Patients with single-level cervical degenerative disc disease commonly undertook anterior discectomy. To compare the effect of anterior cervical discectomy without fusion (ACD), anterior cervical discectomy with fusion by stand-alone cage (ACDF) or anterior cervical discectomy with arthroplasty (ACDA)， a multiple center randomised controlled trial will be performed in patients with single-level cervical disease. The primary outcome will be cervical alignment by upright cervical spine radiographs estimated by Harrison posterior tangent method.

This study will use a multiple center open-label randomised controlled trial to estimate the effect of ACD, ACDF, ACDA for single-level cervical degenerative disc. Patients with arm pain not responding to conservative treatment take part in this trial. They will be randomised assigned into 3 parallel arms. The participants in the each arm will undertake ACD ACDF or ACDA. The baseline is the day of surgery. The Harrison posterior tangent method was used as an estimate for measuring cervical alignment. The primary outcome will be the cervical sagittal alignment estimated by Harrison posterior tangent method.

Inclusion Criteria:

• patients with arm pain not responding to conservative treatment
• lasted longer than 10 weeks
• single level disc degeneration
• mobile spine on dynamic lateral cervical X-rays

Exclusion Criteria:

• severe cardiopulmonary comorbidity
• suspected underlying malignant disease
• radicular syndrome
• spinal-cord compression syndrome
• contraindication for radiography