Back pain after lumbar fusion: why might another disc become a problem?

Written By Bernitta Robinson

This week in clinic, I (principal osteopath Bernitta Willoughby) saw a patient whose history raised a question that will be familiar to many people who have had surgery for a prolapsed disc: if the operation worked well and the pain settled, why has another disc become a problem several years later?

He had grown up on a farm, with heavy lifting forming part of life from a young age, before moving into other work that continued to involve manual handling and loading. He is a physically strong man, accustomed to demanding work, and his back has been exposed to those demands over many years. Previously, he had undergone a lumbar discectomy and fusion following a disc prolapse in the lower part of his back. He recovered well and enjoyed several years without symptoms, but within around five years had developed a new disc prolapse higher in the lumbar spine and is now considering further surgery.

What interested me about this case was the combination of his working history, the previous operation and the questions that a new problem raises. Had the original prolapse weakened other discs? Had the fusion changed how the rest of his spine was moving and carrying load? Or was this another disc problem that might have developed regardless of the surgery? These are reasonable questions, although the answers are rarely as straightforward as identifying one cause.

A lifetime of physical work is relevant to the assessment

When I take a history, I want to understand more than what someone was doing when the current pain began. In this case, farming in his younger years was followed by other physically demanding jobs, so the history was one of repeated loading over a long period rather than a single recent lifting incident.

The discs sit between the vertebrae and help distribute forces as we move, bend and carry. Each has a strong outer ring surrounding a softer central portion, with endplates forming the interface between the disc and the bone above and below. These structures work together with the joints, ligaments and muscles of the spine; lifting places demands on that whole system.

Research supports considering cumulative exposure to heavy physical work. The German EPILIFT study found an association between occupational loading of the lumbar spine and disc disease, looking at activities such as lifting, carrying and working in bent positions. That makes this patient’s history relevant, but it does not establish that farm work in childhood damaged his endplates or caused his current prolapse. We cannot look back through someone’s life and attribute a particular disc problem to one job or period of activity with that degree of certainty.

Being strong also does not tell us how an individual disc is functioning or whether a nerve is being compressed. Equally, a history of physical work does not mean someone has simply “worn their back out”. In clinic, I find it more useful to understand what the person’s back has been asked to do, what they can currently tolerate and whether the demands of their work need adjusting while we establish the next step.

Has the original prolapse weakened the other discs?

A prolapse at one level does not automatically weaken the discs above it. It is helpful here to separate the original disc problem from the effects of the operation used to treat it.

A lumbar discectomy removes the portion of disc material pressing on a nerve. A lumbar interbody fusion joins two vertebrae together, using bone graft and an implant within the disc space. Where someone has had both procedures, the aim includes relieving nerve pressure and stabilising the affected segment, but the fused level no longer contributes movement in the same way.

If only part of the lumbar spine has been fused, the remaining levels still move. Fusion can alter movement and stresses at neighbouring segments, so the question of whether those areas are carrying different loads is a valid one. However, that does not mean every disc above the fusion is overloaded or destined to prolapse. Changes already present before surgery, the spine’s alignment and ongoing degenerative processes may also contribute.

When a level immediately next to a fusion develops changes that cause symptoms, this may be described as adjacent segment disease. It includes more than disc prolapse: narrowing around nerves and changes in vertebral alignment can also be involved. A new problem higher in the lumbar spine is not necessarily adjacent segment disease if it is not directly next to the fusion, which is why the surgical records and current imaging matter when discussing an individual case.

For this patient, altered loading after fusion is a possible part of the explanation, alongside his working history and the condition of the rest of his spine. It would be inappropriate to state that the first operation caused the new prolapse without the evidence to support that conclusion.

What does the research tell us about further surgery?

One study of 1,000 patients who had undergone posterior lumbar interbody fusion found that 9% required further surgery for adjacent segment disease during an average follow-up of 8.3 years. Among those affected, the problem developed an average of 4.7 years after the initial operation. This demonstrates that neighbouring-level problems can arise several years after a successful recovery, although the patients’ average age was 67 and the conditions being treated varied. The figure includes several types of adjacent segment disease and cannot be used as this patient’s personal likelihood of another disc prolapse.

Later problems have also been recorded after discectomy without fusion. In a study of 751 patients, 4% underwent further surgery for neighbouring-level disease over approximately 3.1 years, while 1.86% underwent a neighbouring-level discectomy over approximately 3.45 years. The studies involved different groups and follow-up periods, so their percentages should not be directly compared to judge one operation against another.

The research helps explain why the pattern we sometimes see in practice is plausible, but it cannot tell us exactly what will happen to someone sitting in front of us. New pain after surgery also does not necessarily mean a new prolapse, and a new prolapse does not necessarily mean another operation.

Looking at the current problem as well as the previous surgery

As an osteopath, I assess the whole spine and how the person is moving, alongside the hips and other relevant areas, rather than concentrating solely on the site of the previous operation. I also want to know how the current symptoms differ from the original episode, whether pain travels into the leg, and whether there have been changes in sensation, strength or everyday function.

Where indicated, a neurological examination helps assess nerve function. Previous surgical letters and scan reports can clarify which levels were treated and what procedure was performed, while the current findings help determine whether osteopathic care is appropriate or whether medical investigation should take priority. Examining movement does not allow us to confirm a prolapse by touch or tell how severe nerve compression is.

When treatment is appropriate, I explain the findings and proposed approach, and obtain consent before any hands-on care. Management may include suitable manual therapy alongside exercise, advice and practical adjustments to work or daily activities. The aim is to support function and manage symptoms where we can, with regular review of the response.

With this particular patient, I used dry needling and found it very effective in easing the muscular spasms. This was a useful part of managing his symptoms while he was considering the next stage of care, although relief of the muscular spasm does not mean that the underlying disc prolapse or any nerve compression has resolved. It is an example of how we may be able to help with part of the presentation while recognising that the disc problem itself still needs appropriate assessment and, where indicated, specialist management.

In some cases, the appropriate next step is referral for medical or spinal specialist assessment. New or progressive weakness and other concerning neurological findings may require urgent assessment, while persistent disabling symptoms can warrant a consultant’s opinion. Imaging is considered when it is likely to change management, rather than being necessary for every episode of back pain. NICE advises considering decompression for sciatica when non-surgical treatment has not improved pain or function and scan findings correspond with the symptoms. Nerve involvement alone does not establish that surgery is the only option.

Symptoms that need immediate emergency assessment

If back or leg symptoms are accompanied by new bladder or bowel disturbance, or numbness around the genitals, inner thighs or back passage, go to A&E immediately. Do not wait for a routine appointment.

This includes difficulty starting to pass urine or emptying the bladder, reduced awareness of bladder fullness or urine flow, new loss of bladder or bowel control, or altered sensation when wiping after using the toilet. New changes in genital sensation or sexual function can also be relevant. These may be signs of cauda equina syndrome, a rare but serious compression of the nerves responsible for these functions. You do not need every symptom, and you should not wait for incontinence to develop before seeking emergency help.

For someone who has already been through surgery and returned to a physically demanding life, facing another possible operation can be particularly difficult. This patient’s history reminds us why a new episode deserves a fresh assessment, taking account of the previous procedure, the demands of work and the current nerve symptoms without assuming that one factor explains everything.

At The Waterside Practice in Warboys, Cambridgeshire, that is an important part of our role: helping people understand their symptoms, assessing where osteopathic care may be appropriate and recognising when specialist care is needed. Previous surgery is part of the history, but the decisions we make now need to be guided by the problem the person has today.

Research and guidance links

Bernitta Robinson
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