Interspinous Spacer Relieves Painful Symptoms of Lumbar Spinal Stenosis Study Shows
Commentary by Harel Deutsch, MD and Greger Lønne, MD, PhD
The FDA-approved Superion interspinous spacer provided similar relief from symptoms of neurogenic claudication when compared to historical data from studies of decompressive laminectomy in the treatment of lumbar spinal stenosis, researchers reported in Expert Review of Medical Devices.
“The study shows the Superion is effective in treating some symptoms of lumbar spinal stenosis,” said coauthor Harel Deutsch, MD, Associate Professor of Neurosurgery at Rush University Medical Center, Chicago, IL. “The study implies that the results with Superion or interspinous spacers may be similar to a lumbar laminectomy in some patients. Reoperation rates were noted to be higher in the Superion group.”
The findings are based on data from 190 patients implanted with the Superion device as part of a 2-year prospective, randomized trial, as well as a compilation of data from 19 studies of decompressive laminectomy in which at least one clinical outcomes was reported a minimum of 12 months after surgery. A total of 1,045 patients were represented in the 19 studies.
Preoperatively, the laminectomy group showed slightly higher levels of pain, functional impairment, and condition-specific dysfunction, the authors noted. At 2-years postoperatively, both treatment groups showed “clinically significant gains” across all outcome measures (Table), the authors reported.
“Statistical significance was not assessed in this paper since it compares the results from the prospective study on the results of Superion versus historical studies reporting the effectiveness of a lumbar laminectomy,” Dr. Deutsch explained. “Because the two groups are so different, the authors believed assessing statistical significance was not appropriate in this study.”
“The study implies that the benefits of laminectomy and the Superion device may be similar, especially in some patients with moderate stenosis,” Dr. Deutsch said. “Patients with severe stenosis are probably better candidates for a laminectomy. The risks of surgery in the Superion device interspinous spacer device are much less since the dura and nerve roots are not exposed during the procedure, and the procedure can even be done with local anesthesia rather than general anesthesia. This may be especially important in patients who are not eligible for laminectomy surgery due to other medical issues.”
The authors noted that two meta-analyses of treatments for spinal stenosis noted higher rates of reoperation with interspinous spacers than with decompressive laminectomy, but added that the two interventions have differing indications for use; laminectomy may be best used in patients who are more severely stenotic. They also noted that reoperation with these two procedures poses different risks, as laminectomy requires a wider surgical exposure and dissection of extensive scar tissue, while spacer removal has minimal tissue disruption.
Greger Lønne, MD, PhD
Orthopedic Spine Surgeon
Department of Orthopedic Surgery
Innlandet Hospital Trust
This article by Lauryssen et al fully demonstrates a problematic issue concerning interspinous process decompression devices (IPD) in surgical treatment of lumbar spinal stenosis (LSS). No medical company will campaign for, or invest money in, a treatment in which no implants are sold. We will never see an advertisement for lumbar decompression from a company selling devices, simply because that undermines their sale.
In a paper like this, some issues are illuminated, and others are left in the dark. In my opinion, this paper minimalizes the challenge of the high reoperation rate demonstrated in several studies,1-3 that together with the cost of the device makes this a significantly more expensive method than minimally invasive decompression,4,5 without being superior in effect.1,6 (Even if the name “Superion” indicates something else.) And it over-communicates the risk of surgical decompression—dural tears being the most common—since the outcome also seems to be good in this patient group.7,8
The authors correctly state in the beginning of the paper that one of the major ramifications of the “…increasing proportion of individuals living to advanced age is the impact and burden on the health care system associated with age-related degeneration of the musculoskeletal system." But are more expensive methods with higher reoperation rates the answer to this challenge?
Moreover, the authors list 19 different papers, 13 using the Oswestry Disability Index (ODI) as an outcome measure, without mentioning that this questionnaire comes in different versions, with some different questions. Different ODIs cannot directly be compared without any adjustments, or at least a comment on that.9 Back pain and leg pain is measured by visual analogue scale or numeric rate scale in different ways. Comparing different ways of measuring pain has shown to be less problematic, but still are comment worthy. Comparing different studies with different inclusion and exclusion criteria, with different study design and different adjustments, without fully discussing the implication of these differences, is conspicuous by the absence.
Furthermore, the authors claim in the Expert Commentary that “Interspinous spacers fill a distinct treatment gap in the continuum of care for patients with moderate degenerative lumbar spinal stenosis.” The understanding and treatment of LSS has been known for more than 50 years.10 If this gap is so distinct, why hasn’t it been recognized earlier? Or is this treatment gap only expedient to define now that one can make money on it?
However, I don’t say that IPDs do not have any role in treatment of lumbar spinal stenosis. The safety aspect is appealing. But with a high reoperation rate, the safety aspect begins to crumble. The expenses are higher, the effect is not superior, and the role of IPD is still unclear. The industry should not define our treatment strategy on LSS. Research made independently from the industry has to lead us on the way to better knowledge.
Laminectomy or minimally invasive decompression is, and should still be, the standard of surgical treatment for lumbar spinal stenosis (LSS). It is an effective treatment comparable to other common elective orthopedic treatments7,11 and represents the best use of our resources.
Vertiflex, who sells Superion, wants to put the light on their device. They financially supported the authors of this paper. The authors are biased simply by the way they hold their torch.
1. Stromqvist BH, Berg S, Gerdhem P, et al. X-stop versus decompressive surgery for lumbar neurogenic intermittent claudication: randomized controlled trial with 2-year follow-up. Spine (Phila Pa 1976). 2013;38(17):1436-42.
2. Tuschel A, Chavanne A, Eder C, Meissl M, Becker P, Ogon M. Implant survival analysis and failure modes of the X-Stop interspinous distraction device. Spine (Phila Pa 1976). 2013;38(21):1826-31.
3. Verhoof OJ, Bron JL, Wapstra FH, Royen BJ. High failure rate of the interspinous distraction device (X-Stop) for the treatment of lumbar spinal stenosis caused by degenerative spondylolisthesis. European Spine Journal. 2007;17(2):188-92.
4. Lønne G, Johnsen LG, Aas E, et al. Comparing cost-effectiveness of X-Stop with minimally invasive decompression in lumbar spinal stenosis: a randomized controlled trial. Spine (Phila Pa 1976). 2015;40(8):514-20.
5. Burnett MG, Stein SC, Bartels RH. Cost-effectiveness of current treatment strategies for lumbar spinal stenosis: nonsurgical care, laminectomy, and X-STOP. J Neurosurg Spine. 2010;13(1):39-46.
6. Lønne G, Johnsen LG, Rossvoll I, et al. Minimally invasive decompression versus x-stop in lumbar spinal stenosis: a randomized controlled multicenter study. Spine (Phila Pa 1976). 2015;40(2):77-85.
7. Nerland US, Jakola AS, Solheim O, et al. Minimally invasive decompression versus open laminectomy for central stenosis of the lumbar spine: pragmatic comparative effectiveness study. BMJ. 2015;350:h1603.
8. Tsutsumimoto T, Yui M, Uehara M, Ohta H, Kosaku H, Misawa H. A prospective study of the incidence and outcomes of incidental dural tears in microendoscopic lumbar decompressive surgery. Bone Joint J. 2014;96-B(5):641-5.
9. Fairbank JC. Why are there different versions of the Oswestry Disability Index? J Neurosurg Spine. 2014;20(1):83-6.
10. Verbiest H. A radicular syndrome from developmental narrowing of the lumbar vertebral canal. J Bone Joint Surg Br. 1954;36-B(2):230-237.
11. Hansson T, Hansson E, Malchau H. Utility of spine surgery: a comparison of common elective orthopaedic surgical procedures. Spine (Phila Pa 1976). 2008;33(25):2819-2830.
Response to Commentary
Harel Deutsch, MD
Overall, I agree with Dr. Lønne’s commentary. Laminectomy should be considered first for people with significant lumbar spinal stenosis. Dr. Lønne states there is a role for interspinous devices. For some patients, who are not candidates for a laminectomy, the interspinous device appears to offer another option.