OBJECTIVES: Randomized clinical trial (RCT) evidence comparing cervical and lumbar total disc arthroplasty (TDA) with interbody fusion for degenerative disc disease (DDD) has been provided for different devices by FDA Investigational Device Exemption (IDE) studies. A synthesis of this evidence is needed for decision makers to select the appropriate intervention. This study aims to synthesize current clinical evidence on TDA and evaluate its relative efficacy and safety to interbody fusion. METHODS: A systematic search of Medline and Cochrane library identified 6 RCTs comparing TDA with fusion. These FDA IDE studies on lumbar (3) and cervical TDA (3), had similar designs and patient characteristics and allowed for pooling the outcomes. Efficacy was assessed by the FDA agreed outcomes: 1) > 15 points improvement in neck disability index (NDI, cervical) or Oswestry disability index (ODI, lumbar); 2) neurological success; 3) no subsequent surgery or intervention classified as “failure;” and 4) overall success: a composite measure of the previous outcomes and the absence of major adverse events. Comparative data were synthesised using a Bayesian meta-analytical approach. In contrast to a frequentist analysis, a Bayesian approach allows for calculating the probability of which intervention is the best and is therefore more intuitive for decision making. As a base case scenario a random effects analysis was performed on the intention to treat (ITT) data. RESULTS: The probability of lumbar and cervical TDA of having better outcomes than fusion at 2 years was 91% and 96% for overall success; 76% for ODI and 89% for NDI; 89% and 96% for neurological success; and 61% and 97% for secondary surgery, respectively. CONCLUSIONS: Based on this analysis, both lumbar and cervical TDA are likely to provide a greater net improvement relative to their respective interbody fusion techniques for single level DDD within 2 years in the elective patients.