Update on the evaluation of instability of the lower cervical spine.

Clinical instability of the cervical spine should be diagnosed accurately in order to avoid both unnecessary treatment and the serious consequences of inadequate treatment. A systematic method for evaluation utilizing a checklist is suggested. The checklist is based on biomechanical analysis, anatomic analysis, experimental data and clinical studies. The elements of the checklist include (1) evaluation of anatomic components; (2) static radiographic measurements of sagittal plane displacements; (3) a dynamic (stretch test) evaluation of displacements; (4) evaluation of neurologic status; and (5) a consideration of future anticipated loads to the spine. Based on an analysis of these elements and an assignment of numerical values to each, the stability or instability of the spine can be determined. This systematic checklist approach is recommended as a useful method for evaluating clinical instability, given the currently available knowledge. This methodology and current knowledge about the complex problem of spinal instability have certain limitations. Progress will come with more biomechanical experimental studies and controlled prospective clinical studies.