Spinemathema podcast · Episode 8 · About 8 minutes · October 2026

Episodes are narrated using an AI model of Mr Sadek’s own voice, from scripts he has written and approved.

Read the full article with references: Which Keyhole Operation for Spinal Stenosis? The NORDSTEN Trial

Transcript

Hello and welcome to the Spinemathema podcast. I’m Ahmed Sadek, a neurosurgeon, and in this episode I want to talk about a landmark trial from Norway called NORDSTEN.

NORDSTEN stands for the Norwegian Degenerative Spondylolisthesis and Spinal Stenosis study. It is actually two trials under one name. Most of today is about the first, which compared three different ways of doing a keyhole style decompression operation for lumbar spinal stenosis. At the end I’ll mention its sister trial, which looked at whether people with a slipped vertebra need a fusion.

So let’s start with the condition. Lumbar spinal stenosis is a narrowing of the spinal canal in the lower back. The nerves running down to the legs get squeezed. Typically, people notice pain, heaviness or numbness in the legs when they walk, and it eases when they sit down or bend forward. Many people manage well without an operation. But when symptoms are severe and don’t settle, an operation to make more room for the nerves, called a decompression, is a common option. In fact, the trial authors describe it as the most often performed operation on the adult lower back.

In the past, the standard operation was a full laminectomy, where the bony roof at the back of the spine is removed. Over the last few decades, surgeons have moved towards less invasive techniques that leave the midline structures of the spine in place. There are several of these, and they differ in how much muscle and bone are disturbed. Before NORDSTEN, there was very little good evidence on whether any one of them actually works better. And that’s a perfectly reasonable thing for a patient to want to know.

So how did the trial work? Between February twenty fourteen and October twenty eighteen, four hundred and thirty seven adults with stenosis were recruited at sixteen public hospitals across Norway. Everyone had symptoms and a matching magnetic resonance imaging, or MRI, scan. People with a slipped vertebra, which we call a degenerative spondylolisthesis, were not included in this trial. The typical age was around sixty eight, and just over half were men.

A computer then randomly allocated each person to one of three operations. The first, given to one hundred and forty six people, was a unilateral laminotomy with crossover. That means the surgeon opens a small window on one side, then angles across underneath to clear the opposite side through the same opening. The second, given to one hundred and forty two people, was a bilateral laminotomy, where a small window is opened on each side. The third, given to one hundred and forty nine people, was a spinous process osteotomy. Here, the bony spike you can feel in the middle of your back is cut at its base and moved to one side, with its ligaments still attached, so the canal can be cleared from the middle.

The main measure was the Oswestry Disability Index. That’s a questionnaire scored from nought to a hundred, where a lower score means less disability. The researchers compared how much it changed from before surgery to two years afterwards. They also recorded leg and back pain, quality of life, how long the operation took, blood loss, complications and whether anyone needed a further operation. And then they followed everyone up again at five years.

So what did they find? The short answer is that all three operations worked, and they worked about equally well. At two years, the average disability score had dropped by about eighteen points in the one sided crossover group, and by about twenty points in each of the other two groups. Those differences were small and not statistically significant. Across the whole trial, about seven in ten people met the definition of success, which was a fall of more than thirty percent in their disability score.

Leg pain, back pain, quality of life, hospital stay, blood loss and complications were all similar between the groups. The one clear difference was operating time. Opening both sides took around two hours on average, about half an hour longer than the other two techniques. Over the two years, roughly seven or eight percent of people in the crossover and osteotomy groups, and about four percent in the bilateral group, had a further operation. That difference wasn’t statistically significant either.

The five year results were published in twenty twenty five. Three hundred and fifty eight people, which is eighty two percent of those who took part, completed the follow up. The average improvement was still around eighteen to nineteen points in all three groups, with no meaningful difference, and the rates of further spinal surgery were also similar. So the benefit held up over time, and no technique pulled ahead.

Now, the sister trial. This one included people who did have a slipped vertebra, a forward slip of three millimetres or more, along with stenosis. They were randomly allocated to decompression alone, or decompression plus an instrumented spinal fusion, which uses metal implants to join the vertebrae. At two years, about seventy one percent of the decompression alone group and about seventy three percent of the fusion group had at least a thirty percent improvement in disability. That showed decompression alone was not worse. At five years, the figure was sixty three percent in both groups. By then, sixteen percent of the decompression group and eighteen percent of the fusion group had had another lower back operation.

Let me be fair about the limitations. Patients knew which operation they’d had, and they filled in the questionnaires themselves, so expectations could have played a part. The trial recruited slightly fewer people than planned, though the authors calculated it still had close to the intended statistical power. None of the three techniques was compared with a full laminectomy, because most of the hospitals had already stopped using it. The main trial left out people with a slipped vertebra, so its results apply to stenosis without one. All the surgeons were familiar with all three methods, which may not be true everywhere. And for the five year paper, we only had the summary to work from, so I’ve given you just the headline figures.

So what does this mean for you? If you’re considering a decompression for lumbar stenosis without a slipped vertebra, NORDSTEN is quite reassuring. The three common midline sparing techniques gave similar improvements in disability and pain, similar complication rates and similar chances of needing more surgery, and those results lasted to five years. In practice, I’d suggest it’s more useful to focus on whether surgery is right for you in the first place, and on your surgeon’s experience with their chosen approach, rather than on the name of the technique.

And surgery is not the only option. Many people with stenosis do well with physiotherapy, changes to activity and pain relief. Talk through the benefits, the risks and the alternatives with your spinal team.

Thank you for listening. Please remember that this podcast is general information and not a substitute for advice about your own situation, so do speak to your own doctor or specialist. You’ll find the full article, the diagrams and all the references at spinemathema dot com. And if you found this helpful, please subscribe to the Spinemathema channel on YouTube.

This podcast is general information and is not a substitute for advice about your own situation. Please speak to your GP or specialist.