The benefits of adding lumbar fusion surgery to decompression surgery for spinal stenosis is at best modest and most likely superfluous the results from two studies in this week’s NEJM show.

The SLIP trial randomly assigned 66 patients with stenosis and spondylolisthesis to decompression alone or decompression with fusion showed a small benefit in the primary outcome measure SF-36 at two years (15.2 vs. 9.5, for a difference of 5.7; 95% confidence interval, 0.1 to 11.3; P=0.046).

In the second study involving 247 patients with lumbar spinal stenosis, with or without degenerative spondylolisthesis, decompression surgery plus fusion surgery did not result in better clinical outcomes at 2 years and 5 years than did decompression surgery alone.

“Both trials show clearly that for most patients, stenosis surgery should be limited to decompression when no overt instability is present” said editorialists from The Netherlands.

The evidence also suggested that fusion for the treatment of stenosis could no longer be considered best practice.

The procedure should be restricted to patients who have proven spinal instability, they added.