Inclusion Criteria:  Age: 18~70 years. Diagnosed as degenerative cervical spine myelopathy. Must receive C3-C7 open-door laminoplasty. Agree to join this study and sign the informed consent.  Exclusion Criteria:  Severe cervical spine kyphosis. Cervical spine radiculopathy. Laminoplasty with fusion. Cervical spine anterior column lesion because of tumor, trauma or infection. Severe osteoporosis. Morbid obesity. patients with mental disorder. Pregnancy. History of infection within last 3 months. Severe nervous system disease. Abnormal laboratory report of liver function, kidney function and hematologic system. Poor compliance. Patients with other surgical contraindications. Patients with intemperance or taking drugs. Patients who joined other study within the last 3 months. Patients with a chief complaint of neck pain (VAS score ≥3 points). Left handedness.