Pavlov Ratio = Sagittal Diameter of Cervical Canal (b) / Sagittal Diameter of Cervical Vertebral Body (a)

Note: The sagittal diameter of the cervical canal (b) is the distance from the middle of the posterior vertebral body to the nearest point of the spinous process lamina line; the sagittal diameter of the cervical vertebral body (a) is the anteroposterior diameter of the middle of the vertebral body.

The average normal Pavlov ratio for the Chinese population:

C3: 0.93

C4: 0.91

C5: 0.94

C6: 0.94

If this value is <0.75, it indicates cervical canal stenosis.

The measurement of the sagittal diameter of the cervical canal on lateral X-ray films is evidence for diagnosing cervical canal stenosis. Since the measurement of the sagittal diameter of the cervical canal and vertebral body is affected by the magnification of the X-ray film projection distance, taking the ratio of the sagittal diameter of the cervical canal to the sagittal diameter of the cervical vertebral body is not affected by the magnification and is a more reliable value.