Is cervical disc arthroplasty superior to fusion for treatment of symptomatic cervical disc disease? A meta-analysis

Impact of Gender on Postsurgical Outcomes in Patients Undergoing Anterior Cervical Discectomy and Fusion

BACKGROUND

Prior studies associate male gender with higher complication rates following anterior cervical discectomy and fusion (ACDF), but none has investigated gender influence on patient-reported outcome measures (PROMs) and minimal clinically important difference (MCID) following single-level ACDF.

METHODS

Patients undergoing primary, single-level ACDF were divided into female and male groups. Visual analog scale (VAS) neck/arm, Neck Disability Index (NDI), 12-item short form (SF-12) physical composite score (PCS), PROM information system physical function (PROMIS-PF), and veterans RAND 12-item (VR-12) health survey PCS were collected preoperatively and postoperatively. Simple linear regression analysis evaluated the predictive capability of gender on PROMs. Multiple regression analysis was performed to determine the effects of gender on mean PROMs while accounting for insurance type. Established MCID values determined achievement rates across PROMs. χ ² analysis compared MCID achievement by gender.

RESULTS

A total of 179 women and 134 men were included. Cohorts differed in insurance type, length of stay, and discharge day (P ≤ 0.017, all). Women improved in PROMs at all timepoints (P ≤ 0.049, all) except SF-12 PCS 6 weeks and PROMIS-PF 6 weeks. Men improved in PROMs at all timepoints (P ≤ 0.042) except VAS arm 2 years, SF-12 PCS 6 weeks and 2 years, PROMIS-PF 6 weeks, and VR-12 PCS 6 weeks. Women demonstrated higher SF-12 PCS (P = 0.043) and VR-12 PCS (P = 0.035) 2 years. Multiple regression determined that VAS neck and arm from 6 weeks to 6 months, NDI from preoperative to 6 months, SF-12 PCS and VR-12 PCS from preoperative to 12 weeks, and PROMIS-PF preoperative, 6 weeks, and 6 months were significantly affected by gender and insurance status (P ≤ 0.031, all). MCID achievement rate did not differ for any PROM between genders.

CONCLUSION

Women reported significantly higher long-term physical function health (SF-12 PCS and VR-12 PCS) compared with men, while disability and pain did not differ. Nevertheless, no significant differences in MCID achievement were observed for any PROM studied. Gender does not appear to play a significant role in clinically meaningful recovery following single-level ACDF.

CLINICAL RELEVANCE

Gender has little value in prognostication for determining clinically meaningful recovery after single-level ACDF.

LEVEL OF EVIDENCE: 3

Research protocol: Cervical Arthroplasty Cost Effectiveness Study (CACES): economic evaluation of anterior cervical discectomy with arthroplasty (ACDA) versus anterior cervical discectomy with fusion (ACDF) in the surgical treatment of cervical degenerative disc disease - a randomized controlled trial

INTRODUCTION

To date, there is no consensus on which anterior surgical technique is more cost-effective in treating cervical degenerative disc disease (CDDD). The most commonly used surgical treatment for patients with single- or multi-level symptomatic CDDD is anterior cervical discectomy with fusion (ACDF). However, new complaints of radiculopathy and/or myelopathy commonly develop at adjacent levels, also known as clinical adjacent segment pathology (CASP). The extent to which kinematics, surgery-induced fusion, natural history, and progression of disease play a role in the development of CASP remains unclear. Anterior cervical discectomy with arthroplasty (ACDA) is another treatment option that is thought to reduce the incidence of CASP by preserving motion in the operated segment. While ACDA is often discouraged, as the implant costs are higher while the clinical outcomes are similar to ACDF, preventing CASP might be a reason for ACDA to be a more cost-effective technique in the long term.

METHODS AND ANALYSIS

In this randomized controlled trial, patients will be randomized to receive ACDF or ACDA in a 1:1 ratio. Adult patients with single- or multi-level CDDD and symptoms of radiculopathy and/or myelopathy will be included. The primary outcome is cost-effectiveness and cost-utility of both techniques from a healthcare and societal perspective. Secondary objectives are the differences in clinical and radiological outcomes between the two techniques, as well as the qualitative process surrounding anterior decompression surgery. All outcomes will be measured at baseline and every 6 months until 4 years post-surgery.

DISCUSSION

High-quality evidence regarding the cost-effectiveness of both ACDA and ACDF is lacking; to date, there are no prospective trials from a societal perspective. Considering the aging of the population and the rising healthcare costs, there is an urgent need for a solid clinical cost-effectiveness trial addressing this question.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04623593. Registered on 29 September 2020.

Quality assessment of systematic reviews of surgical treatment of cervical spine degenerative diseases: an overview

OBJECTIVE

To gather all systematic reviews of surgical treatment of degenerative cervical diseases and assess their quality, conclusions and outcomes.

METHODS

A literature search for systematic reviews of surgical treatment of degenerative cervical diseases was conducted. Studies should have at least one surgical procedure as an intervention. Included studies were assessed for quality through Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) and Assessment of Multiple Systematic Reviews (AMSTAR) questionnaires. Quality of studies was rated accordingly to their final score as very poor (<30%), poor (30%-50%), fair (50%-70%), good (70%-90%), and excellent (>90%). If an article reported a conclusion addressing its primary objective with supportive statistical evidence for it, they were deemed to have an evidence-based conclusion.

RESULTS

A total of 65 systematic reviews were included. According to AMSTAR and PRISMA, 1.5% to 6.2% of studies were rated as excellent, while good studies counted for 21.5% to 47.7%. According to AMSTAR, most studies were of fair quality (46.2%), and 6.2% of very poor quality. Mean PRISMA score was 70.2%, meaning studies of good quality. For both tools, performing a meta-analysis significantly increased studies scores and quality. Cervical spondylosis studies reached highest scores among diseases analyzed. Authors stated conclusions for interventions compared in 70.7% of studies, and only two of them were not supported by statistical evidence.

CONCLUSION

Systematic reviews of surgical treatment of cervical degenerative diseases present "fair" to "good" quality in their majority, and most of the reported conclusions are supported by statistical evidence. Including a meta-analysis significantly increases the quality of a systematic review.

Cervical Total Disc Replacement: Long-Term Outcomes

Degenerative disc disease and associated cervical spondylosis or stenosis are common conditions encountered in clinical practice. These conditions may cause progressive cervical radicular or myelopathic symptoms leading to significant impairment. Although anterior cervical discectomy and fusion (ACDF) has been a reliable surgical treatment of cervical myelopathy and radiculopathy, but limitations include loss of cervical range of motion, the concern for adjacent segment degeneration and disease, pseudoarthrosis, complications related to the choice of intervertebral graft, dysphagia, as well as standard anterior cervical approach risk. Cervical total disc arthroplasty has emerged as an alternative operative procedure to ACDF.

Total disc replacement compared with fusion for cervical degenerative disc disease: A systematic review of overlapping meta-analyses

STUDY DESIGN

The present study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement.

OBJECTIVE

The present study aimed to conduct a systematic review of overlapping meta-analyses comparing ACDR with fusion for treating CDDD in order to assist decision makers in their selection among conflicting meta-analyses and to provide treatment recommendations based on the best available evidence.

SUMMARY OF BACKGROUND DATA

Although several meta-analyses have been performed to compare total disc replacement (TDR) and fusion for treating cervical degenerative disc disease (CDDD), their findings are inconsistent.

METHODS

Multiple databases were comprehensively searched for meta-analyses comparing TDR with fusion for treating CDDD. The meta-analyses that comprised only randomized controlled trials (RCTs) were included. Two authors independently assessed the meta-analysis study quality and extracted the data. The Jadad decision algorithm was used to ascertain which meta-analysis studies represented the best evidence.

RESULTS

A total of 14 meta-analysis studies were included. All these studies only included RCTs and were determined as Level-II evidence.

CONCLUSIONS

Cervical disc arthroplasty was superior compared to anterior discectomy and fusion for the treatment of symptomatic cervical disc disease.

An Eight-Year Follow-Up Study on the Treatment of Single-Level Cervical Spondylosis Through Intervertebral Disc Replacement and Anterior Cervical Decompression and Fusion

Objective

To compare the efficacy and safety of the postoperative long‐term effect of the treatment of single‐level cervical spondylosis through anterior cervical discectomy and fusion (ACDF) and artificial cervical disc replacement (ACDR).

Methods

This is a retrospective contrastive study, which was conducted for the period of January 2007 and January 2009 at the Department of Spine Surgery of the First Affiliated Hospital of Xinjiang Medical University. A total of 113 patients were divided into two groups depending on the operation method: ACDF group (fusion group, n = 66) and ACDR group (replacement group, n = 47). The ACDR group comprised of 23 males and 24 females. The age of these patients ranged from 31–60 years, with an average age of 42.89 ± 6.30 years. The ACDF group comprised of 38 males and 28 females. The age of these patients ranged from 28–73 years old, with an average age of 49.38 ± 9.89 years old. The evaluation index included the visual analogue scale (VAS), neck disability index (NDI), range of motion, dysphagia, adjacent vertebral disease, and related complications (prosthesis displacement, heterotopic ossification, etc.).

Results

A total of 113 patients met the inclusion criteria, and these patients receive more than 96 months of follow‐up. The VAS and NDI of these two groups of patients significantly improved, when compared with those before the operation. In the last follow‐up visit, the range of motion in the ACDR group and ACDF group was 43.22 ± 3.58 and 32.54 ± 2.82, respectively, and both are significantly different comparing to the values measured before the operation (P < 0.05). The dysphagia incidence of the ACDR group was higher than that of the ACDF group at the 36th month, but was lower than that of the ACDF group in other points time. In the last follow‐up visit, six patients (12.77%) in the ACDR group and 18 patients (27.27%) in the ACDF suffered from adjacent segment degeneration (ASD). The general complication rate in the replacement group and fusion group was 38.31% and 37.88%, respectively, but the difference between the two groups was not statistically significant (P > 0.05).

Conclusion

Overall, the clinical efficacy and related complication rate of single‐level cervical spondylosis after an anterior cervical approach operation was superior in the ACDR group when compared to the ACDF group.

A Comparative in vivo Study of Semi-constrained and Unconstrained Cervical Artificial Disc Prostheses

PURPOSE

The objective of this study is to directly compare different types of cervical artificial disc implants using an in vivo model capable of simulating the axial load on a neck that is similar to the human neck.

METHODS

Cervical arthroplasty was performed at C3-4 in 14 healthy female adult Alpine goats. The goats were divided into three groups. Group A received Bryan (unconstrained one-piece design); Group B received ProDisc-C (semi-constrained two-piece design); and Group C received Mobi-C (unconstrained three-piece design) artificial discs. The goats were monitored in a veterinary unit for 6 months with radiography at regular intervals.

RESULTS

Each goat tolerated cervical arthroplasty well and had satisfactory placement of their implant per intra-operative radiography. Implants monitored in Group A demonstrated no migration. One out of five implants in Group B experienced anterior migration at 3 months. In Group C, anterior migration and disintegration occurred in all four implants, with migration occurring during the first postoperative week in three implants and after 5 weeks in the fourth.

CONCLUSIONS

Unconstrained multi-piece artificial cervical discs may be prone to anterior migration and extrusion out of the disc space. This outcome deserves attention in individuals with a hypermobile neck and/or an occupation involving the use of a head-supported mass, such as helmets.

Safety and efficacy of cervical disc arthroplasty in preventing the adjacent segment disease: a meta-analysis of mid- to long-term outcomes in prospective, randomized, controlled multicenter studies

Objectives

Cervical disc arthroplasty (CDA) has become an alternative treatment for cervical radiculopathy and myelopathy. This technique preserves appropriate motion at both the index and adjacent disc levels and consequently may prevent adjacent segment degeneration (ASD). The authors performed a meta-analysis to compare the safety and efficacy of CDA to those of the gold standard, anterior cervical discectomy and fusion (ACDF). Both surgical and clinical parameters were employed to verify the hypothesis that CDA can reduce the risk of ASD.

Methods

The meta-analysis comprised high-quality randomized controlled trials that compared CDA and ACDF treatments of cervical degenerative disc disease. Included papers reported data for at least one of the following outcomes: 1) surgical parameters, 2) questionnaire clinical indices (pre- and postoperative values), and 3) complication rates at 24 months; in addition, for ASD we analyzed 60 month or longer follow-ups. We used mean differences (MDs) or ORs to compare treatment effects between CDA and ACDF.

Results

Twenty studies with 3,656 patients (2,140 with CDA and 1,516 with ACDF) met the inclusion criteria. CDA surgery, with mean duration longer than that of ACDF, was associated with higher blood loss. Visual analog scale neck pain score was significantly smaller for CDA (mean difference =−2.30, 95% CI [−3.72; −0.87], P=0.002). The frequency of dysphagia/dysphonia (OR =0.69, 95% CI [0.49; 0.98], P=0.04) as well as the long-term ASD rate for CDA was significantly smaller (OR =0.33, 95% CI [0.21; 0.50], P<0.0001).

Conclusion

A significantly lower probability of ASD reoperations in the CDA cohort after a 60-month or longer follow-up was the most important finding of this study. Despite the moderate quality of this evidence, the pooled data corroborated for the very first time that CDA was efficacious in preventing ASD.

Comparison of Inpatient and Outpatient Preoperative Factors and Postoperative Outcomes in 2-Level Cervical Disc Arthroplasty

OBJECTIVE

The purpose of this study was to evaluate factors associated with inpatient admission following 2-level cervical disc arthroplasty (CDA). A secondary aim was to compare outcomes between those treated on an inpatient versus outpatient basis.

METHODS

Using data from the American College of Surgeons National Surgical Quality Improvement Program database, multivariate logistic regression analysis was used to assess the independent effect of each variable on inpatient or outpatient selection for surgery. Statistical significance was defined by p-values <0.05. The factors considered were age, sex, body mass index (BMI), smoking status, American Society of Anesthesiologists physical status classification, and comorbidities including hypertension, diabetes, history of dyspnea or chronic obstructive pulmonary disease, previous cardiac intervention or surgery, steroid usage, and history of bleeding. In addition, whether the operation was performed by an orthopedic or neurosurgical specialist was analyzed.

RESULTS

The number of 2-level CDA procedures increased from 6 cases reported in 2014 to 142 in 2016, although a statistically significant increase in the number of outpatient cases performed was not seen (p=0.2). The factors found to be significantly associated with inpatient status following surgery were BMI (p=0.019) and diabetes mellitus requiring insulin (p=0.043). There were no significant differences in complication and readmission rates between the inpatient and outpatient groups.

CONCLUSION

Patients undergoing inpatient 2-level CDA had significantly higher rates of obesity and diabetes requiring insulin than did patients undergoing the same procedure in the outpatient setting. With no difference in complication or readmission rates, 2-level CDA may be considered safe in the outpatient setting in appropriately selected patients.

Adverse Events Following Cervical Disc Arthroplasty: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

Cervical arthroplasty is an increasingly popular treatment of cervical radiculopathy and myelopathy. An understanding of the potential adverse events (AEs) is important to help both clinicians and patients. We sought to provide a comprehensive systematic review of the AEs reported in all randomized controlled trials (RCTs) of cervical disc arthroplasty in an attempt to characterize the quality of reporting.

METHODS

We conducted a systematic review of MEDLINE and Web of Science for RCTs of cervical disc arthroplasty reporting AEs. We reported the most frequently mentioned AEs, including dysphagia/dysphonia, vascular compromise, dural injury, and infections. We recorded the presence of industry funding and scored the quality of collection methods and reporting of AEs.

RESULTS

Of the 3734 identified articles, 29 articles met full inclusion criteria. The quality of AE reporting varied significantly between studies, and a combined meta-analysis was not feasible. The 29 articles covered separate 19 RCTs. Eight studies were US Food and Drug Administration (FDA) investigational device exemption (IDE) trials. Rates were recorded for the following AEs: dysphagia/dysphonia (range = 1.3% to 27.2%), vascular compromise (range = 1.1% to 2.4%), cervical wound infection (range = 1.2% to 22.5%), and cerebrospinal fluid leak (range = 0.8% to 7.1%).

CONCLUSIONS

There is a lack of consistency in reporting of AEs among RCTs of cervical arthroplasty. FDA IDE trials scored better in AE event reporting compared to other studies. Standardized definitions for AEs and standardized data collection methodology are needed to improve future studies.

Biomechanical evaluation of cervical disc replacement with a novel prosthesis based on the physiological curvature of endplate

Background

Most of the current available cervical disc prostheses present a flat surface instead of an arcuate surface which is most similar to the morphology of cervical endplate. Therefore, we designed a novel prosthesis (Pretic-I, Trauson) based on the physiological curvature of the cervical endplate. Biomechanical evaluation of cervical disc replacement (CDR) with this novel prosthesis was performed and compared with the Prestige LP prosthesis.

Methods

Three motion segments of 18 cadaveric cervical specimens (C2-C7) were evaluated with a 75 N follower load. Overall, the biomechanics of three models, intact specimen, CDR with the novel prosthesis and CDR with the Prestige LP prosthesis, were studied to gain insight into the effective function of the novel prosthesis. The range of motion (ROM) of all three segments and intradiscal pressure (IDP) on adjacent levels were measured and analysed.

Results

Compared to the intact condition, the ROM of all three segments showed no significant difference in the replacement group. Moreover, there was also no significant difference in the ROM between the two prostheses. Besides, the IDP on the cranial adjacent level showed no obvious difference between the two prostheses; nevertheless, the IDP on the caudal adjacent level of the novel prosthesis was significantly less than the Prestige LP prosthesis.

Conclusions

In summary, the novel disc prosthesis was effective to maintain the ROM at the target segment and adjacent segments. Besides, CDR with the novel prosthesis could reduce the IDP on the caudal adjacent level to a certain extent, compared with the Prestige LP prosthesis.

Electronic supplementary material

The online version of this article (10.1186/s13018-018-0748-7) contains supplementary material, which is available to authorized users.

Symptomatic Adjacent Segment Disease After Anterior Cervical Discectomy for Single-level Degenerative Disk Disease

STUDY DESIGN

A prospective cohort of 142 patients underwent either anterior cervical discectomy alone, anterior cervical discectomy with fusion by cage stand-alone, or anterior cervical discectomy with arthroplasty. We then followed up on their condition for a mean of 9.1±1.9 years (5.6-12.2 y) later.

OBJECTIVE

We aimed to evaluate the annual rate of clinically symptomatic adjacent segment disease (ASD) and to analyze predictive factors.

SUMMARY OF BACKGROUND DATA

Until recent, ASD has been predominantly evaluated radiologically. It is not known whether all patients had complaints. A frequent cited annual rate of ASD is 2.9%, but a growing number of studies report a lower annual rate. Furthermore, maintaining motion to prevent ASD is one reason for implanting a cervical disk prosthesis. However, the results of studies contradict one another.

METHODS

Participants took part in a randomized controlled trial that ended prematurely because of the publication of evidence that did not justify continuation of the trial. The patients were randomly allocated to 3 groups, each of which received one of the abovementioned treatments. We defined symptomatic ASD as signs and symptoms caused by degeneration of an intervertebral disk adjacent to a level of previous anterior cervical disk surgery. At the last follow-up, we were able to ascertain whether clinically symptomatic ASD was present in any of the participants.

RESULTS

The overall annual rate of symptomatic ASD was 0.7%. We found no statistically significant correlations between any of the investigated factors and symptomatic ASD except for the surgical method used. Symptomatic ASD was seen less often in anterior cervical discectomy solely or anterior cervical discectomy with arthroplasty than in anterior cervical discectomy with fusion by plate fixation.

CONCLUSIONS

The annual rate of symptomatic ASD after an anterior cervical discectomy procedure was estimated to be 0.7%. This seems to be related to the procedure, although firm conclusions cannot be drawn.

LEVEL OF EVIDENCE

Level 2-prospective cohort.

Clinical experience and two-year follow-up with a one-piece viscoelastic cervical total disc replacement

BACKGROUND

The purpose of this study is to present clinical outcome data from a 2-year post-market study of a viscoelastic one-piece cervical total disc replacement (TDR) in Europe.

METHODS

Thirty-nine patients were implanted at five surgical sites in an European post-market clinical study. Clinical outcomes included improvement of neck disability index (NDI) and visual analog scale scores for neck and arm pain from baseline to 2-year follow-up, neurological examinations, patients view on the success of surgery, complications, and subsequent surgical interventions.

RESULTS

Thirty patients had the Freedom^® Cervical Disc (FCD) implanted at a single level, and nine patients were implanted at two adjacent levels. The population had a similar distribution of male [20] and female [19] subjects, with a mean age of 45 years. All self-administered outcome measures showed significant clinically important improvements from baseline to the 2-year follow-up. Mean preoperative NDI score improved from 48% to 20%, 13%, 8%, 6% and 4% at 6 weeks, 3, 6, 12, and 24 months, respectively. Average preoperative visual analog scale (VAS) scores of the neck, right and left arm pain intensity and frequency showed significant improvement. All neurological outcome measurements showed immediate improvement from preoperative values and continued improvement throughout 2 years follow-up. From pre-op to 24 months, neurological deficits declined in the population from 21% to 6% for reflex function, 62% to 17% for sensory function, and 38% to 3% for motor function. No patients experienced a deterioration in any measured outcomes compared with the preoperative situation. Patient satisfaction increased over 2 years post-op, with 83% of patients responding that they would "definitely" choose to have the same treatment for their neck/arm condition and another 11% responding that they would "probably" choose to have the same treatment.

CONCLUSIONS

The FCD performs as expected in patients with single-level and two-level degenerative disc disease.

Reporting the results of meta-analyses: a plea for incorporating clinical relevance referring to an example

BACKGROUND CONTEXT

The results of meta-analyses are frequently reported, but understanding and interpreting them is difficult for both clinicians and patients. Statistical significances are presented without referring to values that imply clinical relevance.

PURPOSE

This study aimed to use the minimal clinically important difference (MCID) to rate the clinical relevance of a meta-analysis.

STUDY DESIGN

This study is a review of the literature.

PATIENT SAMPLE

This study is a review of meta-analyses relating to a specific topic, clinical results of cervical arthroplasty.

OUTCOME MEASURE

The outcome measure used in the study was the MCID.

METHODS

We performed an extensive literature search of a series of meta-analyses evaluating a similar subject as an example. We searched in Pubmed and Embase through August 9, 2016, and found articles concerning meta-analyses of the clinical outcome of cervical arthroplasty compared with that of anterior cervical discectomy with fusion in cases of cervical degenerative disease. We evaluated the analyses for statistical significance and their relation to MCID. MCID was defined based on results in similar patient groups and a similar disease entity reported in the literature.

RESULTS

We identified 21 meta-analyses, only one of which referred to MCID. However, the researchers used an inappropriate measurement scale and, therefore, an incorrect MCID. The majority of the conclusions were based on statistical results without mentioning clinical relevance.

CONCLUSIONS

The majority of the articles we reviewed drew conclusions based on statistical differences instead of clinical relevance. We recommend introducing the concept of MCID while reporting the results of a meta-analysis, as well as mentioning the explicit scale of the analyzed measurement.

Trends in the Treatment of Single and Multilevel Cervical Stenosis: A Review of the American Board of Orthopaedic Surgery Database

BACKGROUND

In order to identify any changes in the utilization of new and old techniques, we investigated trends in the operative management of cervical stenosis by orthopaedic surgeons applying for board certification.

METHODS

We queried the American Board of Orthopaedic Surgery database from 1998 to 2013 to identify all of the cervical spine procedures for stenosis that had been performed by candidates taking Part II of the licensing examination. Longitudinal trends were determined for the utilized approach, the individual procedures that had been performed, and whether a motion-preserving technique had been employed.

RESULTS

There were 5,068 cervical spine procedures performed by 1,025 candidates. Procedure totals remained relatively constant until 2011, when a sudden increase of 280% (202 to 768 procedures) was noted. This trend continued, reaching a 460% increase (202 to 1,131 procedures) compared with 2010. The number of candidates only rose by 150% (42 to 105) over the entire study period. The proportion of procedures performed via an anterior approach saw a bimodal distribution; early on, this approach predominated over posterior procedures and was largely driven by the number of corpectomies that were performed. From 2004 to 2011, posterior procedures became more prevalent, but there was a sharp decline in 2011, driven by the large number of anterior cervical discectomies and fusions that were performed. This remained constant through 2013. Lastly, motion-preserving techniques, which included total disc replacement and laminoplasty, had modest increases in utilization from 2005 to 2007. This increased prevalence was short-lived, and it steadily declined through 2014 to <5% utilization.

CONCLUSIONS

The number of candidates performing cervical spine procedures increased more than twofold over a 16-year period. This reflects a larger proportion of the orthopaedic graduates who subspecialize in spine surgery. While the number of surgeons performing spine surgery has increased, the sheer number of procedures that each surgeon performed greatly outpaced the increased number of surgeons. Motion-preserving techniques had their peak utilization in 2007, and have since decreased to <5%, in contrast to fusion techniques, which predominate, comprising >90% of the performed procedures.

Higher reoperation rate following cervical disc replacement in a retrospective, long-term comparative study of 715 patients

PURPOSE

To evaluate rates of secondary surgical interventions in a cohort treated with fusion (ACDF), artificial disc replacement (ADR) or a posterior surgical procedure (PP) because of a cervical degenerative pathology.

METHODS

715 patients treated with any primary cervical surgical intervention between the years 2000 and 2010 were retrospectively evaluated regarding frequency of secondary surgery between the years 2000 and 2015, thus giving a follow-up time of minimum 5 years. Reasons for secondary surgery as well as choice of new intervention were evaluated. Data were collected from a single-center setting.

RESULTS

Follow-up rate was 94%. 79 (11%) patients in total underwent a new operation during follow-up. 50/504 (10%), 27/172 (15%), and 2/39 (5%) of the patients had a second surgical intervention in the ACDF, ADR, and PP groups, respectively. There was a statistically significant higher rate of repeated surgery in the ADR group compared to the ACDF group, OR 1.7 (CI 1.06-2.8), p = 0.03. Risk for repeated surgery at index level was even higher for ADR, OR 5.1 (CI 2.4-10.7), p < 0.001. Reoperation rate because of ASD in the whole cohort did not differ between ACDF and ADR groups, p = 0.40.

CONCLUSION

The group initially treated with artificial disc replacement showed higher rate of reoperations and more implant-related complications. In this cohort, artificial disc replacement was not protective against reoperation because of adjacent segment pathology.

Indirect meta-analysis comparing clinical outcomes of total cervical disc replacements with fusions for cervical degenerative disc disease

Anterior cervical discectomy and fusion (ACDF) and total cervical disc replacement (TDR) are considered effective treatments for patients with cervical degenerative disc disease (CDDD). An indirect meta-analysis including 19 randomized controlled trials (5343 patients) was conducted to compare the clinical outcomes of ACDF with TDR. Primary outcomes including functional indicators (NDI [neck disability index] score, neurological success and patient satisfaction), secondary outcomes including surgical outcomes (operation time, blood loss and length of stay) and secondary surgical procedures (secondary surgery at an adjacent level, secondary surgery at the index level, secondary surgery at both levels, removal, reoperation, revision and supplemental fixation) were included in the study. TDR using the Bryan disc was associated with a greater improvement in NDI score than ACDF (MD = -5.574, 95% CrIs [credible intervals] -11.73--0.219). For neurological success, the Bryan (odds ratio [OR] = 0.559, 95% CrIs 0.323-0.955) and Prestige (OR = 0.474, 95% CrIs 0.319-0.700) discs were superior to ACDF. However, no differences in the patient satisfaction rate were shown between TDR and ACDF. For patients with CDDD, ACDF using allograft and a plate is most effective for determining the surgical parameters. Moreover, TDR using the ProDisc-C, Mobi-C, Prestige and Bryan discs are good choices for improving functional outcomes and reducing secondary surgeries.

Mid-term efficacy and safety of cervical disc arthroplasty versus fusion in cervical spondylosis: A systematic review and meta-analysis

Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are the most commonly used procedures in cervical spondylosis. However, only a few published studies exist in the literature comparing these two operation types, particularly its mid-term efficacy and safety. Furthermore, in those studies, even large sample trials, when compared, have elicited controversial results, making it inconvenient for clinicians to refer to them. The aim of the present study was to clarify the advantages and shortcomings of the two procedures. Articles indexed in the PubMed, Web of Science, Cochrane Library, EMBASE, China Biological Medicine and China National Knowledge Infrastructure (CNKI) databases, as of March 2016, that met our criteria were searched. A total of 18 trials involving 3,040 patients were included in our final analysis. The most important results drawn from the present analysis were as follows: Insignificant differences were identified in the blood loss [weighted mean difference (WMD)=6.23; 95% confidence intervals (CI), −0.85 to 13.32; P=0.08], surgical time [standardized mean difference (SMD)=0.40; 95% CI, −0.01 to 0.82; P=0.06], the time of hospital stay (SMD=0.05; 95% CI, −0.28 to 0.37; P=0.77) and the total complications rate [odds ratio (OR)=0.86; 95% CI, 0.66 to 1.131; P=0.28] on a comparison of the two operation methods. By contrast, comparing CDA with ACDF, the CDA had higher Short Form survey (SF-36) scores (WMD=1.65; 95% CI, 0.61 to 2.69; P=0.002), a larger range of motion in the operation level (SMD=6.53; 95% CI, 3.89 to 9.17; P<0.0001), a higher rate of neurological improvement following the operation (OR=1.80; 95% CI, 1.29 to 2.52; P=0.0006), a lower Visual Analog Scale (VAS) score of neck pain (WMD= 0.16; 95% CI, −0.28 to 0.05; P=0.006) and arm pain (WMD= 0.12; 95% CI, −0.24 to −0.01; P=0.04). In addition, in the mid-term following the surgery, CDA had a lower Neck Disability Index (NDI; SMD=0.18; 95% CI, −0.28 to −0.07; P=0.001) and a lower reoperation rate of adjacent levels (OR=0.54; 95% CI, 0.35 to 0.85; P=0.007) compared with ACDF. Taken together, these results suggested that CDA and ACDF are efficient and safe methods for dealing with cervical spondylosis. However, with respect to certain specific indicators, such as the reoperation rate of adjacent levels following surgery, the former has several advantages.

Discover cervical disc arthroplasty versus anterior cervical discectomy and fusion in symptomatic cervical disc diseases: A meta-analysis

OBJECTIVE

Symptomatic cervical disc disease (SCDD) is a common degenerative disease, and Discover artificial cervical disc, a new-generation nonconstrained artificial disk, has been developed and performed gradually to treat it. We performed this meta-analysis to compare the efficacy and safety between Discover cervical disc arthroplasty (DCDA) and anterior cervical discectomy and fusion (ACDF) for SCDD.

METHODS

An exhaustive literature search of PubMed, EMBASE, and the Cochrane Library was conducted to identify randomized controlled trials that compared DCDA with ACDF for patients suffering SCDD. A random-effect model was used. Results were reported as standardized mean difference or risk ratio with 95% confidence interval.

RESULTS

Of 33 articles identified, six studies were included. Compared with ACDF, DCDA demonstrated shorter operation time (P < 0.0001), and better range of motion (ROM) at the operative level (P < 0.00001). But no significant differences were observed in blood loss, neck disability index (NDI) scores, neck and arm pain scores, Japanese orthopaedic association (JOA) scores, secondary surgery procedures and adverse events (P > 0.05). Subgroup analyses did not demonstrated significant differences.

CONCLUSION

In conclusion, DCDA presented shorter operation time, and better ROM at the operative level. However, no significant differences were observed in blood loss, NDI scores, neck and arm pain scores, JOA scores, secondary surgery procedures and adverse events between the two groups. Additionally, more studies of high quality with mid- to long-term follow-up are required in future.

Durability of cervical disc arthroplasties and its influence factors: A systematic review and a network meta-analysis

BACKGROUND

The durability of cervical disc arthroplasties (CDA) may vary significantly because of different designs and implanting techniques of the devices. Nevertheless, the comparative durability remains unknown.

OBJECTIVES

We aimed to assess the durability of CDAs in at least 2-year follow-up. We analyzed the classifications and causes of secondary surgical procedures, as well as the structural designs of the devices that might influence the durability.

METHODS

PubMed, Medline, Embase, and Cochrane Central Register of Controlled Trials were searched from the inception of each database to September 2015 using the following Keywords: "cervical disc replacement" OR "cervical disc arthroplasty" AND "randomized controlled trial (RCT)." Publication language was restricted to English. The primary outcome was the rate of secondary surgical procedures following CDA or anterior cervical decompression and fusion (ACDF). Pairwise meta-analysis and a Bayesian network meta-analysis were carried out using Review Manager v5.3.5 and WinBUGS version 1.4.3, respectively. Quality of evidence was appraised by Grading of Recommendations Assessment, Development and Evaluation methodology.

RESULTS

Twelve RCTs that met the eligibility criteria were included. Follow-up ranged from 2 years to 7 years. A total of 103 secondary surgical procedures were performed. The most frequent classification of secondary surgical procedures was reoperation (48/103) and removal (47/103). Revision (3/103) and supplementary fixation (2/103) were rare. Adjacent-level diseases were the most common cause of reoperations. The rates of secondary surgical procedures were significantly lower in Mobi-C, Prestige, Prodisc-C, Secure-C group than in ACDF group. No significant difference was detected between Bryan, PCM, Kineflex-C, Discover, and ACDF. Mobi-C, Secure-C, and Prodisc-C ranked the best, the second best, the third best, respectively.

CONCLUSIONS

We concluded that Mobi-C, Secure-C, and Prodisc-C were more durable than ACDF. Precise selection of device size and proper surgical techniques are implicated to be crucial to enhance the perdurability. Device design should concentrate on the imitation of biomechanics of normal cervical disc, and semi-constrained structural device is a better design to make CDA more durable.

Treatment of Single-Level Cervical Spondylosis: Cervical Disk Arthroplasty Versus Anterior Cervical Decompression and Fusion

A meta-analysis was performed to compare cervical arthroplasty with anterior cervical diskectomy and fusion for single-level cervical spondylosis. A comprehensive search was conducted with PubMed, Embase, and the Cochrane Central Register of Controlled Trials from January 1, 2000, to April 30, 2015. Random-effects models were used for heterogeneous data. Fixed-effects models were used for pooled nonheterogeneous data. Mean difference or standard mean difference was used for continuous outcomes, and odds ratio, risk ratio, or risk difference was used for dichotomous outcomes. [Orthopedics. 2017; 40(1):e23-e34.].

Comparison of the more than 5-year clinical outcomes of cervical disc arthroplasty versus anterior cervical discectomy and fusion: A protocol for a systematic review and meta-analysis of prospective randomized controlled trials

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) was almost the "golden standard" technique in treatment of symptomatic cervical degenerative disc disease, however, it cause motion loss of the indexed level, increase the intradiscal pressure and motion of the adjacent levels, and may accelerate the degeneration of adjacent level. Cervical disc arthroplasty (CDA) was designed to preserve the motion of index level, avoid the over-activity of adjacent levels and reduce the degeneration of adjacent disc levels, the process of degeneration of adjacent level is very slowly, long term follow up studies should be conducted, this study aim to compare the more than 5 years' long-term clinical outcomes and safety between CDA and ACDF.

METHODS

A systematic review and meta-analysis that will be performed according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). The electric database of Medline, Embase, and Cochrane library will be systematic search. A standard data form will be used to extract the data of included studies. We will assess the studies according to the Cochrane Handbook for Systematic Reviews of Interventions, and perform analysis in software STATA 12.0. Fixed-effects models will be used for homogeneity data, while random-effects will be used for heterogeneity data. The overall effect sizes will be determined as weighted mean difference (WMD) for continuous outcomes and Relative risk (RR) for dichotomous outcomes.

RESULTS

The results of study will be disseminated via both international conference and peer-review journal.

CONCLUSION

The conclusion of our study will provide the long-term and updated evidence of clinical outcomes and safety between CDA and ACDF, and help surgeon to change better surgical technique for patients.

Cervical disc arthroplasty for symptomatic cervical disc disease: Traditional and Bayesian meta-analysis with trial sequential analysis

OBJECTIVE

Cervical disc arthroplasty (CDA) has been designed as a substitute for anterior cervical discectomy and fusion (ACDF) in the treatment of symptomatic cervical disc disease (CDD). Several researchers have compared CDA with ACDF for the treatment of symptomatic CDD; however, the findings of these studies are inconclusive. Using recently published evidence, this meta-analysis was conducted to further verify the benefits and harms of using CDA for treatment of symptomatic CDD.

METHODS

Relevant trials were identified by searching the PubMed, EMBASE, and Cochrane Library databases. Outcomes were reported as odds ratio or standardized mean difference. Both traditional frequentist and Bayesian approaches were used to synthesize evidence within random-effects models. Trial sequential analysis (TSA) was applied to test the robustness of our findings and obtain more conservative estimates.

RESULTS

Nineteen trials were included. The findings of this meta-analysis demonstrated better overall, neck disability index (NDI), and neurological success; lower NDI and neck and arm pain scores; higher 36-Item Short Form Health Survey (SF-36) Physical Component Summary (PCS) and Mental Component Summary (MCS) scores; more patient satisfaction; greater range of motion at the operative level; and fewer secondary surgical procedures (all P < 0.05) in the CDA group compared with the ACDF group. CDA was not significantly different from ACDF in the rate of adverse events (P > 0.05). TSA of overall success suggested that the cumulative z-curve crossed both the conventional boundary and the trial sequential monitoring boundary for benefit, indicating sufficient and conclusive evidence had been ascertained.

CONCLUSIONS

For treating symptomatic CDD, CDA was superior to ACDF in terms of overall, NDI, and neurological success; NDI and neck and arm pain scores; SF-36 PCS and MCS scores; patient satisfaction; ROM at the operative level; and secondary surgical procedures rate. Additionally, there was no significant difference between CDA and ACDF in the rate of adverse events. However, as the CDA procedure is a relatively newer operative technique, long-term results and evaluation are necessary before CDA is routinely used in clinical practice.

Cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) in symptomatic cervical degenerative disc diseases (CDDDs): an updated meta-analysis of prospective randomized controlled trials (RCTs)

PURPOSE

This meta-analysis of randomized controlled trials (RCTs) aims to evaluate the efficacy and safety in cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) for treating cervical degenerative disc diseases (CDDDs).

METHODS

The authors searched RCTs in the electronic databases (Cochrane Central Register of Controlled Trials, PubMed, EMBASE, Medline, Embase, Springer Link, Web of Knowledge, OVID and Google Scholar) from their establishment to march 2016 without language restrictions. We also manually searched the reference lists of articles and reviews for possible relevant studies. Researches on CDA versus ACDF in CDDDs were selected in this meta-analysis. The quality of all studies was assessed and effective data was pooled for this meta-analysis. Outcome measurements were surgical parameters (operative time, blood loss, and length of hospital stay), clinical indexes [neck disability index (NDI), neurological success, range of motion (ROM), Visual Analogue Score (VAS)], complications [the number of adverse events, adjacent segment disease (ASD), and reoperation]. Subgroup analysis, sensitivity analysis, and publication bias assessment were also performed, respectively. The meta-analysis was performed with software revman 5.3.

RESULTS

37 articles (20 RCTs) with a total 4004 patients (2212 in the CDA and 1792 in the ACDF) met inclusion criteria. Eight types of disc prostheses were used in the included studies. Patients were followed up for at least 2 years in all the studies. No statistically significant differences were found between CDA and ACDF for blood loss [SMD -0.02; 95 % CI (-0.20, 0.17)], length of hospital stay [MD -0.06; 95 % CI (-0.19, 0.06)]. Statistical differences were found between operative time [MD 14.22; 95 % CI (6.73, 21.71)], NDI [SMD -0.27; 95 % CI (-0.43, -0.10)], neurological success [RR 1.13; 95 % CI (1.08, 1.18)], ROM [MD 6.72; 95 % CI (5.72, 7.71)], VAS of neck [SMD -0.40; 95 % CI (-0.75, -0.04)], VAS of arm [SMD -0.55; 95 % CI (-1.04, -0.06)], the rate of adverse events [RR 0.72 95 % CI (0.53, 0.96)], the rate of ASD [RR 0.62; 95 % CI (0.43, 0.88)], and reoperation [RR 0.50; 95 % CI (0.39, 0.63)]. Subgroup analysis stratified by different types of disc prostheses was also performed.

CONCLUSIONS

CDA is associated with higher clinical indexes and fewer complications than ACDF, indicating that it is a safe and effective treatment for CDDDs. However, the operative time of CDA is longer than ACDF. Because of some limitations, these findings should be interpreted with caution. Additional studies are needed. Large, definitive RCTs are needed.

Biomechanical Analysis of a Novel Prosthesis Based on the Physiological Curvature of Endplate for Cervical Disc Replacement

STUDY DESIGN

Biomechanical analysis of a novel prosthesis based on the physiological curvature of endplate was performed.

OBJECTIVE

To compare the biomechanical differences between a novel prosthesis based on the physiological curvature of the endplate and the Prestige LP prosthesis after cervical disc replacement (CDR).

SUMMARY OF BACKGROUND DATA

Artificial disc prostheses have been widely used to preserve the physiological function of treated and adjacent motion segments in CDR, while most of those present a flat surface instead of an arcuate surface which approximately similar to anatomic structures in vivo. We first reported a well-designed artificial disc prosthesis based on the physiological curvature of the endplate.

METHODS

Three motion segments of 24 ovine cervical spines (C2-5) were evaluated in a robotic spine system with axial compressive loads of 50N. Testing conditions were as follows: 1) intact, 2) C3-4 CDR with artificial disc prosthesis based on the physiological curvature of the endplate, and 3) C3-4 CDR with the Prestige LP prosthesis. The range of motion (ROM) and the pressures on the inferior surface of the two prostheses were recorded and analyzed.

RESULTS

As compared to the intact state, the ROM of all three segments had no significant difference in the replacement group. Additionally, there was no significant difference in ROM between the two prostheses. The mean pressure on the novel prosthesis was significantly less than the Prestige LP prosthesis.

CONCLUSION

ROM in 3 groups (intact group, CDR group with novel prosthesis and CDR group with Prestige LP) showed no significant difference. The mean pressure on the inferior surface of the novel prosthesis was significantly lower than the Prestige LP prosthesis. Therefore, the novel artificial disc prosthesis is feasible and effective, and can reduce the implant-bone interface pressure on the endplate, which may be one possible reason of prosthesis subsidence.

Effectiveness and safety of Mobi-C for treatment of single-level cervical disc spondylosis

Aims

In order to evaluate the effectiveness of the Mobi-C implant in cervical disc degeneration, a randomised study was conducted, comparing the Mobi-C prosthesis arthroplasty with anterior cervical disc fusion (ACDF) in patients with single level cervical spondylosis.

Patients and Methods

From January 2008 to July 2009, 99 patients were enrolled and randomly divided into two groups, those having a Mobi-C implant (n = 51; 30 men, 21 women) and those undergoing ACDF (n = 48; 28 men, 20 women).The patients were followed up for five years, with the primary outcomes being the Japanese Orthopaedic Association score, visual analogue scale for pain and the incidence of further surgery. The secondary outcomes were the Neck Disability Index and range of movement (ROM) of the treated segment.

Results

The incidence of further surgery was found to be statistically significant between the two groups (p = 0.49), with seven ACDF patients requiring further surgery and only one Mobi-C patient requiring re-operation. There were significant differences (p < 0.001) between the two groups in the ROM of the treated segment. However, both Mobi-C surgery and ACDF surgery were effective in improving the patient’s clinical symptoms. Take home message: Mobi-C implant surgery is a safe alternative to ACDF surgery in cervical disc degeneration. Cite this article: Bone Joint J 2016;98-B:829–3.

Bryan Cervical Disc Arthroplasty Versus Anterior Cervical Discectomy and Fusion for Treatment of Cervical Disc Diseases: A Meta-analysis of Prospective, Randomized Controlled Trials

STUDY DESIGN

A meta-analysis of randomized controlled trials (RCTs).

OBJECTIVE

The purpose of this study is to evaluate the effectiveness and safety of Bryan cervical disc arthroplasty (BCDA) as compared with anterior cervical discectomy and fusion (ACDF) for treatment of cervical disc diseases (CDDs).

SUMMARY OF BACKGROUND DATA

Previous meta-analyses focused on the comparison of effectiveness and safety between ACDF and CDA, which consisted of various types of disc prostheses. No meta-analysis has been conducted up to present to compare ACDF with a specialized type of artificial cervical disc.

METHODS

We comprehensively searched PubMed, EMBASE, and Cochrane Central Register of Controlled Trails for prospective RCTs that compared BCDA with ACDF. The retrieved results were last updated on October 1, 2015, without language restrictions. We classified the trials into subgroups by short-term and midterm follow-up.

RESULTS

Eight relevant RCTs involving 1816 individuals were included in the meta-analysis. In overall-term follow-up, the clinical outcomes indicated that BCDA was superior to ACDF considering lower NDI scores (P = 0.0009), greater range of motion at the index level (P = 0.02), and fewer adverse events (P = 0.004), but inferior to ACDF considering operation time (P < 0.00001). There was no significant difference between two groups regarding blood loss (P = 0.43), length of hospital stay (P = 0.12), and secondary surgical procedures (P = 0.20).

CONCLUSION

BCDA presented better NDI improvement, greater range of motion at the index level, and fewer adverse events. However, the benefits of BCDA considering blood loss, length of hospital stay, and secondary surgical procedures are still incapable to be proved. More well design studies with longer term follow-up are needed to provide a better evaluation of the effectiveness and safety of the two procedures.

LEVEL OF EVIDENCE

1.

The Role of Posterior Longitudinal Ligament in Cervical Disc Replacement: An Ovine Cadaveric Biomechanical Analysis

Background

Cervical disc replacement (CDR) has been widely used to restore and maintain mobility and function of the treated and adjacent motion segments. Posterior longitudinal ligament (PLL) resection has been shown to be efficient in anterior cervical decompression and fusion. However, less is known about the biomechanical effect of PLL removal versus preservation in cervical disc arthroplasty.

Material/Methods

Three motion segments of 24 ovine cervical spines (C2–C5) were evaluated in a robotic spine system with axial compressive loads of 50 N. These cervical spines were divided in three groups according to the following conditions: (1) intact spine, (2) C3/C4 CDR with the Prestige LP prosthesis and PLL preservation, and (3) C3/C4 CDR with the Prestige LP prosthesis and PLL removal. The ranges of motion (ROMs) were recorded and analyzed in each group.

Results

The C3/C4 ROM in group 3 (CDR with PLL removed) increased significantly in flexion-extension and axial rotation compared with group 1 (intact spine). Moreover, in flexion-extension, the mean total ROM was significantly larger in group 3 than in group 1. All the ROM observed in group 2 (CDR with PLL preserved) did not significantly differ from the ROM observed in group 1.

Conclusions

Compared with intact spines, CDR with PLL removal partly increased ROM. Moreover, the ROM in CDR with PLL preservation did not significantly differ from the ROM observed in intact spines. The PLL appears to contribute to the balance and stability of the cervical spine and should thus be preserved in cervical disc replacement provided that the posterior longitudinal ligament is not degenerative and the compression can be removed without PLL takedown.

Long-term results of anterior cervical corpectomy and fusion with nano-hydroxyapatite/polyamide 66 strut for cervical spondylotic myelopathy

To assess the long-term clinical and radiographic outcomes of anterior cervical corpectomy and fusion (ACCF) with a neotype nano-hydroxyapatite/polyamide 66 (n-HA/PA66) strut in the treatment of cervical spondylotic myelopathy (CSM). Fifty patients with CSM who underwent 1- or 2-level ACCF with n-HA/PA66 struts were retrospectively investigated. With a mean follow-up of 79.6 months, the overall mean JOA score, VAS and cervical alignment were improved significantly. At last follow-up, the fusion rate was 98%, and the subsidence rate of the n-HA/PA66 strut was 8%. The "radiolucent gap" at the interface between the n-HA/PA66 strut and the vertebra was further noted to evaluate the osteoconductivity and osseointegration of the strut, and the incidence of it was 62% at the last follow-up. Three patients suffered symptomatic adjacent segment degeneration (ASD). No significant difference was detected in the outcomes between 1- and 2-level corpectomy at follow-ups. In conclusion, the satisfactory outcomes in this study indicated that the n-HA/PA66 strut was an effective graft for cervical reconstruction. Moreover, the osteoconductivity and osseointegration of the strut is still need to be optimized for future clinical application owing to the notably presence of "radiolucent gap" in present study.

ProDisc-C Total Disc Replacement Versus Anterior Cervical Discectomy and Fusion for Single-Level Symptomatic Cervical Disc Disease: Seven-Year Follow-up of the Prospective Randomized U.S. Food and Drug Administration Investigational Device Exemption Study

BACKGROUND

In patients with single-level cervical degenerative disc disease, total disc arthroplasty can relieve radicular pain and preserve functional motion between two vertebrae. We compared the efficacy and safety of cervical total disc arthroplasty with that of anterior cervical discectomy and fusion (ACDF) for the treatment of single-level cervical degenerative disc disease between C3-C4 and C6-C7.

METHODS

Two hundred and nine patients at thirteen sites were randomly treated with either total disc arthroplasty with ProDisc-C (n = 103) or with ACDF (n = 106). Patients were assessed preoperatively; at six weeks and three, six, twelve, eighteen, and twenty-four months postoperatively; and then annually until seven years postoperatively. Outcome measures included the Neck Disability Index (NDI), the Short Form-36 (SF-36), postoperative neurologic parameters, secondary surgical procedures, adverse events, neck and arm pain, and satisfaction scores.

RESULTS

At seven years, the overall follow-up rate was 92% (152 of 165). There were no significant differences in demographic factors, follow-up rate, or patient-reported outcomes between groups. Both procedures were effective in reducing neck and arm pain and improving and maintaining function and health-related quality of life. Neurologic status was improved or maintained in 88% and 89% of the patients in the ProDisc-C and ACDF groups, respectively. After seven years of follow-up, thirty secondary surgical procedures had been performed in nineteen (18%) of 106 patients in the ACDF group compared with seven secondary surgical procedures in seven (7%) of 103 patients in the ProDisc-C group (p = 0.0099). There were no significant differences in the rates of any device-related adverse events between the groups.

CONCLUSIONS

Total disc arthroplasty with ProDisc-C is a safe and effective surgical treatment of single-level symptomatic cervical degenerative disc disease. Clinical outcomes after total disc arthroplasty with ProDisc-C were similar to those after ACDF. Patients treated with ProDisc-C had a lower probability of subsequent surgery, suggesting that total disc arthroplasty provides durable results and has the potential to slow the rate of adjacent-level disease.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Polyurethane on titanium unconstrained disc arthroplasty versus anterior discectomy and fusion for the treatment of cervical disc disease: a review of level I-II randomized clinical trials including clinical outcomes

PURPOSE

To contrast the clinical and radiologic outcomes and adverse events of anterior cervical discectomy and fusion (ACDF) with a single cervical disc arthroplasty design, the polyurethane on titanium unconstrained cervical disc (PTUCD).

METHODS

This is a systematic review of randomized clinical trials (RCT) with evidence level I-II reporting clinical outcomes. After a search on different databases including PubMed, Cochrane Central Register of Controlled Trials, and Ovid MEDLINE, a total of 10 RCTs out of 51 studies found were entered in the study. RTCs were searched from the earliest available records in 2005 to November 2014.

RESULTS

Out of a total of 1101 patients, 562 were randomly assigned into the PTUCD arthroplasty group and 539 into the ACDF group. The mean follow-up was 30.9 months. Patients undergoing arthroplasty had lower Neck Disability Index, and better SF-36 Physical component scores than ACDF patients. Patients with PTUCD arthroplasty had also less radiological degenerative changes at the upper adjacent level. Overall adverse events were twice more frequent in patients with ACDF. The rate of revision surgery including both adjacent and index level was slightly higher in patients with ACDF, showing no statistically significant difference.

CONCLUSIONS

According to this review, PTUCD arthroplasty showed a global superiority to ACDF in clinical outcomes. The impact of both surgical techniques on the cervical spine (radiological spine deterioration and/or complications) was more severe in patients undergoing ACDF. However, the rate of revision surgeries at any cervical level was equivalent for ACDF and PTUCD arthroplasty.

Strategies to improve the credibility of meta-analyses in spine surgery: a systematic survey

BACKGROUND CONTEXT

Meta-analyses are powerful tools that can synthesize existing research, inform clinical practice, and support evidence-based care. These studies have become increasingly popular in the spine surgery literature, but the rigor with which they are being conducted has not yet been evaluated.

PURPOSE

Our primary objectives were to evaluate the methodological quality (credibility) of spine surgery meta-analyses and to propose strategies to improve future research. Our secondary objectives were to evaluate completeness of reporting and identify factors associated with higher credibility and completeness of reporting.

STUDY DESIGN

This study is based on a systematic survey of meta-analyses.

OUTCOME MEASURES

We evaluated credibility according to the Users' Guide to the Medical Literature and completeness of reporting according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist.

METHODS

We systematically searched MEDLINE, EMBASE, and The Cochrane Library, and two reviewers independently assessed eligibility, credibility, and completeness of reporting. We used multivariable linear regression to evaluate potential associations. Interrater agreement was quantified using kappa and intraclass correlation (ICC) coefficients.

RESULTS

We identified 132 eligible meta-analyses of spine surgery interventions. The mean credibility score was 3 of 7 (standard deviation [SD], 1.4; ICC, 0.86), with agreement for each item ranging from 0.54 (moderate) to 0.83 (almost perfect). Clinical questions were judged as sensible in 125 (95%), searches were exhaustive in 102 (77%), and risk of bias assessments were undertaken in 91 (69%). Seven (5%) meta-analyses addressed possible explanations for heterogeneity using a priori subgroup hypotheses and 24 (18%) presented results that were immediately clinically applicable. Investigators undertook duplicate assessments of eligibility, risk of bias, and data extraction in 46 (35%) and rated overall confidence in the evidence in 24 (18%). Later publication year, increasing Journal Impact Factor, increasing number of databases, inclusion of Randomized Controlled Trials, and inclusion of non-English studies were significantly associated with higher credibility scores (p<.05). The mean score for reporting was 18 of 27 (SD, 4.4; ICC, 0.94).

CONCLUSIONS

The credibility of many current spine surgery meta-analyses is limited. Researchers can improve future meta-analyses by performing exhaustive literature searches, addressing possible explanations of heterogeneity, presenting results in a clinically useful manner, reproducibly selecting and assessing primary studies, addressing confidence in the pooled effect estimates, and adhering to guidelines for complete reporting.

Quality of systematic reviews: an example of studies comparing artificial disc replacement with fusion in the cervical spine

Cervical artificial disc replacement (C-ADR) is now an alternative to anterior cervical discectomy and fusion (ACDF). Many studies have evaluated the efficacy of C-ADR compared with ACDF. This led to a series of systematic reviews and meta-analyses to evaluate the evidence of the superiority of one intervention against the other. The aim of the study presented here was to evaluate the quality of these reviews and meta-analyses. Medline via Ovid, Embase, and Cochrane Library were searched using the keywords: (total disk replacement, prosthesis, implantation, discectomy, and arthroplasty) AND (cervical vertebrae, cervical spine, and spine) AND (systematic reviews, reviews, and meta-analysis). Screening and data extraction were conducted by two reviewers independently. Two reviewers then assessed the quality of the selected reviews and meta-analysis using 11-item AMSTAR score which is a validated measurement tool to assess the methodological quality of systematic reviews. Screening of full reports of 46 relevant abstracts resulted in the selection of 15 systematic reviews and/or meta-analyses as eligible for this study. The two reviewers' inter-rater agreement level was high as indicated by kappa of >0.72. The AMSTAR score of the reviews ranged from 3 to 11. Only one study (a Cochrane review) scored 100% (AMSTAR 11). Five studies scored below (AMSTAR 5) indicating low-quality reviews. The most significant drawbacks of reviews of a score below 5 were not using an extensive search strategy, failure to use the scientific quality of the included studies appropriately in formulating a conclusion, not assessing publication bias, and not reporting the excluded studies. With a significant exception of a Cochrane review, the methodological quality of systematic reviews evaluating the evidence of C-ADR versus ACDF has to be improved.

Postoperative segmental hypermobility after cervical arthroplasty: A possible pathomechanism for outcome failure

We present a 41-year-old man who underwent a cervical discarthroplasty (CDA) C5-6 procedure with an increase of the segmental range of motion from 2.8° to 6.9° and an increase in disc height from 5.8mm preoperatively to 10.4mm postoperatively with an unfavorable long-term clinical outcome. Both anterior cervical discectomy with fusion (ACDF), as well as CDA have been proven to be successful procedures in the management of cervical radiculopathy with good to excellent outcomes and low complication rates. The rationale for CDA over ACDF highlights the preservation of segmental motion and reduction of the incidence of adjacent segment disease. This case report suggests that a hypermobility syndrome and also an overcorrection of the cervical range of motion may be responsible for an unfavorable outcome after CDA.

Cervical total disc replacement is superior to anterior cervical decompression and fusion: a meta-analysis of prospective randomized controlled trials

BACKGROUND

Despite being considered the standard surgical procedure for symptomatic cervical disc disease, anterior cervical decompression and fusion invariably accelerates adjacent segment degeneration. Cervical total disc replacement is a motion-preserving procedure developed as a substitute to fusion. Whether cervical total disc replacement is superior to fusion remains unclear.

METHODS

We comprehensively searched PubMed, EMBASE, Medline, and the Cochrane Library in accordance with the inclusion criteria to identify possible studies. The retrieved results were last updated on December 12, 2014. We classified the studies as short-term and midterm follow-up.

RESULTS

Nineteen randomized controlled trials involving 4516 cases were identified. Compared with anterior cervical decompression and fusion, cervical total disc replacement had better functional outcomes (neck disability index [NDI], NDI success, neurological success, neck pain scores reported on a numerical rating scale [NRS], visual analog scales scores and overall success), greater segmental motion at the index level, fewer adverse events and fewer secondary surgical procedures at the index and adjacent levels in short-term follow-up (P < 0.05). With midterm follow-up, the cervical total disc replacement group indicated superiority in the NDI, neurological success, pain assessment (NRS), and secondary surgical procedures at the index level (P < 0.05). The Short Form 36 (SF-36) and segmental motion at the adjacent level in the short-term follow-up showed no significant difference between the two procedures, as did the secondary surgical procedure rates at the adjacent level with midterm follow-up (P > 0.05).

CONCLUSIONS

Cervical total disc replacement presented favorable functional outcomes, fewer adverse events, and fewer secondary surgical procedures. The efficacy and safety of cervical total disc replacement are superior to those of fusion. Longer-term, multicenter studies are required for a better evaluation of the long-term efficacy and safety of the two procedures.

Motion preservation surgery in the spine

The primary goal of motion preservation surgery in the spine is to maintain normal or near normal motion in an attempt to prevent adverse outcomes commonly seen with conventional spinal fusion, most notably the development of adjacent-level degenerative disc disease. Several different surgical approaches have been developed to preserve motion in the lumbar spine, including total disc replacement, partial disc (nucleus) replacement, interspinous spacers, dynamic stabilization devices, and total facet replacement devices. The design of devices varies greatly. The devices are created using a similar rationale but are unique in design relative to their lumbar counterparts.

Cervical disc arthroplasty versus anterior cervical discectomy and fusion for treatment of symptomatic cervical disc disease: a meta-analysis of randomized controlled trials

OBJECTIVE

The purpose of this study is to compare the effectiveness and safety of cervical disc arthroplasty with anterior cervical discectomy and fusion for treatment of symptomatic cervical disc disease. Anterior cervical discectomy and fusion (ACDF) is the conventional surgical treatment for symptomatic cervical disc disease. Recently, cervical disc arthroplasty (CDA) has been developed to address some of the shortcomings associated with ACDF by preserving function of the motion segment. Controversy still surrounds regarding whether CDA is better.

METHODS

We systematically searched six electronic databases (Medline, Embase, Clinical, Ovid, BIOSIS and Cochrane registry of controlled clinical trials) to identify randomized controlled trials (RCTs) published up to April 2014 in which CDA was compared with ACDF for the treatment of symptomatic cervical disc disease. Effective data were extracted after the assessment of methodological quality of the trials. Then, we performed the meta-analysis.

RESULTS

Eighteen relevant RCTs with a total of 4061 patients were included. The results of the meta-analysis indicated that CDA was superior to ACDF regarding better neurological success (P < 0.00001), greater motion preservation at the operated level (P < 0.00001), fewer secondary surgical procedures (P < 0.00001), and fewer rates of adverse events (P < 0.00001) but inferior to ACDF regarding operative times (P < 0.00001). No significant difference was identified between the two groups regarding blood loss (P = 0.87), lengths of hospital stay (P = 0.76), neck pain scores (P = 0.11) and arm pain scores (P = 0.78) reported on a visual analog scale.

CONCLUSION

The meta-analysis revealed that CDA demonstrated superiorities in better neurological success, greater motion preservation at the operated level, lower rate of adverse events and fewer secondary surgical procedures compared with ACDF. However, the benefits of blood loss, lengths of hospital stay, neck and arm pain functional recovery are still unable to be proved.

Comparison of revision surgeries for one- to two-level cervical TDR and ACDF from 2002 to 2011

BACKGROUND CONTEXT

Cervical total disc replacement (TDR) and anterior cervical discectomy and fusion (ACDF) provide comparable outcomes for degenerative cervical pathology. However, revisions of these procedures are not well characterized.

PURPOSE

The purpose of this study is to examine the rates, epidemiology, perioperative complications, and costs between the revision procedures and to compare these outcomes with those of primary cases.

STUDY DESIGN

This study is a retrospective database analysis.

PATIENT SAMPLE

A total of 3,792 revision and 183,430 primary cases from the Nationwide Inpatient Sample (NIS) database from 2002 to 2011 were included.

OUTCOME MEASURES

Incidence of revision cases, patient demographics, length of stay (LOS), in-hospital costs, mortality, and perioperative complications.

METHODS

Patients who underwent revision for either one- to two-level cervical TDR or ACDF were identified. SPSS v.20 was used for statistical analysis with χ(2) test for categorical data and independent sample t test for continuous data. The relative risk for perioperative complications with revisions was calculated in comparison with primary cases using a 95% confidence interval. An alpha level of less than 0.05 denoted statistical significance.

RESULTS

There were 3,536 revision one- to two-level ACDFs and 256 revision cervical TDRs recorded in the NIS database from 2002 to 2011. The revision cervical TDR cohort demonstrated a significantly greater LOS (3.18 vs. 2.25, p<.001), cost ($16,998 vs. $15,222, p=.03), and incidence of perioperative wound infections (13.6 vs. 5.3 per 1,000, p<.001) compared with the ACDF revision cohort (p<.001). There were no differences in mortality between the revision surgical cohorts. Compared with primary cases, both revision cohorts demonstrated a significantly greater LOS and cost. Furthermore, patients who underwent revision demonstrated a greater incidence and risk for perioperative wound infections, hematomas, dysphagia, and neurologic complications relative to the primary procedures.

CONCLUSIONS

This study demonstrated a significantly greater incidence of perioperative wound infection, LOS, and costs associated with a TDR revision compared with a revision ACDF. We propose that these differences are by virtue of the inherently more invasive nature of revising TDRs. In addition, compared with primary cases, revision procedures are associated with greater costs, LOS, and complications including wound infections, dysphagia, hematomas, and neurologic events. These additional risks must be considered before opting for a revision procedure.

The Mobi-C cervical disc for one-level and two-level cervical disc replacement: a review of the literature

BACKGROUND

Cervical disc arthroplasty (CDA) is a novel motion-preserving procedure that is an alternative to fusion. The Mobi-C disc prosthesis, one of many Food and Drug Administration (FDA)-approved devices for CDA, is the only FDA-approved prosthesis for two-level CDA. Hence, it may allow for improved outcomes compared with multilevel fusion procedures.

PURPOSE

To critically assess the available literature on CDA with the Mobi-C prosthesis, with a focus on two-level CDA.

METHODS

All clinical articles involving the Mobi-C disc prosthesis for CDA through September 1, 2014 were identified on Medline. Any paper that presented Mobi-C CDA clinical results was included. Study design, sample size, length of follow-up, use of statistical analysis, quality of life outcome scores, conflict of interest, and complications were recorded.

RESULTS

Fifteen studies were included that investigated Mobi-C CDA, only one of which was a level Ib randomized control trial. All studies included showed non-inferiority of one-level Mobi-C CDA to one-level anterior cervical discectomy and fusion (ACDF). Only one study analyzed outcomes of one-level versus two-level Mobi-C CDA, and only one study analyzed two-level Mobi-C CDA versus two-level ACDF. In comparison with other cervical disc prostheses, the Mobi-C prosthesis is associated with higher rates of heterotopic ossification (HO). Studies with conflicts of interest reported lower rates of HO. Adjacent segment degeneration or disease, along with other complications, were not assessed in most studies.

CONCLUSION

One-level Mobi-C CDA is non-inferior, but not superior, to one-level ACDF for patients with cervical degenerative disc disease. The Mobi-C CDA procedure is associated with high rates of HO. Two-level Mobi-C CDA may be superior to two-level ACDF. However, insufficient evidence exists, thereby mandating a need for unbiased, well-designed prospective studies with well-defined outcomes in the future.

Effect of anterior cervical discectomy and fusion on adjacent segments in rabbits

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.

Cervical arthroplasty: a critical review of the literature

BACKGROUND CONTEXT

Cervical disc arthroplasty (CDA) is a motion-preserving procedure that is an alternative to fusion. Proponents of arthroplasty assert that it will maintain cervical motion and prevent or reduce adjacent segment degeneration. Accordingly, CDA, compared with fusion, would have the potential to improve clinical outcomes. Published studies have varying conclusions on whether CDA reduces complications and/or improves outcomes. As many of these previous studies have been funded by CDA manufacturers, we wanted to ascertain whether there was a greater likelihood for these studies to report positive results.

PURPOSE

To critically assess the available literature on cervical arthroplasty with a focus on the time of publication and conflict of interest (COI).

STUDY DESIGN/SETTING

Review of the literature.

METHODS

All clinical articles about CDA published in English through August 1, 2013 were identified on Medline. Any article that presented CDA clinical results was included. Study design, sample size, type of disc, length of follow-up, use of statistical analysis, quality-of-life (QOL) outcome scores, COI, and complications were recorded. A meta-analysis was conducted stratifying studies by COI and publication date to identify differences in complication rates reported.

RESULTS

Seventy-four studies were included that investigated 8 types of disc prosthesis and 22 met the criteria for a randomized controlled trial (RCT). All Level Ib RCTs reported superior quality-of-life outcomes for CDA versus anterior cervical discectomy and fusion (ACDF) at 24 months. Fifty of the 74 articles (68%) had a disclosure section, including all Level Ib RCTs, which had significant COIs related to the respective studies. Those studies without a COI reported mean weighted average adjacent segment disease rates of 6.3% with CDA and 6.2% with ACDF. In contrast, the reverse was reported by studies with a COI, for which the averages were 2.5% with CDA and 6.3% with ACDF. Those studies with a COI (n=31) had an overall weighted average heterotopic ossification rate of 22%, whereas those studies with no COI (n=43) had a rate of 46%.

CONCLUSIONS

Associated COIs did not influence QOL outcomes. Conflicts of interest were more likely to be present in studies published after 2008, and those with a COI reported greater adjacent segment disease rates for ACDF than CDA. In addition, heterotopic ossification rates were much lower in studies with COI versus those without COI. Thus, COIs did not affect QOL outcomes but were associated with lower complication rates.

Cervical arthroplasty for moderate to severe disc degeneration: clinical and radiological assessments after a minimum follow-up of 18 months--Pfirrmann grade and cervical arthroplasty

PURPOSE

Clinical outcomes and radiologic results after cervical arthroplasty have been reported in many articles, yet relatively few studies after cervical arthroplasty have been conducted in severe degenerative cervical disc disease.

MATERIALS AND METHODS

Sixty patients who underwent cervical arthroplasty (Mobi-C®) between April 2006 and November 2011 with a minimum follow-up of 18 months were enrolled in this study. Patients were divided into two groups according to Pfirrmann classification on preoperative cervical MR images: group A (Pfirrmann disc grade III, n=38) and group B (Pfirrmann disc grades IV or V, n=22). Visual analogue scale (VAS) scores of neck and arm pain, modified Oswestry Disability Index (mODI) score, and radiological results including cervical range of motion (ROM) were assessed before and after surgery.

RESULTS

VAS and mean mODI scores decreased after surgery from 5.1 and 57.6 to 2.7 and 31.5 in group A and from 6.1 and 59.9 to 3.7 and 38.4 in group B, respectively. In both groups, VAS and mODI scores significantly improved postoperatively (p<0.001), although no significant intergroup differences were found. Also, cervical dynamic ROM was preserved or gradually improved up to 18 months after cervical arthroplasty in both groups. Global, segmental and adjacent ROM was similar for both groups during follow-up. No cases of device subsidence or extrusion were recorded.

CONCLUSION

Clinical and radiological results following cervical arthroplasty in patients with severe degenerative cervical disc disease were no different from those in patients with mild degenerative cervical disc disease after 18 months of follow-up.

Mid- to long-term outcomes after cervical disc arthroplasty compared with anterior discectomy and fusion: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

To evaluate the mid- to long-term clinical outcomes after cervical disc arthroplasty (CDA) as compared with anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic cervical disc disease.

METHODS

A systematic review and a meta-analysis were performed for articles published up to March 2013. Randomized controlled trials that reported mid- to long-term outcomes (≥48 months) after CDA as compared with ACDF were included. Two authors independently extracted the articles and the predefined data.

RESULTS

Five US Food and Drug Administration randomized controlled trials that reported 4-6 years of follow-up data were retrieved. Patients who underwent CDA had a lower mid- to long-term rate of reoperation and had greater mid- to long-term improvements in the Neck Disability Index, neck and arm pain scores, and Short Form 36 Health Survey physical component score than did those who underwent ACDF. Segmental motion was maintained in patients who underwent CDA. The mid- to long-term rates of adjacent segment disease and neurological success were not significantly different between the two groups.

CONCLUSIONS

CDA may result in better mid- to long-term functional recovery and a lower rate of subsequent surgical procedures than ACDF would. A review of the literature showed that only an insufficient number of studies had investigated adjacent segment disease; therefore, it is mandatory that adequate future research should focus in this direction.

Clinical comparison of 2 implantation systems for single-level cervical disk replacement

The safety and effectiveness of 2 implantation systems for single-segment cervical disk replacement-the Bryan Cervical Disc System (Medtronic Inc, Minneapolis, Minnesota) and the ACCEL system (Medtronic Inc)-have not been clinically compared. A prospective, nonrandomized controlled study in consecutive patients with a minimum 2-year follow-up was performed. Fifty patients with single-level cervical disk degeneration who responded poorly to conservative treatment and underwent Bryan Cervical Disc replacement were involved. Fifty patients were included (24 in group A [Bryan Cervical Disc System] and 26 in group B [ACCEL system]).The patients' visual analog scale scores, Neck Disability Index (NDI) scores, Short Form 36 (SF-36) scores, Odom scores, operative time, blood loss, and complications were compared. Patients' baseline statuses were similar (P>.05). Visual analog scale for neck and arm pain, NDI, and SF-36 were significantly improved postoperatively (P<.05) in both groups, and no clinical differences were found between the groups (P>.05). All Odom scores were better than good. Mean operative time and average blood loss in group A (173±42.5 minutes and 250±159.8 mL, respectively), were both significantly higher than the values in group B (137.5±19.3 minutes and 138.1±86.7 mL, respectively) (P<.05). Complications included intraoperative bleeding, temporary throat discomfort, and slight migration of the prosthesis; there was no significant difference in the total complication rates between the 2 groups (P>.05). The 2 implantation systems displayed equal clinical effectiveness and safety, but the ACCEL system appears to have the advantages of shorter operative time and less blood loss.