Durability of cervical disc arthroplasties and its influence factors A systematic review and a network meta-analysis

Background: The durability of cervical disc arthroplasties (CDA) may vary significantly because of different designs and implanting techniques of the devices. Nevertheless, the comparative durability remains unknown. Objectives: We aimed to assess the durability of CDAs in at least 2-year follow-up. We analyzed the classifications and causes of secondary surgical procedures, as well as the structural designs of the devices that might influence the durability. Methods: PubMed, Medline, Embase, and Cochrane Central Register of Controlled Trials were searched from the inception of each database to September 2015 using the following Keywords: "cervical disc replacement" OR "cervical disc arthroplasty" AND "randomized controlled trial (RCT)." Publication language was restricted to English. The primary outcome was the rate of secondary surgical procedures following CDA or anterior cervical decompression and fusion (ACDF). Pairwise meta-analysis and a Bayesian network meta-analysis were carried out using Review Manager v5.3.5 and WinBUGS version 1.4.3, respectively. Quality of evidence was appraised by Grading of Recommendations Assessment, Development and Evaluation methodology. Results: Twelve RCTs that met the eligibility criteria were included. Follow-up ranged from 2 years to 7 years. A total of 103 secondary surgical procedures were performed. The most frequent classification of secondary surgical procedures was reoperation (48/103) and removal (47/103). Revision (3/103) and supplementary fixation (2/103) were rare. Adjacent-level diseases were the most common cause of reoperations. The rates of secondary surgical procedures were significantly lower in Mobi-C, Prestige, Prodisc-C, Secure-C group than in ACDF group. No significant difference was detected between Bryan, PCM, Kineflex-C, Discover, and ACDF. Mobi-C, Secure-C, and Prodisc-C ranked the best, the second best, the third best, respectively. Conclusions: We concluded that Mobi-C, Secure-C, and Prodisc-C were more durable than ACDF. Precise selection of device size and proper surgical techniques are implicated to be crucial to enhance the perdurability. Device design should concentrate on the imitation of biomechanics of normal cervical disc, and semi-constrained structural device is a better design to make CDA more durable.