Comparison of the more than 5-year clinical outcomes of cervical disc arthroplasty versus anterior cervical discectomy and fusion: A protocol for a systematic review and meta-analysis of prospective randomized controlled trials.

Background: Anterior cervical discectomy and fusion (ACDF) was almost the "golden standard" technique in treatment of symptomatic cervical degenerative disc disease, however, it cause motion loss of the indexed level, increase the intradiscal pressure and motion of the adjacent levels, and may accelerate the degeneration of adjacent level. Cervical disc arthroplasty (CDA) was designed to preserve the motion of index level, avoid the over-activity of adjacent levels and reduce the degeneration of adjacent disc levels, the process of degeneration of adjacent level is very slowly, long term follow up studies should be conducted, this study aim to compare the more than 5 years' long-term clinical outcomes and safety between CDA and ACDF.

Methods: A systematic review and meta-analysis that will be performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The electric database of Medline, Embase, and Cochrane library will be systematic search. A standard data form will be used to extract the data of included studies. We will assess the studies according to the Cochrane Handbook for Systematic Reviews of Interventions, and perform analysis in software STATA 12.0. Fixed-effects models will be used for homogeneity data, while random-effects will be used for heterogeneity data. The overall effect sizes will be determined as weighted mean difference (WMD) for continuous outcomes and Relative risk (RR) for dichotomous outcomes.

Results: The results of study will be disseminated via both international conference and peer-review journal.

Conclusion: The conclusion of our study will provide the long-term and updated evidence of clinical outcomes and safety between CDA and ACDF, and help surgeon to change better surgical technique for patients.