Spinal morphological change after posterior lumbar interbody fusion in lumbar spondylolisthesis patients.

Lumbar spondylolisthesis is a degenerative status in the spine. Posterior lumbar interbody fusion (PLIF) with instrumentation has considered as the standard surgical treatment for lumbar instability. Spinal canal and dural sac cross-sectional area (CSA) has been major parameters for evaluating neurologic symptoms. This study is aimed at finding the radiological change using the dural sac CSA and spinal canal CSA as an objective morphological parameter after PLIF. Of the 74 patients (24 men, 50 women; mean age 66.49 years) who had PLIF surgery were checked for preoperative magnetic resonance imaging (MRI) and MRI within 1 week after surgery. T2-weighted axial MRI scans were obtained from each patient. We measured the dural sac and spinal canal CSA on an axial MRI image at the center of L4 to L5 intervertebral disc. The average spinal canal CSA was 70.28 ± 27.77 mm2 in the preoperative MR images and 149.59 ± 35.20 mm2 in the postoperative MR images. The average dural sac CSA was 42.46 ± 18.49 mm2 in the preoperative MR images and 98.93 ± 29.32 mm2 in the postoperative MR images. After the PLIF operation, the mean spinal canal CSA was 112.84 percent increase, and the measn dural sac CSA was 132.99 percent increase. After PLIF, patients had significantly higher dural sac CSA (P < .001) and spinal canal CSA (P < .001). Spinal canal CSA have increased by 112.84 percent and Dural sac CSA have increased by 132.99 percent after PLIF. Thus, before PLIF, the treating physician should carefully explain this result to patient.