Segmental Motion of the Cervical Spine After Total Disc Replacement Using ActivC Versus Discectomy and Fusion Using Stand-alone Cage

Objective: Anterior cervical discectomy and fusion (ACDF) has been a widely accepted procedure for the treatment of cervical disc diseases. However, due to several reports regarding postfusion exacerbation of adjacent segments, a motion-preserving prosthesis was developed. In the present retrospective analysis, total disc replacement (TDR) using ActivC (Aesculap AG, Tuttlingen, Germany) was compared with ACDF using a stand-alone cage. Methods: Among patients diagnosed with cervical disc diseases, those who received either ACDF or TDR at a single level between C3 and C7 from January 2010 to December 2015 were reviewed. Clinical outcomes were assessed using the visual analogue scale for arm and neck pain and the neck disability index. Clinical scales, lateral neutral, and flexion–extension radiographs were taken for all patients preoperatively and 2 months, 6 months, 1 year, and 2 years postoperatively. Global lordosis, C2–C7 Sagittal vertical axis, and T1 slope were measured on lateral neutral radiographs. The segmental range of motion (ROM) of the operated level, cranial adjacent level, and caudal adjacent level were defined as the difference between Cobb angles on flexion–extension lateral radiographs. Results: A total of 53 patients (mean age 48.5 years) were reviewed. Thirty patients were treated with ACDF and the remaining 23 patients received TDR. At the 2-year follow-up, the segmental ROM of operated level was significantly preserved in the TDR group compared with the ACDF group (P = 0.007). Conversely, no significant differences in the ROM at the adjacent segments were observed between the TDR and ACDF groups (P > 0.05). The clinical outcome was excellent in both ACDF and TDR groups and was maintained until the 2-year follow-up. Conclusions: In the present study, TDR using ActivC showed successful motion preservation at the operated level and equivalent results were observed with ACDF based on clinical and radiologic results.