Adjacent segment degeneration and disease after cervical total disc replacement vs anterior cervical discectomy and fusion: a Meta-analysis of randomized controlled trials

English Keywords:Cervical total disc replacement  Anterior cervical discectomy and fusion  Adjacent segment degeneration  Adjacent segment disease  Meta-analysis

English Abstract:

  【Abstract】 Objectives: To analyze whether cervical total disc replacement(TDR) superior to anterior cervical discectomy and fusion(ACDF) in decreasing the incidence of adjacent segment degeneration(ASDeg) and adjacent segment disease(ASDis) by Meta-analysis. Methods: The PubMed, Medline, EMBASE, Cochrane Library, CBM and Wanfang databases were searched up for randomized controlled trials (RCTs) form January 2002 to June 2016, which reported ASDeg, ASDis and reoperation on adjacent segments after TDR and ACDF. The RCTs were evaluated by two investigators independently. A meta-analysis was performed according to the guidelines of Cochrane Collaboration. The tool of Cochrane Collaboration for assessing methodological quality and risk of bias was applied to separate included studies. Data extraction mainly contained the incidence of ASDeg and ASDis which were regarded as direct outcomes, the incidence of reoperation on adjacent segments which was regarded as indirect outcome to reflect adjacent segment degeneration or disease. Follow-up time and trial sites were stratified practically in clinic to perform subgroup-analysis. Eventually the quality of the whole meta-analysis was evaluated by using the grades of recommendation, assessment, development and evaluation(GRADE). Results: Eleven studies with 2,632 patients were included in the meta-analysis. The outcomes showed that the overall rate of adjacent segment degeneration/disease(ASD) in TDR group was statistically lower than that in ACDF group(OR=0.6; 95% CI[0.38, 0.73]; P<0.00001). More specifically, both the incidence of ASDeg and reoperation rate were significantly lower in patients by TDR than in those by ACDF(OR=0.58, 95％CI[0.46, 0.72], P<0.00001; OR=0.52, 95% CI[0.30, 0.87], P=0.01, respectively). Subgroup analysis according to the follow-up time: the rate of ASDeg was lower in patients by TDR than in those by ACDF no matter it was longer than 5 years or not (OR=0.63, P=0.001; OR=0.49, P=0.0002, respectively), and TDR tended to increase the superiority across time. The rate of ASDeg was also statistically different between patients who underwent TDR and patients who underwent ACDF both in the US and China(P<0.0001, P=0.03, respectively). According to GRADE, the overall quality of this Meta-analysis was moderate-quality. Conclusions: TDR significantly decreases the rate of ASDeg and reoperation compared with ACDF, and the superiority may become more apparent over time.