Study Design. Meta-analysis of randomized controlled trials.
Objective. To compare the reported incidence of adjacent segment disease (ASD) requiring surgical intervention between anterior cervical decompression and fusion (ACDF) and total disc arthroplasty (TDA).
Summary of Background Data. The concern for ASD has led to the development of motion-preserving technologies such as TDA. To date, however, no known study has sought to compare the incidence of ASD between ACDF and TDA in major prospective studies.
Methods. A systematic review of IDE and non-IDE trials was performed using PubMed and Cochrane libraries. These databases were thoroughly searched for prospective randomized studies comparing ACDF and TDR. Six studies met the inclusion criteria for a meta-analysis and were used to report an overall rate of ASD for both ACDF and TDA.
Results. Pooling data from 6 prospective studies, the overall sample size at baseline was 1586 (ACDF = 777, TDA = 809) and at the final follow-up was 1110 giving an overall follow-up of 70%. Patients after an ACDF had a lower rate of follow-up overall than those after TDR (ACDF: 67.3% vs. TDR: 72.6%, P= 0.01). Thirty-six patients required adjacent-level surgery after an ACDF at 2 to 5 years of follow-up (6.9%) compared with 30 patients after a TDA (5.1%). The corresponding reoperation rate for ASD was 2.4 ± 1.7% per year for ACDF versus 1.1 ± 1.5% per year for TDR. These differences were not statistically significant (P= 0.44). Using a Kaplan-Meier analysis and historical data, we expect 48 patients in the ACDF group and 55 patients in the TDR group to have symptomatic disease at an adjacent level.
Conclusion. From a meta-analysis of prospective studies, there is no difference in the rate of ASD for ACDF versus TDA. We also report an overall lower rate of follow-up for patients with ACDF than for those with TDR. Future prospective studies should continue to focus on excellent patient follow-up and accurate assessment of patient symptoms that are attributable to an adjacent level as this has been an under-reported finding in prospective studies.
Level of Evidence: 1