Sacroiliac Joint ComplexPhase 4NCT05409443
Conventional vs Bipolar SIJ RFA for Treatment of Sacroiliac Joint Pain
A Phase 4 study testing Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA) and Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA) in people with Sacroiliac Joint Complex and Low Back Pain, run by University of Utah at 3 sites in United States.
Trial summary
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). Read more about this study
- Who is it for?
- Ages 18 to 90 years
- Conditions the study is for
- Sacroiliac Joint Complex, Low Back Pain
- What is being tested?
- Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA) and Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA)
- Type of treatment
- Injection or infusion, Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- 3 sitesUnited States
- Study dates
- 15 Aug 2022to 10 Mar 2025
- Phase
- Phase 4
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 90 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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).
Who cannot join
- 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.
Show all 15Show fewer
- 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.
Trial locations and contacts
3 sites in 1 country.
United States3 sites
University of Utah Farmington Health Center
Farmington, Utah, 84025
University of Utah Orthopaedic Center
Salt Lake City, Utah, 84108
University of Utah South Jordan Health Center
South Jordan, Utah, 84009
About this study
Official title: Conventional or Bipolar Radiofrequency Ablation for the Treatment of Sacroiliac Joint Pain? The COBRA-SIJ Study, a Double-blinded, Randomized, Comparative Trial.
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.
Read more
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:
- Compare the proportion of participants who report ≥50% relief of pain by Numeric Pain Rating Scale (NPRS) after N-SIJRFA versus C-SIJRFA.
- Compare the proportion of participants who report ≥15-point ODI (Oswestry Disability Index) reduction after N-SIJRFA versus C-SIJRFA.
- 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.
- 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.
- 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.
- Determine the effect of PSN ablation on reducing pain related sleep disturbance as measured by the Pain and Sleep Questionnaire (PSQ-3).
- Compare procedural time requirements between those treated with N-SIJRFA versus C-SIJRFA.
- Report adverse effects.
- Report rates of subsequent interventional healthcare utilization including repeat N-SIJRFA versus C-SIJRFA, SIJ injection, and SIJ fusion.
Read the detailed description
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.
- Conditions
- Sacroiliac Joint Complex, Low Back Pain
- Being tested
- Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA), Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA)
- Keywords
- Sacroiliac Joint
- Medical subject headings
- Low Back Pain
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA)Procedure or surgery
- 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.
Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA)Procedure or surgery
- 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.
| Study group | Role | What they receive |
|---|---|---|
| Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA) | Active comparator | N-SIJRFA - using a bipolar "palisade" technique to create a continuous strip lesion. Receives: Procedure: Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA) |
| Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA) | Active comparator | C-SIJRFA - using conventional monopolar periforaminal technique Receives: Procedure: Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Numeric Pain Rating Score
The number of participants with ≥50% change in their Numeric Pain Rating Scale (NPRS) pain score at the 3-month follow-up assessment.
The NPRS is an 11-point numeric scale ranging from 0 to 10, with zero representing "No pain" and ten representing "worst imaginable pain" Using the numbering system, Participants indicate the number that best describes their pain.
Measured: 3 month
Secondary outcomes (23)
Percent of Relief Using the Numeric Pain Rating Scale
The number of participants with ≥50%, relief of pain by the Numeric Pain Rating Scale (NPRS)
The NPRS is an 11-point numeric scale ranging from 0 to 10, with zero representing "No pain" and ten representing "worst imaginable pain" Using the numbering system, Participants indicate the number that best describes their pain.
Measured: 6 month
Percent of Relief Using the Numeric Pain Rating Scale
The number of participants with ≥50%, relief of pain by the Numeric Pain Rating Scale
The NPRS is an 11-point numeric scale ranging from 0 to 10, with zero representing "No pain" and ten representing "worst imaginable pain" Using the numbering system, Participants indicate the number that best describes their pain.
Measured: 12 month
Percent of Relief Using the Numeric Pain Rating Scale
The percentage of participants with ≥50%, relief of pain by Numeric Pain Rating Scale
The NPRS is an 11-point numeric scale ranging from 0 to 10, with zero representing "No pain" and ten representing "worst imaginable pain" Using the numbering system, Participants indicate the number that best describes their pain.
Measured: 18 month
Percent of Relief Using the Numeric Pain Rating Scale. NOTE: The Study Ended Before Month 24 Data Could be Gathered.
The number of participants with ≥50%, relief of pain by Numeric Pain Rating Scale
The NPRS is an 11-point numeric scale ranging from 0 to 10, with zero representing "No pain" and ten representing "worst imaginable pain" Using the numbering system, Participants indicate the number that best describes their pain.
Measured: 24 month
Oswestry Disability Index (ODI) Reduction
The number of participants who report ≥15-point ODI reduction.
The Oswestry Disability Index (ODI) is a questionnaire used to measure the level of function and disability related to lower back pain. It consists of 10 questions that assess pain intensity, personal care, lifting, walking, sitting, standing, sleeping, sex, social life, and travel.
- Each question has 6 statements, rated from 0 (no disability) to 5 (most severe disability).
- The scores for all questions are added and then multiplied by two to obtain the index score, which ranges from 0 to 100.
- A higher score on the ODI indicates a more severe disability caused by low back pain.
Interpretation of ODI Scores:
- 0% to 20%: Minimal disability.
- 21% to 40%: Moderate disability.
- 41% to 60%: Severe disability.
- 61% to 80%: Crippled.
- 81% to 100%: Severely disabled.
Measured: 3 month
Oswestry Disability Index (ODI) Reduction
The number of participants who report ≥15-point ODI reduction.
The Oswestry Disability Index (ODI) is a questionnaire used to measure the level of function and disability related to lower back pain. It consists of 10 questions that assess pain intensity, personal care, lifting, walking, sitting, standing, sleeping, sex, social life, and travel.
- Each question has 6 statements, rated from 0 (no disability) to 5 (most severe disability).
- The scores for all questions are added and then multiplied by two to obtain the index score, which ranges from 0 to 100.
- A higher score on the ODI indicates a more severe disability caused by low back pain.
Interpretation of ODI Scores:
- 0% to 20%: Minimal disability.
- 21% to 40%: Moderate disability.
- 41% to 60%: Severe disability.
- 61% to 80%: Crippled.
- 81% to 100%: Severely disabled.
Measured: 6 month
Oswestry Disability Index (ODI) Reduction
The number of participants who report ≥15-point ODI reduction
The Oswestry Disability Index (ODI) is a questionnaire used to measure the level of function and disability related to lower back pain. It consists of 10 questions that assess pain intensity, personal care, lifting, walking, sitting, standing, sleeping, sex, social life, and travel.
- Each question has 6 statements, rated from 0 (no disability) to 5 (most severe disability).
- The scores for all questions are added and then multiplied by two to obtain the index score, which ranges from 0 to 100.
- A higher score on the ODI indicates a more severe disability caused by low back pain.
Interpretation of ODI Scores:
- 0% to 20%: Minimal disability.
- 21% to 40%: Moderate disability.
- 41% to 60%: Severe disability.
- 61% to 80%: Crippled.
- 81% to 100%: Severely disabled.
Measured: 12 month
Oswestry Disability Index (ODI) Reduction
The number of participants who report ≥15-point ODI reduction
The Oswestry Disability Index (ODI) is a questionnaire used to measure the level of function and disability related to lower back pain. It consists of 10 questions that assess pain intensity, personal care, lifting, walking, sitting, standing, sleeping, sex, social life, and travel.
- Each question has 6 statements, rated from 0 (no disability) to 5 (most severe disability).
- The scores for all questions are added and then multiplied by two to obtain the index score, which ranges from 0 to 100.
- A higher score on the ODI indicates a more severe disability caused by low back pain.
Interpretation of ODI Scores:
- 0% to 20%: Minimal disability.
- 21% to 40%: Moderate disability.
- 41% to 60%: Severe disability.
- 61% to 80%: Crippled.
- 81% to 100%: Severely disabled.
Measured: 18 month
Oswestry Disability Index (ODI) Reduction NOTE: The Study Ended Before Month 24 Data Could be Gathered.
The number of participants who report ≥15-point ODI reduction
The Oswestry Disability Index (ODI) is a questionnaire used to measure the level of function and disability related to lower back pain. It consists of 10 questions that assess pain intensity, personal care, lifting, walking, sitting, standing, sleeping, sex, social life, and travel.
NOTE: The study ended before month 24 data could be gathered.
- Each question has 6 statements, rated from 0 (no disability) to 5 (most severe disability).
- The scores for all questions are added and then multiplied by two to obtain the index score, which ranges from 0 to 100.
- A higher score on the ODI indicates a more severe disability caused by low back pain.
Interpretation of ODI Scores:
- 0% to 20%: Minimal disability.
- 21% to 40%: Moderate disability.
- 41% to 60%: Severe disability.
- 61% to 80%: Crippled.
- 81% to 100%: Severely disabled.
Measured: 24 month
EQ-5D Improvement
The number of patients with clinically significant improvement in the categorical EuroQol 5 Dimensions tool (EQ-5D) (20) defined by ≥0.03 following treatments
Measured: 3 month
EQ-5D Improvement
The number of patients with clinically significant improvement in the categorical EuroQol 5 Dimensions tool (EQ-5D) (20) defined by ≥0.03 following treatments
Measured: 6 month
EQ-5D Improvement
The number of patients with clinically significant improvement in the categorical EuroQol 5 Dimensions tool (EQ-5D) (20) defined by ≥0.03 following treatments
Measured: 12 month
EQ-5D Improvement
The number of patients with clinically significant improvement in the categorical EuroQol 5 Dimensions tool (EQ-5D) (20) defined by ≥0.03 following treatments
Measured: 18 month
EQ-5D Improvement
The proportion of patients with clinically significant improvement in the categorical EuroQol 5 Dimensions tool (EQ-5D) (20) defined by ≥0.03 following treatments
Measured: 24 month
Patient Global Impression of Change (PGIC) Improvement
The number of participants who report being "improved" or "much improved" on the PGIC scale
Measured: 3 month
PGIC Improvement
The number of participants who report being "improved" or "much improved" on the Patient Global Impression of Change (PGIC) scale
Measured: 6 month
PGIC Improvement
The number of participants who report being "improved" or "much improved" on the Patient Global Impression of Change (PGIC) scale
Measured: 12 month
PGIC Improvement
The number of participants who report being "improved" or "much improved" on the Patient Global Impression of Change (PGIC) scale
Measured: 18 month
PGIC Improvement NOTE: The Study Ended Before Month 24 Data Could be Gathered.
The proportions of participants who report being "improved" or "much improved" on the Patient Global Impression of Change (PGIC) scale
Measured: 24 month
The Pain and Sleep Questionnaire Three-item Index (PSQ-3)
The number of participants who had improvement in pain-related sleep disturbance as measured by the PSQ-3.
This index measures the impact of pain on sleep in chronic pain using 3 questions:
- How often do you have trouble falling asleep because of your back pain?
- How often are you awakened by your back pain during the night?
- How often are you awakened by your back pain in the morning?
There are six answers participants will choose from for each question with a corresponding score: Always=1, Very Frequently = 2, Occasionally = 3, Rarely = 4, Very Rarely = 5 and Never = 6.
A high score indicates that the participant's back pain is not interfering with their sleep. Lower scores mean the participant's back pain is interfering with their sleep.
Measured: 3 Months
The Pain and Sleep Questionnaire Three-Item Index (PSQ-3)
The number of participants who had improvement in pain-related sleep disturbance as measured by the PSQ-3.
This index measures the impact of pain on sleep in chronic pain using 3 questions:
- How often do you have trouble falling asleep because of your back pain?
- How often are you awakened by your back pain during the night?
- How often are you awakened by your back pain in the morning?
There are six answers participants will choose from for each question with a corresponding score: Always=1, Very Frequently = 2, Occasionally = 3, Rarely = 4, Very Rarely = 5 and Never = 6.
A high score indicates that the participant's back pain is not interfering with their sleep. Lower scores mean the participant's back pain is interfering with their sleep.
Measured: 6 Months
The Pain and Sleep Questionnaire Three-Item Index (PSQ-3)
The number of participants who had improvement in pain-related sleep disturbance as measured by the PSQ-3.
This index measures the impact of pain on sleep in chronic pain using 3 questions:
- How often do you have trouble falling asleep because of your back pain?
- How often are you awakened by your back pain during the night?
- How often are you awakened by your back pain in the morning?
There are six answers participants will choose from for each question with a corresponding score: Always=1, Very Frequently = 2, Occasionally = 3, Rarely = 4, Very Rarely = 5 and Never = 6.
A high score indicates that the participant's back pain is not interfering with their sleep. Lower scores mean the participant's back pain is interfering with their sleep.
Measured: 12 Months
The Pain and Sleep Questionnaire Three-Item Index (PSQ-3)
The number of participants who had improvement in pain-related sleep disturbance as measured by the PSQ-3.
This index measures the impact of pain on sleep in chronic pain using 3 questions:
- How often do you have trouble falling asleep because of your back pain?
- How often are you awakened by your back pain during the night?
- How often are you awakened by your back pain in the morning?
There are six answers participants will choose from for each question with a corresponding score: Always=1, Very Frequently = 2, Occasionally = 3, Rarely = 4, Very Rarely = 5 and Never = 6.
A high score indicates that the participant's back pain is not interfering with their sleep. Lower scores mean the participant's back pain is interfering with their sleep.
Measured: 18 Months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted8 Jun 2022
- Study start15 Aug 2022
- Primary completion19 Feb 2025
- Study completion10 Mar 2025
Why it stopped: Due to insurance changes for SIJ RFAs, enrollment was slow. The sponsor decided to end the study.
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (23)Papers the sponsor has linked to this study.
- Other trials for Sacroiliac Joint ComplexStudies of the same condition, open and under way.
- More trials run by University of UtahThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- To compare pain and disability outcomes in patients with confirmed SIJC pain after randomization to either N-SIJRFA or C-SIJRFA.
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Utah
- Sponsor type
- University, hospital or other
- Collaborators
- Stratus Medical, INC
- Responsible party
- Principal investigator, Aaron Conger, University of Utah
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05409443
- Sponsor's protocol ID
- IRB 150067
- Status last verified
- May 2026
- First submitted
- 3 Jun 2022
- Last updated
- 26 Jun 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
GBD 2015 Disease and Injury Incidence and Prevalence Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016 Oct 8;388(10053):1545-1602. doi: 10.1016/S0140-6736(16)31678-6.
PubMed 27733282Cohen SP, Chen Y, Neufeld NJ. Sacroiliac joint pain: a comprehensive review of epidemiology, diagnosis and treatment. Expert Rev Neurother. 2013 Jan;13(1):99-116. doi: 10.1586/ern.12.148.
PubMed 23253394Roberts SL, Burnham RS, Ravichandiran K, Agur AM, Loh EY. Cadaveric study of sacroiliac joint innervation: implications for diagnostic blocks and radiofrequency ablation. Reg Anesth Pain Med. 2014 Nov-Dec;39(6):456-64. doi: 10.1097/AAP.0000000000000156.
PubMed 25304483SOLONEN KA. The sacroiliac joint in the light of anatomical, roentgenological and clinical studies. Acta Orthop Scand Suppl. 1957;27:1-127. No abstract available.
PubMed 13478452Bradley KC. The anatomy of backache. Aust N Z J Surg. 1974 Jul;44(3):227-32. doi: 10.1111/j.1445-2197.1974.tb04409.x. No abstract available.
PubMed 4282245Roberts SL, Stout A, Loh EY, Swain N, Dreyfuss P, Agur AM. Anatomical Comparison of Radiofrequency Ablation Techniques for Sacroiliac Joint Pain. Pain Med. 2018 Oct 1;19(10):1924-1943. doi: 10.1093/pm/pnx329.
PubMed 29415262Shih CL, Shen PC, Lu CC, Liu ZM, Tien YC, Huang PJ, Chou SH. A comparison of efficacy among different radiofrequency ablation techniques for the treatment of lumbar facet joint and sacroiliac joint pain: A systematic review and meta-analysis. Clin Neurol Neurosurg. 2020 Aug;195:105854. doi: 10.1016/j.clineuro.2020.105854. Epub 2020 Apr 19.
PubMed 32353665Sahoo RK, Das G, Pathak L, Dutta D, Roy C, Bhatia A. Cryoneurolysis of Innervation to Sacroiliac Joints: Technical Description and Initial Results-A Case Series. A A Pract. 2021 Mar 30;15(4):e01427. doi: 10.1213/XAA.0000000000001427.
PubMed 33783380Nouer Frederico T, Ferraro LHC, Lemos JD, Sakata RK. Chemical neurolysis of the lateral branches of the sacral dorsal rami for the treatment of chronic pain in the sacroiliac joint: Case report and description of the technique. Pain Pract. 2022 Jan;22(1):134-136. doi: 10.1111/papr.13046. Epub 2021 Jun 25. No abstract available.
PubMed 34077624Ibrahim R, Telfeian AE, Gohlke K, Decker O. Endoscopic Radiofrequency Treatment of the Sacroiliac Joint Complex for Low Back Pain: A Prospective Study with a 2-Year Follow-Up. Pain Physician. 2019 Mar;22(2):E111-E118.
PubMed 30921988Najafi A, Sartoretti E, Binkert CA. Sacroiliac Joint Ablation Using MR-HIFU. Cardiovasc Intervent Radiol. 2019 Sep;42(9):1363-1365. doi: 10.1007/s00270-019-02263-0. Epub 2019 Jun 11.
PubMed 31187230Bogduk N. Commentary on King W, Ahmed S, Baisden J, Patel N, MacVicar J, Kennedy DJ. Diagnosis of posterior sacroiliac complex pain: a systematic review with comprehensive analysis of the published data. Pain Med. 2015 Feb;16(2):222-4. doi: 10.1111/pme.12615. Epub 2014 Nov 5. No abstract available.
PubMed 25371349Cohen SP, Strassels SA, Kurihara C, Crooks MT, Erdek MA, Forsythe A, Marcuson M. Outcome predictors for sacroiliac joint (lateral branch) radiofrequency denervation. Reg Anesth Pain Med. 2009 May-Jun;34(3):206-14. doi: 10.1097/AAP.0b013e3181958f4b.
PubMed 19587617Tinnirello A, Barbieri S, Todeschini M, Marchesini M. Conventional (Simplicity III) and Cooled (SInergy) Radiofrequency for Sacroiliac Joint Denervation: One-Year Retrospective Study Comparing Two Devices. Pain Med. 2017 Sep 1;18(9):1731-1744. doi: 10.1093/pm/pnw333.
PubMed 28340063Cheng J, Pope JE, Dalton JE, Cheng O, Bensitel A. Comparative outcomes of cooled versus traditional radiofrequency ablation of the lateral branches for sacroiliac joint pain. Clin J Pain. 2013 Feb;29(2):132-7. doi: 10.1097/AJP.0b013e3182490a17.
PubMed 22688606
Study at a glance
From the registry record, last updated by the sponsor on 26 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Conventional or Bipolar Radiofrequency Ablation for the Treatment of Sacroiliac Joint Pain? The COBRA-SIJ Study, a Double-blinded, Randomized, Comparative Trial.
- ClinicalTrials.gov ID
- NCT05409443
- Acronym / sponsor ID
- IRB 150067
- Conditions
- Sacroiliac Joint Complex, Low Back Pain
- Keywords
- Sacroiliac Joint
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- TerminatedReason stopped: Due to insurance changes for SIJ RFAs, enrollment was slow. The sponsor decided to end the study.
- Enrolment
- 20 participants (actual)
- Lead sponsor
- University of UtahUniversity, hospital or other
- Collaborators
- Stratus Medical, INC
- Study start
- 15 Aug 2022 (actual)
- Primary completion
- 19 Feb 2025 (actual)
- Study completion
- 10 Mar 2025 (actual)
- First posted
- 8 Jun 2022 (actual)
- Results
- Posted 26 Jun 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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:
- Compare the proportion of participants who report ≥50% relief of pain by Numeric Pain Rating Scale (NPRS) after N-SIJRFA versus C-SIJRFA.
- Compare the proportion of participants who report ≥15-point ODI (Oswestry Disability Index) reduction after N-SIJRFA versus C-SIJRFA.
- 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.
- 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.
- 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.
- Determine the effect of PSN ablation on reducing pain related sleep disturbance as measured by the Pain and Sleep Questionnaire (PSQ-3).
- Compare procedural time requirements between those treated with N-SIJRFA versus C-SIJRFA.
- Report adverse effects.
- Report rates of subsequent interventional healthcare utilization including repeat N-SIJRFA versus C-SIJRFA, SIJ injection, and SIJ fusion.
Detailed description
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
- Model description
- To compare pain and disability outcomes in patients with confirmed SIJC pain after randomization to either N-SIJRFA or C-SIJRFA.
| Arm | Type | Receives |
|---|---|---|
| Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA) | Active comparator | Procedure: Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA)N-SIJRFA - using a bipolar "palisade" technique to create a continuous strip lesion. |
| Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA) | Active comparator | Procedure: Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA)C-SIJRFA - using conventional monopolar periforaminal technique |
Who may qualify
- Ages
- 18 to 90 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- 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).
Key exclusion criteria (15 listed)
- 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).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| 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 or surgery | Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA) |
| 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. | Procedure or surgery | Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA) |
Primary outcome
Change in Numeric Pain Rating Score
Time frame: 3 month
The number of participants with ≥50% change in their Numeric Pain Rating Scale (NPRS) pain score at the 3-month follow-up assessment. The NPRS is an 11-point numeric scale ranging from 0 to 10, with zero representing "No pain" and ten representing "worst imaginable pain" Using the numbering system, Participants indicate the number that best describes their pain.
23 secondary outcomes
Percent of Relief Using the Numeric Pain Rating Scale
Time frame: 6 month
Percent of Relief Using the Numeric Pain Rating Scale
Time frame: 12 month
Percent of Relief Using the Numeric Pain Rating Scale
Time frame: 18 month
Percent of Relief Using the Numeric Pain Rating Scale. NOTE: The Study Ended Before Month 24 Data Could be Gathered.
Time frame: 24 month
Oswestry Disability Index (ODI) Reduction
Time frame: 3 month
Oswestry Disability Index (ODI) Reduction
Time frame: 6 month
Oswestry Disability Index (ODI) Reduction
Time frame: 12 month
Oswestry Disability Index (ODI) Reduction
Time frame: 18 month
Oswestry Disability Index (ODI) Reduction NOTE: The Study Ended Before Month 24 Data Could be Gathered.
Time frame: 24 month
EQ-5D Improvement
Time frame: 3 month
EQ-5D Improvement
Time frame: 6 month
EQ-5D Improvement
Time frame: 12 month
EQ-5D Improvement
Time frame: 18 month
EQ-5D Improvement
Time frame: 24 month
Patient Global Impression of Change (PGIC) Improvement
Time frame: 3 month
PGIC Improvement
Time frame: 6 month
PGIC Improvement
Time frame: 12 month
PGIC Improvement
Time frame: 18 month
PGIC Improvement NOTE: The Study Ended Before Month 24 Data Could be Gathered.
Time frame: 24 month
The Pain and Sleep Questionnaire Three-item Index (PSQ-3)
Time frame: 3 Months
The Pain and Sleep Questionnaire Three-Item Index (PSQ-3)
Time frame: 6 Months
The Pain and Sleep Questionnaire Three-Item Index (PSQ-3)
Time frame: 12 Months
The Pain and Sleep Questionnaire Three-Item Index (PSQ-3)
Time frame: 18 Months
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 Jun 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Background: PubMed 27733282GBD 2015 Disease and Injury Incidence and Prevalence Collaborators. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. 2016 Oct 8;388(10053):1545-1602. doi: 10.1016/S0140-6736(16)31678-6.
- Background: PubMed 23253394Cohen SP, Chen Y, Neufeld NJ. Sacroiliac joint pain: a comprehensive review of epidemiology, diagnosis and treatment. Expert Rev Neurother. 2013 Jan;13(1):99-116. doi: 10.1586/ern.12.148.
- Background: PubMed 25304483Roberts SL, Burnham RS, Ravichandiran K, Agur AM, Loh EY. Cadaveric study of sacroiliac joint innervation: implications for diagnostic blocks and radiofrequency ablation. Reg Anesth Pain Med. 2014 Nov-Dec;39(6):456-64. doi: 10.1097/AAP.0000000000000156.
- Background: PubMed 13478452SOLONEN KA. The sacroiliac joint in the light of anatomical, roentgenological and clinical studies. Acta Orthop Scand Suppl. 1957;27:1-127. No abstract available.
- Background: PubMed 4282245Bradley KC. The anatomy of backache. Aust N Z J Surg. 1974 Jul;44(3):227-32. doi: 10.1111/j.1445-2197.1974.tb04409.x. No abstract available.
- Background: PubMed 29415262Roberts SL, Stout A, Loh EY, Swain N, Dreyfuss P, Agur AM. Anatomical Comparison of Radiofrequency Ablation Techniques for Sacroiliac Joint Pain. Pain Med. 2018 Oct 1;19(10):1924-1943. doi: 10.1093/pm/pnx329.
- Background: PubMed 32353665Shih CL, Shen PC, Lu CC, Liu ZM, Tien YC, Huang PJ, Chou SH. A comparison of efficacy among different radiofrequency ablation techniques for the treatment of lumbar facet joint and sacroiliac joint pain: A systematic review and meta-analysis. Clin Neurol Neurosurg. 2020 Aug;195:105854. doi: 10.1016/j.clineuro.2020.105854. Epub 2020 Apr 19.
- Background: PubMed 33783380Sahoo RK, Das G, Pathak L, Dutta D, Roy C, Bhatia A. Cryoneurolysis of Innervation to Sacroiliac Joints: Technical Description and Initial Results-A Case Series. A A Pract. 2021 Mar 30;15(4):e01427. doi: 10.1213/XAA.0000000000001427.
- Background: PubMed 34077624Nouer Frederico T, Ferraro LHC, Lemos JD, Sakata RK. Chemical neurolysis of the lateral branches of the sacral dorsal rami for the treatment of chronic pain in the sacroiliac joint: Case report and description of the technique. Pain Pract. 2022 Jan;22(1):134-136. doi: 10.1111/papr.13046. Epub 2021 Jun 25. No abstract available.
- Background: PubMed 30921988Ibrahim R, Telfeian AE, Gohlke K, Decker O. Endoscopic Radiofrequency Treatment of the Sacroiliac Joint Complex for Low Back Pain: A Prospective Study with a 2-Year Follow-Up. Pain Physician. 2019 Mar;22(2):E111-E118.
- Background: PubMed 31187230Najafi A, Sartoretti E, Binkert CA. Sacroiliac Joint Ablation Using MR-HIFU. Cardiovasc Intervent Radiol. 2019 Sep;42(9):1363-1365. doi: 10.1007/s00270-019-02263-0. Epub 2019 Jun 11.
- Background: PubMed 25371349Bogduk N. Commentary on King W, Ahmed S, Baisden J, Patel N, MacVicar J, Kennedy DJ. Diagnosis of posterior sacroiliac complex pain: a systematic review with comprehensive analysis of the published data. Pain Med. 2015 Feb;16(2):222-4. doi: 10.1111/pme.12615. Epub 2014 Nov 5. No abstract available.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Nimbus Sacroiliac Joint Radiofrequency Ablation (N-SIJRFA) and Conventional Sacroiliac Joint Radiofrequency Ablation (C-SIJRFA) in people with Sacroiliac Joint Complex and Low Back Pain, run by University of Utah at 3 sites in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 15 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: stopped early, as of the sponsor's last update on 26 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
Yes. Results are posted in the registry (first posted 26 Jun 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Numeric Pain Rating Score (time frame: 3 month). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05409443, which also lists 23 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Jun 2026.