A spinal vertebra slips forward over the one below it, or the spine becomes unstable.
Medical records that document measured range of motion are central to this rating. A VA or private examiner should measure forward flexion of the thoracolumbar and cervical spine, as well as extension, lateral flexion, and lateral rotation, so the combined range of motion can be calculated. Each measurement is rounded to the nearest five degrees. Records showing muscle spasm, guarding, or localized tenderness — and whether those findings cause an abnormal gait or an abnormal spinal contour such as scoliosis or abnormal kyphosis — also matter at the 10% and 20% levels.
For higher ratings, imaging or clinical findings that document ankylosis of the cervical or thoracolumbar spine are relevant, along with a description of whether the ankylosis is favorable or unfavorable. Unfavorable ankylosis must result in specific functional consequences defined in the regulation, such as difficulty walking due to limited line of vision, restricted chewing, breathing limited to diaphragmatic respiration, or neurologic symptoms from nerve root stretching.
Your own statements describing how pain, stiffness, or limited motion affect your ability to work, bend, or perform daily tasks can help show the functional impact of your condition alongside the clinical findings.
Conditions that are often caused or made worse by this one. If you have any of these, they may be claimable as secondary service connection.