Pseudoarthrosis: when the fusion did not take, and the pain may not be about that.

A scan says the bones did not join. Before you book another operation, it is worth knowing how often that finding is silent.

This page is about understanding the condition and the role the brain and nervous system can play in it. It is not a diagnosis. Your own clinicians know your case.

What pseudoarthrosis is

A spinal fusion joins two or more vertebrae with bone graft and usually metal hardware, with the goal that the bones heal into one solid block. Pseudoarthrosis, literally false joint, is what the surgeon calls it when that healing is incomplete: movement persists at the level, bone bridging is absent on CT, or the hardware shows signs of loosening. It is one of the most common complications of fusion, more likely with smoking, diabetes, multi-level fusions and certain surgical techniques.

The intuitive story is that an unfused level is unstable, and that instability causes pain. Sometimes that is true: a loose, moving segment with failing hardware can indeed hurt and may need revision. But the index's definition highlights a fact that surprises many people: multiple studies have found that about 30 percent of people with pseudoarthrosis have no symptoms. A false joint can be entirely silent. That makes the finding, on its own, a poor explanation for pain, and it means the two questions, is the fusion solid and why do I hurt, have to be asked separately.

The neuroplastic contribution

The ATNS Index of Neuroplastic Symptoms draws a straightforward conclusion from the numbers. Because so many people with pseudoarthrosis have no symptoms, when symptoms are present, neuroplastic symptoms should be assessed as part of a complete evaluation. The index does not claim the non-union never matters. It says the non-union cannot be assumed to be the cause, and that the nervous system deserves a proper look before anyone decides on a second operation.

Neuroplastic symptoms are real physical symptoms produced by learned patterns in the brain and nervous system, a protective alarm that has become sensitized, rather than by ongoing structural failure. They are not imaginary and not a sign of weakness or of failing to cope with surgery. People who reach spinal fusion have usually had years of pain, multiple investigations, strong beliefs about their spine being damaged, and often considerable fear. That history is precisely what primes a nervous system to keep producing pain. Add a scan report saying the fusion failed, and the brain has every reason to stay on alert. The process is explained in our page on central sensitization, and our guide to chronic back pain covers the back specifically.

Pointers toward a neuroplastic contribution:

• The pain feels much the same as before surgery, or has spread rather than stayed at the fused level.
• There is little correlation between what the scan shows and how you feel day to day.
• Pain tracks stress, sleep and mood more than activity.

What the research shows

A prospective study following patients with symptomatic pseudoarthrosis a year after lateral lumbar interbody fusion found that, without further surgery, more than half went on to fuse by two years, a third had pseudoarthrosis that remained asymptomatic, and only about 12 percent had pseudoarthrosis that stayed symptomatic. The authors concluded that intervention is not needed for everyone in whom non-union is detected at one year.

A retrospective PET/CT study of 36 patients investigated for pseudoarthrosis after lumbar fusion found no correlation between symptom severity and fusion status. A review of pseudoarthrosis in the cervical spine stated that patients with the condition are asymptomatic in approximately 30 percent of cases, the figure the ATNS index cites. And an older series of patients who underwent circumferential fusion to treat lumbar pseudoarthrosis reported a 100 percent fusion rate on imaging, yet a satisfactory clinical outcome in only a little over half. Fixing the bone, in other words, fixed the pain for barely half the patients.

None of these studies examined a neuroplastic-symptom approach, so the evidence for that application is indirect. What the surgical literature itself shows, consistently, is that fusion status and pain are only loosely connected, which is the premise behind the ATNS index's advice.

Signs the brain may be part of the picture

• Your pain is similar in character and location to before the fusion, or has spread.
• Pain fluctuates widely from day to day without any change in the spine.
• Flares follow stress, poor sleep, conflict or a worrying appointment.
• Previous procedures helped briefly, then the pain returned.

A solution that addresses it

When the brain is contributing, the approach that addresses it is pain and symptom reprocessing: education about neuroplastic pain so the spine stops feeling fragile, somatic tracking (meeting back sensations with curiosity rather than alarm), reducing threat and guarding, a graded return to bending, lifting and normal movement, emotional awareness and expression, and acceptance and commitment skills. Trained clinicians deliver this, and it is increasingly available through digital programmes. It does not replace surgical assessment; it addresses the part of the pain that surgery cannot reach.

Cindra is a daily AI companion built around these approaches, with daily check-ins, short practices and plain-language lessons for people whose symptoms have a neuroplastic component. If you are weighing another operation, you can join the waitlist and start the nervous-system work in parallel.

What to do next

Have the fusion and hardware properly assessed. Your surgeon should review CT and dynamic X-rays, check for hardware loosening or infection, and tell you honestly whether the non-union is likely to be the pain source. Seek urgent care for fever, wound problems, new leg weakness or numbness, or any change in bladder or bowel control.

Then ask the two questions separately. Is the fusion solid? And, separately, why do I hurt? If the surgeon cannot confidently connect the two, ask whether a neuroplastic pattern fits your symptoms before deciding on revision surgery.

Then start retraining. Read why hurt is not harm, rebuild movement with pacing, and see the related entries for failed back surgery and spinal instability in the condition index.

This article is for general education and is not medical advice, and it does not diagnose or treat any condition. Persistent symptoms deserve a proper medical assessment to rule out disease or injury before a neuroplastic explanation is considered. If your symptoms are new, changing, or come with red-flag signs such as fever, unexplained weight loss, numbness or weakness, chest pain, or loss of bladder or bowel control, see a clinician promptly.