Addition of Spinal Fusion to Decompression Does Not Benefit Patients with Lumbar Spinal Stenosis

EBM Focus - Volume 11, Issue 17

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Reference - Swedish Spinal Stenosis Study (SSSS) (N Engl J Med 2016 Apr 14;374(15):1413) (level 1 [likely reliable] evidence)

  • Lumbar fusion is often performed in addition to decompressive surgery in patients with moderate-to-severe lumbar spinal stenosis, but evidence for the benefit of fusion is limited.
  • There were no significant differences in disability, pain, or quality of life at 2 year or 5 years comparing decompression plus fusion vs. decompression alone in 247 patients with lumbar spinal stenosis.
  • There were also no significant differences in the subgroup analysis of patients with degenerative spondylolisthesis, further suggesting lumbar fusion may not benefit patients without instability.

The North American Spine Society (NASS) recommends decompressive surgery to improve outcomes in patients with moderate-to-severe lumbar spinal stenosis (Spine J 2013 Jul;13(7):734). Lumbar fusion is not suggested for patients with leg predominant symptoms without instability (Spine J 2013 Jul;13(7):734), but is currently recommended in patients with single-level degenerative lumbar spondylolisthesis and > 20% slippage (NASS May 2013 PDF). In practice, the use of simple fusion is common in either case. In the United States, approximately 25% of patients with lumbar spinal stenosis alone and 80% of patients with lumbar spinal stenosis plus coexisting spondylolisthesis or spondylolysis have lumbar fusion (Spine (Phila Pa 1976) 2013 May 15;38(11):916). However, the evidence supporting spinal fusion during decompression surgery is limited. To evaluate if spinal fusion is associated with increased long-term benefits, the SSSS trial compared decompression plus fusion surgery vs. decompression surgery alone in 247 patients aged 50-80 years with lumbar spinal stenosis.

All patients had spinal stenosis at 1-2 adjacent lumbar vertebral levels and a dural sac cross-sectional area ≤ 75 mm2. All patients also had pseudoclaudication in 1 or both legs and back pain with symptom duration > 6 months, and 55% of patients had degenerative spondylolisthesis. Ninety-two percent of patients were included in the per-protocol analysis. Compared to decompression alone, decompression plus fusion was associated with significantly increased operating times, blood loss, and hospital length of stay. There were no significant differences in efficacy outcomes at 2 years or 5 years including Oswestry Disability Index (ODI) score, use of analgesics for back problems, back pain, leg pain, or quality of life. There were also no significant differences in subgroup analyses of patients with and without degenerative spondylolisthesis and in the modified intention-to-treat analysis including 98% of randomized patients.

This trial provides evidence suggesting decompression alone is sufficient in patients with lumbar spinal stenosis. These results are consistent with the SLIP trial, a small trial restricted to patients who had lumbar grade I degenerative spondylolisthesis with lumbar stenosis (N Engl J Med 2016 Apr 14;374(15):1424). The SLIP trial also randomized patients to decompression plus fusion vs. decompression alone and found no significant differences in the percent of patients achieving a minimally clinically significant benefit at 2 years. In both trials, decompression plus fusion was associated with increased operating times, blood loss, and lengths of hospital stay, indicative of increase cost and recovery time. Overall, the results of these trials suggest patients with lumbar spinal stenosis without instability may not benefit from additional spinal fusion, even in the presence of spondylolisthesis.

For more information, see the Lumbar spinal stenosis and Spondylolisthesis topic in DynaMed Plus. DynaMed users click here and here.


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