A Superiority Trial of Radiofrequency Ablation for Low Back Pain (ASTRAL)

Low back pain is the #1 contributor to years lived with disability, driven mainly by chronic low back pain (CLBP; pain lasting ≥3 months). An obstacle to reducing the societal burden of CLBP is that most treatments have only small magnitude treatment effects (5-10% improvements in functional limitations and pain).

Lumbar radiofrequency ablation (LRFA) is a minimally invasive procedure that is widely performed for CLBP. It can be used in patients for whom CLBP is isolated to the lumbar facet joints, defined by pain relief (“positive responses”) with local anesthetic medial branch blocks (MBBs) to the medial branch nerves. LRFA

applies a thermal lesion to these nerves, temporarily reducing or eliminating CLBP. Unlike most CLBP treatments, LRFA can result in large-magnitude improvements in well-selected patients. However, LRFA is neurodestructive, has potential adverse effects, and there is conflicting evidence regarding its effectiveness.

While some randomized controlled trials (RCTs) and systematic reviews support the effectiveness of LRFA, multiple RCTs of LRFA show no significant effects, including the largest RCT to date. Experts have noted that those RCTs showing no effects may be explained by (1) poor LRFA technique insufficient to adequately

lesion the medial branches, and (2) suboptimal clinical selection criteria for identifying LRFA candidates. The most stringent evidence-based guidelines for LRFA technique and patient selection are those of the Spine Intervention Society (SIS). The SIS guidelines mandate various aspects of technique to optimize medial

branch lesioning and consequent improvements in CLBP. They also include stringent clinical screening criteria for determining appropriate LRFA candidates, such as requiring ≥80% pain improvement to define positive MBB responses, and 2 separate sets of comparative MBBs with low anesthetic volume (