasian is available online. ^©RSNA, 2022.

Long-term clinical outcomes of genicular nerve radiofrequency ablation for chronic knee pain using a three-tined electrode for expanded nerve capture

Objective

Genicular nerve radiofrequency ablation (GNRFA) is an effective treatment option for chronic knee pain in native knee osteoarthritis and total knee arthroplasty (TKA) patients. Recent dissections have revealed significant variability in typical genicular nerve targets and other sensory nerves not included in previous studies. Early, short-term results suggest that more complete sensory denervation with GNRFA may result in more significant pain reduction; however, no long-term clinical outcome exists. We aim to present long-term clinical outcomes after an expanded GNRFA technique with a three-tined radiofrequency cannula.

Methods

Eleven consecutive patients with ≥6 months of knee pain underwent an expanded GNRFA protocol targeting the superomedial (SMGN), superolateral (SLGN), inferomedial genicular nerves (IMGN), in addition to the nerves to vastus medialis (NVM), lateralis (NVL), and intermedius (NVI). Long-term pain and impression of change outcomes were collected in a cross-sectional fashion.

Results

At ≥18 months (mean 24 months) post-GNRFA, 91% (95% CI ​= ​59, 100%), 73% (95% CI ​= ​46, 99%), and 9% (95% CI ​= ​0, 26%) of patients reported ≥50%, ≥80%, and 100% pain relief, respectively. Additionally, 27% (95% CI ​= ​1, 54%) and 64% (95% CI ​= ​35, 92%) of individuals reported a PGIC score of 6 ("much improved") and 7 ("very much improved"), respectively. The proportion of individuals who reported the MCID for the PGIC (score of ≥6) was 91% (95% CI ​= ​59, 100%). There were no adverse events reported amongst the patients in this cohort. No patients progressed to surgery.

Conclusion

This single-arm cohort suggests that an expanded GNRFA protocol targeting SMGN, SLGN, IMGN, NVM, NVL, and NVI nerves with a three-tined electrode, resulted in significant long-term (≥18 months) improvements in pain and patient-perceived global improvement. Large, head-to-head trials are needed to establish whether this GNRFA protocol is superior to those used in previous clinical studies and those currently used more commonly in practice.