A Superiority Trial of Radiofrequency Ablation for Low Back Pain

ASTRAL: A Superiority Trial of Radiofrequency Ablation for Low Back Pain

The purpose of the ASTRAL Study is to evaluate the effectiveness of LRFA (Lumbar radiofrequency ablation) against a control procedure. The ASTRAL Study will enroll individuals with chronic low back pain (CLBP) and randomly assign them to one of three groups: lumbar radiofrequency ablation using conventional electrodes placed parallel to the medial branch nerves (LRFA-C), lumbar radiofrequency ablation using multi-tined electrodes placed perpendicular to the medial branch nerves (LRFA-M), or a simulated radiofrequency ablation procedure.

Low back pain is the #1 contributor to years lived with disability in the United States. Lumbar radiofrequency ablation (LRFA) is a minimally invasive procedure for chronic low back pain (CLBP) commonly used in the US, but the effectiveness of this procedure has yet to be fully explored, and a definitive, double-blind, multicenter RCT demonstrating a clinically relevant benefit of LRFA over a control procedure has yet to be conducted. LRFA-C involves placing a conventional radiofrequency electrode parallel to each targeted medial branch nerve, administering local anesthetic, and confirming placement with nerve stimulation as per standard clinical practice. LRFA-M follows the same processes as LRFA-C, albeit a multi-tined radiofrequency electrode will be used to create larger lesions, and the electrode will be positioned perpendicular to the medial branch nerve. The primary objectives of ASTRAL are to 1) compare the effectiveness of LRFA-C with a simulated LRFA control procedure for improving back-related functional limitations, and 2) compare the effectiveness of LRFA-M with a simulated LRFA control procedure for improving back-related functional limitations. The ASTRAL Study also aims to explore the difference in effectiveness, procedure duration, radiation dosage, and pain intensity between LRFA-C and LRFA-M.

Inclusion Criteria:

• Age ≥18 years
• CLBP of duration ≥ 3 months. Low back pain is defined as occurring between the lower posterior margin of the rib cage and the horizontal gluteal fold.
• Low back pain intensity numerical rating scale (NRS) ≥ 4 with one of the following prior to LRFA: 1) Current low back pain intensity, 2) Average pain over past 7 days, OR 3) Pain intensity without specification of recall period
• Has had conservative treatments for CLBP (physical therapy, exercise therapy, spinal manipulation, massage, acupuncture, etc.)
• Candidate for unilateral LRFA (L1-S1 joints; ≤3 levels); or bilateral LRFA (L1-S1 joints; ≤2 levels)
• 'Positive responses' (≥80% improvement of CLBP pain intensity) to 2 sets of anesthetic-only MBBs (≤0.5cc of local anesthetic)
• Able to read, speak, and understand English sufficient for informed consent purposes
• Stated willingness to comply with all study processes and availability for the duration of the study, and provision of a signed and dated informed consent form

Exclusion Criteria:

• CLBP attributed primarily to specific spine-related conditions (radiculopathy, lumbar spinal stenosis, spinal instability), 'red flag' conditions (infection / malignancy / fracture), and/or inflammatory arthritis (RA, SpA, etc.)
• Prior LRFA
• Prior lumbar facet joint (intra-articular or medial branch nerve) corticosteroid injections (past 6 months)
• Surgery involving one or more of spinal levels where LRFA is to be performed, in the past 2 years
• Lumbar fusion involving the spinal levels where LRFA is considered, at any time
• Prior known severe lumbar central canal stenosis on MRI as defined by Lee (2011): obliteration of the cerebrospinal fluid (CSF), and marked compression of dural sac, and none of the cauda equina can be visually separated from each other. No new MRIs would be done specifically as part of the study processes.
• Prior formal diagnosis of fibromyalgia by a rheumatologist (diagnosis by primary care physician or pain medicine specialist is not sufficient)
• Unstable psychiatric or terminal medical conditions that would limit study participation and the likelihood of follow-up for 12 months post-randomization
• Pregnancy, being a prisoner, or having a prior formal diagnosis of cognitive impairment by a neuropsychologist or neurologist, confirmed by health record documentation
• Participant report of prior formal diagnosis of cognitive impairment by a neuropsychologist or neurologist can be obtained, but participant-reported cognitive impairment by a neuropsychologist or neurologist must be confirmed via health record documentation. No new evaluations for cognitive impairment would be done specifically as part of the study processes.
• Contraindication to local anesthetic, corticosteroid, or any aspects of LRFA
• Cannot reach MBB targets with 11.9cm needle
• Major planned life events over the next 4 months that might interfere with study participation (e.g., major abdominal or chest surgery or extended vacation)