Spinemathema podcast · Episode 14 · About 9 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: Foot Drop From a Slipped Disc or Stenosis: What the Evidence Says

Transcript

Hello and welcome to the Spinemathema podcast. I’m Ahmed Sadek, a neurosurgeon. Today’s episode is a little different from our usual landmark trial spotlights, because the topic is foot drop, and for foot drop there is no landmark trial.

Let me explain what foot drop is first. It’s weakness of the muscles that lift the front of your foot and your toes at the ankle. People often notice the foot slapping down as they walk, or catching their toes on kerbs. When the cause is in the lower back, it’s usually a slipped disc or a narrowing of the spinal canal, called lumbar spinal stenosis, pressing on a nerve root.

The questions patients ask me are very reasonable. Will my foot recover? Will an operation help? And how quickly does it need to be done?

So we searched the medical research database PubMed for randomised trials of surgery, or of the timing of surgery, specifically for foot drop caused by a slipped disc or stenosis. We didn’t find any. Foot drop from the spine is relatively uncommon, and few surgeons would randomly delay an operation for severe weakness. So I want to be clear. There are no randomised trials here. What I’m going to describe is what the best available studies show.

Instead, the evidence comes from systematic reviews, which gather up and combine the results of earlier studies, together with some larger cohort studies that followed groups of patients over time.

The biggest is a review from twenty twenty five that pooled twenty studies with nine hundred and eighteen patients. Most had a slipped disc, about four in five, and most of the rest had stenosis. Every one of those twenty studies was observational, and sixteen of them looked back at past hospital records. A review from twenty twenty one pooled nine studies with four hundred and thirty one patients. A twenty twenty three review pooled nine studies with seven hundred and ninety two patients, looking for factors that predict recovery. A twenty twenty two review pooled six studies with three hundred and twelve patients, to compare surgery within a month against later surgery. And another twenty twenty five review combined the records of individual patients, sixty six in its main analysis, all with weakness on one side treated with surgery at a single level.

Two more studies help with timing. A single centre study followed three hundred and ninety patients with leg weakness of any severity from a slipped disc for at least a year after urgent disc surgery. And a Dutch randomised trial, which compared early surgery with a longer period of non surgical care for sciatica, included one hundred and fifty people with some weakness. Their weakness was mostly milder than typical foot drop, but it’s the nearest thing we have to randomised evidence.

A quick word on how strength is measured. Doctors use the Medical Research Council, or MRC, scale. Nought means no movement at all, and five means normal strength. Grades four and five are usually counted as a good recovery.

So what did the studies find? In the largest review, eighty two percent of people improved by at least one strength grade after decompression surgery. Sixty percent got back to grade four or five. And eighteen percent showed no improvement at all. Pain scores also fell a lot, and reported complications were low, at around one percent. The twenty twenty one review found a similar figure, with about eighty five percent improving.

What predicts a better recovery? The most consistent finding is strength before surgery. People who still had some strength, grade two or three, did better than those with severe or complete weakness. One review put the odds of a good outcome at roughly six times higher with moderate weakness.

Timing is where things get interesting. The individual patient review found that people operated on within six weeks of their symptoms starting were up to six times more likely to recover more, when checked at around a year. The twenty twenty two review found better recovery with surgery within a month. And in the single centre study, surgery within three days was linked with better recovery, for both severe and milder weakness.

Early progress matters too. In the individual patient review, people who had gained at least one grade of strength by three months after surgery were around thirty times more likely to keep improving than those who hadn’t.

Age was a factor in two of the reviews, with people aged forty seven or under doing better in the individual patient analysis. And diabetes was linked with poorer recovery in another review.

But I don’t want to make this sound neater than it is, because the findings don’t all agree. The twenty twenty three review found no clear link between how long the foot drop had been present, or age, and recovery. In the Dutch trial, early surgery gave faster recovery of weakness, but by one year complete recovery was about the same, eighty one percent after early surgery and eighty percent after longer non surgical care. A study across several centres in the United Kingdom and Ireland, with seventy five patients, found that fifty five percent improved after surgery, thirty one percent stayed the same and fifteen percent got worse, with the chance of improving falling a little for each day of delay. And painless foot drop, which is less common, may recover less well, although that comparison was uncertain.

Now, the limitations. Because there’s no randomised trial on timing, we can’t be sure that earlier surgery itself causes better recovery. People who are operated on quickly may differ in other ways, for example in how suddenly and how badly the weakness came on. Most of the studies looked back at records, many were small, and the results varied a lot from one study to another. The reviews also share many of the same studies, so they aren’t independent confirmations of each other. Definitions of foot drop, timing and recovery differed, and follow up was often short. And there’s very little good information on people who didn’t have surgery, so we can’t say how many would have got better on their own.

I should be open with you about one thing. I was the senior author who led the twenty twenty five individual patient review I mentioned, and I was also one of the authors of the study across the United Kingdom and Ireland. I received no funding for either study. I’ve tried to give you a balanced picture of all the evidence, including the parts that don’t agree.

So what does this mean for you? If you notice weakness lifting your foot, please get it checked promptly. Most studies suggest the chances of recovery are better when some strength remains and when the nerve is freed up sooner rather than later, although nobody knows the ideal time window. Surgery helps most people regain some strength, but not everyone recovers fully, and around one in five don’t improve. Your spinal team will weigh how severe and how recent the weakness is, what your scan shows, your general health, and what matters most to you. If recovery is incomplete, physiotherapy and an ankle foot splint can help with walking and safety.

And one important safety message. If you develop sudden foot weakness, or weakness that’s getting worse, contact your doctor, NHS one one one, or your spinal team the same day. And if you have numbness around your back passage, genitals or inner thighs, new trouble passing urine or controlling your bladder or bowels, new sexual problems, or sciatica in both legs, go to A and E straight away. Those can be signs of cauda equina syndrome, which needs emergency treatment.

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.