Instability of the cervical spine is a frequently occurring problem in a number of rheumatologic conditions. The importance of recognizing cervical instability lies in its close association with severe, sometimes irreversible, neurologic compromise that can lead to paralysis or even death. Operative stabilization of cervical instability prior to the onset of irreversible neurologic changes has been advocated. The problem, however, has been that no reliable method has accurately predicted which patients with cervical instability are at risk for spinal cord compression. It has been determined in recent studies that specific measurements of radiographic instability are strongly associated with worsening neurologic compromise. These measurements assess the space available for the spinal cord, and recommendations can be made for surgical stabilization in patients with cervical instability, prior to the onset of neurologic changes.