Plain lumbosacral x-rayss: may disclose spondylolisthesis. AP diameter of canal is usually narrowed (congenitally or acquired) whereas the interpedicular distance (IPD) may be normal 1).
Plain lumbosacral x-rayss Oblique films may demonstrate pars defects. Adding flexion/extension views can assess “dynamic“ in stability.
Degenerative spondylolisthesis with lumbar stenosis is a well-studied pathology and diagnosis is most commonly determined by a combination of magnetic resonance imaging (MRI) and standing plain lumbosacral x-rays. However, routine upright imaging is not universally accepted as standard in all practices.
Routine standing lateral radiographs should be standard practice in order to identify degenerative spondylolisthesis, as nearly 1/3 of cases will be missed on supine MRI. This may have implications on whether or not an arthrodesis is performed on those patients requiring lumbar decompression. Flexion-extension radiographs demonstrated no added value compared to standing lateral xrays for the purposes of diagnosing degenerative spondylolisthesis 2).