Midterm Clinical Outcomes and MR Imaging Changes after Transcatheter Arterial Embolization as a Treatment for Mild to Moderate Radiographic Knee Osteoarthritis Resistant to Conservative Treatment

Genicular Artery Embolization Technique

Genicular artery embolization (GAE) is a safe and effective treatment for knee pain related to osteoarthritis, however there are several aspects of the procedure technique which may be unique. Familiarity with procedural steps, arterial anatomy, embolic endpoints, technical challenges, and potential complications is imperative for good clinical practice and outcomes. The success of GAE depends on correctly interpreting angiographic findings and variable anatomy, navigating small and acutely angled arteries, recognizing collateral supply, and avoiding non-target embolization. The procedure can potentially be performed for a wide range of patients with knee osteoarthritis. When effective, pain relief can be durable for many years. When done meticulously, adverse events from GAE are uncommon.

Genicular Artery Embolization Data Review

Osteoarthritis of the knee poses an ever-expanding healthcare challenge worldwide. Current treatments include conservative methods such as weight loss, pharmacological treatments including NSAIDs, and surgical techniques including total knee arthroplasty. Although frequently successful, contraindications and failure of pharmacological agents leave many, especially with mild-moderate disease, without effective treatment. Genicular artery embolization is an interventional radiology technique being developed to fill this treatment gap. For this procedure to become established, the literature must provide evidence of its underlying scientific principles, safety, efficacy and economic viability. Pathological investigation of osteoarthritis reveals that low-level inflammation plays a crucial role in disease development. Joint inflammation stimulates neoangiogenesis and accompanying neuronal growth, with the degree of microvascular invasion being correlated with more severe pain in animal models. These neovessels provide a target for embolization however, the microscopic effects of this intervention are yet to be elucidated. The side effects of GAE have been extensively investigated with no severe adverse events being recorded. Skin discoloration and puncture site hematoma are the most common, occurring in 10%-65% and 0%-17% of patients respectively. The literature also discusses ways to minimize these events. Phase one studies provide promising evidence of efficacy, demonstrating an 80% improvement in Visual Analogue Scale (VAS) and a mean difference of 36.8 in Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores at 24-months. These positive signals are also supported by a single randomized control trial. A single study has been completed regarding the cost of GAE, however further work is needed. The GAE literature demonstrates a safe procedure with promising initial evidence of efficacy. Future work should further elucidate the pathology of osteoarthritis and ways in which embolization modifies this process, alongside providing further randomized control evidence that aligns with the recommendations from the National Institute for Health and Care Excellence. The future of GAE is exciting!

Knee and Shoulder Vascular Anatomy

In the past decade, angiographic studies have demonstrated neovessels in or in the vicinity of affected joints in many musculoskeletal conditions that used to be considered wear and tear joint disease, such as knee osteoarthritis, frozen shoulder, and overuse injuries. The novelty of this finding is showing the presence of neovascularity at an angiographically detectable level, as compared to histologically evident neovessels that had been discovered years ago. These neovessels have now become the target of interventions in a growing field called muscoskeletal embolotherapy. An in-depth and all-encompassing understanding of the vascular anatomy that could specifically assist performing of these procedures is paramount. Such an understanding will help ensure success in clinical outcomes and avoid much dreaded complications. This review discusses the vascular anatomy relevant to the 2 most commonly performed musculoskeletal embolotherapies, genicular artery embolization and transarterial embolization for frozen shoulder.

Role of geniculate artery embolization in the treatment of knee pain secondary to osteoarthritis

Background

Osteoarthritis (OA) is a leading cause of chronic knee pain and disability with a reported prevalence of 25–30% of the population. Knee OA has traditionally been thought as a degenerative disease only related to chronic repetitive injury “wear and tear” mechanism, yet it is now considered as a much more complex disease of inflammatory nature induced by cytokines and inflammatory mediators through abnormal neo-vascularization (angiogenesis). The rational of geniculate artery embolization (GAE) is based on the hypothesis that suggesting a direct relationship between the abnormal angiogenesis and the chronic knee pain. As a novel treatment option based on occlusion of these abnormal neo-vessels via geniculate artery embolization, we postulated that such a mechanism will relieve pain and improve the quality of life. GAE has been previously approved as a safe and effective treatment in cases of post-knee arthroplasty hemarthrosis.

Purpose

To evaluate the feasibility, safety, and efficacy of geniculate artery embolization for OA-related knee pain.

Materials and methods

Sixteen patients with knee pain secondary to chronic OA refractory to conservative therapies for at least 6 months and not yet fit for total knee replacement were enrolled in a prospective single arm interventional study. GAE was performed using 150–300 μm microspheres. Patients were assessed and followed up using the visual analogue scale (VAS) for pain and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) for the overall knee function at baseline and at 1 week, 1, 3, and 6 months post-embolization.

Results

A total 16 patients presented by knee pain secondary to chronic OA were enrolled. All of them showed a remarkable improvement in the VAS and WOMAC scores, with better clinical outcome after GAE. Pre- versus post-embolization ± MDs in VAS score from 8.38 ± 0.81 (baseline) to 2.88 ± 1.54 after 6 months (post-embolization) equivalent to 66.66% improvement. There was also a satisfactory improvement in the WOMAC scores, with ± MDs drop from 77.94 ± 10.62 (baseline) to 49.69 ± 15.43 (post-embolization) equivalent to 37.41% improvement. No severe or life-threatening complications were reported.

Conclusions

GAE holds promise as an effective minimally invasive procedure for the treatment of knee pain secondary to OA and could be introduced as a safe technique with no serious complications.

Genicular artery embolization for treatment of knee osteoarthritis pain: Systematic review and meta-analysis

Objective

Genicular artery embolization (GAE) is a novel, minimally invasive procedure for treatment of knee osteoarthritis (OA). This meta-analysis investigated the safety and effectiveness of this procedure.

Design

Outcomes of this systematic review with meta-analysis were technical success, knee pain visual analog scale (VAS; 0-100 scale), WOMAC Total Score (0-100 scale), retreatment rate, and adverse events. Continuous outcomes were calculated as the weighted mean difference (WMD) versus baseline. Minimal clinically important difference (MCID) and substantial clinical benefit (SCB) rates were estimated in Monte Carlo simulations. Rates of total knee replacement and repeat GAE were calculated using life-table methods.

Results

In 10 groups (9 studies; 270 patients; 339 knees), GAE technical success was 99.7%. Over 12 months, the WMD ranged from -34 to -39 at each follow-up for VAS score and -28 to -34 for WOMAC Total score (all p ​< ​0.001). At 12 months, 78% met the MCID for VAS score; 92% met the MCID for WOMAC Total score, and 78% met the SCB for WOMAC Total score. Higher baseline knee pain severity was associated with greater improvements in knee pain. Over 2 years, 5.2% of patients underwent total knee replacement and 8.3% received repeat GAE. Adverse events were minor, with transient skin discoloration as the most common (11.6%).

Conclusions

Limited evidence suggests that GAE is a safe procedure that confers improvement in knee OA symptoms at established MCID thresholds. Patients with greater knee pain severity may be more responsive to GAE.

Two-year outcomes comparing Embosphere® microspheres versus Imipenem Cilastatin for genicular artery embolization in patients with moderate to severe knee osteoarthritis

BACKGROUND

Genicular artery embolization (GAE) is a novel technique and has the potential to provide midterm relief of pain for patients with mild-to-moderate knee osteoarthritis resistant to conservative management. This study compares the efficacy and safety of trisacryl gelatin microspheres to Imipenem/Cilastatin particles for GAE with 2 years of clinical follow-up.

METHODS

In this retrospective study, eight patients with knee osteoarthritis (11 knees) who underwent GAE with 100-300 μm trisacryl gelatin microspheres particles were compared with six patients (nine knees) who underwent GAE with Imipenem/Cilastatin particles. Clinical outcomes were evaluated at 3-month and 24-month follow-ups and compared to baseline using the WOMAC questionnaire.

RESULTS

The median follow-up was 796 days (range: 736-808). There were no significant differences in clinical outcome measures at the 3-month or 24-month follow-up. Both embolic materials resulted in a decrease in Pain WOMAC and Total WOMAC scores at 3 months (p < 0.05), and the effect of treatment on Pain WOMAC and Total WOMAC score reduction was sustained until the 24-month follow-up (p < 0.05). Minor events (Clavien-Dindo classification grade I) included transient cutaneous color change (n = 3) and transient leg numbness (n = 1) after embolization with trisacryl gelatin microspheres particles (p = 0.08). All minor adverse events resolved spontaneously. There were no major adverse events.

CONCLUSION

One hundred to three hundred μm trisacryl gelatin microspheres particles can be considered for genicular artery embolization and is comparable to Imipenem/Cilastatin particles in pain reduction of moderate to severe knee osteoarthritis. A sustained effect is observed for up to 2 years of follow-up.

Mechanism of action of genicular artery embolization in a rabbit model of knee osteoarthritis

OBJECTIVES

To establish a rabbit osteoarthritis model for genicular artery embolization (GAE) experiments and to investigate the cellular mechanism of action of this novel procedure for interventional radiologists.

METHODS

Rabbit knee osteoarthritis was surgically modeled by anterior cruciate ligament transection and medial partial meniscectomy of the bilateral hindlimbs followed by 10 weeks of incubation. Rabbits exhibiting synovitis on magnetic resonance imaging were randomly divided into two groups: the bilateral GAE group and the control (sham procedure) group. Four weeks later, the rabbits' mobility (moving time, sec/10 min) and the histopathological features of each knee were assessed, and inter-group differences were evaluated using Student's t-test and ordinal/linear logistic models with generalized estimating equations.

RESULTS

Osteoarthritis modeling and endovascular procedures were successful in 15 of 20 rabbits (8 and 7 in the GAE and control groups, respectively). There was no significant difference in moving times between the two groups (p = .958). The degree of structural cartilage damage was similar in both groups (p = .780). However, the synovial proliferation (p = .016), synovial hypertrophy (p < .001), and villous hyperplasia of the synovial stroma (p = .002) scores were significantly lower in the GAE group than in the control group. The CD3+ cell density (p = .018) and CD3 + cell-infiltrated area (p = .019) were also significantly lower in the GAE group than in the control group.

CONCLUSION

GAE can limit inflammatory processes in the synovium of osteoarthritis-affected knees.

KEY POINTS

Surgical transection of the anterior cruciate ligament and medial partial meniscectomy of rabbit knees provides a useful animal model for research of genicular artery embolization. Osteoarthritic knees treated by genicular artery embolization showed milder synovial proliferation (p = .016), synovial hypertrophy (p < .001), and villous hyperplasia of the synovial stroma (p = .002) than the untreated knees. Osteoarthritic knees treated by genicular artery embolization presented lower CD3+ cell density (p = .018) and CD3+ cell-infiltrated area (p = .019) in the synovium than the untreated knees.

Transcatheter Arterial Embolization for Alleviating Chronic Musculoskeletal Pain and Improving Physical Function: A Narrative Review

Chronic musculoskeletal pain imposes immense suffering and diminishes the quality of life for millions of patients worldwide; the pain persists despite the use of standard conservative treatments. Increases in our understanding of the pathophysiological mechanisms underlying musculoskeletal disorders indicate the involvement of inappropriate angiogenesis. Accordingly, the resulting neovessels are the target of emerging treatments for chronic musculoskeletal pain, including transarterial embolization. The use of this noninvasive procedure to treat pain refractory to standard therapy in a variety of musculoskeletal conditions is the focus of numerous recent investigations. Here, we describe the pathophysiological indications for the use of transarterial embolization and summarize the findings of studies investigating its use in a variety of histopathological conditions and anatomical sites.

Embolization of genicular arteries in patients with knee osteoarthritis as an alternative for refractory pain treatment: A systematic review

BACKGROUND

Genicular artery embolization emerges as an innovative technique described for the treatment of refractory pain in patients with knee osteoarthritis. This review summarizes the available data on the efficacy of genicular artery embolization in patients with knee osteoarthritis (OA) and refractory pain as an alternative treatment or associated with pharmacological treatment.

METHODS

Review according to PRISMA® standards on genicular artery embolization and knee osteoarthritis.

RESULTS

Thirteen publications out of a total of 63 studies reporting data from 914 patients were analyzed according to inclusion criteria. The indication of embolization was performed in patients with severe chronic pain refractory to conservative treatment and moderate-to-severe knee OA. Only minor complications have been reported.

CONCLUSION

Genicular artery embolization is a possible and potentially very effective alternative in the treatment of chronic refractory pain in patients with knee OA, without serious complications. All studies conclude in favor of embolization of the genicular arteries in the treatment of chronic refractory pain in patients with knee OA.

Alteration of chronic inflammatory status by transarterial embolization in frozen shoulder evaluated by 18-fluorine-fluoro-2-deoxyglucose positron-emission tomography/computed tomography

BACKGROUND

Frozen shoulder (FS) is speculated to have an inflammatory etiology. On angiography, abnormal angiogenesis is observed around the affected shoulder, suggesting a possible source of inflammation and pain. The effectiveness and safety of transarterial embolization (TAE) targeting abnormally proliferating blood vessels have been reported. This study investigated changes in chronic inflammatory and hypoxic status before and after TAE in FS by 19-fluorine-fluoro-2-deoxyglucose (FDG) positron-emission tomography/computed tomography as a possible mechanism of the therapeutic response to TAE.

METHODS

Fifteen patients with unilateral FS, persistent for more than 6 months, who were refractory to conservative treatments, underwent TAE using the temporary embolic agent imipenem/cilastatin. Patients underwent positron-emission tomography/computed tomography with FDG (as a biomarker of inflammation) before and 8 weeks after TAE. Regional uptake was evaluated by the maximum standardized uptake value. The lesion-side-to-(contralateral-) normal-side uptake ratio was also calculated. Pain and functional scales, range-of-motion, and laboratory tests, including white blood cell, C-reactive protein, interleukin 6, vascular endothelial growth factor, and tumor necrosis factor α were evaluated.

RESULTS

On FDG-PET, the average maximum standardized uptake value of the lesion-side was significantly greater than that of the normal-side (maximum standardized uptake value before TAE: 3.11 ± 1.25 vs 1.95 ± 1.15, P = .0001; 8-weeks post-TAE: 2.36 ± 0.74 vs 1.78 ± 0.69, P = .0002). The mean lesion-side-to-(contralateral-) normal-side uptake ratios before TAE (1.71 ± 0.60) decreased after TAE (1.37 ± 0.29, P = .011). The decrease of FDG uptake (-21.1 ± 12.2%) showed a significant correlation with the change in the pain scale score (r = -0.56, P = .039) and extension score (r = -0.59, P = .026).

CONCLUSION

Chronic inflammation in FS, as demonstrated by FDG uptake, was decreased after TAE. Thus, chronic inflammation is likely to be an underlying mechanism that should be targeted for symptomatic improvement of frozen shoulder.

At the Edge of Orthopaedics: Initial Experience with Transarterial Periarticular Embolization for Knee Osteoarthritis in a Romanian Population

Background: Transarterial embolization (TAE) of genicular artery branches is a relatively new technique that has emerged as a promising method for delaying invasive knee surgery in patients suffering from degenerative knee osteoarthritis (OA). In mild to moderate OA, invasive major surgery can be safely postponed, and patients with major risk factors now have an alternative. Our aim was to examine the impact of TAE on clinical outcomes in individuals with degenerative knee OA over a 12-month period. Methods: A case series of 17 patients diagnosed with knee OA and treated with TAE was included in the study. Every patient was clinically evaluated at different timeframes according to the Western Ontario and McMaster Universities’ arthritis index, knee injury, and osteoarthritis outcome scores, and the 36-item short-form survey (WOMAC, KOOS, and SF-36). Results: At the first follow-up (1 month), KOOS and WOMAC improved from 46.6 ± 13.2 (range 27.3–78.2) to 56.5 ± 13.9 (range 32.3–78.4; p = 0.023) and 49.5 ± 13.2 (range 29.3–82.3) to 59.8 ± 12.6 (range 39.3–83.5, p = 0.018), respectively. Physical SF-36 improved significantly from 42.1 ± 7.75 (range 30.3–57.3) to 50.5 ± 9.9 (range 35.6–67.9; p = 0.032). No significant changes in scores were observed at three, six, or twelve months after TAE. Conclusions: TAE provided early pain reduction and considerable improvement in quality of life without complications for a consecutive sample of Romanian patients with mild to severe knee OA.

Anatomical description and short-term follow up clinical results for ultrasound-guided injection of medial collateral ligament bursa: New conservative treatment option for symptomatic degenerative medial meniscus tear

BACKGROUND

In this study, we investigated newly developed ultrasound (US)-guided medial collateral ligament (MCL) bursa injection as a conservative therapy for symptomatic degenerative medial meniscal (MM) tears. We aimed to describe the anatomical target and precise technique of this injection, confirm its accuracy using fresh cadaveric knees, and then evaluate preliminary clinical outcomes.

METHODS

Anatomical studies were performed on three fresh cadavers. For the clinical study, 50 patients with medial knee joint pain without knee osteoarthritis were treated with US-guided MCL bursa injection. Severity of pain was assessed pre-injection, and 1 week and 4 weeks post-injection using a 0-10 numerical rating scale (NRS). Clinical success was defined as a full return to daily activities. All patients underwent magnetic resonance imaging (MRI) within 1 week of the first injection. Patients who underwent surgery within 12 months of the first injection were investigated as clinically unsuccessful cases, and MRI and arthroscopic findings were examined.

RESULTS

Compared with pre-injection (6.8 ± 1.2), the average NRS score was significantly lower at 1 week (1.8 ± 2.0) and at 4 weeks (1.5 ± 1.7) post-injection (both P < 0.01). The primary clinical success rate was 76.0%, and injection-related adverse events were not observed. Nine patients underwent surgery (arthroscopic surgery for degenerative flap tear (n = 7) and high tibial osteotomy for medial meniscus posterior root tear and proximal tibial malalignment (n = 2)).

CONCLUSIONS

US-guided MCL bursa injection is safe, reproducible, and effective for symptomatic MM degenerative tears. However, US-guided injections of the MCL bursa may be ineffective for flap tears and posterior root tears.

Feasibility of Neovessel Embolization in a Large Animal Model of Tendinopathy: Safety and Efficacy of Various Embolization Agents

Targeting neovessels in chronic tendinopathies has emerged as a new therapeutic approach and several embolization agents have been reported. The aim of this study was to investigate the feasibility of embolization with different agents in a porcine model of patellar tendinopathy and evaluate their safety and efficacy. Eight 3-month-old male piglets underwent percutaneous injection of collagenase type I to induce patellar tendinopathies (n = 16 tendons). They were divided into four groups (2 piglets, 4 tendons/group): the control group, 50–100 µm microspheres group, 100–300 µm microspheres group, and the Imipenem/Cilastatin (IMP/CS) group. Angiography and embolization were performed for each patellar tendon on day 7 (D7). The neovessels were evaluated visually with an angiography on day 14. The pathological analysis assessed the efficacy (Bonar score, number of neovessels/mm²) and safety (off-target persistent cutaneous ischemic modifications and presence of off-target embolization agents). The technical success was 92%, with a failed embolization for one tendon due to an arterial dissection. Neoangiogenesis was significantly less important in the embolized groups compared to the control group angiographies (p = 0.04) but not with respect to histology (Bonar score p = 0.15, neovessels p = 0.07). Off-target cutaneous embolization was more frequently depicted in the histology of the 50–100 µm microspheres group (p = 0.02). Embolization of this animal model with induced patellar tendinopathy was technically feasible with different agents and allowed assessing the safety and efficacy of neovessel destruction. Particles smaller than 100 µm seemed to be associated with more complications.

6-Month Follow-up of Lateral Femoral Circumflex Artery Embolization to Control Pain Related to Hip Osteoarthritis and Greater Trochanteric Pain Syndrome

Purpose

To present the preliminary results of a cohort of 13 patients with hip osteoarthritis (OA) and great trochanteric pain syndrome (GTPS) refractory to conservative management or physical therapy and no indication for surgery treated with embolization of the lateral femoral circumflex artery.

Material and Methods

This is a single-center prospective cohort from July 2019 to September 2020. Visual analogue scale (VAS) and Western Ontario and MacMaster Universities (WOMAC) were used to compare the symptoms before and after 6-month follow-up. Technical success was considered when at least one artery responsible for the hyperemic synovium was embolized. Complications and adverse events were noted.

Results

In total, 13 patients were included; mean age was 62.4 (± 11.0) years. 10 (76.9%) patients were treated for GTPS and 3 (23.1%) for hip OA. Nine patients were treated with imipenem/cilastatin (I/C) alone. Microsphere 100–300 μm and I/C were combined in 4 patients. The WOMAC Index had a statistically significant decrease in the total from 77 to 27 points (p = 0.001). Pain, rigidity and physical activity have also significantly reduced (19 to 5, p = 0.001; 6 to 2, p = 0.002 and 53 to 22, p = 0.001, respectively). VAS score had a significant decrease (10 to 2, p = 0.002). Two patients present posterior tight numbness, spontaneously improved within 30 days.

Conclusion

In this cohort, lateral femoral circumflex artery embolization was a safe and effective treatment for patients with hip pain due to OA and GTPS.

The efficacy of transcatheter arterial embolization for knee pain on patients with knee osteoarthritis: A case series

BACKGROUND

Knee osteoarthritis (OA) is accompanied by inflammation and angiogenesis. Modifying angiogenesis through transcatheter arterial embolization (TAE) can be a potential treatment for knee OA.

OBJECTIVE

We subjected five OA knees in three patients to TAE and report the results of our post-treatment observations.

CASE DESCRIPTION

Three patients that had experienced knee pain for a minimum of one year prior to the study, and whose pain had persisted despite conservative treatment, were included in this study. Patients more often chose conservative treatment over surgical treatment. Pain and functional scales were evaluated before, immediately, and 1 month after TAE using the Numeric Rating Scale (NRS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). TAE was performed by an experienced interventional radiologist. The average values of NRS evaluated before and after 5 TAEs were 5.2 before TAE, 3 immediately after TAE, and 3.6 after 1 month of TAE, and the average values of WOMAC were 52, 38.4, and 36.4, respectively. There were no major adverse effects.

CONCLUSION

The examined cases support the conclusion that TAE is an effective treatment for patients with knee OA. Substantial pain relief and WOMAC improvement were observed both immediately and one month after TAE.

Emerging Targets for the Treatment of Osteoarthritis: New Investigational Methods to Identify Neo-Vessels as Possible Targets for Embolization

Osteoarthritis (OA) is the major cause of disability, affecting over 30 million US adults. Continued research into the role of neovascularization and inflammation related to osteoarthritis in large-animal models and human clinical trials is paramount. Recent literature on the pathogenetic model of OA has refocused on low-level inflammation, resulting in joint remodeling. As a result, this has redirected osteoarthritis research toward limiting or treating joint changes associated with persistent synovitis. The overall goal of this review is to better understand the cellular and tissue-specific mechanisms of inflammation in relation to a novel OA treatment modality, Genicular Artery Embolization (GAE). This article also assesses the utility and mechanism of periarticular neovascular embolization for the treatment of OA with a particular emphasis on the balance between pro-angiogenic and anti-angiogenic cytokines, inflammatory biomarkers, and imaging changes.

Assessing the Effects of Geniculate Artery Embolization in a Non-Surgical Animal Model of Osteoarthritis

PURPOSE

To create a non-surgical animal model of osteoarthritis (OA) to evaluate effects of embolotherapy during geniculate artery embolization.

MATERIALS AND METHODS

Fluoroscopy-guided injections of 700mg Sodium-Monoiodoacetate were made into the left stifle in 6 rams. Kinematic data were collected pre/post-induction. 10-weeks post-induction, subjects 1, 4-6 underwent MRI with dynamic contrast enhancement (DCE-MRI), and angiography (subjects 1, 3, 4-6) with angiographic scoring to identify regions with greatest disease severity for superselective embolization (75-250μm microspheres, subjects 1, 3, 4, and 6). Target vessel size was measured. 24-weeks after angiography, DCE-MRI, angiography, and euthanasia were performed and bilateral stifles harvested. Medial/lateral tibial and femoral condyles, patella and synovium samples were cut, preserved, decalcified, and scored with OARSI criteria. Stifle and synovium WORMS and MOST scores were obtained. Ktrans and extracellular volume fraction (ve) were calculated from DCE-MRI along lateral synovial regions of interest.

RESULTS

Mean gross/microscopic pathological scores were elevated at 38/61. Mean synovitis score was elevated at 9.2. Mean pre/post-embolization angiographic scores were 5/3.8, respectively. Mean Superior/Transverse/Inferior Geniculate artery diameters(mm) were 3.1±1.21, 2.0±0.50, and 1.6±0.41. Mean Pre/post-embolization cartilage/synovitis scores were elevated at 35.13/73.3 and 5.5/9.2, respectively. Subjects 4-6 K_trans/v_e values were elevated at 0.049/0.38, 0.074/0.53, and 0.065/0.51. Altered gait of the hind limb was observed in all subjects post-induction, with reduced joint mobility. No skin or osteonecrosis were observed.

CONCLUSION

A non-surgical ovine animal knee OA model was created which allowed the collection of angiographic, histopathological, MRI and kinematic data were obtained to study the effects of geniculate artery embolization.

Transcatheter arterial embolization of abnormal neovessels in a swine model of knee arthritis

BACKGROUND

In recent years, transcatheter arterial embolization (TAE) using imipenem/cilastatin (IPM/CS) has attracted attention as a treatment for relieving osteoarthritis (OA) pain. However, IPM/CS is not approved by Japanese medical insurance for use as an embolic material. Therefore, it is necessary to develop new embolic materials for TAE to relieve OA pain. The purpose of this study was to develop a swine model of knee arthritis and embolize abnormal neovessels (ANs) using two different embolic materials. We compared the embolic effects and tissue damage in knees.

METHODS

Knee arthritis was induced by intra-articular injection of papain into 12 knees in six female swine. The swine were divided into two groups of three swine each (six knees per group) for embolization of ANs in the knees with either IPM/CS or soluble gelatin sponge particles (SGSs). Three days after embolization, we compared the embolic effects using angiography and the tissue damage histopathologically.

RESULTS

ANs were observed in all 12 knees at 42 days after papain injection. The ANs disappeared and the patent arteries were recanalized 3 days after TAE in all 12 knees. Histopathological evaluation revealed synovitis changes, such as synovial thickening and inflammatory cell infiltration, in all 12 knees. There was no evidence of skin or muscle necrosis in either group. The appearance of ANs, recanalization of the parent arteries, and histopathological outcomes were not significantly different between the two groups.

CONCLUSION

SGSs were as safe as IPM/CS for TAE of ANs in this swine model of knee arthritis.

Genicular Artery Embolization for Primary Knee Osteoarthritis

Genicular artery embolization (GAE) is a novel treatment for knee osteoarthritis (OA) with increasing interest and utilization worldwide. The genicular arteries are selectively embolized using microspheres with subsequent cessation of abnormal synovial hyperemia, a process believed to arrest the inflammatory changes and pain associated with OA. Current data indicate that GAE offers sustained, 6-month improvement in Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) and visual analog scale scores in 80 to 85% of patients with mild to moderate OA. As GAE gains traction, future studies are needed to establish its safety and efficacy relative to placebo and other standard-of-care therapies while also characterizing populations for which it is most effective.

Safety and Efficacy of Embolization with Microspheres in Chronic Refractory Inflammatory Shoulder Pain: A Pilot Monocentric Study on 15 Patients

Purpose: Musculoskeletal (MSK) embolization is emerging in tendinopathy treatment. The objective of this study was to assess the efficacy and safety of MSK embolization with microspheres in the treatment of chronic shoulder pain. Patients and methods: This retrospective monocentric study included patients with chronic shoulder pain resistant to 6 months or more of conventional therapies who were treated with MSK embolization between 2017 and 2021. Embolization was performed using calibrated 100–250 µm microspheres. Clinical success was defined as pain reduction, i.e., a decrease in the visual analogue scale (VAS) pain score of ≥50% at 3 months after MSK embolization as compared to baseline. Adverse events were collected. Results: Fifteen patients (11 women, 4 men) were included, with a median age of 50.3 years (IQR: 46.7–54.5). The median duration of symptoms was 26.6 months (20.6–39.8). The median VAS pain scores were 7.0 (7.0–8.0) at baseline, 6.0 (3.5–7.0) at 1 month, 5.0 (4.5–6.5) and 5.0 (3.0–7.4) at 3 months and 6 months (p = 0.002). Three patients (20%) reported clinical success at 3 months. Three patients experienced minor complications after embolization (paresthesia, n = 2; transient osteo-medullary edema, n = 1) and two patients had moderate complications (transient skin ischemia). Conclusion: MSK embolization with microspheres for treatment of refractory chronic shoulder pain showed moderate results in terms of clinical success and safety.

GAUCHO - Trial Genicular Artery Embolization Using Imipenem/Cilastatin vs. Microsphere for Knee Osteoarthritis: A Randomized Controlled Trial

Genicular artery embolization (GAE) has emerged as a treatment option to improve quality of life in patients suffering from moderate-to-severe pain refractory to conservative treatment of knee osteoarthritis, with encouraging results. This paper describes the study protocol of a single-center, double-blind, randomized controlled trial designed to evaluate and compare the safety and efficacy of GAE using imipenem/cilastatin vs. microspheres for the treatment of moderate-to-severe pain associated with knee osteoarthritis. We hypothesized that there will be no difference in safety and efficacy outcomes. The study received ethics approval of the institutional review board with number 4.364.391 / CAAE: 37590820.3.0000.5342 and is registered onto the Registro Brasileiro de Ensaios Clinicos (ReBEC), with number RBR-2h5rwgb. Technical success was defined as embolization of at least 1 feeding artery supplying the hyperemic synovium of the knee joint. Primary outcome: clinical success was defined as improvement in symptoms, 50% reduction in Western Ontario and McMaster Universities Osteoarthritis Index pain scores or an increase of at least 10 points in the Knee Injury and Osteoarthritis Outcome Score from baseline to 3 months of follow-up. Secondary outcome: radiological success was defined as significant improvement in the Whole-Organ Magnetic Resonance Imaging Score for knee synovitis considering the embolized areas at 12 months of follow-up after GAE and a reduction in the analgesia or other conservative therapies for knee pain used by the patient at 3 and 12 months of follow-up. Clinical assessments will be performed before GAE, during GAE and at hospital discharge (for Visual Analog Scale of pain), and at 30 days, 3 months, and 12 months after GAE.

Transarterial Embolization for the Treatment of Chronic Musculoskeletal Pain: A Systematic Review of Indications, Safety, and Efficacy

OBJECTIVE

The study objective was to evaluate the safety and efficacy of transcatheter arterial "embolization" (TAE) in the treatment of chronic "musculoskeletal pain" refractory to standard therapy.

METHODS

PubMed, EMBASE, and Cochrane Central Register of Controlled Trials were searched for original research articles evaluating TAE in patients with musculoskeletal conditions from database inception to January 21, 2020. Search terms employed were as follows: "embolization", "pain", "knee osteoarthritis", joint replacement, epicondylitis, tenderness, inflammation, WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), microspheres, Embozene, geniculate artery, neovascularity, transcatheter, embolic, imipenem/cilastatin sodium, angiogenesis, and "musculoskeletal". Studies involving particle "embolization" for painful musculoskeletal conditions were included. Studies of TAE for hemarthrosis or malignancy-related "musculoskeletal pain" were excluded.

RESULTS

The primary search yielded 1,099 sources; 7 articles and 4 abstracts were included for data extraction. All were cohorts or case series, with low risk of bias and moderate to poor level of evidence. Heterogeneity between studies was high, precluding meta-analysis. The reviewed studies reported the safety and efficacy of TAE for the treatment of "knee osteoarthritis"; adhesive capsulitis of the shoulder; tendinopathy/enthesopathy of the knee, shoulder, elbow, and ankle; and cervical myalgia. All TAEs were reported as technically successful without major complications or subsequent serious adverse events, including no reported osteonecrosis, cutaneous ulceration, limb ischemia, cartilage degeneration, or myotendinous injury. TAE significantly reduced pain and improved function for all of the treated conditions, with durable response up to 24 months post procedure.

CONCLUSION

TAE appears to be a safe and effective treatment for some types of chronic refractory "musculoskeletal pain". Randomized placebo-controlled studies are necessary to confirm these findings.

Transcatheter arterial embolization for benign chronic inflammatory joint pain: a systematic review and meta-analysis

PURPOSE

To evaluate the efficacy and safety of transcatheter arterial embolization for the treatment of chronic inflammatory joint pain via a systematic review and meta-analysis.

MATERIALS AND METHODS

The MEDLINE and EMBASE databases were searched for studies reporting outcomes in patients with chronic inflammatory joint pain treated with transcatheter arterial embolization. Meta-analyses of pain score changes, changes in proportions of patients on analgesic medications, range of motion changes, technical success rates, and adverse events rates were performed. Subgroup analyses were conducted with respect to pain site (knee vs. shoulder).

RESULTS

Fourteen observational studies, including 346 patients, were reviewed. The pooled technical success rate was 95.8%, and no major adverse events were observed. The pooled mean difference in pain score at 1 week; 1, 3, and 6 months; and 1 year were 3.1, 4.0, 4.2, 5.1, and 5.5, respectively. Subgroup analysis demonstrated that shoulder embolization was associated with greater reduction of pain than knee embolization at 3 and 6 months (p<0.001 and p=0.018, respectively), whereas there was no significant difference in this regard between the sites at 1 month (p=0.734). The pooled proportions of patients on analgesic medication at baseline, 1, 3, 6, and 12 months were 81.1%, 36.3%, 42.3%, 28.2%, and 22.4%, respectively. The pooled estimated increases in range of motion among patients who underwent shoulder embolization were 55.6° for anterior elevation and 64.7° for abduction.

CONCLUSION

Transcatheter arterial embolization is an effective and safe therapeutic option for patients with chronic inflammatory joint pain.

Genicular artery embolization as a novel treatment for mild to moderate knee osteoarthritis: protocol design of a randomized sham-controlled clinical trial

Introduction

Knee osteoarthritis is a common disease with pain as the most prevalent symptom. Previous cohort studies have shown genicular artery embolization to reduce pain symptoms in patients with mild to moderate knee osteoarthritis. Patients resistant to conservative therapy but not eligible yet for surgical treatment due to young age or comorbidities may profit from an effective and sustained pain reduction treatment. This study is a randomized sham-controlled trial to evaluate the efficacy of genicular artery embolization in patients with knee osteoarthritis.

Methods and analysis

Fifty-eight patients with mild-to-moderate knee osteoarthritis will be recruited and randomly allocated to the treatment or control group in a 1:1 ratio. Participants in the treatment group will undergo genicular artery embolization. Patients in the control group will undergo sham treatment. Outcome measurements will be assessed at baseline and after 1, 4, 8, and 12 months with questionnaires, pressure pain threshold testing, and MR imaging. The MR imaging protocol is designed to (semi)quantitatively assess osteoarthritis in the knee joint. The primary outcome is the change from baseline of the Knee injury and Osteoarthritis Outcome Score (KOOS) pain subscale after 4 months. Secondary outcomes include change in osteoarthritis-related questionnaires, pressure pain threshold, and OA-related MRI features, particularly synovitis and bone marrow lesions.

Ethics and dissemination

This trial will determine the efficacy of genicular artery embolization compared to a sham treatment. This is of importance to assess before proceeding to larger-scale efficiency studies and, ultimately, implementing this treatment into day to day clinical practice.

Trial registration

ClinicalTrials.gov NCT03884049. Registered on 21 March 2019

Collagenase-Induced Patellar Tendinopathy with Neovascularization: First Results towards a Piglet Model of Musculoskeletal Embolization

Background: Therapeutic strategies targeting neovessels responsible for musculoskeletal chronic pain have emerged, including neovessels embolization. Our study aimed to develop a large animal model of patellar tendinopathy with neovascularization. Methods: Nine 3-month-old male piglets (18 patellar tendons) received percutaneous injections of increasing doses of collagenase (0 to 50 mg) at day 0 (D0). Tendinopathy was evaluated by ultrasound (D7 and D14). Neovascularization was evaluated visually and on angiographies. Bonar score was used for histological analysis (D14). Correlations were evaluated using Spearman’s rank (Rs) test. Results: Research protocol was well tolerated. All tendons were enlarged with a median increase of 31.58% [25–40.28] at D7 (p = 0.244) at D7 and 57.52% [48.41–91.45] at D14 (p = 0.065). Tendons with collagenase injection had more hypoechoic changes, with one tendon rupture (p = 0.012). Neovascularization was reported above 5 mg collagenase (p < 0.01) at D7 and D14 with dose-related neovessels induction (Rs = 0.8, p < 0.001). The Bonar score increased above 5 mg collagenase, correlated with the dose (Rs = 0.666, p = 0.003). Conclusions: The study shows the feasibility, safety and reproducibility of this new large animal model of patellar tendinopathy with neovascularization after collagenase injection. It will allow studying new treatments on direct embolization of neovessels by endovascular approach.

Cadaveric Classification of the Genicular Arteries with Implications for the Interventional Radiologist

PURPOSE

To document and assess the genicular arterial variation in a large multicenter cadaveric sample and generate an anatomical classification with implications for Genicular Artery Embolization (GAE).

MATERIALS AND METHODS

A sample of 212 donor body lower limbs were dissected from three medical school institutions. The descending genicular artery (DGA), superior lateral genicular artery, superior medial genicular artery, middle genicular artery, inferior lateral genicular artery, inferior medial genicular artery, and anterior tibial recurrent artery (ATRA) were identified for gross anatomical appearance, location of origin, diameter of vessels, and variation in branching patterns.

RESULTS

A total of 198 DGA, 204 popliteal origin genicular arteries and 183 ATRA were adequately preserved and reviewed. Three types (A:26%, B: 71%, C:5%) of DGA branching patterns were proposed along with six types (I: 28%; II: 22%; III 15%; IV: 15%: V 10%; VI: 6%) of popliteal origin genicular artery branching variants. Right vs left comparisons did not reveal clinically significant differences in vessel distance (p = 0.30 - 0.82).

CONCLUSION

Despite the large number of possible anatomical variations of the genicular arteries, six main patterns corresponded to over 96% of the cases. The description and classification of the genicular arterial anatomy may provide useful information to the interventional radiologist and add to the technical nuances of GAE.

Geniculate Artery Embolization: Role in Knee Hemarthrosis and Osteoarthritis

Roughly 37% of Americans 60 years of age and older experience chronic pain due to osteoarthritis (OA) of the knee. After conservative treatment (pharmacologic, physical therapy, and joint injections) fails, patients often require total knee arthroplasty to alleviate pain and regain knee function. Given the high economic burden of surgery paired with its invasive nature, many patients with this degenerative joint disease seek alternative treatment. Moreover, many patients with severe knee OA who also have comorbidities that preclude surgery-most often morbid obesity-are left without options. Geniculate artery embolization (GAE) is a minimally invasive intra-arterial intervention that was originally developed for the treatment of knee hemarthrosis that has recently been adapted for symptomatic knee OA. Through selective embolization of geniculate branches corresponding to the site of knee pain, GAE inhibits the neovascularity that contributes to the catabolic and inflammatory drive of OA. Preliminary trials over the past decade have demonstrated promising clinical results, including decreased pain and improved function and quality of life after treatment. Given such success, GAE provides another minimally invasive treatment option for knee OA to patients who feel reluctant to undergo or are ineligible for surgery. The authors review the radiographic manifestations and current standard of treatment of OA and hemarthrosis of the knee. Procedural technique, embolic selection, and clinical evidence for GAE in the treatment of OA and hemarthrosis of the knee are also explored. The online slide presentation from the RSNA Annual Meeting is available for this article. ^©RSNA, 2021.

Musculoskeletal Interventions: A Review on Genicular Artery Embolization

Symptomatic knee pain is one of the most common joint diseases that affects millions of people worldwide. The treatment for knee pain secondary to osteoarthritis (OA) begins with conservative therapy and progresses to surgical intervention when conservative therapy fails. Genicular artery embolization (GAE) offers an alternative option for patients who are poor surgical candidates. Multiple studies have been conducted worldwide demonstrating the safety and efficacy of GAE in patients with mild to moderate OA. The purpose of this article is to describe the current literature on GAE and highlight the latest findings from a randomized controlled trial comparing GAE versus sham embolization.

A Review of Musculoskeletal Embolization to Treat Pain Outside of the Knee

Chronic inflammation leading to musculoskeletal pain has garnered interest in the past decade with the success of genicular artery embolization for knee pain secondary to osteoarthritis. Outside the knee joint, musculoskeletal embolization has been applied to other anatomical locations, mainly shoulder pain secondary to adhesive capsulitis and elbow pain secondary to lateral epicondylitis. The success of these early trials and other case reports highlights the efficacy of musculoskeletal embolization and its future potential.

Characteristics of the descending genicular artery blood flow velocity in patients with knee osteoarthritis

BACKGROUND

In patients with knee osteoarthritis (KOA), the descending genicular artery (DGA) showed abnormal angiogenesis. However, the non-invasive assessment method of DGA remains unclear. The aim of this study was to clarify the characteristics of blood flow velocity of the DGA in patients with KOA and to examine the factors involved in the changes.

METHODS

The KOA group included 22 knees of 22 patients with KOA (4 males, 18 females; mean age, 72.3 ± 7.5 years) and the control group included 22 knees (4 males, 18 females; mean age, 71.3 ± 5.4 years) of 22 healthy adults. The peak systolic blood flow velocity (PSV) in each group was measured using ultrasonography. The KOA group was classified into the effusion group and the non-effusion group based on observed effusion, and the PSV was compared between the two groups. The relationships between PSV and suprapatellar bursa intracavitary distance, pain, femorotibial angle, Japanese Knee Osteoarthritis Measure were also investigated.

RESULTS

The PSV in the KOA group (51.5 ± 12.9 cm/s) was significantly higher than that in the control group (29.3 ± 4.4 cm/s) (P < 0.01). In the KOA group, PSV in the effusion group (55.5 cm/s (51.2-59.4 cm/s)) was significantly higher than that in the non-effusion group (39.1 cm/s (35.1-44.4 cm/s)) (P < 0.01). The PSV was positively and significantly correlated with both suprapatellar bursa intracavitary distance (r = 0.81: P < 0.01) and pain (r = 0.48: P < 0.05).

CONCLUSIONS

The PSV measurement in the DGA is useful for the evaluation of non-invasive synovitis of patients with KOA.

Comparison of Minimally Invasive Procedures to Treat Knee Pain Secondary to Osteoarthritis: A Systematic Review and Meta-Analysis

PURPOSE

To review and indirectly compare the outcomes of minimally invasive therapies for the treatment of lower urinary tract symptoms secondary to benign prostatic hyperplasia.

MATERIALS AND METHODS

A literature search via Medline and Cochrane Central databases was completed for randomized control studies published between January 2000 to April 2020 for the following therapies: Rezum, Urolift, Aquablation, and prostate artery embolization (PAE). Data on the following variables were included: international Prostate Symptom Score (IPSS), maximum urinary flow rate (Qmax), quality of life (QoL), and post-void residual (PVR). Standard mean differences between treatments were compared through a meta-analysis using transurethral resection of the prostate (TURP) to assess differences in treatment effect.

RESULTS

No significant difference in outcomes between therapies were noted for IPSS at the 3-, 6-, and 12-month follow-ups. Although outcomes for rezum were only available out to 3 months, there were no consistently significant differences in outcomes when comparing Aquablation vs PAE vs Rezum. TURP PVR was significantly better than Urolift at 3-, 6-, and 12 months. No significant differences in minor or major AEs were noted.

CONCLUSION

Although significant differences in outcomes were limited, aquablation and PAE were the most durable at 12 months. PAE has been well studied on multiple randomized control trials with minimal adverse events while aquablation has limited high quality data and has been associated with bleeding-related complications.

Results from a US Investigational Device Study of Adhesive Capsulitis Embolization (ACE) in the treatment of Shoulder Pain: The ACE Study

PURPOSE

To evaluate the safety and efficacy of arterial embolization to relieve shoulder pain secondary to Adhesive Capsulitis (AC).

METHODS AND MATERIALS

20 patients (18F, 2M: Mean age 51y) with AC resistant to > 30 days of conservative treatment were enrolled in a multi-center prospective study. Adhesive Capsulitis Embolization (ACE) was performed with 75 or 200 um spherical particles. Subjects were assessed before and after the procedure with MRI, VAS (0-100 mm), Single Assessment Numeric Evaluation (SANE, 0-100), and American Shoulder and Elbow Surgeons (ASES, 0-100) scores. Adverse Events (AEs) were recorded at all follow-up time points.

RESULTS

Hypervascularity was identified and embolization was technically successful in all patients with 83 arteries embolized in 20 patients. Baseline VAS, SANE, and ASES scores before the procedure were 89.2 mm, 27.2, and 30.9 mm, respectively. 1 (n=19), 3 (n=18), and 6 (n=12) months follow-up demonstrated significant improvements: 1 mo VAS (Δ Mean = -31.8, p = 1.2E-11), SANE (Δ Mean = 22.1, p = 1.8E-8), and ASES (Δ Mean = 14.2, p = 4.3E-5): 6 mon VAS (Δ Mean = -62.1, p = 7.0E-11) SANE (Δ Mean = 55.4, p = 4.1E-10), and ASES (Δ Mean = 44.5, p = 1.8E-6). Due to the coronavirus pandemic, the study was ended early and six patients did not complete the 6-month follow-up. No major adverse events were noted.

CONCLUSION

Interim findings suggest that arterial embolization is safe and effective for patients with AC refractory to conservative treatment.

Genicular Artery Embolization for the Treatment of Symptomatic Knee Osteoarthritis

Genicular artery embolization (GAE) is a novel therapy to treat patients with symptomatic knee osteoarthritis (OA) by reducing synovial arterial hypervascularity. This study evaluates the safety and efficacy of GAE for the treatment of symptomatic knee OA.

Methods

A prospective, single-center, open-label U.S. Food and Drug Administration-approved investigational device exemption study was conducted. Patients enrolled in the study were 40 to 80 years old, with moderate or severe knee OA (Kellgren-Lawrence grade 2, 3, or 4), who previously had failure of conservative therapy. Baseline pain (visual analog scale [VAS]) and symptom scores (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]) were assessed. After femoral arterial access was achieved, GAE of 1, 2, or 3 genicular arteries supplying the location of the subject's pain, as determined by digital subtraction angiography and cone-beam computed tomography, was performed using 100-μm particles. Adverse events and symptoms scores were assessed at 1 week, 1 month, 3 months, 6 months, and 1 year after GAE.

Results

Over a 10-month period, 40 subjects were enrolled. The median age was 69 years (range, 49 to 80 years). The median body mass index was 29 kg/m² (range, 19 to 44 kg/m²). Knee OA severity was grade 2 in 18% of the patients, grade 3 in 43%, and grade 4 in 40%. Technical success was achieved in 100% of the subjects. Transient skin discoloration and transient mild knee pain after the procedure were common and expected. Treatment-related adverse events included a groin hematoma requiring overnight observation in 1 subject, self-resolving focal skin ulceration in 7 subjects, and an asymptomatic small bone infarct on magnetic resonance imaging at 3 months in 2 subjects. The WOMAC total and VAS pain scores decreased by 61% and 67% at 12 months from a median baseline of 52 (of 96) and 8 (of 10), respectively. Twenty-seven patients (68%) had a reduction of ≥50% in both WOMAC total and VAS pain scores.

Conclusions

This prospective trial demonstrates that GAE is effective and durable in reducing pain symptoms from moderate or severe knee OA that is refractory to other conservative therapy, with an acceptable safety profile.

Level of Evidence

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

Effects of isometric contraction of the quadriceps on the hardness and blood flow in the infrapatellar fat pad

[Purpose] This study aimed to clarify the influence of the isometric contraction of the quadriceps (ICQ) with low intensity on the circulation in the infrapatellar fat pad (IFP). [Participants and Methods] The participants were 7 males and 5 females, with an average age of 21.5 ± 1.4 years. IFP hardness was measured using shear wave ultrasound elastography and Biodex. Tissue oxygenation was measured via near-infrared spectroscopy using oxygenated hemoglobin (O2Hb), deoxygenated hemoglobin (HHb), and total hemoglobin (cHb) as indices. The mean values were calculated for three periods: 1 min of rest immediately before the exercise task (before ICQ), the lower limit of the 10 sets during the exercise task (during ICQ), and 3–4 min after the exercise task (after ICQ). IFP hardness was compared between resting conditions and ICQ, and tissue oxygenation was compared before, during, and after ICQ. [Results] ICQ significantly increased IFP hardness. Tissue hemoglobin, O2Hb, and cHb decreased significantly during ICQ and increased after ICQ compared to that before ICQ. HHb decreased during ICQ and recovered significantly after ICQ. [Conclusion] In healthy participants, low-intensity ICQ increases the hardness and oxygenation of the IFP. This study may partly explain the unknown pain relief mechanism of exercise therapy.

Cadaveric and Angiographic Anatomical Considerations in the Genicular Arterial System: Implications for Genicular Artery Embolisation in Patients with Knee Osteoarthritis

PURPOSE

Genicular artery embolisation (GAE) is a novel treatment for patients with knee osteoarthritis (OA). Cadaveric dissection was undertaken to provide a complete description of the relevant arterial anatomy in order to perform safe and effective GAE.

MATERIALS

Twenty human lower limb specimens were dissected. The morphology of the genicular arteries and presence of anastomotic connections was recorded and compared with angiographic images from patients having undergone GAE. Vessels were measured to investigate the risk of non-target embolisation (NTE), taking a diameter of 300 microns as the threshold for significance.

RESULTS

The descending genicular artery (DGA) is the dominant vessel in medial OA, with 95% of cases revealing vessel division into muscular, saphenous and osteoarticular branches from a single pedicle. The superior medial genicular artery (SMGA) had a shared origin with the middle genicular artery (MGA) in 25% of cases. NTE to the MGA may damage the cruciate ligaments. In 85% of cases, there was an anastomosis between the DGA and SMGA, often encountered at angiography. The mean diameter of the anastomoses was 850 micron, presenting a risk for NTE. An anastomosis between the Inferior Medial Genicular Artery (IMGA) and medial sural artery was found in 5% of cases; the medial sural artery supplies blood to the tibial nerve and should be avoided. The IMGA and inferior lateral genicular artery provided supply to the patellofemoral joint in 69% and 88% of cases, respectively.

CONCLUSION

An in-depth knowledge of genicular artery anatomy is required for interventional radiologists to perform safe and effective GAE in patients with knee osteoarthritis.

Multicenter Randomized Sham Controlled Study of Genicular Artery Embolization for Knee Pain Secondary to Osteoarthritis

PURPOSE

To assess the safety and efficacy of genicular artery embolization (GAE) compared with a sham procedure in the treatment of knee pain secondary to mild to moderate osteoarthritis (OA).

MATERIALS AND METHODS

A multicenter, single-blinded, randomized controlled trial was conducted to evaluate knee OA symptom reduction after GAE versus sham procedure. Subjects (n = 21) with mild to moderate OA and intractable knee pain were randomized 2:1 to either GAE or a sham procedure. Subjects who were randomized to the sham procedure and did not report clinical improvement in both the total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and visual analog scale (VAS) scores were unblinded and able to crossover to treatment at 1 month. Longitudinal data were collected for 12 months, and subjects were excluded if they required additional analgesics at follow-up. Reductions in the VAS and total WOMAC scores were compared using mixed-effects linear regression models.

RESULTS

All subjects in the sham group failed to show significant improvements at 1 month and crossed over to the treatment arm. There was a statistically significantly greater pain reduction in the treatment group than in the sham group at 1 month (VAS, 50.1 mm; standard error [SE], 10.6; 95% confidence interval [CI], 29.0, 72.3; P<.01). Disability improvement was also significantly greater in the treatment group (WOMAC, 24.7 points; SE, 10.4; 95% CI, 3.5, 45.9; P=.02). Only minor adverse events were reported. Five subjects were excluded after increased analgesic use. Sensitivity analysis with all excluded patients confirmed significant improvements at 1 and 12 months.

CONCLUSION

In patients with mild to moderate knee OA, GAE results in symptomatic improvement greater than the sham procedure with clinically significant reduction in pain and disability.

Current Status of Trans-Arterial Embolization in Pain Management of Musculoskeletal Inflammatory Conditions - An Evidence-Based Review

OBJECTIVE

To summarize the literature on trans-arterial embolization in inflammatory musculoskeletal conditions, focusing on efficacy and safety.

MATERIALS AND METHODS

PRISMA guidelines were followed. A systematic literature search revealed 19 studies, with a total of 394 participants, eligible for inclusion.

RESULTS

The included studies consisted of case reports/series and non-randomized interventional studies, with knee osteoarthritis and adhesive capsulitis of the shoulder as the most frequent conditions. In all studies except one, pain was reduced up to four years after treatment. All adverse events were transient. Due to high heterogeneity, meta-analysis was not possible.

CONCLUSION

The included early studies showed encouraging results regarding efficacy and safety. However, randomized, placebo-controlled trials are warranted.

Intra-Arterial Infusion of Imipenem/Cilastatin Sodium through a Needle Inserted into the Radial Artery as a New Treatment for Refractory Trapeziometacarpal Osteoarthritis

PURPOSE

To evaluate the efficacy and safety of intra-arterial infusion of temporary embolic material with/without radiographic monitoring via a needle placed into the radial artery to occlude abnormal neovessels for trapeziometacarpal osteoarthritis.

MATERIALS AND METHODS

Thirty-one patients having Eaton stage II or III osteoarthritis, with a symptom duration longer than 6 months, resistant to conservative therapy for at least 3 months were prospectively enrolled. All procedures were performed by infusing imipenem/cilastatin sodium through a 24-gauge needle that was percutaneously inserted into the radial artery. Seven patients underwent the procedure with fluoroscopy, and 21 patients underwent the procedure without fluoroscopy. The mean Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) score, numerical rating scale (NRS), and Patient Global Impression of Change (PGIC) scale were evaluated before and at 2, 6, and 24 months after the first procedure.

RESULTS

Technical success was 100%. The mean procedure time (from the beginning of local anesthesia to the removal of needle) was 2.9 minutes ± 1.6. The QuickDASH score improved from the baseline to 2, 6, and 24 months (49.2 ± 11.2 vs 22.1 ± 11.2, 20.9 ± 16.6, and 19.5 ± 16.1, respectively, all P <.001). The NRS improved from the baseline to 2, 6, and 24 months (7.2 ± 1.1 vs 3.1 ± 1.8, 2.8 ± 2, and 2.5 ± 2.1, respectively, all P <.001). Improvement on PGIC was observed in 84%, 81%, and 77% of patients at 2, 6, and 24 months, respectively. No major adverse events were encountered.

CONCLUSIONS

Intra-arterial infusion of temporary embolic material is a feasible treatment option for trapeziometacarpal osteoarthritis.

Osteoarthritis-Related Knee Pain Treated With Genicular Artery Embolization: A Systematic Review and Meta-analysis

BACKGROUND

Genicular artery embolization (GAE) is an innovative technique that has been investigated as a supplementary treatment method for chronic pain secondary to knee osteoarthritis (OA).

PURPOSE

To evaluate the current evidence on the effectiveness and safety of GAE for OA-related knee pain.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic literature search was conducted in the PubMed, Web of Science, EMBASE, and Scopus databases to identify studies related to knee OA treated with GAE. Treatment agents were categorized as Embozene, imipenem/cilastatin, resorbable microspheres, and polyvinyl alcohol. The main outcomes were the mean difference (MD) in pre- and postembolization pain based on the visual analog scale (VAS) or the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores as well as changes in the need for pain medication. Random- and fixed-effects models were applied for data analysis.

RESULTS

Of 379 initially inspected publications, 11 (N = 225 patients; 268 knees) were included in the final review. The quality of the studies was fair in 8 and poor in 3-categorized according to the National Institutes of Health quality assessment tool. Overall, 119, 72, 13, and 21 patients were treated with imipenem/cilastatin, Embozene, resorbable microspheres, and polyvinyl alcohol, respectively. Symptomatic improvement was reported in all studies. The pooled effect size, characterized by MD, showed a significant improvement in the VAS and WOMAC pain scores, with better functional status after GAE. Pre- versus postembolization MDs in VAS scores ranged from 32 within the first week to 58 after a 2-year follow-up (equivalent to 54% and 80% improvement, respectively). There was a similar trend in the overall WOMAC scores, with MDs ranging from 28.4 to 36.8 (about 58% and 85% improvement, respectively). GAE resulted in a decreased need for pain medication for knee OA, with a 27%, 65%, and 73% decline in the number of patients who used opioids, nonsteroidal anti-inflammatory drugs, and intra-articular hyaluronic acid injection, respectively (P < .00001 for all). No significant difference between embolic agents was seen with regard to post-GAE pain reduction. No severe or life-threatening complications were reported.

CONCLUSION

OA treated by GAE using different embolic particles can be considered generally safe, with good efficacy and no reported serious complications.

Short-term Results of Transcatheter Arterial Embolization for Chronic Medial Epicondylitis Refractory to Conservative Treatment: A Single-Center Retrospective Cohort Study

PURPOSE

To evaluate the effectiveness and safety of transcatheter arterial embolization (TAE) for chronic medial epicondylitis (ME) refractory to conservative treatments.

MATERIALS AND METHODS

This retrospective study included ten patients (14 procedures) who underwent TAE between May of 2018 and April of 2020 to treat chronic ME refractory to conservative treatments for at least 3 months. Imipenem/cilastatin sodium was used in 12 procedures, and quick-soluble gelatin sponge particles were used in the ensuing two procedures as an embolic agent. The visual analogue scale (VAS, 0-10) score and Quick Disabilities of the Arm, Shoulder, and Hand (Quick-DASH) scores were assessed at baseline and at different post-treatment times (1 day; 1 week; 1, 3, and 6 months; and an open period). The clinical success of the procedure was defined as a decrease of more than 70% in the Quick-DASH scores at 6 months compared to the baseline.

RESULTS

Clinical success was achieved in 12 of 14 procedures (85.7%). No major complications were observed during the follow-up periods. The mean VAS scores were significantly decreased at 1 day, 1 week, 1 month, 3 months and 6 months (7.6 at baseline vs. 3.6, 3.6, 3.6, 3, and 0.9 after treatment; all P < .01). The mean Quick-DASH scores at baseline decreased significantly at 1 day, 1 week, and at 1, 3, and 6 months after treatment (71.9 vs. 48.5, 44, 37.7, 30.2, and 8.4; all P < .01). These improvements endured in nine patients for up to 12 months after treatment.

CONCLUSION

TAE effectively and safely relieved pain and promoted functional recovery in chronic ME patients refractory to conservative treatments. TAE may be a feasible treatment option for patients with ME intractable to conservative treatments.

Angiographic Analysis of the Anatomical Variants in Genicular Artery Embolization

Purpose Genicular artery embolization (GAE) has been proposed as a novel technique to treat painful synovitis related to osteoarthritis. An in-depth understanding of the genicular arterial anatomy is crucial to achieve technical success and avoid nontarget-related complications. Given the lack of previous angiographic description, the present study analyzes genicular arterial anatomy and proposes an angiographic classification system.

Materials and Methods Angiographic findings from 41 GAEs performed during two US clinical trials from January 2017 to July 2019 were reviewed to analyze the anatomical details of the following vessels: descending genicular artery (DGA), medial superior genicular artery (MSGA), medial inferior genicular artery (MIGA), lateral superior genicular artery (LSGA), lateral inferior genicular artery (LIGA), and anterior tibial recurrent artery (ATRA). The diameter, angle of origin, and anastomotic pathways were recorded for each vessel. The branching patterns were classified as: medially, M1 (3/3 arteries present) vs M2 (2/3 arteries present); and laterally, L1 (3/3 arteries present) vs L2 (2/3 arteries present).

Results A total of 91 genicular arteries were embolized: DGA (26.4%), MIGA (23.1%), MSGA (22.0%), LIGA (14.3%), and LSGA/ATRA (14.3%). The branching patterns were: medially = M1, 74.4% (n = 29), M2, 25.6% (n = 10); and laterally = L1, 94.9% (n = 37), L2, 5.1% (n = 2). A common origin for MSGA and LSGA was noted in 11 patients (28.2%). A direct DGA origin from the popliteal artery was reported in three patients (7.7%, n = 3).

Conclusions A thorough understanding of the geniculate arterial anatomy is important for maximizing postprocedural pain reduction while minimizing complications, procedure time, and radiation exposure during GAE.

A Rat Model of Frozen Shoulder Demonstrating the Effect of Transcatheter Arterial Embolization on Angiography, Histopathology, and Physical Activity

PURPOSE

To assess the angiographic findings and the effects of transcatheter arterial embolization on physical activity and histopathology using a frozen shoulder rat model.

MATERIALS AND METHODS

First, the angiographic and histopathologic findings of rats in which the shoulder was immobilized with molding plaster for 6 weeks (n = 4) were compared to control rats with normal non-immobilized shoulders (n = 4). Next, a total of 16 frozen shoulder rats were divided into 2 groups. In the transcatheter arterial embolization group (n = 8), imipenem/cilastatin was injected into the left thoracoacromial artery. The changes of physical activity before and after procedures were evaluated and compared with a saline-injected control group (n = 8). Histopathologic findings were also compared between the 2 groups.

RESULTS

Angiography revealed abnormal shoulder staining in all of the rats with a frozen shoulder. On histopathology, the numbers of microvessels and mononuclear inflammatory cells in the synovial membrane of the joint capsule were significantly higher compared with the control rats (both P = .03). In the transcatheter arterial embolization group, the running distance and speed were improved (P = .03 and P = .01, respectively), whereas there were no significant differences in the control group. The number of microvessels and mononuclear inflammatory cells in the transcatheter arterial embolization group were significantly lower than the control group (P = .002 and P = .001, respectively).

CONCLUSIONS

The rat frozen shoulder model revealed the development of neovascularization. Transcatheter arterial embolization decreased the number of blood vessels and inflammatory changes in the frozen shoulder and increased the moving distance and speed of the rats.