I. Cervical spine instability: X-ray: bone spur vacuum intervertebral space narrowing Dynamic film: intervertebral body angle >11°, relative displacement >3.5mm, intervertebral space >1.7mm under 1/3 body weight heavy traction. II. Lumbar spinal stenosis: X-ray: 1. Transverse diameter <18mm (distance between the two pedicles); Sagittal diameter <18mm. 2. <10mm on contrast. III. Atlanto-occipital Instability: Powers ratio: adult >5mm instability; pediatric >10mm instability. Diagnosis of lumbar instability: 1. There are multiple lumbar and leg pains with acute onset and limited lumbar extension and flexion activities, which can be alleviated by bed rest or lumbar immobilization. Sometimes the lumbar spine can be “stuck” with pain after slight activity. 2. Destruction of the anterior or posterior lumbar spine structure. 3, Lumbar hyperextension and hyperflexion X-ray shows that the vertebral body slips ≥3mm.