The benefit of adding lumbar fusion surgery to decompression surgery for spinal stenosis was nonexistent in one large clinical trial and very modest in another, according to separate reports published online April 13 in the New England Journal of Medicine.
Both studies indicated that, given the considerable cost and the potential complications associated with lumbar fusion, it may not be worthwhile to add it to decompression surgery for spinal stenosis. “The goal of surgery in lumbar spinal stenosis is to improve walking distance and to relieve pain by decompression of the nerve roots. The addition of instrumented fusion – ‘just to be sure’ – for the treatment of the most frequent forms of lumbar spinal stenosis does not create any added value for patients and might be regarded as an overcautious and unnecessary treatment,” Dr. Wilco C. Peul and Dr. Wouter A. Moojen said in an editorial accompanying the two reports.
Surgical decompression of spinal stenosis using laminectomy is increasingly being supplemented with lumbar fusion, which is thought to firm up spinal instability and minimize the risk of future deformity. In the United States, approximately half of patients who have surgery for spinal stenosis undergo fusion procedures. Of those who also show degenerative spondylolisthesis on preoperative imaging studies, 96% undergo fusion procedures because many spine surgeons see this as a sign of instability and a mandatory indication for fusion. However, the evidence supporting the use of fusion plus decompression, as opposed to decompression alone, is weak, according to the investigators who conducted the Swedish Spinal Stenosis Study. The other study in the New England Journal of Medicine, the Spinal Laminectomy Versus Instrumented Pedicle Screw (SLIP) trial, was conducted in the United States.
Both of those clinical trials were performed to shed further light on the issue.
In the Swedish Spinal Stenosis Study, the investigators assessed outcomes in 247 patients aged 50-80 years who were treated at seven Swedish hospitals over the course of 6 years. This open-label, superiority trial randomly assigned 124 patients to decompression surgery alone and 123 to decompression plus fusion. The primary outcome measure was score on the Oswestry Disability Index (ODI), which measures disability and quality of life in patients with low-back pain, 2 years after surgery. The ODI scale runs from 0 to 100, with higher scores indicating more severe disability, said Dr. Peter Försth of the department of surgical sciences at Uppsala (Sweden) University and the Stockholm Spine Center and his associates.
At 2 years, there was no significant difference between the two study groups; the decompression-only group had a mean ODI score of 24, and the fusion group had a mean score of 27. The ODI scores in both groups had improved from baseline to a similar degree: by 17 points with decompression alone and by 15 points with fusion. In addition, fusion surgery was not superior to decompression alone regardless of whether patients had any degree of spondylolisthesis and regardless of whether they had severe spondylolisthesis involving a vertebral slip of 7.4 mm or more, the investigators reported (N Engl J Med. 2016 April 13. doi: 10.1056/NEJMoa1513721).The two study groups also showed no significant differences in secondary outcome measures, including performance on the 6-minute walk test and subjective patient assessment of improvement in walking ability. Moreover, these results persisted in the 144 patients who were assessed at 5-year follow-up.
In contrast, decompression alone was associated with fewer complications than decompression plus fusion. Postoperative wound infection developed in only 4% of the decompression-only group, compared with 10% of the fusion group. Although this study wasn’t adequately powered to draw firm conclusions regarding complications, a previous analysis of registry data reported that adding fusion surgery to decompression surgery doubles the risk of severe adverse events in older patients, Dr. Försth and his associates said.
Decompression alone also was markedly less expensive than fusion surgery. Mean direct costs were $6,800 higher for fusion than for decompression alone, because of the additional operating time needed, the extended hospital stay, and the cost of the implant.
In the SLIP trial, the researchers compared outcomes in 66 patients aged 50-80 years who all had spinal stenosis with grade 1 degenerative spondylolisthesis. The participants were randomly assigned to undergo decompression alone (35 patients) or decompression plus fusion (31 patients) at five U.S. medical centers, said Dr. Zoher Ghogawala of the Alan and Jacqueline B. Stuart Spine Research Center in the department of neurosurgery at Lahey Hospital and Medical Center, Burlington, Mass., and his associates.
The primary outcome measure was the physical-component summary score on the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) 2 years after surgery. This scale also runs from 0 to 100, but higher scores indicate better physical health. Five points was prespecified as the minimal clinically important difference on the SF-36.