Final answer:
The best method to diagnose spinal fusion non-union is primarily through imaging techniques such as X-rays, followed by CT scans and sometimes MRI when necessary, correlating these findings with the patient's clinical symptoms.
Step-by-step explanation:
To diagnose a non-union of spinal fusion, healthcare professionals typically start with plain X-rays, which can reveal changes in the positioning of hardware, loss of correction, or persistence of a visible gap between the fused bone segments. In cases where X-ray results are inconclusive, a CT scan is often considered the next best step, as it provides a more detailed image of the bone, allowing for the assessment of bony trabeculae and fusion mass. If metallic hardware causes artifacts on a CT scan, causing difficulty in assessing fusion, an MRI might be utilized, even though it is less commonly used for this purpose.
Other potential methods include the use of functional tests such as flexion-extension X-rays, which can show abnormal movement at the fusion site, or bone scans, which can detect changes in bone metabolism. It is important to integrate the clinical presentation with the imaging findings for an accurate diagnosis.