Elsevier

World Neurosurgery

Volume 126, June 2019, Pages e1228-e1234
World Neurosurgery

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

https://doi.org/10.1016/j.wneu.2019.02.233Get rights and content

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.

Introduction

Anterior cervical fusion has been widely accepted as the gold standard procedure in cervical degenerative disc diseases. However, Goffin et al.1 and Hilibrand et al.2 reported degenerative changes in the adjacent segments of the fusion level on long-term follow-up. Biomechanical studies have shown fusion to increase intradiscal pressure and motion of adjacent segments,3, 4 and in some reports, fusion surgery was suggested to actually increase segmental range of motion (ROM) at adjacent levels.5, 6 In 1989, the ball-and-socket type artificial disc composed of stainless steel was introduced by Cummins7; subsequently, cervical motion preservation prostheses have been extensively studied for degenerative disc diseases.5, 6, 7, 8, 9, 10, 11, 12

Although several authors suggest the long-term results of total disc replacement (TDR) are not inferior to anterior cervical discectomy and fusion (ACDF),12, 13 whether TDR actually prevents degeneration in adjacent segments remains unclear.9 In addition, debate continues because many studies have failed to show statistically significant increase of the ROM of the adjacent segments.3, 11, 14, 15

There are many different types of TDR, each with certain advantages and disadvantages. Because a new prosthesis has been developed and improved, the evaluation of TDR conducted using data from previously performed TDRs may not be accurate. We presumed that recently developed artificial disc devices can provide better results compared with the early devices.

The outcomes between TDR with artificial disc ActivC (Aesculap AG, Tuttlingen, Germany; Figure 1) and ACDF using a stand-alone cage performed in our hospital were compared. Although several studies on TDR have been previously conducted, studies on ActivC are lacking, thus, the present study provides valuable new evidence.

Section snippets

Ethics Statement

Approval for this retrospective review was obtained from the institutional review board (number: 2018AS0054). The requirement for written informed consent was waived by the board.

Patient Population

Patients diagnosed with cervical disc diseases and who received either ACDF using stand-alone cage or TDR using ActivC at a single level from C3–C4 to C6–C7 from January 2010 to December 2015 were reviewed. Patient exclusion criteria were as follows: multilevel surgery; surgery combined with laminectomy, laminoplasty,

Results

A total of 53 patients (mean age 48.5 years) were reviewed. Thirty patients (22 males and 8 females) were treated with ACDF and the remaining 23 patients (15 males and 8 females) received TDR. As shown in Table 1, baseline characteristics were not different between the 2 groups. The most frequent operated level was C5–C6 in both groups (56.7% and 69.6%, respectively) followed by C4–C5 (20.0% and 13.0%, respectively). In addition, operative time or blood loss did not differ between the two

Discussion

In many TDR clinical studies, motion preservation in the operative segments was reported as successful.5, 6, 8, 10, 11, 12 In recent years, improvements in prosthesis maximized bone anchoring and minimized bone sacrifice while reproducing physiologic motion beyond simply preserving motion.16, 17 A standard guideline based on the heterogeneity of artificial disc devices has yet to be established.9 ActivC (Figure 1) is a third-generation artificial disc prosthesis that has a dorsally located

Conclusions

Based on the results of the present study, the clinical outcomes for ACDF and TDR were equally favorable for 2 years after surgery. TDR using ActivC showed excellent motion preservation at the operated level during the 2 years of follow-up. Regarding segmental motion of the adjacent levels, both groups did not show significant differences. Considering the excellent motion preservation, the long-term results of TDR using ActivC are promising.

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      On the other hand, the laminoplasty provided higher preservation of the cervical ROM. We believe that the cervical lordosis preservation should be set as a treatment goal, often being challenging to deal with postsurgical cervical kyphotic deformities, highly affecting patients quality of life.10,11 Furthermore, postsurgical kyphosis often has an onset longer than the standard reported follow-up, thus its incidence and clinical significance could have been underestimated in previous clinical studies.31,42

    Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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