Utility of flexion-extension radiographs in evaluating the degenerative cervical spine.

Study Design: Retrospective cohort of 258 consecutive patients.
Objective: The purpose of this study is to determine the: (1) percentage of flexion-extension radiographs that revealed pathology not appreciated on neutral radiographs in the nontrauma population, and (2) frequency that these views led to a change in the management of these patients.
Summary of Background Data: The utility of flexion-extension radiographs in the evaluation of the spine trauma or preoperative patient is well accepted, but the role of dynamic radiographs in the degenerative population is not well defined.
Methods: Consecutive patients presenting with axial cervical, upper extremity radicular, or myelopathic symptoms underwent upright anteroposterior, neutral lateral, and flexion-extension lateral radiographs. Patients with recent trauma, rheumatoid arthritis, prior cervical fracture, prior cervical surgery, inadequate radiographs, or congenital anomalies were excluded. Three observers reviewed all radiographs after determining the best measurement method by a priori analysis of interobserver reliability.
Results: Listhesis was observed on 23 of the neutral lateral images; 6 of these were found to have changes between flexion and extension (2-4 mm). Two patients (1%) had spondylolisthesis on flexion-extension radiographs not visualized on neutral lateral radiographs. A subsequent review of these patients' charts revealed no change in management based on these findings.
Conclusions: Cervical flexion-extension radiographs are a method of assessing potential instability. In the degenerative population studied here, 1% had spondylolisthesis noted only on the flexion-extension images, and 3% had a change in spondylolisthesis. None of these, however, led to a changes in clinical management. These data, in conjunction with the extra cost and radiation exposure associated with additional views, led us to no longer regard dynamic radiographs as a useful part of the initial imaging for the patient with degenerative cervical conditions.