Does zero-profile anchored cage accompanied by a higher postoperative subsidence compared with cage-plate construct? A meta-analysis

Abstract

Background Zero-profile anchored cage (ZP) has been widely used for its lower occurrence of dysphagia. However, it is still controversial whether it has the same stability as the cage-plate construct (CP) and increases the incidence of postoperative subsidence. We compared the rate of subsidence after anterior cervical discectomy and fusion (ACDF) with ZP and CP to determine whether the zero-profile device had a higher subsidence rate?Methods We performed a meta-analysis of studies which compared the subsidence rate of ZP and CP. An extensive and systematical search covered Medline, Embase and Web of Science databases according to PRISMA guidelines and identified ten articles that satisfied our inclusion criteria. Relevant clinical and radiological data were extracted and analysed by RevMan 5.3 software.Results Ten trials involving 626 patients were included in this meta-analysis. The incidence of postoperative subsidence in ZP group was significantly higher than with CP group [15.1% (89/588) vs. 8.8% (51/581), OR = 1.97 (1.34, 2.89), P = 0.0005]. In subgroup analysis, we found that the definition of subsidence did not affect the higher subsidence rate in the ZP group. Considering the quantity of operative segments, there was no significant difference in the incidence of subsidence between the two groups after single-level fusion (OR 1.43, 95% CI 0.61-3.37, P = 0.41). However, the subsidence rate of the ZP group was significantly higher than the CP group (OR 2.61, 95% CI 1.55-4.40, P = 0.0003) after multi-level surgery. There were no significant differences in intraoperative blood loss, JOA score, NDI score, fusion rate and cervical aligment in the final followup between the two groups. In addition, the CP group had a longer operation time and a higher incidence of dysphagia at each follow-up time than the ZP group.Conclusion ZP had a higher risk of postoperative subsidence than CP. Although there was a high occurrence of swallowing discomfort, we are more agreed that the anterior plate should be used in multi-level surgery as far as possible to reduce the subsidence and adverse clinical symptoms in the long term.