Sacroiliac joint injections and radiofrequency ablation for pain management: A clinical review

Abstract

Sacroiliac (SI) joint pain is a widely prevalent, and frequent cause of chronic low back pain. Therefore, this review aimed to evaluate current evidence on the investigation and treatment of SI joint injections and radiofrequency ablation (RFA), outline the comparative effectiveness, and future treatments. Clinical studies were collected from databases, such as Scopus, MEDLINE, PubMed, EMBASE, Cochrane Library, Web of Science, Google Scholar, ClinicalTrials.gov, and CINAHL. Image-guided diagnostic injections are the reference standard for confirming the SI joint pain. Therapeutic steroid injections offer only temporary benefit, whereas RFA, in particular, cooled or bipolar methods offer longer-lasting benefit, lasting up to 6 months to 12 months. Comparative experimental studies showed better performance of RFA than injections in a well-selected population. There are fewer invasive options that include regenerative treatments, including using platelet-rich plasma and mesenchymal stem cells, which are on the horizon, but the evidence presented in the studies is limited. The pain in the SI joint ought to be managed in a multimodal and evidence-based pain management approach that focuses on the correct diagnosis. RFA remains the most widely supported intervention in offering long-term relief, and biologic and neuro-modulation therapies are areas where research can potentially improve in the future.

Key Words: Low back pain; Sacroiliac joint pain; Conventional radiofrequency ablation; Steroid injections; Intra-articular injection

Core Tip: This clinical review summarizes current evidence on diagnostic sacroiliac (SI) joint injections and therapeutic interventions, particularly steroid injections and radiofrequency ablation (RFA). Image-guided diagnostic injections remain the gold standard for confirming SI joint-related pain. While steroid injections may provide short-term relief, RFA-especially cooled or bipolar techniques-demonstrates more durable pain reduction lasting up to 6-12 months in appropriately selected patients. Emerging regenerative therapies such as platelet-rich plasma and mesenchymal stem cells show promise but require further high-quality clinical evidence to establish their effectiveness.

INTRODUCTION

The pain in sacroiliac (SI) joints is currently considered among the leading causes of chronic lower back pain and is also difficult to distinguish from other similar presenting syndromes[1]. Meanwhile, 15%-30% of patients facing non-radicular axial lower back pain reporting the experience of pain in that area[2]. However, the etiology of SI joint pain remains a complex issue and is debatable due to the joint’s complexity and the pain’s misleading characteristics, together with other diseases of the back and pelvis[3]. SI joint dysfunction can impact the quality of life of patients and may either produce disability, psychological complications, or even the introduction of healthcare accessibility[4]. This is one of the main challenges in treating SI joint pain because there exists no universal and generic diagnostic criterion which would have been accepted worldwide. Clinical provocative tests and imaging can point towards the role of the SI joint, but they are not specific enough, and the current reference standard is a diagnostic block[5,6]. The management strategies too have evolved, and lately intra-articular injections and radiofrequency ablation (RFA) have assumed significance in management, whereas the evidence that has been established since long with regards to the long-term effectiveness of the respective treatments remains average and limited, respectively[7,8]. The current literature review aims to collate the existing evidence on the SI joint injection and RFA procedures, referring to their anatomic assumptions, method of procedure, clinical efficacy, and risks. Relevant clinical studies, guidelines, and randomized controlled trials were searched across different databases such as Scopus, MEDLINE, PubMed, EMBASE, Cochrane Library, Web of Science, Google Scholar, ClinicalTrials.gov, and CINAHL. Analyzing established and emergent practices, this paper will be able to inform clinicians in evidence-based decision-making to benefit patients in such a hard-to-treat area of pain management.

Pathophysiology and anatomy of the SI joint

The SI joint is a unique and the largest axial joint in the body, found between the pelvic bones and sacrum on either side[3]. It plays a significant role in transferring load between the trunk and the lower limbs[9]. SI joints are also helpful in absorbing shocks through the pelvis structures of the joint of pelvic morphology, fat tissues, and ligaments[10]. Structurally, the SI joint is not simply a dichotomous structure of anterior synovial-posterior ligament, but rather an integral mechanical unit, and its joint cavity is continuously distributed in a C-shape, with both the anterior and posterior parts covered by fibrocartilage, and there is a significant posterior synovial recess[9,11]. These ligaments offer great stability to the joint, limiting joint movement to a minimal range of approximately 2 to 4 degrees[10,12]. While sacrospinous ligaments are used to connect the ischial spine to the lateral edge of the sacrum and do not participate in the stabilization of the SI joint as they are part of the pelvic floor suspension structure[13] (Figure 1).

Figure 1 Joint structure[10]. A: The sacroiliac joint is in a position, where joint lines run parallel to the line of gravity; B: The sacral articular surface; C: The cross-sectional image of joint, shows posterior and anterior regions are syndesmoses and synovial joints; D: Syndesmosis, which is composed of sacrospinous ligaments, posterior sacroiliac ligaments, iliolumbar ligaments, and scarotuberous ligaments from posterior side; E: The ilium articular surface. Meanwhile, the redlines on both sacrum and ilium side indicate the synovial regions. Citations: Toyohara R, Ohashi T. A literature review of biomechanical studies on physiological and pathological sacroiliac joints: Articular surface structure, joint motion, dysfunction and treatments. Clin Biomech (Bristol) 2024; 114: 106233. Copyright ©The Author(s) 2024. Published by Elsevier Ltd. The article is open access (Supplementary material).

The joint has an uneven surface, along with the fibrocartilage on the iliac surface and hyaline cartilage on the sacral surface, which combine to give the joint stability and limited movement, but also make it catastrophically vulnerable to degenerative changes over time[14]. Histological analysis indicated the presence of nerve fibers within the capsule of joint and adjoining ligaments[15]. It has also been described that innervation occurs primarily due to the lateral branches of the dorsal rami of S1-S3, with minimal contribution from the dorsal rami of L5, and possibly L4[16,17]. However, due to the involvement of the superior gluteal nerve, which can cause variability in the pain pattern, the pain may radiate to the buttocks, the groin, or even the posterior thigh[14,18]. In addition, the lateral branches of S2 often share a common trunk with S1, and the branches of S3 may be absent. In many cases, pain in the SI joint is pathophysiological normal and presumably results from the changes in biomechanics, and is broadly sub-grouped into different categories, including inflammatory, infectious, mechanical, degenerative, neoplastic and traumatic[19]. It can also be caused by pregnancy-related conditions of ligamentous laxity, leg length discrepancy, or lumbar fusion surgery with altered load distribution[3,9]. With time, degenerative changes of the joint surface, or inflammatory arthropathies, such as spondyloarthropathies, may also contribute to the development of chronic pain, by inducing synovial inflammation or loading of ligaments around the joint[20]. Such a combination of restricted movement, profound mechanical burden, and extensive innervation is why the SI joint can be a significant pain source, as well as a complicated condition to diagnose and treat.

Presentation and diagnostics of SI joint pain

The issue in diagnosing SI joint pain is quite elusive due to variability in its presentation, and patients may report pain from multiple locations, such as the thoracolumbar fascia, the piriformis region, lumbar disks or facets, limbs, lumbar muscles, and referred pain[2]. Moreover, the most typical SI joint pain referral sites are depicted in Figure 2. The causes of these varied pain presentations may include the area’s peculiar innervation, adjacent structures irritation, sclerotomal pain referral, and variable joint injury localizations[21].

Figure 2 Most typical sacroiliac joint pain referral sites are associated with sacroiliac joint pain[2]. This illustration represents a typical region of referred pain originating from the SI joint, shown in both anterior and posterior views. In the anterior view, pain commonly localizes to the hip and groin regions, with extension into lateral aspect of the upper leg. In the posterior view, the most frequent pain distribution includes the lower back and lower buttock, with radiation extending along the lateral thigh and upper leg. Citations: Samolsky Dekel BG, Campesato M, Salis E, Secli R, Sorella MC, Vasarri A, Ventola M. Things to know about Sacroiliac Joint Pain. Open Pain J 2024; 17: E18763863320151. Copyright ©The author(s) 2024. Published by Bentham Open. The article is open access (Supplementary material).

The SI joint pain diagnosis is based on a multifaceted process, which usually involves careful evaluation, including differentiation from other pain generators in the region[17]. First step should be taking history and then appropriate physical examination, which is based on a sequence of provocative tests, including flexion, abduction, external rotation tests, Gaenslen tests, Gaenslen test (modified), thigh thrust tests, sacral compression and distraction tests, all of which work to re-create pain by loading the SI joint, as described in Figure 3[17,22,23].

Figure 3 Clinical provocative tests for the assessment of sacroiliac joint pain[17]. These tests are most commonly used physical examination tests designed to reproduce pain arising from the SI joint with the application of controlled mechanical stress across the joint. A: Flexion-abduction-external-rotation test; B: Gaenslen test; C: Gaenslen test (modified); D: Thigh thrust; E: Compression test; F: Distraction test. Citations: Buchanan P, Vodapally S, Lee DW, Hagedorn JM, Bovinet C, Strand N, Sayed D, Deer T. Successful Diagnosis of Sacroiliac Joint Dysfunction. J Pain Res 2021; 14: 3135-3143. Copyright ©The author(s) 2021. Published by Dove Medical Press. The article is open access (Supplementary material).

Published studies have demonstrated that three or more provocative tests have a sensitivity and specificity of 91% and 78%, respectively[23]. Other conditions may be excluded via imaging techniques such as magnetic resonance imaging (MRI), computed tomography (CT), and bone scans, although these techniques cannot confirm pain in the SI joint itself when the nature of the pain is not inflammatory[24,25]. Moreover, imaging studies have reported low accuracy and varied sensitivity and specificity, thus, questioning their role in the case of SI joint pain[26,27]. Additionally, non-inflammatory arthropathy associated with SI joint pain shows few findings on imaging modalities, however, it can be helpful in observing joint space narrowing, sclerosis, and osteophytes[17]. Due to these low accuracy and sensitivity, the use of image-guided diagnostic blocks has become the gold standard: In case a patient has a substantial decrease in pain of up to 75% following intra-articular injection of a local anesthetic, the diagnosis of SI joint-generated pain can be considered positive[5].

Despite moderate evidence of diagnostic injections concerning specificity, they fail to represent extra-articular causes of pain, such as supporting ligaments, which may also reduce the idea of SI joint dysfunction[24,25]. Finally, using several combined methods such as an accurate history of the patient, clustered provocative testing, and elimination of any other diagnoses through imaging and diagnostic injections is the most robust method of diagnosis[28-30]. This complex procedure assists clinicians in making better diagnoses and providing more effective follow-ups by applying proper target interventions. In this context, SI joint injections serve an essential role in both the diagnostic evaluation and therapeutic management of SI joint pain.

INJECTIONS OF THE SI JOINTS

Diagnostic SI joint injections

Diagnostic SI joint injections are aimed at confirming the SI joint as the primary generator of pain. These injections are given after administering a local anesthetic into the joint cavity to minimize inflammation and relieve pain[31]. Intra-articular injections are vital when performed with the aid of image guidance, usually fluoroscopy or CT, to enhance safety and effectiveness of the procedure and support correct intra-articular positioning[32]. Generally, it is advised to inject less than 2.5 mL to avoid extravasation from the joint, which can be leaked onto nearby neural structures and compromise the targeted injection specificity[5]. Usually, local anesthetics work by blocking sodium channels, and the interval of pain relief should be correlated with the anesthetic activity duration[33]. For the confirmatory response, criteria of at least 75% pain relief from a local anesthesia are required for the diagnosis of SI joint pain[27]. Furthermore, fluoroscopy is the most common imaging modality, which is used for guiding the injections, however, the same procedure can be performed with other imaging modalities, like CT, when one is unable to assess the joint through fluoroscopy due to the presence of dorsal marginal osteophytes. For pregnant females, MRI or ultrasound could be considered for the administration of these injections[5].

Despite their widespread use, diagnostic SI injections are associated with certain limitations related to anatomical variations, capsular defects, and structural communication with the S1 foramen, which present procedural challenges for consistent intra-articular access[25]. In addition, false-positive responses may occur due to placebo effects, anesthetic spread to structures or concurrent extra-articular pain generators, such as muscles or ligaments[34].

Therapeutic SI joint injections

Therapeutic SI joint injections combine local anesthetics and pharmacological agents, and the most frequently used pharmacological agents are long-acting corticosteroids (triamcinolone) and local anesthetics (bupivacaine or ropivacaine), which could provide immediate pain relief. Pain scores have been reported to be significantly reduced, ranging from several weeks to several months, and some patients reported the positive effects after more than six months[5,35]. These injections are primarily used for the reduction of inflammation and alleviating symptoms rather than to provide long-term structural modification[36]. Corticosteroid injections may substantially decrease pain and Disease Activity Scores in inflammatory diseases such as spondyloarthropathies, with effects that are occasionally long-lived and extend up to six months[37]. In addition, injections of betamethasone, triamcinolone, and methylprednisolone steroid contents, when administered to patients with SI joint pain, demonstrated a significant improvement at the 3, 6, and 12-month follow-up[38]. Similarly, CT-guided steroid intra-articular injections for SI joint pain in patients with active sacroiliitis can achieve sufficient pain control for the duration of 6 months[39]. In another observational study, 351 patients were treated with fluoroscopically guided unilateral or bilateral intra-articular SI joint injections and pain relief was observed using Numeric Rating Scale and 60% and > 40% patients achieved Minimal Clinically Important Difference after 1 month and 6 months after injection, respectively[38]. A meta-analysis also demonstrated a significant (P < 0.001) reduction in the Visual Analog Scale (VAS) scores from 8.2 to 3.2 at short-term follow-up, and after mid-term follow-up, VAS was 3.3, while for long-term follow-up, it was 5.1[40].

However, due to potential adverse events, such as elevated glucose level, inadequate cortisol release from the adrenal glands due to negative feedback, diminished bone density, and increased systolic blood pressure, which are associated with steroids[41,42]. As a result, there is increasing demand for safer alternatives, like platelet-rich plasma (PRP), biologics, which can provide a rich supply for autologous growth factors[40,43].

KEY INJECTION APPROACHES

Among the available approaches, the three principal needle approaches, the inferior approach to intra-articular SI joint injection, has been used most commonly in clinical practice. In addition, other approaches, such as superior and tangential approaches, can be used as alternatives with their clinical potential and relevance[44].

Inferior injection approach

Currently, the inferior injection approach under the guidance of fluoroscopy has been considered as a gold standard for the treatment of SI joint pain[45]. It targets the lower third of the SI joint, where joint space is typically wider and more accessible[46]. Furthermore, the target points are the inferior part (lower one third) of the joints, once needles are in place, the injection is most likely to be in the joint, as described in Figure 4[47-49]. The inferior injection approach has been demonstrated to have a high success rate in achieving the intra-articular delivery without much difference in the complication rates[50]. Generally considered safe, complications can occur, but they are relatively rare. Reported adverse events include transient increased pain, bleeding, infection, and in some studies, temporary lower limb weakness or ataxia, particularly following diagnostic blocks rather than therapeutic steroid injections[51]. Meanwhile, this approach may have limitations due to complexity, such as joint degeneration, anatomic variation, osteophytes or narrowing[52]. Therefore, alternative approaches should also be considered.

Figure 4 The inferior approach (lower one-third) of the sacroiliac joint is outlined using fluoroscopy[49]. Citations: Gupta S. Double needle technique: An alternative method for performing difficult sacroiliac joint injections. Pain Physician 2011; 14: 281-284. Copyright ©The American Society of Interventional Pain Physicians. Published by the American Society of Interventional Pain Physicians. The article is open access (Supplementary material).

Among the alternatives, the superior injection approach is advisable when the inferior injection approach is difficult to perform[53]. This approach targets the upper third of the joint, and requires more precise angulation because the joint space is narrower superiorly and often partially fused, with a higher success rate (90%), and satisfaction rate (79%) among patients and no serious adverse events[53,54]. Under the guidance of fluoroscopy at 10°-20° contralateral oblique angulation, with minor adjustments, can be successfully implemented with varying degrees of success[55].

Double needle approach

In this approach, the needle tip is advanced under continuous fluoroscopy, while the C-arm is moved in the right and left oblique directions (dynamic fluoroscopy). The needle should be within the line of the joint[49]. Likewise, another needle is advanced in another joint line. Once both needles are in line, dye is released. If the spread is unsatisfactory, then it is injected through the other needle (Figure 5). Meanwhile, outcomes demonstrated success, when patients were treated with this approach for SI joint[49]. Furthermore, O-arm-guided injection also demonstrated a significant reduction in the pain (3.1 from 8.5) in 81% patients[56]. Meanwhile, this approach is easy to perform and effectively reduces the pain by targeting injury pathology in the surrounding joint capsule and the intra-articular space[57].

Figure 5 Dynamic fluoroscopy indicating two needles for the treatment of sacroiliac joint[49]. Citations: Gupta S. Double needle technique: An alternative method for performing difficult sacroiliac joint injections. Pain Physician 2011; 14: 281-284. Copyright ©The American Society of Interventional Pain Physicians. Published by the American Society of Interventional Pain Physicians. The article is open access (Supplementary material).

Overall, SI joint injections play a dual role, diagnostically, by confirming the joint as the pain generator when significant relief follows local anesthetic injection; and therapeutically, by providing clinically meaningful pain relief that can improve function and quality of life, especially when conservative treatments have failed.

RFA ON OF THE SI JOINT

RFA

RFA has become an important minimally invasive option for treating the SI joint pain, particularly in patients experiencing continuous disabling pain despite conservative measures, and has shown a positive response to diagnostic blocks[58]. It works by delivering a high-frequency alternating electrical current through needle-like electrodes placed close to the specific and targeted nerve under the guidance of imaging modalities, such as MRI, CT, ultrasound or fluoroscopy[59]. Notably, it does not remove any tissue or permanently damage the nerve, it causes localized nerve injury, and pain relief persists until regeneration of the nerve occurs[60]. The rationale behind RFA is to interrupt nociceptive signaling by creating controlled thermal lesions that target the lateral branches of the sacral dorsal rami and sometimes the L5 dorsal ramus, which innervate the posterior aspect of the SI joint[61]. Because these nerves are usually used to convey signals from the posterior joint capsule, adjacent periarticular structures, and interosseous ligaments, which are associated with pain, their ablation is intended to reduce pain originating from the posterior SI joint[11].

The analgesic impact of RFA primarily depends on the size and extent of the thermal lesion created around the tip of the electrode[62]. In conventional RFA, the lesion is relatively ellipsoid and small, which extends only a few millimeters from the active tip and requires more precise placement of the electrode for the successful capture of the targeted nerve[63]. Later, a more advanced RFA type, cooled RFA, was developed with internal circulating fluid, that prevents overheating at the electrode tip, allowing energy to cover a larger area and creating broader and spherical lesions[64]. Larger lesion volumes increase the likelihood of effective capture of the nerve and are often associated with more long-lasting and consistent pain relief. Clinically, RFA is considered among the most effective methods used for the relief of pain conditions mediated by sensory nerves, including SI joint pain, and targets pain transmission rather than the underlying structural cause[58]. Meanwhile, confirmation of the pain source is essential for optimal outcomes. For optimal outcomes, it is necessary to understand different types of RFA.

These techniques, including conventional RFA, cooled RFA, pulsed RF, and more recently, bipolar ‘palisade’ RFA and endoscopic-guided RFA, play an important role in the management of pain associated with the SI joint. Each method differs in lesion size, duration of action, and complexity of the procedure[65,66].

Conventional RFA

Conventional RFA is a form of thermal ablation that employs heat in the form of current delivered through an electrode to a localized area to induce denaturation of proteins in tissue cells, resulting in the death of cells[67]. It typically involves heating of the targeted nerves to a temperature of 60 °C oat the active tip at each location and increasing the tissue temperature > 80 °C for 150 seconds[68,69]. In addition, the lesion created is relatively ellipsoid and small, and following the shape of the tip of the active electrode, while its size of the lesion can be altered by adjusting temperature or denervation time, as described in Figure 6[70].

Figure 6 This medical illustration compares the sacroiliac joint pre and post radiofrequency ablation. A: This image shows the correct posterior anatomical view of the sacrum and ilium. The lateral branches of the posterior sacral nerves are visible, and a radiofrequency ablation probe is positioned on one of them, ready for the procedure; B: This image shows the same posterior view after the radiofrequency ablation procedure has been performed. A thermal lesion is now visible at the tip of the probe, and the targeted nerve is ablated, interrupting the pain signals. RFA: Radiofrequency ablation.

Cooled RFA

Cooled RFA was developed to address the limitation of small lesion size associated with conventional RFA. Compared to conventional RFA, cooled RFA uses the electrode, which is internally cooled by circulating fluid, helpful in preventing excessive heating at the electrode-tissue interface[71]. This cooling allows continued delivery of energy without the damage of tissue or impedance rise, enabling heat to spread more broadly into surrounding tissue. As a result, it provides larger ablative zones to capture a greater number of afferent nociceptive fibers[72,73]. The increased volume of lesion improves the likelihood of capturing nerves with unpredictable or variable courses, making cooled RFA particularly advantageous in complex anatomical regions, like the posterior SI joint[68]. Moreover, a strip of lesioned tissue can be created using recommendations provided by the equipment manufacturers (Figure 7)[74].

Figure 7 Placement of probes during cooled radiofrequency ablation of dorsal sacral nerve fibers supplying sacroiliac joints[74]. Citations: Biswas BK, Dey S, Biswas S, Mohan VK. Water-cooled radiofrequency neuroablation for sacroiliac joint dysfunctional pain. J Anaesthesiol Clin Pharmacol 2016; 32: 525-527. Copyright ©Journal of Anaesthesiology Clinical Pharmacology. Published by Research Society of the Anaesthesiology Clinical Pharmacology. The article is open access (Supplementary material).

Pulsed RFA

Pulsed radiofrequency (PRF) is another novel therapeutic technique, which can be used for the effective management of pain without the destruction of tissue and painful sequelae associated with conventional RFA[75]. It uses radiofrequency current in 20 milliseconds short, high-voltage burst, the silent phase (480 milliseconds) of pulse radiofrequency allows time for the elimination of heat, keeping the temperature of the target tissue below 42 °C for 120 seconds to target the SI joint region[76,77]. Because of this temperature, no thermal coagulation occurs, therefore, PRF is considered a neuromodulator rather than a neurodestructive technique[78]. Overall, PRF is found to be an effective and safe technique, with increased evidence to support its use in the management of pain[79]. Moreover, pain reduction occurs due to the alterations in neuronal signaling, expression of genes, and synaptic transmission rather than direct nerve injury[77,80].

Bipolar RFA

It involves the simultaneous use of two active electrodes placed in close proximity, allowing current to flow directly between these electrodes rather than from an active electrode to a distant grounding pad[81]. This configuration resulted in generating larger and more uniform lesions within the tissue, and it may also be helpful, particularly when targeting broader nerve distributions[82]. Furthermore, bipolar radiofrequency treatment creates continuous (strip) lesions, which are proportional in size to the distance between the probes[83]. An example is found in bipolar RFA, which has been illustrated to shorten procedure time (> 50%), use radiation rather than cooled RFA, and achieve greater chances of pain relief (> 50%) for up to 12 months, without any complications[65].

Endoscopic-guided RFA

In addition, with endoscopic-guided RFA, there is a direct visualization of the target nerves, leading to a high degree of pain and disability indices reductions, with patient satisfaction described to be over 80 percent[84]. Efficacy data suggest that RFA can achieve at least 50% pain relief in roughly 50%-70% of patients at three to six months, although the effect size diminishes over time, likely due to nerve regeneration[85]. Importantly, repeat procedures remain an option for recurrent pain. Complication rates are generally low and include transient numbness, localized soreness, and rarely, neuritis or infection[86]. Overall, while more randomized controlled trials are needed, RFA, particularly advanced methods like endoscopic RFA, offers a safe and effective alternative for patients with chronic SI joint pain who are not surgical candidates and have failed conservative treatment (Table 1).

Table 1 A comparison of various radiofrequency ablation techniques.

Technique	Target/approach	Lesion size and coverage	Procedure complexity	Typical duration of effect	Ref.
Conventional RFA	Lateral branches of sacral dorsal rami ± L5 dorsal ramus	Small focal lesions. Requires multiple needle placements	Moderate. Precise needle placement. Fluoroscopy	3-6 months. 50%-70% achieve. ≥ 50% pain relief	[61]
Cooled RFA	Similar targets. Uses an internally cooled electrode	Larger spherical lesions. Better covers anatomical variability	Higher. Specialized equipment. Longer lesion cycle	6-12 months. Better sustained benefit	[65]
PRF	Modulates nerve without thermal lesion	Very small/non-destructive lesions	Low-moderate. Shorter procedure. Lower risk	3-6 months. Repeatable. Useful for fragile nerves	[65,75]
Bipolar ‘Palisade’ RFA	Two parallel electrodes create linear lesions. Targets multiple nerves	Larger continuous strip lesions. Broader nerve coverage	Higher. Requires dual electrode placement. Faster	About 12 months. Reported higher rates of pain relief	[65,87]
Endoscopic-guided RFA	Direct visualization of target nerves with an endoscope	Precise lesioning under visual control	High. Specialized training and equipment are required	About 6-12 months. > 80% patient satisfaction	[66,84]

RFA: Radiofrequency ablation; PRF: Pulsed radiofrequency.

CLINICAL OUTCOMES AND PATIENT-REPORTED BENEFITS

Recent prospective studies and systematic reviews emphasize that while procedural success is measured by pain scores, broader patient-reported outcomes such as quality of life, function, and opioid consumption are increasingly recognized as essential. Beyond reductions in pain scores alone, recent research increasingly highlights improvements in functional capacity, disability indices, and overall quality of life following SI joint interventions. A systematic review of 16 studies also concluded that RFA has clinical benefits in patients with SI joint, however, beyond 1 year, there is a lack of evidence, showing any potential[58]. Another systematic review and meta-analysis demonstrated that RFA techniques, including cooled, pulsed and thermal RFAs, significantly reduced SI joint-associated pain for up to 12 months, without any serious complications[87,88]. Similarly, Xu et al[89] observed that patients receiving RFA had lower disability indices and reduced analgesic requirements compared to those treated with steroid injections. In another large multicenter randomized trial, cooled RFA produced not only significant pain relief at three months, but also better scores in the Oswestry Disability Index (ODI) and EuroQoL-5 compared to standard medical management, reflecting meaningful functional gains and quality of life improvements[7]. Importantly, these benefits have been elongated to repeat RFA procedures with little increase in complications[90]. Similarly, combining intra-articular pulsed RFA with methylprednisolone injection led to sustained improvements in both disability scores and patient-reported global impression of change lasting up to 12 months[91]. Observational studies also support these findings. For instance, Kristoff et al[38] reported that over 60% of patients achieved clinically meaningful improvements in pain and physical function one month after SI joint steroid injection, with benefits persisting in a substantial proportion at three and six months[92]. Notably, recent retrospective data also show that adding lateral branch radiofrequency neurotomy to standard SI joint interventions improves long-term quality of life measures and daily function[93]. Collectively, these findings suggest that future research should measure broader patient-centered benefits besides pain relief, such as mobility, reduced opioid use, and return to daily activities, are as important as raw pain scores for better guide clinical decisions, and should remain key endpoints in future research and clinical practice.

COMPARATIVE ANALYSIS: INJECTIONS VS RFA

A growing body of comparative research highlights that while both steroid injections and RFA help to manage SI joint pain, they differ notably in terms of duration of benefit, functional improvement, complications, and long-term cost-effectiveness (Table 2). Recent randomized trials and observational studies consistently show that RFA techniques, including conventional, cooled, and pulsed RFA, offer longer-lasting pain relief and superior functional outcomes. In a randomized controlled trial, at 1-, 3-, and 6-months post-treatment, ≥ 50% pain relief was achieved in 73%, 60%, and 53% of patients in the RFA group, whereas only 20% of patients in the steroid injection group reported similar relief at one month, and none sustained benefit beyond 3 months[94]. A systematic review and meta-analysis showed that the pain intensity and the disability score were significantly lower in the RFA group at 3 and 6 months than in the group that was treated using steroid injections[89]. In a retrospective study, the estimated mean duration of pain relief was approximately 82 days with RFA compared to 38 days with steroid injections[95]. Similarly, the pulsed RFA technique showed longer sustained benefits and better functional outcomes than intra-articular steroid injections at both 3 and 6 months. One prospective study comparing pulsed RFA with intra-articular methylprednisolone injection reported sustained pain reduction and better ODI scores at six months in the RFA group (mean ODI: 8.0 vs 13.1; P < 0.01), with significantly higher patient-reported global perceived effect[96]. Similarly, a larger comparative study with an 18-month follow-up showed that while both groups had pain reduction at 3 months, RFA maintained a significant advantage at 6, 12, and 18 months compared to steroid injections[97]. Cost-effectiveness analyses further support RFA, particularly newer bipolar RFA approach, which reduced operating time by more than 50%, radiation exposure by over 80%, and cost by more than $1000 per case compared to cooled RFA, while providing significantly better pain outcomes at 3, 6, and 12 months[65]. Moreover, repeat RFA procedures can extend the duration of pain relief and further reduce healthcare utilization and costs[90]. Steroid injections remain valuable for short-term relief, particularly for acute inflammatory flares, with pain relief lasting weeks to a few months. In a prospective study, mean VAS scores decreased from 5.8 at baseline to 3.0 at 6 months, but functional improvement plateaued[35]. RFA, on the other hand, not only prolongs benefit but also achieves greater reduction in analgesic requirements, fewer repeated procedures, and lower long-term healthcare costs. Complication rates remain low for both treatments, but RFA may carry a slightly higher risk of transient neuritis, while injections can rarely lead to infection or steroid-related side effects[87]. Functional improvement mirrors these pain findings: In most comparative studies, patients receiving RFA reported better ODI scores and global satisfaction scores, especially at 6-12 months post-procedure[96,97]. Overall, while SI joint injections are useful for short-term relief and diagnostic confirmation, RFAs, particularly cooled, pulsed, and bipolar approaches, provide longer-lasting pain reduction, better functional outcomes for longer-term, and greater cost-effectiveness, making it the preferred choice for carefully selected patients with chronic SI joint pain instead of conservative care (Table 2).

Table 2 A comparison of sacroiliac joint injections and radiofrequency ablation.

Aspect	Sacroiliac joint injections	Radiofrequency ablation
Primary purpose	Diagnostic and short-term therapeutic relief	Longer-term therapeutic relief
Mechanism	Anti-inflammatory effect from corticosteroids; immediate block from local anesthetic	Thermal lesioning interrupts nociceptive nerve signaling
Typical duration of benefit	Weeks to a few months (often less than 3-6 months)	Several months, median often 6-12 months; repeatable
Functional improvement	Moderate, short-term; ODI scores improve but often plateau by six months	Greater and longer-lasting ODI improvement; higher global perceived effect
Evidence strength	Fair (level III); effective especially for acute flares or inflammatory causes	Moderate (RCTs and meta-analyses); superior to injections for chronic mechanical pain
Ideal patient profile	Acute inflammation, diagnostic uncertainty, or limited comorbidities	Chronic mechanical sacroiliac joint pain with proven response to diagnostic blocks
Repeatability	Readily repeatable; risk accumulates with steroids (e.g., tissue atrophy)	Repeatable, sustained benefit is possible; nerve regeneration may limit duration
Cost-effectiveness	Lower upfront cost; less equipment, higher long-term cost due to repeat procedures	Higher upfront cost, but lower cost per month of pain relief and reduced downstream care utilization
Technical demands	Requires image guidance, but technically straightforward	More complex: Multiple lesion targets, requires skill, and specialized equipment
Risk profile	Low; transient pain flare, bleeding, infection, steroid-related effects	Low; rare neuritis, numbness; similar infection risk when performed properly

RCT: Randomized controlled trial; ODI: Oswestry Disability Index.

SAFETY PROFILE AND COMPLICATIONS

Both SI joint injections and RFA are generally low-risk, recent data clarify their complication profiles. For RFA, the safety profile is quite favorable. Large retrospective analyses report transient local soreness and neuritis as the most frequent complications after RFA, typically resolving within weeks[95]. Although temporary numbness or paresthesia may arise, nerve damage is uncommon with the aid of standardized needle positioning and guided by fluoroscopy or CT[87]. Recent developments in bipolar or cooled RFA methods have not even demonstrated higher complication rates than traditional methods[87]. Complications that are severe, such as infection or motor weakness, are uncommon when the appropriate technique and image guidance are followed[98]. Recent literature demonstrates the safety of SI joint interventions when performed with correct technique and image guidance. In comparison, SI joint injection complication rates are quite low, with most of them confined to the local soreness of short duration, a mild neuritis, or a systemic effect of the steroid used, such as transient hyperglycemia[99]. In addition, steroid injections can be predisposed to systemic risks, including steroid flare, transient hyperglycemia or tissue atrophy, particularly when done repeatedly[99]. Meanwhile, serious adverse events, including infection or neurological deficit, are exceedingly rare. These observations reinforce the need for standardized protocols, careful patient selection, and shared decision-making to mitigate risks while maximizing benefits. However, across large retrospective audits, no major adverse events have been reported, reinforcing the view that SI joint injections and RFA remains minimally invasive, well-tolerated options with low procedural risk when patient selection and procedural techniques are carefully controlled.

EMERGING AND ADJUNCT THERAPIES

Advanced therapies for SI joint pain have gained interest in recent years (Table 3), particularly as alternatives for patients who either fail to respond to conventional injections and RFA or who seek less invasive, biologically driven options. Among these, PRP and mesenchymal stem cells (MSCs) stand out as promising regenerative therapies[100-102]. PRP, which utilizes concentrated autologous growth factors to promote tissue healing and reduce inflammation, remains the most extensively studied biologic option. Clinical studies showed that PRP injections can provide meaningful pain reduction and functional improvement for 3-6 months in patients with chronic SI joint pain unresponsive to standard care[43,103,104]. Prospective single-arm studies also confirm short-term improvement in disability scores, although pain relief often declines slightly by three months[43]. In addition, PRP could also allow decreasing opioid doses and increase the daily function, even up to a year after the procedure[105,106]. However, a lack of standardization and high costs are some of the major barriers. MSC injections are also promising, particularly in patients who have degenerative joint disease or chronic inflammation. MSCs are linked to pain and disability improvement and potential structural repair through cartilage regeneration and an anti-inflammatory pathway[107,108]. Nevertheless, PRP and MSC therapy are still restricted by high cost, non-standardization in preparation, and the limited number of high-quality randomized controlled trials[107,108]. More than biologics, surgical neuromodulation interventions such as pulsed RFA serve as a substitute for pain in the SI joint, which is difficult to treat[109]. As compared to conventional RFA, pulsed radiofrequency (PRF) implements periodic current to modulate nerve activity without the severe effects of thermal lesioning. Small trials and case reports indicate that PRF could achieve significant pain reduction that could last for a few months, even in complex cases, such as SI joint metastases[110,111]. Recent comparative analyses reveal that, though traditional RFA may be better in terms of mitigating pain and disability, PRF is also an appealing, risk-emergence supplement for patients, such as those who cannot tolerate conventional RFA[110,112]. However, effect sizes are generally lower than those in conventional RFA, and evidence remains weaker.

Table 3 A summary of emerging and adjunct therapies for sacroiliac joint pain.

Aspect	Sacroiliac joint injections	Radiofrequency ablation
Primary purpose	Diagnostic and short-term therapeutic relief	Longer-term therapeutic relief
Mechanism	Anti-inflammatory effect from corticosteroids; immediate block from local anesthetic	Thermal lesioning interrupts nociceptive nerve signaling
Typical duration of benefit	Weeks to a few months (often less than 3-6 months)	Several months, median often 6-12 months; repeatable
Functional improvement	Moderate, short-term; ODI scores improve but often plateau by six months	Greater and longer-lasting ODI improvement; higher global perceived effect
Evidence strength	Fair (level III); effective especially for acute flares or inflammatory causes	Moderate (RCTs and meta-analyses); superior to injections for chronic mechanical pain
Ideal patient profile	Acute inflammation, diagnostic uncertainty, or limited comorbidities	Chronic mechanical sacroiliac joint pain with proven response to diagnostic blocks
Repeatability	Readily repeatable; risk accumulates with steroids (e.g., tissue atrophy)	Repeatable, sustained benefit is possible; nerve regeneration may limit duration
Cost-effectiveness	Lower upfront cost; less equipment, higher long-term cost due to repeat procedures	Higher upfront cost, but lower cost per month of pain relief and reduced downstream care utilization
Technical demands	Requires image guidance, but technically straightforward	More complex: Multiple lesion targets, requires skill, and specialized equipment
Risk profile	Low; transient pain flare, bleeding, infection, steroid-related effects	Low; rare neuritis, numbness; similar infection risk when performed properly

ODI: Oswestry Disability Index; RFA: Radiofrequency ablation; RCT: Randomized controlled trials.

Overall, regenerative treatments such as PRP and MSCs, as well as neuromodulation options, including PRF, have the potential to serve as supporting rain to conventional SI joint therapies. Although initial results are positive, more high-level studies are required to determine their long-term effectiveness, cost-effectiveness, and the right choice of patients (Table 3).

ECONOMIC IMPLICATIONS

Beyond clinical efficacy, the economic impact of SI joint interventions is gaining research attention. Recent comparative cost analyses suggest that although RFA incurs higher upfront costs related to equipment and procedural time, it offers superior cost-effectiveness over time by reducing repeat interventions and opioid dependency[89]. Bipolar and cooled RFA have specifically shown the possibility of reducing costs, especially because they take less time to complete and lead to less exposure to radiation[65,87]. On the other hand, a single steroid injection, though more expensive per treatment, might be more expensive in the long run, given that the injections are less effective and are to be repeated more frequently[99]. As value-based care is incorporated into the health care system, these findings indicate the necessity of adopting a careful economic modeling approach that accounts for both direct and indirect costs (including lost productivity) as well as patient-focused outcomes to inform the selection of SI joint intervention strategies.

RECOMMENDTIONS AND FUTURE PROSPECTS

Future studies should target high-quality randomized controlled trials that compare emerging techniques (bipolar, cooled, endoscopic RFA), head-to-head comparison studies of regenerative therapies such as PRP and MSCs with a standard intervention, and long-term studies (> 12 months) to determine durability and the need for repeat procedures. In addition, investigators are urged to examine patient-centered outcomes such as opioid reduction, quality of life, and functional improvement. Such studies would help streamline the patient population and protocol, resulting in more individualized approaches.

CONCLUSION

The SI joint pain is a major cause of low back pain that is complex to diagnose and treat. Management has changed with image-guided diagnostic injections, steroid injections, and RFA. Meanwhile, RFA has lasting effects and is more cost-effective than injections. Future treatment options appear promising for the unresponsive patient with the development of biologic injectable and neuromodulation, awaiting validation. Patient care and outcomes improvement require reliance on evidence-based practice to meet the requirements of rigorous diagnostic algorithms and ongoing research.