RecruitingNot ApplicableNCT07222462

A Superiority Trial of Radiofrequency Ablation for Low Back Pain

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

Sponsor

University of Washington

Enrollment

300 participants

Start Date

Feb 4, 2026

Study Type

INTERVENTIONAL

Conditions

Chronic Low Back Pain (CLBP)

Summary

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.

Eligibility

Min Age: 18 Years

Inclusion Criteria8

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 Criteria13

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)

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Interventions

PROCEDURELumbar radiofrequency ablation with conventional electrodes (LRFA-C)

LRFA-C positions a conventional thermal radiofrequency electrode at each medial branch nerve to be ablated and administers local anesthetic to the nerve. Parallel placement of the electrode will be achieved. Once the electrode is in correct position and nerve stimulation testing done, a radiofrequency lesion is generated, achieving a temperature 80°C-90°C, lasting 90-120 seconds. If a 16-gauge or larger electrode is used, no second lesion needs to be made. If an 18-gauge electrode is used, the electrode will be repositioned slightly by withdrawing or repositioning parallel to the 1st ablation site, or by rotating the electrode, and a 2nd lesion made. Local corticosteroid injection is then performed at the ablation site at a total corticosteroid equivalent of 80mg triamcinolone, divided equally among the medial branches targeted; this dose can be reduced as needed according to the medical status of each patient. This process is applied for each medial branch nerve targeted.

PROCEDURELumbar radiofrequency ablation with multi-tined electrodes (LRFA-M)

LRFA-M positions a multi-tined thermal radiofrequency electrode at each medial branch nerve to be ablated and administers local anesthetic to the nerve. However, the multi-tined thermal radiofrequency electrode is thought to achieve larger lesions and thus does not require parallel electrode placement; the LRFA-M electrode will be placed perpendicular to the medial branch nerve. All subsequent processes are the same as for LRFA-C. This includes local corticosteroid injection at each ablation site at a total corticosteroid equivalent of 80mg triamcinolone, divided equally among the medial branches targeted; this dose can be reduced as needed according to the medical status of each patient. This process is applied for each medial branch nerve targeted.

PROCEDURESimulated lumbar radiofrequency ablation

The simulated LRFA control procedure will be performed in an identical fashion to LRFA-M, except 1) after electrode positioning, a neurodestructive lesion will not be made; and 2) a pre-recorded audio recording of the procedure will be played (out of view of the patient, immediately adjacent to the RFA machine) in order to simulate the beeping and other sounds of the machine and to ensure the appropriate length of the simulated procedure. The electrode will remain in place for the 90-120 seconds that lesioning would normally take, but without heat application. The electrode will then be repositioned to simulate a second lesion, also of duration 90-120 seconds. Local corticosteroid injection is then performed at the ablation site at a total corticosteroid equivalent of 80mg triamcinolone, divided equally among the medial branches targeted; this dose can be reduced as needed according to the medical status of each patient. This process is applied for each medial branch nerve targeted.