Cervical disc arthroplasty versus anterior cervical discectomy and fusion for the treatment of single-level disc degenerative disease with preoperative reversible kyphosis

Highlights

• Patients with preoperative reversible kyphosis were included in this study.

• Single-level CDA and ACDF achieved satisfactory and comparable clinical results.

• CDA was non-inferior to ACDF regarding the postoperative cervical alignment.

• CDA group had a relatively high incidence of HO formation.

Abstract

Objective

Whether and when cervical disc arthroplasty (CDA) could be indicated for preoperative cervical spine kyphosis is unclear. The purpose of the study was to compare the clinical and radiological outcomes of single-level CDA and single-level anterior cervical discectomy and fusion (ACDF) in the patient with preoperative reversible kyphosis.

Patients and methods

From 2014–2018, patients who underwent single-level CDA and single-level ACDF were consecutively reviewed. The Japanese Orthopedic Association score, Neck Disability Index and VAS were used to evaluate clinical outcomes. Range of motion (ROM), C2-7 Cobb angle, functional spinal unit (FSU) angle, and heterotopic ossification (HO) were assessed.

Results

Thirty-eight CDA patients (a mean follow-up of 39.8 months) and 42 ACDF patients (37.6 months) with preoperative reversible kyphosis were included. Both groups had significant improvements in clinical outcomes, without statistically significant differences. Before surgery, there was no significant difference in cervical alignment and ROM between groups. After surgery, both groups had a significant increase in C2-7 angle and FSU without significant inter-group differences. At the last follow-up, CDA group consisted of 5 cases of lordosis, 11 cases of kyphosis and 22 cases of straight spine, while the corresponding case number in ACDF group was 4, 12 and 26 (P = 0.866). The C2-7 ROM was preserved in both groups. The segmental ROM of CDA group decreased mildly from 8.3° preoperatively to 5.1° finally, whereas the segmental ROM of ACDF group decreased significantly to nearly zero. 60.5 % (23/38) patients in CDA group developed HO with 9 levels of grade Ⅲ and 3 levels of grade Ⅳ.

Conclusion

For the patients with single-level disc degenerative disease and preoperative reversible kyphosis, both CDA and ACDF achieved satisfactory and comparable clinical results. CDA was non-inferior to ACDF regarding the radiological outcomes of cervical alignment. Patients in CDA group had a relatively high incidence of HO formation.

Introduction

Anterior cervical discectomy and fusion (ACDF) is traditionally the standard procedure to manage cervical degenerative disease that involves less than 3 levels. It could be indicated for various cervical disc pathology like segmental instability, severe facet joint degeneration and kyphosis [1]. For patients with preoperative kyphosis, short segment fusion operation could remarkably increase cervical lordosis by appropriate placement of interbody spacer [2]. Moreover, current studies [[3], [4], [5], [6]] indicated the stand-alone cage with integrated screw fixation had the similar capacity for maintaining segmental and overall alignment in comparison to the interbody cage plus anterior plate.

In recent years, cervical disc arthroplasty (CDA) provides a viable motion-preserving option for cervical degenerative disease. By maintaining the motion of the surgical level, CDA has the potential to decrease the biomechanical stress on adjacent levels, theoretically slowing down adjacent segment degeneration. Several randomized controlled studies reported that CDA achieved equivalent or superior outcomes compared with fusion [[7], [8], [9]]. However, it remained controversial whether CDA could be indicated for patient with kyphosis. On the one hand, most surgeons took a cautious and suspicious attitude towards the application of CDA in the spine with malalignment because of its lack of anterior column support and specific considerations to the segmental kyphosis after insertion with BRYAN® Cervical Disc (Medtronic, Sofamor Danek, Memphis) [10,11]. One the other hand, some authors found CDA could restore the cervical alignment to some extent [[12], [13], [14], [15], [16]]. Our previous study [16] found the cervical alignment of patients with preoperative reversible kyphosis experienced significant improvements after single-level CDA, although it was still significantly inferior to that of matched patients with preoperative lordosis.

The purpose of this study was to evaluate and compare the clinical and radiological outcomes of single-level CDA with Prestige-LP Disc (Medtronic Sofamor Danek, Memphis, TN) and single-level ACDF with Zero-P Spacer (Synthes GmbH Switzerland, Oberdorf, Switzerland) in the patient with preoperative reversible kyphosis. In this study, special attention was paid to the radiological outcome of cervical alignment.