[1] It is believed that one or more of the subsystems must have failed if joint instability occurs, usually a torn or overstretched ligament.
[citation needed] The bony components that may relate to the potential for joint instability can be measured by use of x-rays.
Plain film lateral x-rays can be used to evaluate for translations anteriorly (anterolisthesis) or posteriorly (retrolisthesis).
Where plain films indicate the likelihood of these translations being significant, flexion-extension views can be utilized to determine the dynamic range of movement of joints.
This allows for a more accurate view of any potential instability issues.