The research’s objectives were to determine whether obtaining only neutral upright radiographs would cause any additional cases of degenerative cervical spondylolisthesis (DCS) to go undetected and to evaluate the diagnostic efficacy of magnetic resonance imaging (MRI). DCS and instability may result in neck pain, myelopathy, and radiculopathy. Standard anteroposterior and lateral radiographs and MRIs can show most cervical spine pathology, but spondylolisthesis and instability are dynamic issues. Occasionally, conventional imaging can miss DCS. The percentage of patients who had cervical spondylolisthesis as seen on lateral neutral, flexion-extension, and MRI images was compared by researchers. They used established criteria to define instability as less than 2 mm of listhesis on neutral imaging and less than 1 mm of motion between flexion-extension radiographs. A total of 111 patients with (555 cervical levels) were examined. On radiographs taken in neutral and/or flexion-extension of 41 patients, 36.9% of them had cervical spondylolisthesis. Of the 77 levels of spondylolisthesis, 17 (22.1%) were missed by neutral radiographs (P,0.05). About 20 levels (26.0%) were missed when only flexion-extension radiographs were used (P=0.02). About 37.7% of the 29 levels of DCS visible on the radiograph—or 29 levels—were missed by the MRI (P=0.004). Lateral flexion-extension views can be useful for diagnosing DCS. These views are useful in identifying a sizeable cohort of patients who would remain undiagnosed based only on neutral radiographs. Additionally, 38% of DCS cases were found by radiographs but missed by MRI. Therefore, lateral radiographs can be a useful addition when instability is suspected or when neutral radiographs and MRI are unable to identify the cause of a patient’s neck or arm pain.

Source- journals.lww.com/jspinaldisorders/Fulltext/2022/08000/The_Utility_of_Flexion_Extension_Radiographs_in.5.aspx