Some patients have no symptoms at all with a failed fusion. Movement occurs at the fusion site but they aren't aware of it. This is called a pseudoarthrosis, which means false joint.
But if a patient reports pain and/or other symptoms, then X-rays may be taken. If screws have come loose or start to back out, this will show up on the X-ray.
Special studies using fluoroscopy combined with motion tracking software can show motion at the fusion site. Fluoroscopy is a type of X-ray that allows the physician to watch the spinal segments as the head and neck bend forward and back.
Computer technology makes it possible to magnify and view the moving vertebrae on a screen. The software analyzes the movement and reports the presence or absence of motion. This method also allows the surgeon to see where the movement is coming from.
Many patients who have a fusion and later develop a pseudoarthrosis still report improvement. Further treatment may not be needed. When necessary, revision surgery can be performed.