Two-level total disc replacement vs. fusion: any difference in reoperation rate?

© AME Medical Journal. All rights reserved. AME Med J 2017;2:55 amj.amegroups.com In this issue of the Clinical Spine Surgery, Radcliff et al. report on the results of five-year follow-up of reoperation rates in a prospective and randomized trial comparing 2-level lumbar total disc replacement (TDR) vs. fusion. 2-level lumbar TDR is a relatively novel procedure and its role in the surgical treatment of degenerative disc disease (DDD) should be fully scrutinized in comparison to 2-level fusion. However, it should be uncommon for an investigator to hold a well-controlled prospective randomized study with appropriate number of patients in long-term follow-up. Au fond there are few high-level studies reporting long-term reoperation rates in comparison between 2-level TDR and 2-level fusion. The current study comparing 2-level TDR and fusion in many patients is certainly a high-level and rare study despite its limitations, as this study includes well controlled, randomized, and longer-term follow-up research compared to the other relevant studies in the literature. As the authors indicated, this study was based on a US Food and Drug Administration (FDA) investigational device exemption comparing TDR to fusion for the treatment of symptomatic 2-level contiguous lumbar DDD. In the present study, there was a significantly lower rate of index levels reoperation in the TDR (5.6%) patients compared with circumferential fusion control patients (19.1%). This finding heralds TDR’s superiority to fusion in terms of safety. A survivorship analysis revealed that the estimated reoperation free survival at 5 years was 89.8% for all patients. The reoperation-free survival was significantly increased in the TDR (94.1%) versus fusion (80.0%) cohorts (P=0.0020). The most common reason for index levels reoperation was instrumentation removal (9/11=82%) in the fusion population. The overall rate of adjacent segment disease (ASD) requiring surgery was 3.5% (8/229). There were 4 adjacent segment reoperations in the fusion population (4/68=5.9%) and TDR (4/161=2.5%, P=0.24) respectively. The rate of index level reoperation in TDR population, 5.6%, seems to be rather low but relatively comparable to that of the index level reoperation in other 2-level TDR studies in the literature, which ranges 8.1% to 20% (1-3). In the present study, 2-level TDR has better outcome in terms of reoperation. The reoperation-free survivor was significantly increased in TDR. There were significantly fewer reoperations in 2-level TDR than those of 2-level of fusion (superior to fusion). But the result became insignificantly different, when the instrumentation removal was excluded in the reoperation of the fusion population (non-inferior to fusion). Recently, Siepe et al. (4) reported the results of the assessment of the midand long-term efficacy and safety of TDR in 151 single-level and 29 2-level TDR cases. In their report, deteriorating clinical results and higher complication rates were observed in the cohort of two-level TDR. They hypothesized the reason of this observation that the latest technique of lumbar TDR may Editorial