Three-dimensional computed tomography and multiplanar reformations in the assessment of pseudarthrosis in posterior lumbar fusion patients.

Three-dimensional (3-D) surface reconstructions and multiplanar computed tomography (CT) reformations were obtained in 30 patients with clinically suspected spinal fusion pseudarthrosis. The imaging studies were blind-reviewed and the results were compared with the clinical and surgical findings. Sagittal, planar, and curved coronal two-dimensional (2-D) reformations were more useful in the detection of bony nonunion than were axial CT scans, as the latter required more extensive analysis. Three-dimensional surface "cuts" adequately demonstrated pseudarthrosis in most cases. In some instances, however, segmentation artifacts created artifactual clefts or implied solidity, which contrasted with the interpretation of the 2-D images. Sagittal 3-D cuts were helpful in demonstrating bony central and lateral stenosis. Three-dimensional surface reconstructions demonstrated superficial clefts and outlined the complex anatomy of the spinal fusions, thus facilitating pre- and intraoperative planning. The amount of bone stock available for pseudarthrosis repair at the fusion site and the need for additional harvesting of bone from the iliac crest also could be assessed easily. 3-D CT proved to be useful as an adjunctive imaging method in the evaluation of posterior lumbar fusion patients suspected of pseudarthrosis.