Conventional vs Bipolar SIJ RFA for Treatment of Sacroiliac Joint Pain

Specific Aims The sacroiliac joint complex (SIJC) is a diathrodial, synovial joint and posterior ligamentous network that receives both anterior innervation from the lumbosacral plexus as well as posterior sensory innervation via the posterior sacral network (PSN). The PSN is comprised by the lateral branches S1-S3 posterior rami, with variable contributions from S4 lateral branch, L4 medial branch, and L5 dorsal ramus. Pain signals originating from the SIJC can be interrupted with image-guided percutaneous radiofrequency ablation (RFA) of the PSN, thereby reducing pain and disability in carefully selected patients.

A prior systematic review estimated that 32-89% of patients achieve at least 50% pain relief for six months after some type of PSN ablation. Many experts suspect that heterogenous RFA techniques and technology are responsible for the variable success rates seen across published studies. Cadaveric work suggests that targeting the PSN with a large bipolar strip lesions would result in \>95% PSN neural capture compared to a smaller lesion produced by a conventional, monopolar, periforaminal RFA technique which may capture as low as 2.5% of the PSN. Nimbus is a commonly used multi-tined RFA probe whose large bipolar lesion size make it an ideal option for complete PSN neural ablation. Both the Nimbus (N-SIJRFA) and conventional (C-SIJRFA) techniques and technologies are commonly used; however, there are no prospective RCT's comparing them, and the clinical significance remains unknown.

Problem: There are no randomized controlled trials comparing novel technologies like N-SIJRFA to C-SIJRFA.

Purpose: To compare pain and disability outcomes in patients with confirmed SIJC pain after randomization to either N-SIJRFA or C-SIJRFA.

Central Hypothesis: N-SIJRFA will be more effective in improving pain and function compared to patients treated with C-SIJRFA at 3, 6, 12, 18, and 24 months.

Specific Aims:

1. Compare the proportion of participants who report ≥50% relief of pain by Numeric Pain Rating Scale (NPRS) after N-SIJRFA versus C-SIJRFA.
2. Compare the proportion of participants who report ≥15-point ODI (Oswestry Disability Index) reduction after N-SIJRFA versus C-SIJRFA.
3. Compare the proportion of participants with clinically significant improvement in the categorical EuroQol 5 Dimensions tool (EQ-5D) defined by ≥0.03, after N-SIJRFA versus C-SIJRFA.
4. Compare the proportions of participants who report being "improved" or "much improved" on the Patient Global Impression of Change (PGIC) scale after N-SIJRFA versus C-SIJRFA.
5. Evaluate the differences in success rates for pain improvement, functional improvement and satisfaction in those experiencing ≥ 50%, ≥ 80%, and 100% pain relief after either prognostic PSN blocks or intra-articular (IA) sacroiliac joint (SIJ) injections.
6. Determine the effect of PSN ablation on reducing pain related sleep disturbance as measured by the Pain and Sleep Questionnaire (PSQ-3).
7. Compare procedural time requirements between those treated with N-SIJRFA versus C-SIJRFA.
8. Report adverse effects.
9. Report rates of subsequent interventional healthcare utilization including repeat N-SIJRFA versus C-SIJRFA, SIJ injection, and SIJ fusion.

Low back pain affects the majority of individuals at some time in their lives. The estimated point prevalence of low back pain in 2015 was 7.3%, indicating that 540 million may be affected at any given time (1). The etiology of low back pain may be multifactorial but commonly is often attributed to nociception arising sacroiliac joint complex (SIJC) in as many as 15-30% of patients (2). The SIJC is a diathrodial, synovial joint that receives both anterior innervation from the lumbosacral plexus as well as posterior sensory innervation via the posterior sacral network (PSN) (3). The PSN is comprised by the lateral branches S1-S3 posterior rami, with variable contributions from S4 lateral branch, L4 medial branch, and L5 dorsal ramus (3-6). These have been targeted for neurotomy most commonly with image-guided percutaneous radiofrequency ablation (RFA) (7), but also with percutaneous cryoneurolysis (8), chemical neurolysis (9), endoscopic-guided RFA (10), and MRI high frequency ultrasound treatment (MRI-HIFU) (11).

Prior systematic review has suggested that 32-89% of patients may achieve at least 50% pain relief for six months, while 11-44% of patients achieved 100% pain relief for the same period (12). Although elements of patient selection likely affect this estimate (13), studies have used a variety of different RFA techniques to target the PSN which also may impact success rates. Few studies have directly compared these techniques, but cadaveric work has suggested that targeting the PSN with bipolar strip lesions results in substantially higher rates of neural capture compared to periforaminal RFA performed with conventional monopolar electrodes (6). Further, the rate of complete neural capture with a periforaminal conventional monopolar RFA may be as low as 12.5%, which is perhaps one reason why some clinical studies have shown increased probability of success in groups treated with technologies known to create larger lesions (13,14). Similar effectiveness has been observed for periforaminal techniques with both conventional monopolar compared to larger cooled monopolar lesions (15), as well as between large continuous-lesion multi-electrode lesioning compared to periforaminal conventional monopolar technique (16). However, no study has directly compared a bipolar strip lesion using a "palisade" technique (N-SIJRFA) to a conventional monopolar periforaminal method, the latter of which is used commonly in many practice settings.

The primary purpose of the current study is to evaluate the effectiveness of RFA of the PSN using a bipolar "palisade" technique to create a continuous strip lesion compared to conventional monopolar periforaminal technique in the treatment of patients with sacroiliac joint complex pain. Given the findings of recent cadaveric studies, the results of the proposed work may substantially impact the current treatment paradigm for PSN neurotomy.

Eligibility Criteria:
Inclusion Criteria:

* Adult participants aged 18-90 years old with at least 3 months of low back pain who have not responded to at least 3 months of conservative treatment.
* 7-day average NPRS for low back pain of at least 4/10 at baseline
* Pain relieved by at least 50% by either a fluoroscopically-guided intraarticular sacroiliac joint injection including a local anesthetic and a fluoroscopically-guided PSN block or dual fluoroscopically-guided PSN blocks.
* Participants capable of understanding and providing consent in English and capable of complying with the outcome instruments used.

A pain diary with appropriate diagnostic categories of relief (100% relief, 80-99% relief, etc.), will be provided. Duration of pain relief will not be used as it has been shown to only marginally improve diagnostic confidence (17).

Exclusion Criteria:

* History of SIJ fusion.
* Prior SIJ RFA procedure
* Symptomatic hip osteoarthritis
* Active lumbar radicular pain
* Evidence of hardware loosening (in participants with history lumbar or lumbosacral fusion).
* Presence of pacemaker or neurostimulator.
* Chronic widespread pain or somatoform disorder (e.g., fibromyalgia).
* More than 50 mg morphine-equivalent per day opioid use.
* Active bacterial infection or treatment of infection with antibiotics within the past 4 weeks.
* Medical conditions causing significant functional disability (e.g., stroke, COPD).
* Addictive behavior, severe clinical depression, or psychotic features.
* History of anaphylactic reaction to any medication used.
* Those receiving remuneration for their pain treatment (e.g., disability, worker's compensation).
* Those involved in active litigation relevant to their pain.
* The participant is incarcerated.