Comparison of Adjacent Segment Motion after Anterior Cervical Fusion Using Standalone Cage versus Total Disc Replacement Using Activ C

Anterior cervical discectomy and fusion (ACDF) has been a widely accepted procedure for treatment of cervical disc diseases. However, several reports about postfusion exacerbation of adjacent segments gave rise to development of motion preserving prosthesis. We present the retrospective analysis comparing total disc replacement (TDR) using Activ C (Aesculap, Germany) with ACDF using standalone cage.Materials and Methods From January 2010 to December 2012, among patients diagnosed of cervical disc diseases, patients who received either ACDF or TDR at single level were reviewed. Clinical outcome was assessed using visual analogue scale (VAS) of arm pain and neck pain. For all patients, lateral flexion and extension radiographs were taken at preoperative and 1 year after operation. The segmental range of motion (ROM) of operated level, rostral adjacent level, and caudal adjacent level were measured from plain dynamic radiographs using Cobb angle. Multilevel ACDF and hybrid method were not included in this series.Results A total of 40 patients (mean age 46.3 years) were reviewed. Fifteen patients were treated with TDR and the remaining 25 patients received ACDF. At the time of 1-year follow-up, the segmental ROM of operated level was significantly preserved in TDR group ( p = 0.017), whereas the motions of rostral and caudal adjacent levels were greater in ACDF group than TDR group (7.1 versus 6.6 degrees and 6.6 versus 5.1 degrees, respectively). However, the ROM of adjacent segments did not show statistical significance.Conclusions In the present study, we found that TDR using Activ C showed favorable motion preservation at the operated level. Radiologically, the ACDF group showed more increase of adjacent segment motion 1 year after surgery, which implies that TDR using Activ C may have advantages in preventing adjacent segmental diseases compared with ACDF.