Clinical Trial Finder

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.

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.

Arms

Active Comparator: Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA)

N-SIJRFA - using a bipolar "palisade" technique to create a continuous strip lesion.

Active Comparator: Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA)

C-SIJRFA - using conventional monopolar periforaminal technique

Interventions

Procedure: - Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA)

- Electrodes are positioned along the lateral sacral crest lateral to the inflection points of the S1, S2 and S3 lateral foraminal walls along first to third transverse sacral tubercles maintaining a craniocaudal line with an interelectrode distance of no more than 15mm. - The appropriate locations are confirmed in both AP and lateral views and the tines are deployed. Following injection of lidocaine, lesions are performed at 85 degrees Celsius for 180 seconds at each site for bipolar sites and 80 degrees Celsius for 90 seconds for the monopolar site. Following ablation, the tines are retracted for all electrodes prior to removal.

Procedure: - Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA)

- To target the L4 medial branch and L5 dorsal ramus, an electrode will be placed in parallel between the junction of the L5 transverse process and superior articular process and the sacral ala and S1 superior articular process. - A periforaminal electrode position will be used to target the lateral branches from S1 to S3. An 22-G cannula with a 5-mm exposed tip will be directed to a location approximately 3-5mm lateral to the PSFA of S1, S2, and S3. The "analog clock" positions for the probes at S1 and S2 levels will be 1:00, 3:00, and 5:30 on the right, and 6:30, 9:00, and 11:00 on the left. For the S3 level the positions at 1:30 and 4:30 on the right, and 7:30 and 10:30 on the left will be used (6,18). - The appropriate locations are confirmed in both AP and lateral views. Following injection of lidocaine, monopolar RFA is performed for 90 seconds at 80 degrees Celsius at each location.