Cervical disc arthroplasty versus fusion for single-level symptomatic cervical disc disease: a meta-analysis of randomized controlled trials

Health Care Costs Following Anterior Cervical Discectomy and Fusion or Cervical Disc Arthroplasty

STUDY DESIGN

Observational cohort study.

OBJECTIVE

To describe the postoperative costs associated with both anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) in the two-year period following surgery.

SUMMARY OF BACKGROUND DATA

CDA has become an increasingly common alternative to ACDF for the treatment of cervical disc disorders. Although a number of studies have compared clinical outcomes between both procedures, much less is known about the postoperative economic burden of each procedure.

MATERIALS AND METHODS

By analyzing a commercial insurance claims database (Marketscan, Merative), patients who underwent one-level or two-level ACDF and CDA procedures between January 1, 2017 and December 31, 2017 were identified and included in the study. The primary outcome was the cost of payments for postoperative management in the two-year period following ACDF or CDA. Identified postoperative interventions included in the study were: (i) physical therapy, (ii) pain medication, (iii) injections, (iv) psychological treatment, and (iv) subsequent spine surgeries.

RESULTS

Totally, 2304 patients (age: 49.0±9.4 yr; male, 50.1%) were included in the study. In all, 1723 (74.8%) patients underwent ACDF, while 581 (25.2%) underwent CDA. The cost of surgery was similar between both groups (ACDF: $26,819±23,449; CDA: $25,954±20,620; P =0.429). Thirty-day, 90-day, and two-year global costs were all lower for patients who underwent CDA compared with ACDF ($31,024 vs. $34,411, $33,064 vs. $37,517, and $55,723 vs. $68,113, respectively).

CONCLUSION

Lower two-year health care costs were found for patients undergoing CDA compared with ACDF. Further work is necessary to determine the drivers of these findings and the associated longer-term outcomes.

Comparison of discover cervical disc arthroplasty and anterior cervical discectomy and fusion for the treatment of cervical degenerative disc diseases: A meta-analysis of prospective, randomized controlled trials

Objective

This study aims to evaluate the clinical efficacy and safety between Discover cervical disc arthroplasty (DCDA) and anterior cervical discectomy and fusion (ACDF) in Cervical degenerative disc diseases.

Methods

Two researchers independently conducted a search of PubMed, EMBASE, and Cochrane Central Register of Controlled Trails (CENTRAL) for randomized controlled trials (RCTs) following the Cochrane methodology guidelines. A fixed-effects or random-effects model was applied based on different heterogeneity. Review Manager (Version 5.4.1) software was used to perform data analysis.

Results

A total of 8 RCT studies were included in this meta-analysis. The results indicate that the DCDA group had a higher incidence of reoperation (P = 0.03) and a lower incidence of ASD (P = 0.04) than the CDA group. There was no significant difference between two groups regarding NDI score (P = 0.36), VAS ARM score (P = 0.73), VAS NECK score (P = 0.63), EQ-5D score (P = 0.61) and dysphagia incidence (0.18).

Conclusion

DCDA and ACDF have similar results in terms of NDI scores, VAS scores, EQ-5D scores, and dysphagia. In addition, DCDA can reduce the risk of ASD but increases the risk of reoperation.

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.

A meta-analysis comparing the short- and mid- to long-term outcomes of artificial cervical disc replacement(ACDR) with anterior cervical discectomy and fusion (ACDF) for the treatment of cervical degenerative disc disease

PURPOSE

Anterior cervical discectomy and fusion (ACDF) surgery is commonly performed to treat cervical degenerative disc disease (CDDD). The lost of range of motion (ROM) is also found after ACDF, which contributes to degenerate in adjacent segment disease (ASD). Artificial cervical disc replacement (ACDR), an alternative to ACDF, is developed to preserve the ROM and reduce ASD. This article aims to compare the outcomes between ACDR and ACDF in the short-, mid-, and long-term.

METHODS

Databases including Cochrane, Embase, PubMed, and Web of Science were searched. Only RCTs were included in this meta-analysis, and the search strategy followed the requirements of the Cochrane Handbook. The strength of evidence was assessed using GRADE. Two reviewers independently assessed the methodological quality of each included study and extracted the relevant data.

RESULTS

Thirty prospective RCTs were included. Prolonged operative duration, better overall success, neurological success, and NDI success rates were found in ACDR group in all follow-up periods, with lower dysphagia/dysphonia during short-term follow-up. Moreover, a lower ASD was found in ACDR group during long-term follow-up and overall analysis, with lower reoperation rates in all follow-up periods. Comparable length of hospital stay and blood loss were found in both groups. Moreover, ASD was similar in short- and mid-term follow-ups, while dysphagia/dysphonia incidence was similar in mid- and long-term follow-ups. The incidence of implant events was comparable in all follow-up periods (p > 0.05).

CONCLUSIONS

ACDR is as effective as ACDF and superior for some success rates. Disc replacement can reduce the risk of dysphagia/dysphonia, ASD, and re-operation.

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.

A Comprehensive Meta-Analysis of the Adjacent Segment Parameters in Cervical Disk Arthroplasty Versus Anterior Cervical Discectomy and Fusion

STUDY DESIGN

This is a meta-analysis of controlled trials.

OBJECTIVE

To assess the overall condition of adjacent segment of cervical disk arthroplasty (CDA) compared with anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

With the increase in CDA and ACDF, surgeons are taking more attention to adjacent segment degeneration (ASDeg) and adjacent segment disease (ASDis). There are more and more meta-analyses comparing the efficacy of CDA with ACDF, however, there are few meta-analyses referring to adjacent segment parameters, and investigators are still unable to arrive at the same conclusion.

METHODS

Several important databases were searched for controlled trials comparing CDA and ACDF before February 2016 according to PRISMA guidelines. The analysis parameters included follow-up time, operative segments, cervical range of motion (ROM), adjacent segment motion, ASDeg, ASDis and adjacent segment reoperation. The risk of bias scale and Newcastle-Ottawa Scale were used to assess the papers. Subgroup analysis and sensitivity analysis were used to analyze the reason for high heterogeneity.

RESULTS

Forty-one controlled trials fulfilled the inclusion criteria, including 36 English papers and 5 Chinese. The average follow-up time of all included patients was 39 months. Compared with ACDF, the rate of adjacent segment reoperation in the CDA group was significantly lower (P<0.01), and the advantage of CDA group increased with the increasing of follow-up time according to subgroup analysis. The rate of ASDeg in CDA was significantly lower than that of ACDF (P<0.01). There was no statistical difference between upper and lower ASDeg using the same surgical method (P>0.05). CDA provided a greater cervical ROM than did ACDF (P<0.01). There was a lower adjacent segment ROM and the rate of ASDis in CDA compared with ACDF (P<0.05).

CONCLUSIONS

Compared with ACDF, the advantages of CDA were lower ASDeg, ASDis, adjacent segment reoperation and adjacent segment motion; and higher cervical ROM. However, there was no statistical difference between upper and lower adjacent segment ROM/ASDeg using the same surgery.

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.

Neck pain and dysphagia associated to disc protrusion and reduced functional stability: A case report

BACKGROUND

Deglutition dysfunction like dysphagia may be associated with cervical symptoms.

FINDINGS

A young female complained of pain on the neck and swallowing dysfunction that was reduced by means of isometric contraction of cervical muscles. Magnetic resonance imaging revealed an anterior C5-C6 disc protrusion associated with a lesion of the anterior longitudinal ligament. Barium radiograph showed a small anterior cervical osteophyte at C6 level and dynamic X-ray excluded anatomical instability. The treatment included manual therapy and active exercises to improve muscular stability.

CONCLUSIONS

Diagnostic hypothesis was a combination of cervical disc dysfunction associated with C6 osteophyte and reduced functional stability.

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.

Revision surgery for cervical artificial disc: Surgical technique and clinical results

OBJECTIVE

Cervical artificial disc replacement (C-ADR) was developed with the goal of preserving mobility of the cervical segment in patients with degenerative disc disease. So far, little is known about experiences with revision surgery and explantation of C-ADRs. Here, we report our experience with revision the third generation, Galileo-type disc prosthesis from a retrospective study of two institutions.

PATIENTS AND METHODS

Between November 2008 and July 2016, 16 patients with prior implantation of C-ADR underwent removal of the Galileo-type disc prosthesis (Signus, Medizintechnik, Germany) due to a call back by industry. In 10 patients C-ADR was replaced with an alternative prosthesis, 6 patients received an ACDF. Duration of surgery, time to revision, surgical procedure, complication rate, neurological status, histological findings and outcome were examined in two institutions.

RESULTS

The C-ADR was successfully revised in all patients. Surgery was performed through the same anterior approach as the initial access. Duration of the procedure varied between 43 and 80min. Access-related complications included irritation of the recurrent nerve in one patient and mal-positioning of the C-ADR in another patient. Follow up revealed two patients with permanent mild/moderate neurologic deficits, NDI (neck disability index) ranged between 10 and 42%.

CONCLUSIONS

Anterior exposure of the cervical spine for explantation and revision of C-ADR performed through the initial approach has an overall complication rate of 18.75%. Replacements of the Galileo-type disc prosthesis with an alternative prosthesis or conversion to ACDF are both suitable surgical options without significant difference in outcome.

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.

Cervical cages placed bilaterally in the facet joints from a posterior approach significantly increase foraminal area

PURPOSE

Foraminal stenosis is a common cause of cervical radiculopathy. Posterior cervical cages can indirectly increase foraminal area and decompress the nerve root. The aim of this study was to assess the influence of bilateral posterior cervical cages on the surface area and shape of the neural foramen.

METHODS

Radiographic analysis was performed on 43 subjects enrolled in a prospective, multi-center study. CT scans were obtained at baseline and 6- and 12-months after cervical fusion using bilateral posterior cervical cages. The following measurements were performed on CT scan: foraminal area (A), theoretical area (TA), height (H), superior diagonal (DSI), inferior diagonal (DIS), and inferior diagonal without implant (DISI). Comparisons were performed using R-ANOVA with a significance of α < 0.05.

RESULTS

Foraminal area, height, TA and DISI were significantly greater following placement of the implant. The mean (SD) A increased from 4.01 (1.09) mm(2) before surgery to 4.24 (1.00) mm(2) at 6 months, and 4.18 (1.05) mm(2) at 12 months after surgery (p < 0.0001). Foraminal height (H) increased from mean (SD) 9.20 (1.08) mm at baseline to 9.65 (1.06) mm and 9.55 (1.14) mm at 6- and 12-months post-operatively, respectively (p < 0.0001). The mean DIS did not change significantly. There was a significant decrease in DSI: 6.18 (1.59) mm pre-operatively, 5.95 (1.47) mm and 5.73 (1.46) mm at 6- and 12-months (p < 0.0001).

CONCLUSIONS

Implantation of bilateral posterior cervical cages can increase foraminal area and may indirectly decompress the nerve roots. Correlation between increase in foraminal area and clinical outcomes needs further investigation.

Preliminary Analysis of Adjacent Segment Degeneration in Patients Treated with Posterior Cervical Cages: 2-Year Follow-Up

OBJECTIVE

Select patients with unremitting symptoms of cervical radiculopathy may be treated with indirect foraminal decompression and fusion via placement of a cervical cage placed bilaterally through a tissue sparing, posterior approach. Segmental fusion is known to affect adjacent segments. The aim of this study was to assess the affect of posterior fusion using bilateral cervical cages on adjacent segment degeneration (ASDegeneration) at 2 years postoperatively.

METHODS

Fifty-three patients enrolled in a prospective multicenter study who completed the imaging protocol were available for follow-up at 2 years. Lateral cervical radiographs were acquired preoperatively and at 1- and 2-years postoperatively. Imaging was evaluated for adjacent level degeneration using the following criteria: disk height ratio (DHR) defined as the ratio of the disk height and the lower vertebrae height measured at level above and below; proximal junctional kyphosis (PJK); Kellgren and Lawrence osteoarthritis severity grade (KLOSG); and heterotopic ossification (HO). The results were compared with a repeated analysis of variance test and Bonferroni correction; P < 0.05 was considered significant.

RESULTS

At 2 years postoperatively, there were no revision surgeries at the operated level or new surgeries at the adjacent levels. Of the 102 segments evaluated, ASDegeneration was identified at 21 levels cranial to and 21 levels caudal to the index level. At 2 years, new mild ASDegeneration signs developed at 3 levels: 1 in the level above and 2 in the level below the operated segment. In patients with pre-existing disk degeneration, mild progression of ASDegeneration signs developed in 6 upper and 2 lower segments. There were no significant changes in DHR and PJK in all patients; however, when patients with signs of ASDegeneration only were evaluated, a significant decrease of the DHR was found. The mean DHRs before surgery and 1 and 2 years after surgery in all patients were 44.0 ± 8.1, 44.0 ± 8.2, and 43.1 ± 8.4 (P = 0.1006) and in ASD patients were 43.8 ± 7.3, 41.9 ± 6.3, and 39.6 ± 8.3 (P = 0.0062), respectively. Overall, at 2 years postoperatively, ASDegeneration was identified in 9 patients (17.6% when compared with all evaluated patients before surgery).

CONCLUSIONS

In the current study, 5.9% of subjects treated with posterior cervical cages placed bilaterally between the facet joints developed adjacent segment degeneration at 2 years. Mild progression of existing degeneration was observed in 11.8% of subjects. Further evaluation to establish long-term incidence is needed.

Long Term Societal Costs of Anterior Discectomy and Fusion (ACDF) versus Cervical Disc Arthroplasty (CDA) for Treatment of Cervical Radiculopathy

BACKGROUND

Current literature suggests that anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) have comparable clinical outcomes for the treatment of cervical radiculopathy. Given similar outcomes, an understanding of differences in long-term societal costs can help guide resource utilization. The purpose of this study was to compare the relative long-term societal costs of anterior cervical discectomy and fusion (ACDF) to cervical disc arthroplasty (CDA) for the treatment of single level cervical disc disease by considering upfront surgical costs, lost productivity, and risk of subsequent revision surgery.

METHODS

We completed an economic and decision analysis using a Markov model to evaluate the long-term societal costs of ACDF and CDA in a theoretical cohort of 45-65 year old patients with single level cervical disc disease who have failed nonoperative treatment.

RESULTS

The long-term societal costs for a 45-year old patient undergoing ACDF are $31,178 while long-term costs for CDA are $24,119. Long-term costs for CDA remain less expensive throughout the modeled age range of 45 to 65 years old. Sensitivity analysis demonstrated that CDA remains less expensive than ACDF as long as annual reoperation rate remains below 10.5% annually.

CONCLUSIONS

Based on current data, CDA has lower long-term societal costs than ACDF for patients 45-65 years old by a substantial margin. Given reported reoperation rates of 2.5% for CDA, it is the preferred treatment for cervical radiculopathy from an economic perspective.

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.

Advanced Multi-Axis Spine Testing: Clinical Relevance and Research Recommendations

Back pain and spinal degeneration affect a large proportion of the general population. The economic burden of spinal degeneration is significant, and the treatment of spinal degeneration represents a large proportion of healthcare costs. However, spinal surgery does not always provide improved clinical outcomes compared to non-surgical alternatives, and modern interventions, such as total disc replacement, may not offer clinically relevant improvements over more established procedures. Although psychological and socioeconomic factors play an important role in the development and response to back pain, the variation in clinical success is also related to the complexity of the spine, and the multi-faceted manner by which spinal degeneration often occurs. The successful surgical treatment of degenerative spinal conditions requires collaboration between surgeons, engineers, and scientists in order to provide a multi-disciplinary approach to managing the complete condition. In this review, we provide relevant background from both the clinical and the basic research perspectives, which is synthesized into several examples and recommendations for consideration in increasing translational research between communities with the goal of providing improved knowledge and care. Current clinical imaging, and multi-axis testing machines, offer great promise for future research by combining invivo kinematics and loading with in-vitro testing in six degrees of freedom to offer more accurate predictions of the performance of new spinal instrumentation. Upon synthesis of the literature, it is recommended that in-vitro tests strive to recreate as many aspects of the in-vivo environment as possible, and that a physiological preload is a critical factor in assessing spinal biomechanics in the laboratory. A greater link between surgical procedures, and the outcomes in all three anatomical planes should be considered in both the in-vivo and in-vitro settings, to provide data relevant to quality of motion, and stability.

WITHDRAWN: Arthroplasty versus fusion in single-level cervical degenerative disc disease

Background

There is ongoing debate about whether fusion or arthroplasty is superior in the treatment of single level cervical degenerative disc disease. Mainly because the intended advantage of arthroplasty over fusion, that is, the prevention of symptoms due to adjacent segment degeneration in the long term, is not confirmed yet. Until sufficient long‐term results become available, it is important to know whether results of one of the two treatments are superior to the other in the first one to two years.

Objectives

To assess the effects of arthroplasty versus fusion for radiculopathy or myelopathy, or both due to single level cervical degenerative disc disease.

Search methods

We searched the following databases for randomised controlled trials (RCTs): CENTRAL (The Cochrane Library 2011, Issue 2), MEDLINE, EMBASE, and EBMR. Additionally, we searched the System for Information on Grey Literature (SIGLE), subheading Biological and Medical Sciences, the US Food and Drug Administration (FDA) database on medical devices, and Clinicaltrials.gov to identify trials in progress. We also screened the reference list of all selected papers. Date of search: 25 May 2011.

Selection criteria

We included RCTs that directly compared any type of cervical fusion with any type of arthroplasty, with at least one year of follow‐up. Primary outcomes were arm pain, neck pain, neck‐related functional status, patient satisfaction, neurological outcome, and global health status. Secondary outcomes were the presence of (radiological) fusion, revision surgery at the treated level, secondary surgery on adjacent levels, segmental mobility of treated and adjacent levels, and work status.

Data collection and analysis

Study selection was performed independently by three review authors, and 'Risk of bias' assessment and data extraction were performed by two review authors. In case of missing data or insufficient information for a judgement about risk of bias, we tried to contact the study authors or the study sponsor. The data were entered into RevMan by one review author and subsequently checked by a second review author. We assessed the quality of evidence using GRADE. We analysed heterogeneity and performed sensitivity analyses for the pooled analyses.

Main results

We included nine studies (2400 participants), five of which had a low risk of bias. Eight of these studies were industry sponsored. The most important results showed low‐quality evidence for a small but significant difference in alleviation of arm pain at one to two years in favour of arthroplasty (mean difference (MD) ‐1.54; 95% confidence interval (CI) ‐2.86 to ‐0.22; 100‐point scale). A small study effect could not be ruled out for this outcome in the sensitivity analyses. This means that smaller studies (or small published subsets of larger studies) showed larger differences for this outcome, which may indicate publication bias. Also, moderate‐quality evidence showed a small difference in neck‐related functional status at one to two years in favour of arthroplasty (MD ‐2.79; 95% CI ‐4.73 to ‐0.85; 100‐point scale) and a small difference in neurological outcome in favour of arthroplasty (risk ratio (RR) 1.05; 95% CI 1.01 to 1.09). These two outcomes were robust to sensitivity analyses. For none of the primary outcomes, was a clinically relevant difference shown. Additionally, there was high‐quality evidence for a large, statistically significant difference in segmental mobility at one to two years (measured as degrees segmental range of motion) at the treated level (MD 6.90; 95% CI 5.45 to 8.35). There was low‐quality evidence that there was no statistically significant difference in secondary surgery at the adjacent levels at one to two years (RR 0.60; 95% CI 0.35 to 1.02). The latter was not robust to sensitivity analyses.

Authors' conclusions

There was a tendency for clinical results to be in favour of arthroplasty; often these were statistically significant. However, differences in effect size were invariably small and not clinically relevant for all primary outcomes. Significance was often gained or lost in the varying sensitivity analyses, probably owing to the relatively small number of studies, in combination with the small differences that were found. Given the fact that all of the included studies were not blinded, this could be due to patient or carer expectations. However, at this time both treatments can be seen as valid options with respect to results at a maximum of one to two years. Given the current absence of truly long‐term results, use of these mobile disc prostheses should still be limited to clinical trials. There was high‐quality evidence that the goal of preservation of segmental mobility in arthroplasty was met. A statistically significant effect on the incidence of secondary symptoms at adjacent levels, the primary goal of arthroplasty over fusion, was not found at one to two years. If there was a protective effect, this should become clearer over time. A future update, when studies with 'truly long‐term' results (five years or more) become available, should focus on this issue.

A herniated disc in the neck often causes radiating pain, numbness, and weakness in muscles of the neck, shoulders, arms, and hands. It may also lead to symptoms in the trunk and legs.

When there is no or insufficient relief of symptoms with non‐surgical treatment, surgery can be an option. Traditional 'fusion' surgery involves fusion of the two bones of the spine (the vertebrae) that form the disc space. Motion between these two vertebrae is then no longer possible.

It has been suggested that this may cause the adjacent parts of the spine to become more mobile, as compensation. This in turn might accelerate normal wear and tear in these parts of the spine, which could lead to new symptoms. At present this is not confirmed.

Mobile disc prostheses have been introduced in an effort to reduce the amount of new symptoms at the longer term after surgery by preserving motion between the vertebrae involved. Long‐term results are not available yet. However, it is important to know whether disc arthroplasty is at least as effective as fusion in relieving symptoms, the primary aim of surgery.

In this review we have searched for all studies in which the patient receives one of these two possible treatments at random.

We identified nine studies (2400 participants), and considered five of these to have high methodological quality. This review shows that patients who were treated with a mobile disc prosthesis had less pain radiating to the arm one to two years after surgery, and less disability owing to these complaints. However, the actual differences were very small, only between 1 and 5 points on a 100‐point scale. The overall quality of the evidence was low to moderate, which means that including new studies in future years could change these conclusions. The conclusion that mobility is in fact preserved after placement of a mobile disc prosthesis, compared to traditional 'fusion' surgery, is unlikely to change. Whether this preserved mobility will lead to fewer new symptoms in the future is uncertain based on results for the first one to two years after surgery.

Therefore, a comparison of results in the long term (five years or more) will be made when more studies with long‐term results have become available.

Incidence of adjacent segment degeneration in cervical disc arthroplasty versus anterior cervical decompression and fusion meta-analysis of prospective studies

PURPOSE

To evaluate the incidence of adjacent segment disease (ASD) requiring surgical intervention between anterior cervical decompression and fusion (ACDF) and total disc replacement (TDR).

BACKGROUND

The concern for ASD has led to the development of motion-preserving technologies such as TDR. However, whether replacement arthroplasty in the spine achieves its primary patient-centered objective of lowering the frequency of adjacent segment degeneration is not verified yet.

METHODS

A comprehensive literature search was performed using PubMed, Cochrane Central Register of Controlled Trials and Embase. These databases were thoroughly searched for prospective randomized studies comparing ACDF and TDR. Eight studies met the inclusion criteria for a meta-analysis and were used to report an overall rate of ASD for both ACDF and TDR.

RESULTS

Pooling data from 8 prospective studies, the overall sample size at baseline was 1,726 patients (889 in the TDR group and 837 in the ACDF group). The ACDF group had significantly more ASDs compared with the TDR group at 24 months postoperatively [odds ratios (OR), 1.31; 95 % confidence interval (CI), 1.04-1.64; p = 0.02]. The TDR group had significantly fewer adjacent segment reoperations compared with the ACDF group at 24 months postoperatively (OR, 0.49; 95 % CI, 0.25-0.96; p = 0.04).

CONCLUSIONS

For patients with one-level cervical degenerative disc disease (CDDD), total disc replacement was found to have significantly fewer ASDs and reoperations compared with the ACDF. Cervical replacement arthroplasty may be superior to ACDF in ASD. Therefore, cervical arthroplasty is a safe and effective surgical procedure for treating CDDD. We suggest adopting TDR on a large scale.

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.

Anterior cervical discectomy with arthroplasty versus anterior cervical discectomy and fusion for cervical spondylosis

This meta-analysis aims to estimate the benefits and drawbacks associated with anterior cervical discectomy with arthroplasty (ACDA) versus anterior cervical discectomy and fusion (ACDF) for cervical spondylosis. Of 3651 identified citations, 10 randomised controlled studies involving 2380 participants were included. Moderate quality evidence supports that patients in the ACDA group had: (1) a higher Neck Disability Index (NDI) success rate at 3 month (relative risk [RR]=0.85, 95% confidence interval [CI] 0.78 to 0.93, p=0.0002) and 2 year follow-up (RR=0.95, 95%CI 0.91 to 1.00, p=0.04); (2) greater neurological success at 2 year follow-up (RR=0.95, 95%CI 0.92 to 0.98); and (3) were more likely to be employed within 6 weeks after surgery (RR=0.80 95%CI 0.66 to 0.96). In summary, the current evidence indicates that ACDA is associated with a higher NDI success rate in the short and long-term as well as a higher neurological success rate. Patients who undergo ACDA may also have a greater likelihood of being employed in the short-term. However, all of the evidence reviewed is of moderate or low quality and the clinical significance often marginal or unclear. Additional data are needed to compare the benefits and limitations of ACDA and ACDF.

Rate of adjacent segment disease in cervical disc arthroplasty versus single-level fusion: meta-analysis of prospective studies

STUDY DESIGN

Meta-analysis of randomized controlled trials.

OBJECTIVE

To compare the reported incidence of adjacent segment disease (ASD) requiring surgical intervention between anterior cervical decompression and fusion (ACDF) and total disc arthroplasty (TDA).

SUMMARY OF BACKGROUND DATA

The concern for ASD has led to the development of motion-preserving technologies such as TDA. To date, however, no known study has sought to compare the incidence of ASD between ACDF and TDA in major prospective studies.

METHODS

A systematic review of IDE and non-IDE trials was performed using PubMed and Cochrane libraries. These databases were thoroughly searched for prospective randomized studies comparing ACDF and TDR. Six studies met the inclusion criteria for a meta-analysis and were used to report an overall rate of ASD for both ACDF and TDA.

RESULTS

Pooling data from 6 prospective studies, the overall sample size at baseline was 1586 (ACDF = 777, TDA = 809) and at the final follow-up was 1110 giving an overall follow-up of 70%. Patients after an ACDF had a lower rate of follow-up overall than those after TDR (ACDF: 67.3% vs. TDR: 72.6%, P= 0.01). Thirty-six patients required adjacent-level surgery after an ACDF at 2 to 5 years of follow-up (6.9%) compared with 30 patients after a TDA (5.1%). The corresponding reoperation rate for ASD was 2.4 ± 1.7% per year for ACDF versus 1.1 ± 1.5% per year for TDR. These differences were not statistically significant (P= 0.44). Using a Kaplan-Meier analysis and historical data, we expect 48 patients in the ACDF group and 55 patients in the TDR group to have symptomatic disease at an adjacent level.

CONCLUSION

From a meta-analysis of prospective studies, there is no difference in the rate of ASD for ACDF versus TDA. We also report an overall lower rate of follow-up for patients with ACDF than for those with TDR. Future prospective studies should continue to focus on excellent patient follow-up and accurate assessment of patient symptoms that are attributable to an adjacent level as this has been an under-reported finding in prospective studies.

LEVEL OF EVIDENCE

1.

Arthroplasty versus fusion in single-level cervical degenerative disc disease: a Cochrane review

STUDY DESIGN

A systematic review of randomized controlled trials (RCTs).

OBJECTIVE

To assess the effects of arthroplasty versus fusion in the treatment of radiculopathy or myelopathy, or both, due to single-level cervical degenerative disc disease.

SUMMARY OF BACKGROUND DATA

There is ongoing debate about whether fusion or arthroplasty is superior in the treatment of single-level cervical degenerative disc disease. Mainly because the intended advantage of arthroplasty compared with fusion, prevention of symptoms due to adjacent segment degeneration in the long term, is not confirmed yet. Until sufficient long-term results become available, it is important to know whether results of 1 of the 2 treatments are superior to the other in the first 1 to 2 years.

METHODS

We searched electronic databases for randomized controlled trials. We included randomized controlled trials that directly compared any type of cervical fusion with any type of cervical arthroplasty, with at least 1 year of follow-up. Study selection was performed independently by 3 review authors, and "risk of bias" assessment and data extraction were independently performed by 2 review authors. In case of missing data, we contacted the study authors or the study sponsor. We assessed the quality of evidence.

RESULTS

Nine studies (2400 participants) were included in this review; 5 of these studies had a low risk of bias. Results for the arthroplasty group were better than the fusion group for all primary comparisons, often statistically significant. For none of the primary outcomes was a clinically relevant difference in effect size shown. Quality of the evidence was low to moderate.

CONCLUSION

There is low to moderate quality evidence that results are consistently in favor of arthroplasty, often statistically significant. However, differences in effect size were invariably small and not clinically relevant for all primary outcomes.

LEVEL OF EVIDENCE

1.

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

BACKGROUND

As the current standard treatment for symptomatic cervical disc disease, anterior cervical decompression and fusion may result in progressive degeneration or disease of the adjacent segments. Cervical disc arthroplasty was theoretically designed to be an ideal substitute for fusion by preserving motion at the operative level and delaying adjacent level degeneration. However, it remains unclear whether arthroplasty achieves that aim.

QUESTIONS/PURPOSES

We investigated whether cervical disc arthroplasty was associated with (1) better function (neck disability index, pain assessment, SF-36 mental and physical health surveys, neurologic status) than fusion, (2) a lower incidence of reoperation and major complications, and (3) a lower risk of subsequent adjacent segment degeneration.

METHODS

We conducted a comprehensive search in MEDLINE(®), EMBASE, and Cochrane Central Register of Controlled Trials and identified 503 papers. Of these, we identified 13 reports from 10 randomized controlled trials involving 2227 patients. We performed a meta-analysis of functional scores, rates of reoperation, and major complications. The strength of evidence was evaluated by using GRADE profiler software. Of the 10 trials, six trials including five prospective multicenter FDA-regulated studies were sponsored by industry. The mean follow-ups of the 10 trials ranged from 1 to 5 years.

RESULTS

Compared with anterior cervical decompression and fusion, cervical disc arthroplasty had better mean neck disability indexes (95% CI, -0.25 to -0.02), neurologic status (risk ratio [RR], 1.04; 95% CI, 1.00-1.08), with a reduced incidence of reoperation related to the index surgery (RR, 0.42; 95% CI, 0.22-0.79), and major surgical complications (RR, 0.45; 95% CI, 0.27-0.75) at a mean of 1 to 3 years. However, the operation rate at adjacent levels after two procedures was similar (95% CI, 0.31-1.27). The three studies with longer mean follow-ups of 4 to 5 years also showed similar superiority of all four parameters of cervical disc arthroplasty compared with fusion.

CONCLUSIONS

For treating symptomatic cervical disc disease, cervical disc arthroplasty appears to provide better function, a lower incidence of reoperation related to index surgery at 1 to 5 years, and lower major complication rates compared with fusion. However, cervical disc arthroplasty did not reduce the reoperation rate attributable to adjacent segment degeneration than fusion. Further, it is unclear whether these differences in subsequent surgery including arthroplasty revisions will persist beyond 5 years.

Five-year results of cervical disc prostheses in the SWISSspine registry

BACKGROUND

The Swiss Federal Office of Public Health demanded a nationwide HTA-registry for cervical total disc arthroplasty (TDA), to decide about its reimbursement. The goal of the SWISSspine registry is to generate evidence about the safety and efficiency of cervical TDA.

MATERIALS AND METHODS

Three hundred thirty-two cases treated between 3.2005 and 6.2006 who were eligible for 5 years follow-ups were included in the study. Follow-up rates for 3-6 months, 1, 2 and 5 years were 84.6, 74.4, 50.6 and 64.8 %, respectively. Outcome measures were neck and arm pain, medication, quality of life, intraoperative and postoperative complication and revision rates. In addition, segmental mobility, ossification, adjacent and distant segment degeneration were analyzed at the 5-year follow-up.

RESULTS

There was significant, clinically relevant and lasting reduction of neck (preop/postop 60/21 VAS points) and arm pain (preop/postop VAS 67/17) and a consequently decreased analgesics consumption and quality of life improvement (preop/postop 0.39/0.82 EQ-5D points) until the 5-year follow-up. The rates for intraoperative and early postoperative complications were 0.6 and 7.2 %, respectively. In 0.6 % an early and in 3.9 % a late revision surgery was performed. At the 5-year follow-up, the average range of motion of the mobile segments (88.2 %) was 10.2°. In 40.7 % of the patients osteophytes at least potentially affecting range of motion were seen.

CONCLUSIONS

Cervical TDA appeared as safe and efficient in long-term pain alleviation, consequent reduction of pain killer consumption and in improvement of quality of life. The improvement is stable over the 5 years postoperative period. The vast majority of treated segments remained mobile after 5 years, although 40.7 % of patients showed osteophytes.

Arthroplasty versus fusion in single-level cervical degenerative disc disease

BACKGROUND

There is ongoing debate about whether fusion or arthroplasty is superior in the treatment of single level cervical degenerative disc disease. Mainly because the intended advantage of arthroplasty over fusion, that is, the prevention of symptoms due to adjacent segment degeneration in the long term, is not confirmed yet. Until sufficient long-term results become available, it is important to know whether results of one of the two treatments are superior to the other in the first one to two years.

OBJECTIVES

To assess the effects of arthroplasty versus fusion for radiculopathy or myelopathy, or both due to single level cervical degenerative disc disease.

SEARCH METHODS

We searched the following databases for randomised controlled trials (RCTs): CENTRAL (The Cochrane Library 2011, Issue 2), MEDLINE, EMBASE, and EBMR. Additionally, we searched the System for Information on Grey Literature (SIGLE), subheading Biological and Medical Sciences, the US Food and Drug Administration (FDA) database on medical devices, and Clinicaltrials.gov to identify trials in progress. We also screened the reference list of all selected papers. Date of search: 25 May 2011.

SELECTION CRITERIA

We included RCTs that directly compared any type of cervical fusion with any type of arthroplasty, with at least one year of follow-up. Primary outcomes were arm pain, neck pain, neck-related functional status, patient satisfaction, neurological outcome, and global health status. Secondary outcomes were the presence of (radiological) fusion, revision surgery at the treated level, secondary surgery on adjacent levels, segmental mobility of treated and adjacent levels, and work status.

DATA COLLECTION AND ANALYSIS

Study selection was performed independently by three review authors, and 'Risk of bias' assessment and data extraction were performed by two review authors. In case of missing data or insufficient information for a judgement about risk of bias, we tried to contact the study authors or the study sponsor. The data were entered into RevMan by one review author and subsequently checked by a second review author. We assessed the quality of evidence using GRADE. We analysed heterogeneity and performed sensitivity analyses for the pooled analyses.

MAIN RESULTS

We included nine studies (2400 participants), five of which had a low risk of bias. Eight of these studies were industry sponsored. The most important results showed low-quality evidence for a small but significant difference in alleviation of arm pain at one to two years in favour of arthroplasty (mean difference (MD) -1.54; 95% confidence interval (CI) -2.86 to -0.22; 100-point scale). A small study effect could not be ruled out for this outcome in the sensitivity analyses. This means that smaller studies (or small published subsets of larger studies) showed larger differences for this outcome, which may indicate publication bias. Also, moderate-quality evidence showed a small difference in neck-related functional status at one to two years in favour of arthroplasty (MD -2.79; 95% CI -4.73 to -0.85; 100-point scale) and a small difference in neurological outcome in favour of arthroplasty (risk ratio (RR) 1.05; 95% CI 1.01 to 1.09). These two outcomes were robust to sensitivity analyses. For none of the primary outcomes, was a clinically relevant difference shown. Additionally, there was high-quality evidence for a large, statistically significant difference in segmental mobility at one to two years (measured as degrees segmental range of motion) at the treated level (MD 6.90; 95% CI 5.45 to 8.35). There was low-quality evidence that there was no statistically significant difference in secondary surgery at the adjacent levels at one to two years (RR 0.60; 95% CI 0.35 to 1.02). The latter was not robust to sensitivity analyses.

AUTHORS' CONCLUSIONS

There was a tendency for clinical results to be in favour of arthroplasty; often these were statistically significant. However, differences in effect size were invariably small and not clinically relevant for all primary outcomes. Significance was often gained or lost in the varying sensitivity analyses, probably owing to the relatively small number of studies, in combination with the small differences that were found. Given the fact that all of the included studies were not blinded, this could be due to patient or carer expectations. However, at this time both treatments can be seen as valid options with respect to results at a maximum of one to two years. Given the current absence of truly long-term results, use of these mobile disc prostheses should still be limited to clinical trials. There was high-quality evidence that the goal of preservation of segmental mobility in arthroplasty was met. A statistically significant effect on the incidence of secondary symptoms at adjacent levels, the primary goal of arthroplasty over fusion, was not found at one to two years. If there was a protective effect, this should become clearer over time. A future update, when studies with 'truly long-term' results (five years or more) become available, should focus on this issue.

Anterior cervical discectomy with arthroplasty versus arthrodesis for single-level cervical spondylosis: a systematic review and meta-analysis

OBJECTIVE

To estimate the effectiveness of anterior cervical discectomy with arthroplasty (ACDA) compared to anterior cervical discectomy with fusion (ACDF) for patient-important outcomes for single-level cervical spondylosis.

DATA SOURCES

Electronic databases (MEDLINE, EMBASE, Cochrane Register for Randomized Controlled Trials, BIOSIS and LILACS), archives of spine meetings and bibliographies of relevant articles.

STUDY SELECTION

We included RCTs of ACDF versus ACDA in adult patients with single-level cervical spondylosis reporting at least one of the following outcomes: functionality, neurological success, neck pain, arm pain, quality of life, surgery for adjacent level degeneration (ALD), reoperation and dysphonia/dysphagia. We used no language restrictions. We performed title and abstract screening and full text screening independently and in duplicate.

DATA SYNTHESIS

We used random-effects model to pool data using mean difference (MD) for continuous outcomes and relative risk (RR) for dichotomous outcomes. We used GRADE to evaluate the quality of evidence for each outcome.

RESULTS

Of 2804 citations, 9 articles reporting on 9 trials (1778 participants) were eligible. ACDA is associated with a clinically significant lower incidence of neurologic failure (RR = 0.53, 95% CI = 0.37-0.75, p = 0.0004) and improvement in the Neck pain visual analogue scale (VAS) (MD = 6.56, 95% CI = 3.22-9.90, p = 0.0001; Minimal clinically important difference (MCID) = 2.5. ACDA is associated with a statistically but not clinically significant improvement in Arm pain VAS and SF-36 physical component summary. ACDA is associated with non-statistically significant higher improvement in the Neck Disability Index Score and lower incidence of ALD requiring surgery, reoperation, and dysphagia/dysphonia.

CONCLUSIONS

There is no strong evidence to support the routine use of ACDA over ACDF in single-level cervical spondylosis. Current trials lack long-term data required to assess safety as well as surgery for ALD. We suggest that ACDA in patients with single level cervical spondylosis is an option although its benefits and indication over ACDF remain in question.