Radiofrequency techniques to treat chronic knee pain: a comprehensive review of anatomy, effectiveness, treatment parameters, and patient selection

Efficacy and safety of minimally invasive interventions targeting the genicular nerves for knee osteoarthritis: A meta-analysis

IMPORTANCE

Osteoarthritis (OA) is a prevalent and disabling joint disorder. Minimally invasive interventions targeting the genicular nerves are widely used for the clinical management of knee OA, but evidence on their efficacy and safety remains uncertain.

OBJECTIVE

To assess the efficacy and safety of minimally invasive interventions targeting the genicular nerves in knee OA.

DATA SOURCES

We searched MEDLINE, Embase, CENTRAL and clinical trial registries, from inception to August 2024.

STUDY SELECTION

We included randomised controlled trials evaluating minimally invasive interventions targeting the genicular nerves in patients with knee OA. Comparators included sham/placebo (main comparison), intra-articular injections, and usual care.

DATA EXTRACTION AND SYNTHESIS

Data were extracted independently by two reviewers following the PRISMA guidelines. Risk of bias was assessed using the Cochrane RoB-2 tool, and evidence certainty was evaluated according to the GRADE approach. A random-effects meta-analysis was conducted.

MAIN OUTCOME(S) AND MEASURES(S)

The primary outcomes were pain intensity, physical function, and serious adverse events. Secondary outcomes included quality of life and patient-reported global perceived effect.

RESULTS

Twenty-five trials were included (n= 2049) evaluating radiofrequency ablation (RFA), genicular nerve block (GNB) and cryoneurolysis. The certainty of evidence was consistently low to very low across all comparisons. RFA may provide moderate short-term pain relief (0 - 10 scale) compared to sham at 4 weeks (MD -1.70, 95% CI -3.03 to -0.36) and 12 weeks (MD -1.86, 95% CI -2.82 to -0.89), but there was no benefit at 24 and 48 weeks, and no improvements in function at any time point. The evidence is very uncertain for GNB, with only a single trial suggesting small pain reduction and moderate functional improvements at 4 weeks. For cryoneurolysis, very low certainty evidence suggests minimal short-term effects on pain and function. No differences in serious adverse events were observed between minimally invasive interventions and sham/placebo.

CONCLUSIONS AND RELEVANCE

The evidence supporting the use of RFA for the management of knee OA is highly uncertain, with modest, short-term benefits that are not sustained. Given the very low certainty of current data, we advise against its routine use until more robust evidence is available.

PROTOCOL REGISTRATION

PROSPERO - CRD42023454756.

A cadaveric study of the innervation of the anterior compartment of the knee

PURPOSE

Anterior knee pain can significantly affect the quality of life of those living with it. One approach to addressing anterior knee pain involves the selective denervation of the patella to reduce afferent pain transmission, but there has been no consensus on the number, location, or origin of the nerves innervating the patella. In this study, we review existing literature on anterior knee innervation and present findings from our cadaveric dissection to provide a detailed description of the innervation of the anterior knee joint.

MATERIALS AND METHODS

Two independent authors reviewed the literature on anterior knee innervation from PubMed and Embase, and a sub-search was conducted on the relationship between the infrapatellar branch of the saphenous nerve (IPBSN) and the anterior knee compartment. Subsequently, two fresh-frozen cadavers were dissected to determine whether the saphenous nerve innervates the anterior knee compartment and to confirm, through tissue biopsies stained with laminin and beta-III-tubulin, whether previously described nerves innervate the patella.

RESULTS

A total of 463 and 304 entries on patellar innervation and saphenous nerve anatomy, respectively, were identified through PubMed and Embase. Descriptions of the nerves innervating the patella were found to be inconsistent and are summarized. No studies identified branches of the IPBSN directly innervating the patella or patellar tendon. On cadaveric dissection, we found that anterior knee innervation comprised the nerves within the distal vastus medialis and lateralis muscles, the medial and lateral retinacular nerves, and occasionally a branch of the IPBSN that innervated the inferomedial anterior knee skin.

CONCLUSIONS

This study is the first to provide histological confirmation of patellar innervation by the IPBSN. Our findings suggest that an approach based on a positive response to differential nerve blocks, followed by resection of the nerves implicated in that anterior compartment knee pain, may be more effective in treating persistent anterior knee pain than circumferential electroablation of the patella or routine resection of the IPBSN.

LEVEL OF EVIDENCE

Level III.

Radiofrequency treatment for chronic knee pain in people with knee osteoarthritis

OBJECTIVES

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: To assess the benefits and harms of radiofrequency treatment of the genicular nerves in people with chronic knee pain due to knee osteoarthritis.

Genicular Nerve Block Versus Genicular Nerve Ablation for Knee Osteoarthritis: A Systematic Review of Randomized Controlled Trials and Retrospective Studies

This systematic review aimed to compare the efficacy and safety of genicular nerve ablation and genicular nerve block (GNB) in pain control and functional improvement in knee osteoarthritis (OA) patients using a systematic review of randomized controlled trials (RCTs) and retrospective studies. We searched PubMed, Google Scholar, Cochrane, Science Direct, and Web of Science using specific keywords until April 2023. The primary outcome measures were visual analog scale (VAS) and numerical rating scale (NRS) scores for pain. The secondary outcome measures included functional outcomes assessed by the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score and complications. Four RCTs and two comparative studies met the inclusion criteria. The analysis revealed that both genicular nerve ablation and nerve block effectively reduced pain and improved functionality. Ablation possibly provided more substantial and long-lasting effects than diagnostic blocks. However, the superiority of ablation compared to therapeutic block with steroids is still not conclusive in pain reduction. Functional capacity improvements were comparable between ablation and therapeutic block. Adverse events were minimal and transient.

9. Chronic knee pain

INTRODUCTION

Chronic knee pain is defined as pain that persists or recurs over 3 months. The most common is degenerative osteoarthritis (OA). This review represents a comprehensive description of the pathology, diagnosis, and treatment of OA of the knee.

METHODS

The literature on the diagnosis and treatment of chronic knee pain was retrieved and summarized. A modified Delphi approach was used to formulate recommendations on interventional treatments.

RESULTS

Patients with knee OA commonly present with insidious, chronic knee pain that gradually worsens. Pain caused by knee OA is predominantly nociceptive pain, with occasional nociplastic and infrequent neuropathic characteristics occurring in a diseased knee. A standard musculoskeletal and neurological examination is required for the diagnosis of knee OA. Although typical clinical OA findings are sufficient for diagnosis, medical imaging may be performed to improve specificity. The differential diagnosis should exclude other causes of knee pain including bone and joint disorders such as rheumatoid arthritis, spondylo- and other arthropathies, and infections. When conservative treatment fails, intra-articular injections of corticosteroids and radiofrequency (conventional and cooled) of the genicular nerves have been shown to be effective. Hyaluronic acid infiltrations are conditionally recommended. Platelet-rich plasma infiltrations, chemical ablation of genicular nerves, and neurostimulation have, at the moment, not enough evidence and can be considered in a study setting. The decision to perform joint-preserving and joint-replacement options should be made multidisciplinary.

CONCLUSIONS

When conservative measures fail to provide satisfactory pain relief, a multidisciplinary approach is recommended including psychological therapy, integrative treatments, and procedural options such as intra-articular injections, radiofrequency ablation, and surgery.

Knee osteoarthritis: disease burden, available treatments, and emerging options

Osteoarthritis (OA) is a prevalent condition that affects nearly 528 million people worldwide, including 23% of the global population aged ⩾40, and is characterized by progressive damage to articular cartilage, which often leads to substantial pain, stiffness, and reduced mobility for affected patients. Pain related to OA is a barrier to maintaining physical activity and a leading cause of disability, accounting for 2.4% of all years lived with disability globally, reducing the ability to work in 66% of US patients with OA and increasing absenteeism in 21% of US patients with OA. The joint most commonly involved in OA is the knee, which is affected in about 60%-85% of all OA cases. The aging population and longer life expectancy, coupled with earlier and younger diagnoses, translate into a growing cohort of symptomatic patients in need of alternatives to surgery. Despite the large number of patients with knee OA (OAK) worldwide, the high degree of variability in patient presentation can lead to challenges in diagnosis and treatment. Multiple society guidelines recommend therapies for OAK, but departures from guidelines by healthcare professionals in clinical settings reflect a discordance between evidence-based treatment algorithms and routine clinical practice. Furthermore, disease-modifying pharmacotherapies are limited, and treatment for OAK often focuses solely on symptom relief, rather than underlying causes. In this narrative review, we summarize the patient journey, analyze current disease burden and nonsurgical therapy recommendations for OAK, and highlight emerging and promising therapies-such as cryoneurolysis, long-acting corticosteroids, and gene therapies-for this debilitating condition.

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.

Advanced Interventional Procedures for Knee Osteoarthritis: What Is the Current Evidence?

The prevalence of knee osteoarthritis (OA) is the highest among all joints and likely to increase over the coming decades. Advances in the repertoire of diagnostic capabilities of imaging and an expansion in the availability and range of image-guided interventions has led to development of more advanced interventional procedures targeting pain related to OA pain while improving the function of patients presenting with this debilitating condition. We review the spectrum of established advanced interventional procedures for knee OA, describe the techniques used to perform these procedures safely, and discuss the clinical evidence supporting each of them.

Treatment of Warthin's Tumors of the Parotid Gland With Radiofrequency Ablation: A Systematic Review of the Current Literature

Objective: Warthin's tumors of the parotid gland can be safely observed. Definitive treatment usually requires parotidectomy under general anesthesia. The decision to operate on Warthin's tumors of the parotid gland can be complicated in patients who wish to avoid risks of surgery and general anesthesia. This systematic review explores the potential of radiofrequency ablation (RFA) as a minimally invasive alternative. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) model was used to collect 3 relevant studies that focused on RFA treatment for Warthin's tumors. The cumulative averages for tumor size and cosmetic scores were then quantified for patients with Warthin's tumors who underwent RFA therapy. The PRISMA systematic review method was employed to the PubMed and EMBASE databases. The comprehensive search term "Warthin Tumor Treatment" yielded 1299 articles from the years 1955 to 2023, 3 of which met inclusion criteria and were then selected. Results: The 3 quantitative studies collectively assessed 37 patients with Warthin's tumors treated with RFA. Patients experienced an average tumor size reduction of 85.03% at 12 months post-RFA. There were minimal complications associated with RFA in these patients. Conclusion: This study suggests that RFA is an alternative to parotidectomy for the symptomatic treatment of Warthin's tumors. RFA procedures demonstrated substantial tumor size reduction with few complications. However, further meta-analysis and comparison with alternative treatments is warranted to establish RFA's role in treatment of Warthin's tumors. The study is limited by its reliance on only 2 databases and a lack of comprehensive examination of different RFA settings.

A retrospective assessment of the effectiveness of pulsed radiofrequency ablation in the treatment of chronic pain caused by advanced knee osteoarthritis

INTRODUCTION

Patients suffering from severe chronic pain often have problems finding an appropriate combination of painkillers. We retrospectively evaluated the effectiveness and safety of pulsed radiofrequency ablation (pRFA) of the genicular nerves in 96 patients with knee osteoarthritis (KO). We hypothesized that age, sex, and body mass index (BMI) may influence the quality of the pRFA treatment.

MATERIAL AND METHODS

A diagnostic blockade with total volume of 9 ml of 1% lidocaine (WZF, Poland) combined with 4 mg of dexamethasone with subsequent pRFA with a radio frequency of 300-500 kHz under ultrasound guidance was used during the procedure. The study participants were assessed during regular monthly visits until 12 months.

RESULTS

The nerves' ultrasound identification was successful in 90.62% of the cases. According to the numeric rating scale (NRS), pain was reduced by 50% or more in 64.06% of the cases. The average pain relief period lasted just over 7 and a half months. There were no pRFA-related complications or side effects of the drugs used.

CONCLUSIONS

pRFA seems to be safe and effective for the treatment of chronic pain in KO. The outcome of the treatment may be related to the patient's age (block duration increased with patient age) and sex (in women, the therapeutic effect was more effectively prolonged) in our study group. There was also higher effectiveness of pRFA in high-BMI patients, which was close to statistical significance ( P = 0.053).

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.

Treatment options for symptomatic knee osteoarthritis in adults

ABSTRACT

Knee osteoarthritis is a common medical condition in adults, especially among older adults. The incidence and prevalence of knee osteoarthritis are increasing, and many healthcare providers manage patients with symptomatic presentations. This article reviews the most common nonsurgical and surgical treatment options for knee osteoarthritis, emphasizing evidence-based and practical therapies.

Ultrasound-Guided Genicular Nerve Blocks for Anterior Cruciate Ligament Reconstruction Surgery in an Outpatient Setting: A Case Series

Arthroscopic knee anterior cruciate ligament (ACL) reconstruction is commonly performed as an outpatient surgery, where adequate pain control and early ambulation play key roles in recovery and discharge. Peripheral nerve blocks aid in this purpose. Blockade of the genicular nerves, the articular branches of the knee, has recently become popular for knee surgery. We report on four patients who underwent ACL reconstruction with ultrasound-guided genicular nerve blocks (GNBs) under general anesthesia. The blocks were reliably performed without any complications, and the patients experienced good pain control, reduced opioid intake, and timely discharge following the surgery. These findings necessitate future investigations into the use of GNBs in ACL reconstruction.

Genicular nerve radiofrequency ablation: An option for knee osteoarthritis pain

ABSTRACT

Genicular nerve radiofrequency ablation is an option to treat osteoarthritic knee pain unresponsive to conservative and minimally invasive measures. This article reviews genicular nerve radiofrequency ablation, neuroanatomy of the knee, patient selection, results, and risks and complications of the procedure.

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.

Interventional Therapies for Osteoarthritis: An Update

Osteoarthritis (OA) is one of the most common diseases worldwide and is expected to increase in incidence as the age of the general population rises. Both oral medications, such as NSAIDs, and surgical treatments used for OA management have limitations. Demand is rising for minimally invasive techniques such as intraarticular injections and percutaneous interventions for use in place of or in conjunction with oral medications and surgical therapies, and the past 2 decades have seen a rapid expanse in both pharmacologic and nonpharmacologic minimally invasive OA treatments. Image guidance with fluoroscopy, CT, or ultrasound is often used in conjunction with these procedures to achieve precise treatment localization to achieve maximal therapeutic effect. The choice of modality used for image guidance is often influenced by clinician experience, patient characteristics, and equipment availability. This article reviews the mechanisms of action, contraindications, complications, and efficacy of conventional and developing minimally invasive OA treatments. The minimally invasive treatment options described in this Review include therapeutic injections such as antiinflammatory agents, viscosupplements, and biologics, as well as nonpharmacologic treatments of subchondroplasty, nerve ablation, genicular artery embolization, intraarticular pulsed radiofrequency therapy, and MRI-guided focused ultrasound therapy.

Consensus Guidelines on Interventional Therapies for Knee Pain (STEP Guidelines) from the American Society of Pain and Neuroscience

Knee pain is second only to the back as the most commonly reported area of pain in the human body. With an overall prevalence of 46.2%, its impact on disability, lost productivity, and cost on healthcare cannot be overlooked. Due to the pervasiveness of knee pain in the general population, there are no shortages of treatment options available for addressing the symptoms. Ranging from physical therapy and pharmacologic agents to interventional pain procedures to surgical options, practitioners have a wide array of options to choose from - unfortunately, there is no consensus on which treatments are "better" and when they should be offered in comparison to others. While it is generally accepted that less invasive treatments should be offered before more invasive ones, there is a lack of agreement on the order in which the less invasive are to be presented. In an effort to standardize the treatment of this extremely prevalent pathology, the authors present an all-encompassing set of guidelines on the treatment of knee pain based on an extensive literature search and data grading for each of the available alternative that will allow practitioners the ability to compare and contrast each option.

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.

Total Knee Arthroplasty After Genicular Nerve Radiofrequency Ablation: Reduction in Prolonged Opioid Use Without Increased Postsurgical Complications

Genicular nerve radiofrequency ablation (GNRFA) is an increasingly used nonsurgical treatment modality for patients with advanced knee osteoarthritis. Previous studies have demonstrated this to be an effective and safe method to decrease pain and increase functionality in this patient population. The purpose of this study was to compare 2-year postoperative complication rates and rates of prolonged postoperative opioid usage between patients undergoing total knee arthroplasty (TKA) after previous GNRFA and those undergoing TKA alone.

Associations of Healthcare Utilization and Costs with Increasing Pain and Treatment Intensity Levels in Osteoarthritis Patients: An 18-Year Retrospective Study

Introduction

Osteoarthritis (OA) is a complex disease, and prior studies have documented the health and economic burdens of patients with OA compared to those without OA. Our goal was to use two strategies to further stratify OA patients based on both pain and treatment intensity to examine healthcare utilization and costs using electronic records from 2001 to 2018 at a large integrated health system.

Methods

Adult patients with ≥1 pain numerical rating scale (NRS) and diagnosis of OA were included. Pain episodes of ≥90 days were defined as mild (0–3), moderate (4–6), or severe (7–10) based on initial NRS. Patients were initially classified as mild and moved to moderate-severe OA if any of eight treatment-based criteria were met. Outpatient visits (OP), emergency department visits (ED), inpatient days, and healthcare costs (both all-cause and OA-specific) were compared among pain levels and OA severity levels as frequencies and per-member-per-year rates, using generalized linear regression models adjusting for age, sex, and body mass index, with contrasts of p < 0.05 considered significant.

Results

We identified 127,656 patients, 92,576 with pain scores. Moderate and severe pain were associated with significantly higher rates of OA-related utilization and costs, and all-cause ED visits and pharmacy costs. Moderate-severe OA patients had significantly higher OA-related utilization and costs, and all-cause OP, ED and pharmacy costs.

Conclusions

Pain and treatment intensity were both strongly associated with OA-related utilization but not consistently with all-cause utilization. Our results provide promising evidence of better criteria and approaches for predicting disease burden and costs in the future.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-022-00448-7.

Functional Outcomes and Physical Performance of Knee Osteoarthritis Patients After Ultrasound-Guided Genicular Nerve Radiofrequency Ablation

OBJECTIVE

To elucidate the effectiveness of ultrasound-guided genicular nerve radiofrequency ablation in alleviating pain as well as its effects on functional outcomes, quality of life and physical performance in knee osteoarthritis patients.

DESIGN

Prospective observational study.

SETTING

Patients were recruited within one community hospital.

SUBJECTS

Patients with knee osteoarthritis.

METHODS

The subjects underwent ultrasound-guided radiofrequency ablation of genicular nerves after showing a positive response to a diagnostic block. Outcome assessments were performed at baseline and at 2 and 12 weeks posttreatments using the 36-item Short Form Health Survey (SF-36), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and a physical performance evaluation including balance tests, quadriceps muscle strength test, two-minute walking test and knee joint proprioception test.

RESULTS

Thirteen out of 38 patients were eligible for genicular nerve radiofrequency ablation. There were significant improvements from baseline to posttreatment in the numeric rating scale score, physical health domain score of SF-36, and pain and stiffness domain scores of the WOMAC. Regarding physical performance, the step test result significantly improved over the 12 weeks of follow-up. On the other hand, no significant deteriorations in the single leg stance test, isokinetic quadriceps muscle strength test, knee joint proprioception test or two-minute walking test results were observed after radiofrequency ablation of genicular nerves.

CONCLUSIONS

Radiofrequency ablation of genicular nerves may significantly alleviate pain and improve functional outcomes in knee osteoarthritis patients. More importantly, static balance control and quadriceps muscle strength were preserved and there was a change of proprioception in the good direction.

Effectiveness of Ultrasound-Guided Canal Adductor Blockade for Chronic Pain and Functioning in Knee Osteoarthritis: A Prospective Longitudinal Observational Study

Methods

Seventy-seven patients with chronic knee osteoarthritis pain received ultrasound-guided ACB with 14 ml 0.25% levobupivacaine and 100 mcg clonidine. At baseline and 1 month after the blockade, we assessed maximal and minimal pain intensity in the knee using a numeric rating scale (NRS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS). The range of motion in extension and flexion (ROMext and ROMflex) and quadriceps muscle strength of both knees (QS), Timed Up and Go Test (TUG), and 30-Second Chair Stand Test (30CST) results were determined at baseline, 1 hour, 1 week, and 1 month after the blockade.

Results

ACB with levobupivacaine and clonidine appeared to decrease pain severity (NRS_max 8.13 to 4.2, p < 0.001 and NRS_min 3.32 to 1.40, p < 0.001). Similarly, knee ROMext decreased from 3.90 preintervention to 2.89 postintervention at 1 month, p < 0.001; ROMflex decreased from 5.70 to 3.29, p < 0.001; TUG time decreased from 3.22 to 2.93, <0.001; QS increased from 18.43 to 22.77, p < 0.001; CST increased from 8.23 to 10.74, p < 0.001. The KOOS for pain (36.40 to 58.34), symptoms (52.55 to 64.32), activities of daily living functions (ADLs, 36.36 to 60.77), and quality of life (QoL, 17.87 to 30.97) also increased, all p < 0.001.

Conclusion

ACB appeared to decrease pain and increase ambulation. If our preliminary results are reproducible in a planned randomized controlled trial, ACB could be a useful adjunctive pain therapy in patients with disabling pain due to knee OA.

Latest Evidence-Based Application for Radiofrequency Neurotomy (LEARN): Best Practice Guidelines from the American Society of Pain and Neuroscience (ASPN)

Radiofrequency neurotomy (RFN), also known as radiofrequency ablation (RFA), is a common interventional procedure used to treat pain from an innervated structure. RFN has historically been used to treat chronic facet-joint mediated pain. The use of RFN has more recently expanded beyond facet-joint mediated pain to peripherally innervated targets. In addition, there has also been the emergence of different radiofrequency modalities, including pulsed and cooled RFN. The use of RFN has been particularly important where conservative and/or surgical measures have failed to provide pain relief. With the emergence of this therapeutic option and its novel applications, the American Society of Pain and Neuroscience (ASPN) identified the need for formal evidence-based guidance. The authors formed a multidisciplinary work group tasked to examine the latest evidence-based medicine for the various applications of RFN, including cervical, thoracic, lumbar spine; posterior sacroiliac joint pain; hip and knee joints; and occipital neuralgia. Best practice guidelines, evidence and consensus grading were provided for each anatomical target.

Ultrasound-guided pulsed radiofrequency of the saphenous nerve for knee osteoarthritis pain: a pilot randomized trial

Aim: Knee osteoarthritis is a degenerative disease complicated by pain and functional limitation. Newer pain-relieving interventions include pulsed radiofrequency (PRF), but studies on its efficacy have limitations including lack of control group and retrospective design that prevent sound conclusions. Materials & methods: We conducted a blind prospective randomized sham-controlled crossover pilot trial according to the CONSORT guidelines, to evaluate the efficacy of ultrasound-guided saphenous nerve PRF in gonarthritis pain. Results: Sixteen patients completed the study. Pain and function significantly improved after real PRF (numerical rating scale mean difference = 3.31), which was superior to sham PRF over time for pain (3 months) and function (6 months). Conclusion: PRF of the saphenous nerve is an alternative to relieve pain in gonarthritis. Our results provide data to support a sample size calculation for future trials. Clinical trial registration: NCT04454710.

Efficacy and safety of magnetic resonance-guided focused ultrasound treatment for refractory chronic pain of medial knee osteoarthritis

OBJECTIVE

To elucidate the efficacy and safety of MRgFUS in the treatment for refractory pain derived from medial knee OA.

METHODS

Twenty patients with medial knee OA eligible for total knee arthroplasty were included in this prospective, non-controlled study (UMIN000010193). MRgFUS treatment was provided at the site of most severe tenderness around the medial femorotibial joint of each patient under real-time monitoring of temperature. The goal temperature of the targeted bone surface was 55 °C. Numerical rating scale (NRS) worst pain scores, Western Ontario and McMaster Universities osteoarthritis index (WOMAC) scores, EuroQol 5 dimensions index (EQ-5D) scores and pressure pain threshold (PPT) were evaluated before treatment (baseline) and at 1 week and 1, 3, 6, and 12 months post-treatment, respectively. Complications and adverse events were also assessed clinically and radiographically.

RESULTS

Treatment response (a 50% or greater decrease in NRS score) was seen in 14 patients (14/19, 73.7%) at 12 months post-treatment. Mean NRS score rapidly decreased at 1 month after treatment and continued to decline through the following 12 months. At final follow-up, mean NRS score was 3.2 ± 1.9, significantly lower than at baseline (p = 0.0013). Mean WOMAC and EQ-5D scores also improved significantly from 1 month after treatment. Fifteen patients showed significant sustained increases in PPTs at the sites of most severe tenderness. No serious adverse events were observed during and after treatment.

CONCLUSIONS

MRgFUS treatments were effective not only for managing refractory pain, but also for improving physical functions without adverse events in elderly patients with medial knee OA.

Ultrasound-guided genicular nerve blocks following total knee arthroplasty: a randomized, double-blind, placebo-controlled trial

INTRODUCTION

Local anesthetic blockade of the genicular nerves, known targets of radiofrequency ablative techniques for knee pain, has not previously been studied in a randomized controlled trial evaluating acute pain after knee arthroplasty. We hypothesized that genicular nerve blockade added to an existing block regimen in total knee arthroplasty would result in a reduction in 24 hours opioid consumption.

METHODS

Patients (American Society of Anesthesiologists 1-3, aged 18-85 years) undergoing primary total knee arthroplasty were randomized to receive single-injection nerve blocks of the superolateral, superomedial, and inferomedial genicular nerves with injectate (15 mL 0.25% bupivacaine and 2 mg dexamethasone or 15 mL saline placebo). All subjects received a standard oral analgesic regimen, spinal anesthetic with 12.5 mg isobaric bupivacaine, infiltration between the popliteal artery and capsule of the knee with 0.2% ropivacaine, and postoperative adductor canal perineural infusion with 0.2% ropivacaine. The primary outcome was 24 hours opioid consumption (measured in morphine milliequivalents).

RESULTS

Forty (40) subjects were enrolled. Opioid consumption at 24 hours was significantly lower in the BLOCK group compared with the SHAM group (23±20 vs 58±35, p<0.001), and this difference remained significant at 48 hours (50±40 vs 98±56, p=0.004). Pain scores were reduced in the BLOCK group at time 6 hours (2.6±1.9 vs 4.3±2.2, p=0.012), but were otherwise similar at remaining time points. Patient satisfaction at 24 hours and 20 m walk test times were similar between groups.

DISCUSSION

Genicular nerve blockade was associated with a reduction in opioid consumption at 24 hours in primary total knee arthroplasty patients.

TRIAL REGISTRATION NUMBER

NCT03706313.

A Comparison of Genicular Nerve Blockade With Corticosteroids Using Either Classical Anatomical Targets vs Revised Targets for Pain and Function in Knee Osteoarthritis: A Double-Blind, Randomized Controlled Trial

OBJECTIVE

Compare the effectiveness of genicular nerve blockade (GNB) using classical anatomical targets (CT) versus revised targets (RT) in patients suffering from chronic knee osteoarthritis pain.

DESIGN

Double-blinded randomized controlled trial.

SETTING

Pain medicine center of a teaching hospital.

METHODS

We randomly assigned 55 patients with chronic knee osteoarthritis pain to receive a GNB (using a fluid mixture of 2 mL: lidocaine 1% + 20 mg triamcinolone) with either classical targets (CT-group, n = 28) or revised targets (RT-group, n = 27). Numeric rating pain scale (NRS), Oxford knee score (OKS), Western Ontario and McMaster Universities osteoarthritis index score (WOMAC), Quantitative analgesic questionnaire (QAQ) and global perceived effects were assessed at baseline, and at 1-hour, 24-hours, 1, 4, and 12 weeks post-intervention.

RESULTS

The RT-group showed greater reduction in NRS mean score at 1-hour post-intervention (2.4 ± 2.1 vs 0.4 ± 0.9, 95% confidence interval (CI) [.0-.8] vs [1.6-3.2], P < .001). The proportion of patients achieving more than 50% knee pain reduction was higher in the RT-group at each follow up interval, yet these differences were statistically significant only at 1-hour post intervention (82.1% [95% CI = 63.1-93.9] vs 100% [95% CI = 97.2-100] P = .02). Both protocols resulted in significant pain reduction and joint function improvement up to 12 weeks post-intervention.

CONCLUSIONS

The revised technique allowed more pain relief as well as greater proportion of successful responders at 1-hour post intervention. The large volume injected during therapeutic GNB could have compensated the lack of precision of the classical anatomical targets, mitigating differences in outcomes between both techniques.

Evaluating predictors of pain reduction after genicular nerve radiofrequency ablation for chronic knee pain

Aim: Radiofrequency ablation (RFA) of genicular nerves can treat refractory chronic knee pain. This study evaluated association between patient and procedural characteristics and pain improvement after genicular nerve RFA. Materials & methods: A retrospective chart review. Data were extracted from patients who underwent thermal or cooled RFA of the knee. Results: A total of 124 patients were included. 81% of patients reported ≥75% pain relief after diagnostic nerve blocks. 35% reported ≥50% pain reduction from the RFA. Predictors of improved pain outcomes included higher baseline pain, no depression and thermal (vs cooled) RFA. Conclusion: Identifying patients who may benefit the most from genicular RFA is still not clear. Pain reduction differences between patients with and without depression and RFA type deserves further exploration.

Pain relief following genicular nerve radiofrequency ablation: does knee compartment matter?

Aim: To investigate the effect of knee osteoarthritis (OA) compartment location on pain relief following genicular radiofrequency ablation. Materials & methods: A retrospective chart review was performed on 62 patients. Visual analog scale scores at 3 and 6 months post procedure were compared with baseline and between compartment groups. Results: Pain significantly improved for all patients at 3 and 6 months (p < 0.001 and p = 0.005, respectively). Medial compartment OA was a significant predictor of improvement at 3 months (p = 0.042). Patellofemoral compartment OA was a significant predictor for a higher visual analog scale at 3 months (p = 0.018). Conclusion: Compartmental location of knee OA impacts pain relief following genicular radiofrequency ablation. Future protocols could target nerves based on which compartments are more affected on imaging.

Safety and efficacy comparison of three- vs four-needle technique in the management of moderate to severe osteoarthritis of the knee using cooled radiofrequency ablation

PURPOSE

To analyze the safety and efficacy of image-guided genicular nerve cooled radiofrequency ablation (C-RFA) for the treatment of pain in non-surgical candidates with moderate to severe knee osteoarthritis (OA) and to compare three- vs four-needle technique.

METHOD

This retrospective study included 50 consecutive patients with pain from moderate to severe knee OA refractory to anti-inflammatory analgesia that failed multiple intra-articular lidocaine-steroid injections and who were non-surgical total knee arthroplasty candidates because of comorbidities. Patients initially underwent anesthetic blocks of the superior medial/lateral femoral and inferior medial tibial genicular nerve branches and in some cases the suprapatellar genicular nerve branch. Radiofrequency ablations of the same nerve branches were performed 1-2 weeks after the nerve blocks. Follow-up outcome was collected at approximately 2 weeks, 1, 3, and 6 months after the C-RFA procedure utilizing VAS and clinically validated questionnaires.

RESULTS

A total of 77 knees were treated. The mean total KOOS score improved significantly from baseline at 24.7 ± 14.1 to 59.4 ± 26.5 at 6 months after treatment (p < 0.0001), with significant improvement in mean pain score from 25.5 ± 15.2 to 64.5 ± 25.2 (p < 0.0001) and mean stiffness score from 35.1 ± 21.9 to 65.8 ± 24.9 (p < 0.0001). At 6 months, 65% of all patients demonstrated decreased opiate medication usage, 79% of patients in the four-needle, and 45% of patients in the three-needle arms (p = 0.03). No complications were reported.

CONCLUSIONS

The four-needle treatment approach offers an advantage in the overall efficacy in treating stiffness and pain in patients with moderate-to-severe OA refractory to conservative treatments leading to decreased opiate usage without complications.

A Randomized Controlled Trial to Compare Analgesia and Functional Improvement After Continuous Neuroablative and Pulsed Neuromodulative Radiofrequency Treatment of the Genicular Nerves in Patients with Knee Osteoarthritis up to One Year After the Intervention

OBJECTIVES

To compare the analgesic and functional outcomes of continuous neuroablative radiofrequency (CNARF) and pulsed neuromodulative radiofrequency (PNMRF) treatment of genicular nerves up to 1 year after the intervention and to identify predictors associated with a successful outcome (defined as an at least 50% reduction in the pre-interventional visual analog scale [VAS] rating) after genicular radiofrequency treatment.

DESIGN

A prospective randomized controlled trial.

SETTING

The Pain Department of the Jerez de la Frontera University Hospital, Cadíz, Spain, from January 2018 until May 2019.

SUBJECTS

Patients with grade 3-4 gonarthritis suffering from knee pain, with a VAS score ≥5 for >6 months.

METHODS

Eligible participants were randomly assigned to receive either CNARF or PNMRF of the superior medial, superior lateral, and inferior medial genicular nerves. The VAS and Western Ontario and McMaster Universities Osteoarthritis (WOMAC) scores were assessed before and at 1, 6, and 12 months after treatment. Medication use was quantified before and at 6 months after the intervention. Potential characteristics associated with the efficacy of radiofrequency intervention were explored by using multivariable statistical models.

RESULTS

A total of 188 participants were included. The magnitude and duration of beneficial effect and reduction in analgesic use were significantly greater in the CNARF group. Success at 6 months after radiofrequency treatment decreased with grade 4 gonarthritis; higher pre-interventional VAS score; and concomitant depression, anxiety disorder, and diabetes mellitus.

CONCLUSIONS

Therapeutic efficacy and reduction in analgesic consumption were superior after CNARF. Treatment success at 6 months after radiofrequency intervention decreased with more severe gonarthritis; higher pre-interventional pain intensity; and concomitant depression, anxiety disorder, and diabetes mellitus.

Clinical and technical factors associated with knee radiofrequency ablation outcomes: a multicenter analysis

BACKGROUND

There has been a surge in interest in radiofrequency ablation (RFA) of the genicular nerves over the past decade, with wide variability in selection, technique and outcomes. The aim of this study is to determine factors associated with treatment outcome.

METHODS

We retrospectively evaluated the effect of 23 demographic, clinical and technical variables on outcomes in 265 patients who underwent genicular nerve RFA for knee pain at 2 civilian and 1 military hospital. A primary outcome was designated as a > 30% decrease in average knee pain score lasting at least 3 months without cointerventions.

RESULTS

The overall rate of a positive response was 61.1% (95% CI 55.2% to 67.0%). In univariable analysis, larger electrode size (p=0.01), repeated lesions (p=0.02), having>80% pain relief during the prognostic block (p=0.02), not being on opioids (p=0.04), having no coexisting psychiatric condition (p=0.02), having a lower baseline pain score (p=0.01) and having >3 nerves targeted (p=0.02) were associated with a positive outcome. In multivariate logistic analysis, being obese (OR 3.68, 95% CI 1.66 to 8.19, p=0.001), not using opioids (OR 0.35, 95% CI 0.16 to 0.77, p=0.009), not being depressed (OR 0.29, 95% CI 0.10 to 0.82, p=0.02), use of cooled RFA (OR 3.88, 95% CI 1.63 to 9.23, p=0.002) and performing multiple lesions at each neural target (OR 15.88, 95% CI 4.24 to 59.50, p<0.001) were associated with positive outcome.

CONCLUSIONS

We identified multiple clinical and technical factors associated with treatment outcome, which should be considered when selecting patients for RFA treatment and in the design of clinical trials.

Is Cooled Radiofrequency Genicular Nerve Block and Ablation a Viable Option for the Treatment of Knee Osteoarthritis?

Background

The purpose of this study was to determine demographic and psychosocial factors that influence the effectiveness of cooled radiofrequency genicular nerve ablation (C-RFA) and block in patients with chronic knee pain secondary to osteoarthritis (OA).

Methods

A retrospective review was completed including patients with knee OA who underwent genicular nerve ablation or block or both. Patient information collected included opioid use, psychological comorbidities, smoking history, body mass index, and medical comorbidities. Success was defined using the Osteoarthritis Research Society International criterion of greater than or equal to 50% reported pain relief from the procedure. Patients without a diagnosis of knee OA and patients with ipsilateral total knee arthroplasty were excluded. Patient factors were compared between (1) those that did or did not respond to the initial block and (2) those that did or did not respond to C-RFA.

Results

Of the 176 subjects that underwent genicular nerve block, 31.8% failed to respond to the procedure. Subjects that failed the initial block were significantly more likely to have psychological comorbidities, smoking history, and diabetes. Of the subjects that proceeded to genicular nerve ablation, 53.7% reported less than 50% pain relief, and 46.3% reported pain relief greater than or equal to 50% at the first follow-up visit. While the presence of psychological comorbidities, smoking, and diabetes were associated with first-stage block failures, these patient factors were not associated with second-stage ablation failures.

Conclusions

C-RFA may be an effective adjunct therapy as part of a multimodal pain regimen; however, individual patient characteristics must be considered.

[Interdisciplinary position paper: the value of radiofrequency denervation in the treatment of chronic pain]

Radiofrequency denervation has been established for many years as an important minimally invasive procedure for the treatment of chronic pain conditions. Positive experiences of many users for various indications are contrasted by a nonuniform evidence. With meticulous patient selection and correct assessment of the indications a longer term reduction of pain, a reduced need for analgesics and an improvement in the quality of life can be achieved. The aim of this interdisciplinary position paper is to present the value of radiofrequency denervation in the treatment of chronic pain. The summarized recommendations of the expert group are based on the available evidence and on the clinical experiences of Austrian centers that frequently implement the procedure. The position paper contains recommendations on patient selection and proven indications. We discribe safety aspects, complications, side effects and contraindications.

Lower limb kinematics improvement after genicular nerve blockade in patients with knee osteoarthritis: a milestone study using inertial sensors

Background

Genicular nerve blockade is a possible treatment for patients with knee osteoarthritis. Pain relief and improvement in functioning is expected. This procedure could be of major interest for patients in low-income countries where total knee arthroplasty is not available for the population. This study aims at assessing the immediate benefits on pain, gait, and stairs kinematics after a genicular nerve blockade in patients suffering from knee osteoarthritis in Cameroun.

Methods

A prospective study was carried out on 26 subjects in Cameroun. A genicular nerve blockade was performed on 14 women with painful knee osteoarthritis grade 2–4. Lower limb joint angles were recorded with inertial sensors before and 1 h after injection. Patient-reported outcomes of pain and perceived difficulty were collected, as well as 10 m and 6 min walking tests. A reliability analysis of inertial sensors was performed on a sample of 12 healthy subjects by calculating the intraclass correlation coefficient and the standard error of measurement.

Results

Pain and perceived difficulty decreased significantly (p < 0.001). Cadence increased significantly in stairs climbing (upstairs: + 7.7 steps/min; downstairs: + 7.6 steps/min). There was an improvement for hip sagittal range of motion during gait (+ 9.3°) and pelvis transverse range of motion in walking upstairs (− 3.3°). Angular speed range of the knee in the sagittal plane and of the hip in the frontal plane increased significantly in stairs descent (+ 53.7°/s, + 94.5°/s).

Conclusions

This study quantified improvement of gait and stair climbing immediately after a genicular nerve blockade in patients suffering from knee OA in Cameroon. This is the first study objectifying this effect, through wearable sensors.

Trial registration

Pan African Clinical Trial Registry, PACTR202004822698484. Registered 28 March 2020 - Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-020-03836-8.

Validation of a new protocol for ultrasound-guided genicular nerve radiofrequency ablation with accurate anatomical targets: cadaveric study

INTRODUCTION

Ultrasound (US)-guided radiofrequency ablation (RFA) of genicular nerves (GNs) is increasingly performed to manage chronic knee pain. The anatomical foundations supporting the choice of original targets for US-guided GN-RFA have been thoroughly improved by recent anatomical studies. Therefore, this study aimed to provide a new protocol with revised anatomical targets for US-guided GN-RFA and to assess their accuracy in a cadaveric model.

MATERIALS AND METHODS

Fourteen fresh-frozen cadaveric knees were used. After a pilot study with 4 knees, five consistent nerves were targeted in the other 10 knees with revised anatomical landmarks: superior medial genicular nerve (SMGN), superior lateral genicular nerve (SLGN), inferior medial genicular nerve (IMGN), recurrent fibular nerve (RFN) and the infrapatellar branch of the saphenous nerve (IPBSN). For each nerve, the lumen of radiofrequency (RF) cannula was prefilled with non-diffusible black paint, and then the cannula was inserted at the target site under US guidance. After US verification of correct placement, the stylet was introduced in the cannula to create a limited black mark on the tissues at the top of the active tip. Anatomical dissection was performed to assess for accuracy.

RESULTS

The proportion of nerves directly found in contact with the black mark was 7/10, 8/10, 10/10 and 9/10 for the SMGN, SLGN, IMGN and RFN, respectively. The proportions of nerve captured by the theoretical largest monopolar RF lesions were 100% for the SMGN, IMGN and RFN, and IPBSN and 95% for SLGN. The mean distances from the center of the black mark to the targeted nerve were 2.1±2.2 mm, 1.0±1.4 mm, 0.75±1.1 mm and 2.4±4.5 mm for the SMGN, SLGN, IMGN and RFN, respectively.

CONCLUSION

US-guided GN-RFA with revised anatomical targets resulted in accurate capture of the five targeted nerves. This protocol provides precise sensory denervation of a larger panel of nerves, targeting those whose constancy regarding anatomical location has been clearly demonstrated. It is expected to improve the clinical outcomes.

A Review of Non-Surgical Pain Management in Osteoarthritis

Osteoarthritis is a prominent cause of disability in older adults, especially with an increasingly obese and aging population. Clinical management of pain secondary to osteoarthritis should focus on education and self-management with exercise and weight management as a priority. Surgical intervention should only be considered once conservative measures have failed. This review provides a clinical update on the pathogenesis, diagnosis, and management of osteoarthritis.

Cooled Radiofrequency Genicular Neurotomy

Knee osteoarthritis, a chronic degenerative condition, can be a debilitating and limiting process with affected patients presenting with symptoms such as pain, restrictive range of motion, and swelling. This condition commonly afflicts millions of people with a higher incidence among the elderly that results from chronic mechanical repetitive loading. The treatment of pain generating conditions such as arthritis in large joints is complex requiring interventions of varying focuses such as weight loss, anti-inflammatory medications, corticosteroid, hyaluronic and viscosupplementation injections, and prescription opioids. A gap in the treatment options of this ailment currently exists between short term pain solutions and surgical approaches such as total knee arthroplasty that may offer longer pain relief. Cooled radiofrequency ablation is an emerging technique that offers a minimally invasive alternative for treating knee pain with a clinical relevance in patients who are not surgical candidates due to coexistent medical comorbidities or those who are undesiring of surgery. This procedure uses radiofrequency ablation that blocks genicular nerves from transmitting knee pain signals to the brain. Further research will allow the application of this technique to treat other sensory nerves in large joints such as the hip and shoulder.

Anatomical study of the descending genicular artery and implications for image-guided interventions for knee pain

INTRODUCTION

The descending genicular artery (DGA) has recently been mentioned as accompanying some nerves in the medial aspect of the knee joint. This could be clinically relevant as the arteries could serve as landmarks for accurate nerve capture during ultrasound-guided nerve blockade or ablation. The aim of this cadaveric study was to investigate the anatomical distribution of the DGA, assess the nerves running alongside its branches, and discuss the implications for regional anesthesia and knee pain interventions.

METHODS

We dissected the femoral artery (FA) all along its course to identify the origin of the DGA, from which we carefully dissected all branches, in 27 fresh-frozen human specimens. Simultaneously, we systematically dissected the nerves supplying the medial aspect of the knee from proximally to distally and identified those running alongside the branches of the DGA. The surrounding anatomical landmarks were identified and measurements were recorded.

RESULTS

The DGA was found in all specimens, arising from the FA 130.5 ± 17.5 mm (mean ± SD) proximally to the knee joint line. Seven distribution patterns of the DGA were observed. We found three consistent branches from the DGA running alongside their corresponding nerves at the level of the medial aspect of the knee: the artery of the superior-medial genicular nerve, the artery of the infrapatellar branch of the saphenous nerve, and the saphenous branch of the DGA.

CONCLUSION

The consistent arteries and surrounding landmarks found in this study could help to improve the capture of the targeted nerves during ultrasound-guided interventions.

Cooled Radiofrequency Ablation Compared with a Single Injection of Hyaluronic Acid for Chronic Knee Pain: A Multicenter, Randomized Clinical Trial Demonstrating Greater Efficacy and Equivalent Safety for Cooled Radiofrequency Ablation

BACKGROUND

Knee osteoarthritis is a painful and sometimes debilitating disease that often affects patients for years. Current treatments include short-lasting and often repetitive nonsurgical options, followed by surgical intervention for appropriate candidates. Cooled radiofrequency ablation (CRFA) is a minimally invasive procedure for the treatment of pain related to knee osteoarthritis. This trial compared the efficacy and safety of CRFA with those of a single hyaluronic acid (HA) injection.

METHODS

Two hundred and sixty subjects with knee osteoarthritis pain that was inadequately responsive to prior nonoperative modalities were screened for enrollment in this multicenter, randomized trial. One hundred and eighty-two subjects who met the inclusion criteria underwent diagnostic block injections and those with a minimum of 50% pain relief were randomized to receive either CRFA on 4 genicular nerves or a single HA injection. One hundred and seventy-five subjects were treated (88 with CRFA and 87 with HA). Evaluations for pain (Numeric Rating Scale [NRS]), function (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]), quality of life (Global Perceived Effect [GPE] score and EuroQol-5 Dimensions-5 Level [EQ-5D-5L] questionnaire), and safety were performed at 1, 3, and 6 months after treatment.

RESULTS

Demographic characteristics did not differ significantly between the 2 study groups. A total of 158 subjects (76 in the CRFA group and 82 in the HA group) completed the 6-month post-treatment follow-up. In the CRFA group, 71% of the subjects had ≥50% reduction in the NRS pain score (primary end point) compared with 38% in the HA group (p < 0.0001). At 6 months, the mean NRS score reduction was 4.1 ± 2.2 for the CRFA group compared with 2.5 ± 2.5 for the HA group (p < 0.0001). The mean WOMAC score improvement at 6 months from baseline was 48.2% in the CRFA group and 22.6% in the HA group (p < 0.0001). At 6 months, 72% of the subjects in the CRFA group reported improvement in the GPE score compared with 40% in the HA group (p < 0.0001).

CONCLUSIONS

CRFA-treated subjects demonstrated a significant improvement in pain relief and overall function compared with subjects treated with a single injection of HA. No serious adverse events related to either procedure were noted, and the overall adverse-event profiles were similar.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

A Randomized Controlled Pilot Study Comparing the Efficacy of Pulsed Radiofrequency Combined With Exercise Versus Exercise Alone in Pain Relief and Functional Improvement for Chronic Knee Osteoarthritis

OBJECTIVES

To compare the long-term efficacy between pulsed radiofrequency (PRF) combined with passive stretching (PRF-PS) exercise and PS exercise alone in reducing pain and improving quadriceps muscle strength and knee function.

METHODS

Sixty-two participants were randomly assigned with a 1:1 allocation to the PRF-PS exercise group or the PS exercise group. Level of pain, muscle strength, and knee function were assessed from baseline to the first, third, and sixth months after treatment using the VAS, peak torque (PT), and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), respectively.

RESULTS

There were no significant differences at baseline between the 2 groups. Compared to exercise alone, participants achieved superior efficacy with PRF-PS in pain relief, improvement of muscle strength, and knee function. Moreover, the improvement of all variables was maintained for a longer period of time in the PRF-PS group. The reduction in participants' VAS pain intensity scores was superior for PRF-PS vs. PS with overall estimation (adjusted mean difference: -1.85 cm; 95% confidence interval [CI] -2.25, -1.45 cm; P = 0.000). The increase in participants' PT scores was superior for PRF-PS vs. PS with overall estimation (adjusted mean difference: 15.53 N. m; 95% CI 7.07, 23.98 N. m; P = 0.000; and 12.62 N. m; 95% CI 0.96, 24.28 N. m; P = 0.000 for PT 60 degrees/s and PT 180 degrees/s, respectively). The reduction in participants' WOMAC scores was superior for PRF-PS vs. PS with overall estimation (adjusted mean difference: -16.43; 95% CI -22.22, -10.64; P = 0.000).

DISCUSSION

The improvement in pain relief and knee function might be associated with restoration of muscle strength after PRF-PS exercise by overcoming muscle inhibition.

Periarticular needle-based therapies can cause periprosthetic knee infections

Periarticular needle-based therapies such as dry needling, acupuncture, and genicular nerve radiofrequency ablation are becoming more popular for treatment of knee osteoarthritis. These therapies are also being used after total knee arthroplasty for persistent postoperative pain. Although limited published evidence exists for the risk of periprosthetic joint infection after these procedures, we describe one case of periprosthetic joint infection developing shortly after dry needling and another case developing shortly after genicular nerve blocks. We present details of these 2 cases along with a review of the literature regarding the use of periarticular needle-based therapies after total knee arthroplasty.

Current versus revised anatomical targets for genicular nerve blockade and radiofrequency ablation: evidence from a cadaveric model

Introduction

Recent studies have proposed revised anatomical targets to improve accuracy of genicular nerve (GN) radiofrequency ablation (RFA). This study aims to compare the accuracy of classical and revised techniques for fluoroscopic-guided GN-RFA in cadaveric models.

Materials and methods

Fourteen knees from seven fresh frozen human cadavers were included in this study. For each cadaver, RF cannulas were placed to capture the GN according to the current targets in one knee, and the revised targets in the other knee, randomly. The stylet was removed from the cannula, plunged into non-diffusible black paint, and reintroduced entirely in the cannula, to create a limited black spot on the tissues at the top of the active tip. Anatomical dissection was performed, and the accuracy of both techniques was compared.

Results

The mean distance from the top of the active tip to the nerve was significantly lower with revised than current targets for the superior-medial GN (0.7 mm vs 17.8 mm, p=0.01) and the descending branch of the superior-lateral GN (3.7 mm vs 24.4 mm, p=0.02). In both superior-medial GN and superior-lateral GN, the accuracy rate was higher with revised than current targets: 100% vs 0% and 64% vs 35%, respectively. In addition, the accuracy of revised targets for the recurrent fibular nerve and the infrapatellar branch of saphenous nerve was 100%.

Conclusion

This study demonstrates that the revised targets are more accurate than the current targets for GN-RFA.

Alternate treatment approach to subchondral insufficiency fracture of the knee utilizing genicular nerve cooled radiofrequency ablation and adjunctive bisphosphonate supplementation: A case report

Subchondral insufficiency fractures of the knee are commonly misdiagnosed fractures that are both very painful and difficult to treat. A conservative treatment modality to control symptoms during rehabilitation has not previously been described. This case report presents the alternate use of cooled radiofrequency ablation technique of the genicular nerves for pain relief and bisphosphonate infusion to address the underlying poor bone mineralization/density with imaging follow-up before and after instituted treatments. A middle-aged female patient presenting with atraumatic pain in the medial aspect of the left knee diagnosed on an original magnetic resonance imaging as an insufficiency fracture and debilitating pain. Multiple-surgeon opinions of total knee arthroplasty were not a consideration the patient wanted or could consider given her lifestyle. Cooled radiofrequency ablation of the genicular nerve branches was performed with significant-complete pain relief achieved that lasted at least 6 months. Bisphosphonate infusions were instituted to address the underlying osteoporosis detected by a dual energy X-ray absorptiometry (DEXA) scan. Clinical performance after the radiofrequency ablations was followed with clinically validated surveys (The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)/Knee Injury and Osteoarthritis Outcome Score (KOOS)) at 2 weeks, 1, 3, and 6 months. Patient was also asked to follow a restricted-modified weight-bearing plan for 3 months followed by physical therapy. Eight weeks apart of bisphosphonate infusions were delivered after proper administration of vitamin D. There was resolution of the insufficiency fracture at the medial femoral condyle between the magnetic resonance imaging exams within 4.5 months apart treated with restricted weight-bearing regimen. Pain resolution, significant improved function, and range of motion were the end results of our instituted treatment plan. This case reports presents an alternate pathway for the treatment of this condition especially when there is lack of consensus among physicians in how to best address this condition.

Domain Heterogeneity in Radiofrequency Therapies for Pain Relief: A Computational Study with Coupled Models

The objective of the current research work is to study the differences between the predicted ablation volume in homogeneous and heterogeneous models of typical radiofrequency (RF) procedures for pain relief. A three-dimensional computational domain comprising of the realistic anatomy of the target tissue was considered in the present study. A comparative analysis was conducted for three different scenarios: (a) a completely homogeneous domain comprising of only muscle tissue, (b) a heterogeneous domain comprising of nerve and muscle tissues, and (c) a heterogeneous domain comprising of bone, nerve and muscle tissues. Finite-element-based simulations were performed to compute the temperature and electrical field distribution during conventional RF procedures for treating pain, and exemplified here for the continuous case. The predicted results reveal that the consideration of heterogeneity within the computational domain results in distorted electric field distribution and leads to a significant reduction in the attained ablation volume during the continuous RF application for pain relief. The findings of this study could provide first-hand quantitative information to clinical practitioners about the impact of such heterogeneities on the efficacy of RF procedures, thereby assisting them in developing standardized optimal protocols for different cases of interest.

A rare complication of knee hematoma after genicular nerve radiofrequency ablation

Background:

Genicular nerve radiofrequency ablation (RFA) is an intervention to treat patients with chronic knee pain who have failed previous conservative, pharmacologic, and surgical interventions. Vascular complications following interventional procedures of the knee are extremely rare. A delay in diagnosis may be detrimental for the viability of the affected limb and may ultimately require amputation.

Case Presentation:

A 76-year-old man with a history of severe bilateral knee osteoarthritis and grade 4 chondromalacia presented to our clinic with refractory, severe bilateral knee pain and received a bilateral genicular nerve RFA. He returned 4 days later with right medial thigh pain and a magnetic resonance imaging study revealing a hematoma along the anteromedial aspect of the right distal femoral diaphysis measuring 13.3 × 4.5 × 3.0 cm. After collaboration between pain medicine and orthopedic surgery services, decision was made to treat patient conservatively with rest, compression, elevation, ice application, tramadol, and gabapentin, but with close follow-up and a low threshold to intervene with diagnostic and therapeutic angiography with embolization if bleeding worsened; he reported resolution of his pain after a 4-day and 1-month follow-up.

Conclusion:

This is the first report describing iatrogenic vascular injury in the knee after a genicular RFA procedure. Pain medicine physicians should be aware of the vascular anatomy of the knee, particularly paying close attention to variations after previous surgeries. Future trials should investigate modalities that minimize vascular complications including concomitant use of ultrasonography with fluoroscopy and other forms of RFA including pulsed or cooled RFA.

Accuracy of fluoroscopic-guided genicular nerve blockade: a need for revisiting anatomical landmarks

BACKGROUND AND OBJECTIVES

Genicular nerve blockade (GNB) and radiofrequency ablation (RFA) have recently emerged as treatment options for patients with chronic knee pain. However, an increasing number of anatomical studies and systematic reviews concluded that the anatomical basis for needle placement was unclear, incomplete and somewhat inaccurate. This study was designed to assess the accuracy of updated anatomical landmarks for fluoroscopy-guided blockade of the consistent genicular nerves in a cadaveric model.

METHODS

Based on a comprehensive review of recent anatomical studies and prior dissection of 21 fresh cadaver knees, we defined bony landmarks with high likelihood of successful ablation of the five consistent genicular nerves (GN). We tested the accuracy of GNBs using the above-stated anatomical landmarks in 10 intact fresh cadaveric knees. Needle placement was guided by fluoroscopy and 0.5 mL of 0.1% methylene blue was injected at the site of each nerve. The knees were subsequently dissected to assess the accuracy of the injections. If the nerve was dyed with blue ink, the placement was considered accurate.

RESULTS

The accuracy of our injections was 100% for the superior medial genicular nerve, inferior medial GN, infrapatellar branch of saphenous nerve and recurrent fibular nerve. The superior lateral GN was dyed in 90% of specimens.

CONCLUSION

This study provides physicians with precise anatomical landmarks for the five consistent GN for fluoroscopic-guided GNB. Our revised technique, which targets more nerves with increased accuracy, could potentially lead to improved therapeutic benefits on chronic knee pain.