Revision Surgeries at the Index Level After Cervical Disc Arthroplasty – A Systematic Review
Article information
Abstract
Objective
To perform a systematic literature review on revision surgeries at the index level after cervical disc arthroplasty (CDA) failure.
Methods
A systematic literature review was performed according to the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. Prospective studies on patients who required a secondary surgery after CDA failure were included for analysis. The minimum follow-up for these studies was 5 years.
Results
Out of 864 studies in the original search group, a total of 20 studies were included. From a total of 4,087 patients, 161 patients required a reoperation at the index level. A total of 170 surgeries were performed, as some patients required multiple surgeries. The most common secondary procedures were anterior cervical discectomy and fusion (ACDF) (68%, N = 61) and posterior cervical fusion (15.5%, N = 14), followed by other reoperation (13.3%, N = 12). The associated outcomes for those who required a revision surgery were rarely mentioned in the included literature.
Conclusion
The long-term revision rate at the index level of failed CDA surgery was 3.9%, with a minimum 5-year follow-up. ACDF was the most commonly performed procedure to salvage a failed CDA. Some patients who required a new surgery after CDA failure may require a more extensive salvage procedure and even subsequent surgeries.
INTRODUCTION
Cervical disc arthroplasty (CDA) is well-acknowledged as a motion-sparing alternative to treat mild cervical degenerative disease [1]. In comparison to anterior cervical discectomy and fusion (ACDF), CDA can achieve comparable patient-reported and clinical outcomes [2,3]. Specifically, several studies have shown that CDA can improve postoperative cervical range of motion and lower the risk of adjacent segment disease [2,3]. However, to our knowledge, there is no systematic review detailing how surgeons are managing patients when CDA fails.
The reported revision rate after CDA varies widely in the literature. Although many of the randomized trials reported a low rate of secondary surgeries after CDA, as high as 15% of reoperations were documented in retrospective studies, which may due to different indications for revisions as well as differences in CDA [4,5]. Additionally, due to the lack of clear definitions for failure, such as the term revision used interchangeably for replacing a new implant, reposition of a dislocated device or even removal and then performing an ACDF, for instance, it is difficult to evaluate the characteristics of revisions after a CDA, as well as the outcome of these patients.
To address the limitations, this systematic review focuses on revision surgery after CDA. The purpose of our review is to provide a comprehensive assessment on the existing literature on the underlying reasons for CDA failure, the types of secondary procedures performed, and the associated outcomes of revision surgery.
MATERIALS AND METHODS
We performed a systematic literature review to evaluate revision surgeries after CDA. This systematic review followed the guidance of PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) [6]. The PEO frameworks used in this review were as follows: Patients: with degenerative cervical disc disease requiring surgical treatment; Exposure: cervical arthroplasty requiring a new surgical intervention at the index treated level; Outcomes: type of secondary intervention, number of reoperations, outcomes.
1. Search Strategy
We reviewed PubMed for randomized controlled trials or prospective cohort studies that reported data on causes and outcome after a revision surgery for CDA. All existing studies up until April 26, 2020, were queried and reviewed. We searched for studies from the reference list of included studies and other relevant data in addition to potentially eligible studies. The first search was performed using the following keywords: “cervical arthroplasty prospective” with 864 studies. The second search was performed using the following keywords: “cervical disc arthroplasty” with 59 studies. All titles and abstracts were screened. A flow chart detailing our search selection can be seen in Fig. 1.
1) Methodological quality evaluation
All the studies were analyzed for internal validity integrity and graded for level of evidence in accordance to the Oxford Centre for Evidence-based medicine [7].
2) Eligibility criteria
Prospective studies with a minimum follow-up of 5 years. Studies focused on patients who underwent a CDA; studies in English language; studies reporting secondary surgeries at the index level after a CDA (revision, removal, redo, explant, etc.).
2. Data Collection Process
One (AFJ) of the authors independently extracted data from the included studies using a piloted data extracted form, resolving any discrepancies through discussion with the others. The references of relevant studies were cross-checked for additional studies not identified by the electronic search.
3. Data Extraction
The following data were extracted from the included studies: number of patients, study design, follow-up period, number of revisions surgeries, and details of subsequent surgeries followed a CDA were evaluated (e.g., index vs. adjacent vs. nonadjacent levels, type of revision), and associated outcomes after revision surgery.
RESULTS
1. Study Selection
A total of 20 studies were included. There were 10 prospective randomized multicenter studies (level 1 of evidence), 3 prospective randomized single-center studies (level 1 of evidence), and 7 prospective cohort studies (level 2 of evidence). A total of 4,087 patients were included [8-27]. Follow-up rates, when documented, varied from 54% to 92%, with the exception of the study by Walraevens et al. [8] which had only 26 of 89 patients with a follow-up at 8 years (29.2%). All the information extracted from the studies are summarized in Table 1 [8-27].
2. Reoperation at the Index Level
There were 161 patients who had at least 1 reoperation at the index level. The reoperation rate was 3.9% with a minimum 5-year of follow-up. Of note, these 161 patients had 170 surgeries, as some of them had one or more revision procedures.
3. Procedure for Reoperation the Index Level
In the majority of the studies, the procedure performed was not clearly described. When “removal” was mentioned in the studies, we inferred that an ACDF was performed after removal of the device. When reoperation/revision was mentioned, we inferred that the CDA was replaced by another implant or the patients had the implant repositioned, but a fusion was not performed, as many authors used the terms “removal” and “revision” in the same study with different meanings.
When mentioned in the study results (90 patients), the revision procedures performed were: ACDF/removal: 61 (68%); supplemental fixation/posterior cervical fusion: 14 (15.5%); reoperation/revision: 12 (13.3%); posterior decompression/laminectomy: 2 (2.2%); anterior cervical corpectomy and fusion: 1 (1.1%). Of note, the levels of revision procedures included were not always mentioned, but some of them involved additional levels.
Of note, Sasso et al. [22] did not have a revision surgery at the index surgery after the procedure, but 3 of the 242 patients who were planning to have a CDA required an intraoperative ACDF due to severe disc degeneration, small disc space, and inadequate visualization of the index level (C67). We considered this as a failure CDA at the index level.
4. Reasons for Reoperation at the Index Level
Interestingly, information about a patient’s outcome after revision surgery at the index level was rarely described in the included studies. An exception to this was Hacker et al. [10], who reported the outcomes of 3 patients: one had a Bryan disc subluxation and subtle findings of myelopathy and underwent an ACDF with a fair outcome. Another had local kyphosis after a Bryan disc and subsequently underwent a 2-level ACDF with a good outcome. Finally, a patient with a Prestige cervical disc had neck and arm pain, and loss of vertebral height and deformity. This patient required CDA removal and underwent a 2-level fusion, but the grafts subsided causing marked kyphosis requiring an additional procedure: a corpectomy and posterior fusion – with a fair outcome according to the authors.
The following indications for revision surgeries at the index level were documented: progressive symptoms/ongoing neck or arm pain (the most common cause described), disc subluxation, segmental deformity, myelopathy after surgery, ossification causing pain and kyphosis, oversized implant, intraoperative fractures of the posterior vertebral wall, malpositioned implant [10,11,12,13,19,20,21].
DISCUSSION
In our review, we focused on high-quality studies discussing secondary surgery at the index level after a failed CDA. Most of the specific literature about CDA is about its safety and even superiority in clinical outcomes when compared with ACDF, as well as its potential to preserve motion. However, there is a paucity of data on the indications for reoperation, as well as the outcome of this group of patients, which are of paramount importance for patient counseling preoperatively.
Park et al. [28] performed a retrospective evaluation of 21 patients who underwent a revision surgery after a CDA and had a minimum 2-year follow-up. In the primary procedure, 14 patients had a single level CDA, 2 patients had a 2-level CDA and 5 patients had 2-level hybrid surgery. The reasons for revision surgery were as follows: 17 (80.9%) were revised by poor patient selection according to them (such as severe cervical spondylosis or ossification of the posterior longitudinal ligament), 7 by insufficient decompression (35%), and 7 by implant malposition (35%), with 6 (28.5%) subsidences, 3 osteolysis (14.25%) and 1 postoperative infection (4.7%). To treat these failures, 16 patients had their CDA removed followed by 1-level ACDF (N = 11), 2-level ACDF (N = 3), 1-level corpectomy (N = 1), posterior laminoforaminotomy and fusion (N = 3), and combined procedures due to infection and osteolysis (N = 2). Using Odom’s scale, 86% of the patients were satisfied in the final follow-up. Similarly, with the results of our review, ACDF was the most commonly used salvage procedure following CDA failure, but it may include additional levels or supplementary posterior cervical surgery, increasing the morbidity of the procedure and potential complications. Interestingly, proper patient selection may decrease the reoperation rates. As stated in the study of Park et al. [5], CDA is not appropriate for all cases. Instead, CDA should be considered for those with preserved disc height, less severe degenerative disease, without spinal instability or deformities (such as kyphotic configuration of the segment) and osteoporosis [29].
The outcome of revisions procedures has rarely been studied. Only Hacker et al. [10] reported the outcomes, with fair results in 2 of 3 cases, requiring more complex salvage procedures. Additionally, the time for reoperation is quite variable in the literature. Zigler et al. [11] reported 30 (5.6%) reoperations in 535 patients who had a CDA using the ProDisc-C. The mean time for reoperation was 78.3 months, ranging from 24 to 181 months. They also reported no surgeries for device failure. In our review, the terms used in the studies were not also clear. For instance, some authors used the term “removal,” which we inferred that an ACDF was used instead. Revision or reoperation may be used interchangeably, for drainage a hematoma or to replace the CDA or even repositioning the implant. For this reason, a detailed analysis is limited. The U.S. Food & Drug Administration defines revision surgery as a procedure that adjusts or modifies the original implant configuration; removal surgery as a procedure that removes one or more components of the original implant and replacement by a different type of implant [30,31]. The misuse of these terms may lead to a wrong interpretation of the types of subsequent surgeries.
The reoperation rate at the index level obtained in our review was 3.9%, with the most common salvage procedure being an ACDF (68%). Skovrlj et al. [31] discussed the options for a failed CDA. They proposed that, for infection, extrusion, malposition, subsidence, or retropulsion, the most reasonable option is to remove the implant and perform an ACDF. In cases where there is excessive bone removal of 1 or even 2 vertebral bodies, a 1- or 2-level corpectomy may be necessary, which may increase the morbidity of the procedure. Additionally, if by any reason a plate is not possible, posterior fixation may be also considered. For patients who had radiculopathy with foraminal stenosis, a posterior decompression (with or without fusion) is an option. Of note, salvage procedures increase the risk of complications and may be potentially associated with a less favorable outcome. In our review, we found reoperations for all the reasons reported by Skovrlj et al. with exception of infection.
Our study is limited by the lack of specific and high-quality studies evaluating revision surgeries at the index level – the included studies did not focus on revision at the index level. The use of only PubMed database for searching clinical studies may reduce the number of included articles. Another limitation is the unclear use of the terms revision and removal in the studies, not always clear enough leading to potential bias in the interpretation of the types of subsequent surgeries. Finally, the heterogeneity in the data presentation and the low level of details, such as lack of final outcome for revision patients, may weaken our final interpretation. However, the results provide useful insight on CDA reoperations and the need for studies focusing on outcomes after revision CDA.
CONCLUSION
We report a reoperation rate of 3.9% after a long-term follow-up after a primary CDA. ACDF was the most common procedure to salvage a failed CDA. Some patients with CDA failure may require a more extensive salvage procedure and even subsequent surgeries. Future prospective studies addressing specifically the management and outcome of patients who failed a CDA are necessary.
Notes
The authors have nothing to disclose.