Chronic low back pain (LBP) is a common problem without a consistently effective treatment, and patients and providers remain in search of minimally invasive options to provide relief. Radiofrequency denervation (RFD) of the lumbar facet joints is an attractive option as it is minimally invasive and should theoretically provide longer-lasting relief than an injection of steroid or local anesthetic. Unfortunately, results from RCTs have been mixed, and this matches anecdotal clinical experience. Given the mixed results, Dr. Poetscher and his colleagues from Brazil performed a meta-analysis that combined the results of the RCTs comparing lumbar RFD to placebo or steroid injection. They noted that the trials tended to have methodological limitations, but they were able to perform meta-analysis of three RCTs comparing RFD to placebo and two trials comparing RFD to steroid injection. All these analyses focused on improvement on a ten point visual analog pain scale. Compared to both placebo and facet joint steroid injection, RFD resulted in about 2 more points of improvement on a ten point scale, differences that were statistically significant. As a reference point, one study concluded that a 2.5 point improvement represented a “substantial clinical benefit.”1 Formal meta-analysis evaluating functional outcomes was not possible, but two of three trials comparing RFD to placebo reported a significant functional improvement, with the Oswestry Disability Index improving 6.5 to 10 points more with RFD. The authors found no studies demonstrating an improvement in return to work, and there were no cost-effectiveness data available.
While meta-analysis of RCTs is considered the pinnacle of the evidence hierarchy, the authors are quick to point out the methodological limitations of the included studies. They noted that all studies had at least a moderate risk of bias, generally due to problems regarding randomization, blinding, and loss to follow-up. This could lead to selection, performance, detection, and attrition bias. The strength of the conclusions that can be drawn with a meta-analysis or systematic review is based on the quality of the included studies, and in this case the studies had substantial limitations. Additionally, the magnitude of improvement associated with RFD was relatively small. As such, the jury remains out on lumbar RFD. A major factor limiting the success of the procedure is the inability to predict in advance who is going to benefit from the procedure. Given the relatively high failure rate of the procedure, progress on that front is essential if the procedure is going to continue to be used. While many protocols require a response to a medial branch block prior to RFD, it has actually been shown that this is a relatively poor predictor of RFD response. Like most meta-analyses, the authors conclude that future, high quality RCTs are needed, and I can’t agree with them more.
Please read Dr. Poetscher’s article on this topic in the July 15 issue. Does this change how you use lumbar RFD? Let us know by leaving a comment on The Spine Blog.
Adam Pearson, MD, MS
Associate Web Editor
1. Glassman SD, Copay AG, Berven SH, Polly DW, Subach BR, Carreon LY. Defining substantial clinical benefit following lumbar spine arthrodesis. J Bone Joint Surg Am 2008;90:1839-47.