Cervical kinematics and radiological changes after Discover artificial disc replacement versus fusion

Department of Orthopaedic Surgery, Changzheng Hospital, No. 415 Feng Yang Rd, Shanghai 200003, China.
The spine journal: official journal of the North American Spine Society (Impact Factor: 2.43). 09/2013; 14(6). DOI: 10.1016/j.spinee.2013.07.432
Source: PubMed


The cervical disc arthroplasty has emerged as a promising alternative to the anterior cervical discectomy and fusion (ACDF) in patients with radiculopathy or myelopathy with disc degeneration disease. The advantages of this technique have been reported to preserve the cervical mobility and possibly reduce the adjacent segment degeneration. However, no studies have compared the clinical outcomes and radiological results in patients treated with Discover artificial disc replacement to those observed in matched group of patients that have undergone ACDF.
We conducted this clinical study to compare the cervical kinematics and radiographic adjacent-level changes after Discover artificial disc replacement with ACDF.
Analysis and evaluation of data acquired in a comparative clinical study.
The number of patients in the Discover and ACDF group were 149 and 196, respectively.
The Neck Disability Index (NDI) and visual analog scale (VAS) pain score were evaluated. The range of movement (ROM) by the shell angle, the functional segment unit and global angles were measured, and the postoperative radiological changes at adjacents levels were observed.
A total of 149 patients with symptomatic single or two-level cervical degenerative diseases received the Discover cervical artificial disc replacement from November 2008 to February 2010. During the same period, there were a total of 196 patients undergoing one or two-level ACDF. The average follow-up periods of the Discover disc group and ACDF group were 22.1 months and 22.5 months, respectively. Before surgery, patients were evaluated using static and dynamic cervical spine radiographs in addition to computerized tomography and magnetic resonance imaging. Static and dynamic cervical spine radiographs were obtained after surgery and then at 3- and 6-month follow-up. Then, the subsequent follow-up examinations were performed at every 6-month interval. The clinical results in terms of NDI and VAS scores, the parameters of cervical kinematics, postoperative radiological changes at adjacent levels, and complications in the two groups were statistically analyzed and compared. No funding was received for this study, and the authors report no potential conflict of interest-associated biases in the text.
Although the clinical improvements in terms of NDI and VAS scores were achieved in both the Discover and ACDF group, no significant difference was found between the two groups for both single- (VAS p=.13, NDI p=.49) and double-level surgeries (VAS p=.28, NDI p=.21). Significant differences of cervcial kinematics occurred between the Discover and the ACDF group for both the single- and double-level surgeries at the operative segments (p<.001). Except the upper adjacent levels for the single-level Discover and ACDF groups (p=.33), significant increases in adjacent segment motion were observed in the ACDF group compared with the minimal ROM changes in adjacent segment motion noted in the Discover group, and the differences between the two groups for both single and double-level procedures were statistically significant (p<.05). There were significant differences in the postoperative radiological changes at adjacent levels between the Discover and ACDF groups for the single-level surgery (p<.001, χ(2)=18.18) and the double-level surgery (p=.007, χ(2)=7.2). No significant difference of complications was found between the Discover and ACDF groups in both single (p=.25, χ(2)=1.32) and double-level cases (p=.4, χ(2)=0.69).
The adjacent segment ROM and the incidence of radiographic adjacent-level changes in patients undergoing ACDF were higher than those undergoing Discover artificial disc replacement. The cervical mobility was relatively well maintained in the Discover group compared with the ACDF group, and the Discover cervical disc arthroplasty can be an effective alternative to the fusion technique.

15 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Study Design. A Markov transition state model was developed to evaluate the cost-effectiveness of Anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR) at five years.Objective. To determine the cost-effectiveness of ACDF and CDR at five years.Introduction. ACDF and CDR are surgical options for the treatment of an acute cervical disc herniation with associated myelopathy/radiculopathy. Cost-effectiveness analysis (CEA) provides valuable information regarding which intervention will lead to a more efficient utilization of healthcare resourcesMethods. Outcome and complication probabilities were obtained from existing literature. Physician costs were based on a fixed percentage of 140% of 2010 Medicare reimbursement. Hospital costs were determined from the Nationwide Inpatient Sample (NIS). Utilities were derived from responses to health state surveys (Short Form 36) at baseline and at 5 years from the treatment arms of the Prodisc-C trial. Incremental cost effectiveness ratios (ICER) were used to compare treatments. One-way sensitivity analyses were performed on all parameters within the model.Results. CDR generated a total five-year cost of $102,274, while ACDF resulted in a five-year cost of $119,814. CDR resulted in a generation of 2.84 QALY's, whereas ACDF resulted in 2.81. The ICER was -$557,849 per QALY gained. CDR remained the dominant strategy below a cost of $20,486. ACDF was found to be a cost-effective strategy below a cost of $18,607. CDR was the dominant strategy when the utility value was above 0.713. CDR remained the dominant strategy assuming an annual complication rate less than 4.37%.Conclusions. ACDF and CDR were both shown to be cost effective strategies at five years. CDR was found to be the dominant treatment strategy in our model. Further long-term studies evaluating the clinical and quality of life outcomes of these two treatments are needed to further validate the model.
    Spine 08/2014; 39(23). DOI:10.1097/BRS.0000000000000562 · 2.30 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study is to investigate the effect of anterior cervical discectomy with internal fixation and fusion at different levels on adjacent segments in rabbits. Sixty New Zealand rabbits were randomly divided into four groups, one control group and three model groups, with 15 in each group. Each group underwent anterior cervical internal fixation and fusion at C3-4, C4-5, and C5-6 levels respectively. X-ray film was examined three, six and nine months after fusion to observe the changes in intervertebral space and endplate of adjacent segment. Immunohistochemistry was utilized to evaluate the effects of different fusion methods on adjacent segments of spine. As time went by, in model groups, the majority of cartilage endplates were calcified, as examined by X-ray. Immunohistochemical results of the intervertebral disc showed that the expression levels of collagen type II in nucleus pulposus were decreased significantly, while the expression levels collagen type I in annular fibrosus were increased. And collagen type I tends to replace collagen type II gradually in nucleus pulposus as time goes by. The change in collagen between upper and lower adjacent segments at C3-4 and C4-5 showed no statistical significance after fixation and fusion (p > 0.05). But for C5-6, the change showed statistical significance (p < 0.05). Cervical internal fixation and fusion can induce intervertebral disc degeneration of adjacent segment in rabbits, and cervical internal fixation and fusion operated at different levels may result in different effects on adjacent segments of cervical intervertebral disc.
    International Journal of Clinical and Experimental Medicine 11/2014; 7(11):4291-9. · 1.28 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Several previous studies comparing artificial disc replacement (ADR) and fusion have been conducted with cautiously positive results in favor of ADR. This study is not, in contrast to most previous studies, an investigational device exemption-study required by the Food and Drug Administration for approval to market the product in the U.S. This study was partially funded with unrestricted institutional research grants by the company marketing the artificial disc, used in this study. To compare outcomes between the concepts of an artificial disc to treatment with anterior cervical decompression and fusion (ACDF) and to register complications associated to the two treatments during a follow-up time of two years. Randomized controlled multicenter trial, including three spine centers in Sweden. Patients seeking care for cervical radiculopathy who fulfilled inclusion criteria. In total, 153 patients were included. Self-assessment with NDI as primary outcome variable and EQ-5D and VAS as secondary outcome variables. Patients were randomly allocated to either treatment with the Depuy Discover artificial disc or fusion with iliac crest bone graft and plating. Randomization was blinded to both patient and caregivers until time for implantation. Adverse events, complications, and revision surgery was registered as well as loss of follow-up. Data was available in 137 (91%) of the included and initially treated patients. Both groups improved significantly after surgery. NDI changed from 63.1 to 39.8 in an intention -to-treat analysis. No statistically significant difference between the ADR and the ACDF groups could be demonstrated with NDI values of 39.1 and 40.1 respectively. Nor in secondary outcome measures (EQ-5D and VAS) could any statistically significant differences be demonstrated between the groups. Nine patients in the ADR group and three in the fusion group underwent secondary surgery because of various reasons. Two patients in each group underwent secondary surgery because of adjacent segment pathology. Complication rates were not statistically significant between groups. Artificial disc replacement did not result in better outcome compared to fusion measured with Neck Disability Index two years after surgery. Copyright © 2015 Elsevier Inc. All rights reserved.
    The spine journal: official journal of the North American Spine Society 02/2015; 15(6). DOI:10.1016/j.spinee.2015.02.039 · 2.43 Impact Factor
Show more