Artificial Disc Replacement versus Fusion in the Cervical Spine: A Systematic Review of Systematic Reviews

Abstract

Introduction Artificial disc replacement versus fusion in the cervical spine: A systematic review of systematic reviews. Materials and Methods A combination of the following keywords was used in the search for systematic reviews: (total disk replacement, prosthesis, implantation, diskectomy, arthroplasty) and (cervical vertebrae, cervical spine, spine) and (pain, disability, quality of life) and (systematic reviews, reviews, meta-analysis) . These keywords were used as MESH headings where appropriate. The search was conducted on August 18, 2013, by a Cochrane-trained academic librarian. The following databases were searched: [Medline via Ovid, Embase, Cochrane Database of Systematic Reviews, Google scholar]. Manual search of reviews and discussion articles and case studies were also attempted by the two authors. The authors screened the results of the search independently according to pre-designed eligibility criteria. For the article to be selected for further consideration it has to be a systematic review and/or meta-analysis of randomized controlled trials that attempted to compare between the two interventions at the cervical region. Results The electronic search produced 881 hits of which 145 were duplicates. Initial screening of the abstracts resulted in selection of 68 articles for further evaluation. Five more articles were identified through manual search. The final judgment of the two reviewers was to include 10 systematic reviews and/or meta-analyses in this overview. The number of randomized trials reviewed by the selected reviews varies from 2 to 27. Other discrepancies between the reviews included: the follow up period, the outcomes considered and reporting of heterogeneity or publication bias of the included studies. Eight reviews and meta-analyses concluded that overall C-ADR is more effective and probably superior to ACDF specifically in neurological success, low rate of secondary operation and most pain outcomes. One meta-analysis concluded that ACDF is associated with shorter operative time and less blood loss compared with C-ADR. However, a Cochrane review critically evaluated the differences between the clinical outcomes of the two interventions and while confirmed that C-ADR superiority may be statistically significant in many of these outcomes, the differences between C-ADR and ACDF is small. This was also evident in all meta-analyses evaluated here. Conclusion C-ADR may be superior, or at least equivalent, to ACDF in most clinical and patients' outcomes but the effect size of the difference is small and more time and research is needed to reach a definitive conclusion. A robust systematic reviewing is also recommended.