Segmental kinematics and adjacent level degeneration following disc replacement versus fusion: RCT with three years of follow-up

The Statistical Fragility of Trials Comparing Cervical Disc Arthroplasty and Anterior Cervical Discectomy and Fusion: A Meta Analysis

STUDY DESIGN

Meta-analysis.

OBJECTIVE

To assess the robustness of randomized controlled trials (RCTs) that compared cervical disc arthroplasty (CDA) and anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic degenerative cervical pathology by using fragility indices.

SUMMARY OF BACKGROUND DATA

RCTs comparing these surgical approaches have shown that CDA may be equivalent or even superior to ACDF due to better preservation of normal spinal kinematics.

MATERIALS AND METHODS

RCTs reporting clinical outcomes after CDA versus ACDF for degenerative cervical disc disease were evaluated. Data for outcome measures were classified as continuous or dichotomous. Continuous outcomes included: Neck Disability Index, overall pain, neck pain, radicular arm pain, and modified Japanese Orthopedic Association scores. Dichotomous outcomes included: any adjacent segment disease (ASD), superior-level ASD, and inferior-level ASD. The fragility index (FI) and continuous FI (CFI) were determined for dichotomous and continuous outcomes, respectively. The corresponding fragility quotient (FQ) and continuous FQ were calculated by dividing FI/CFI by sample size.

RESULTS

Twenty-five studies (78 outcome events) were included. Thirteen dichotomous events had a median FI of 7 [interquartile range (IQR): 3-10], and the median FQ was 0.043 (IQR: 0.035-0.066). Sixty-five continuous events had a median CFI of 14 (IQR: 9-22) and a median continuous FQ of 0.145 (IQR: 0.074-0.188). This indicates that, on average, altering the outcome of 4.3 patients out of 100 for the dichotomous outcomes and 14.5 out of 100 for continuous outcomes would reverse trial significance. Of the 13 dichotomous events that included a loss to follow-up data, 8 (61.5%) represented ≥7 patients lost. Of the 65 continuous events reporting the loss to follow-up data, 22 (33.8%) represented ≥14 patients lost.

CONCLUSION

RCTs comparing ACDF and CDA have fair to moderate statistical robustness and do not suffer from statistical fragility.

Ten-Year Outcomes of Cervical Disc Arthroplasty Versus Anterior Cervical Discectomy and Fusion : A Systematic Review With Meta-Analysis

STUDY DESIGN

A systematic review with meta-analysis of randomized controlled trials and comparative retrospective cohort studies.

OBJECTIVE

The purpose of this study is to compare the 10-year outcomes of cervical disc arthroplasty (CDA) with those of anterior cervical discectomy and fusion (ACDF) for the treatment of cervical degenerative disc disease (CDDD).

SUMMARY OF BACKGROUND DATA

ACDF is the gold standard for the treatment of CDDD. However, the loss of motion at the operative level may accelerate adjacent segment disease (ASD). The preservation of motion with CDA attempts to prevent this complication of cervical fusion. Short-term and mid-term data reveal comparable results for CDA versus ACDF; however, long-term results are unknown.

MATERIALS AND METHODS

A systematic review with meta-analysis was performed to determine if CDA had improved outcomes compared with ACDF at 10-year follow-up. PubMed and Web of Science database searches through 2023 were performed to identify randomized controlled trials and comparative retrospective cohort studies involving treatment of one-level or two-level CDDD.

RESULTS

Six studies were eligible for analysis. CDA had significantly improved neck disability index and visual analog scale scores but lower Japanese Orthopaedic Association scores compared to ACDF at 10-year follow-up ( P < 0.05). None of these results met minimal clinically important differences. CDA had significantly fewer secondary surgeries and adverse events compared to ACDF ( P <0.05). There were no significant differences in neurological success.

CONCLUSIONS

The authors found that significantly fewer secondary surgeries and adverse events were seen after CDA than after ACDF at 10-year follow-up. CDA had statistically, but not clinically, improved neck disability index and visual analog scale scores but lower Japanese Orthopaedic Association scores in comparison to ACDF. CDA was not significantly different from ACDF in terms of a successful neurological outcome.

Artificial intelligence in predicting early-onset adjacent segment degeneration following anterior cervical discectomy and fusion

PURPOSE

Anterior cervical discectomy and fusion (ACDF) is a common surgical treatment for degenerative disease in the cervical spine. However, resultant biomechanical alterations may predispose to early-onset adjacent segment degeneration (EO-ASD), which may become symptomatic and require reoperation. This study aimed to develop and validate a machine learning (ML) model to predict EO-ASD following ACDF.

METHODS

Retrospective review of prospectively collected data of patients undergoing ACDF at a quaternary referral medical center was performed. Patients > 18 years of age with > 6 months of follow-up and complete pre- and postoperative X-ray and MRI imaging were included. An ML-based algorithm was developed to predict EO-ASD based on preoperative demographic, clinical, and radiographic parameters, and model performance was evaluated according to discrimination and overall performance.

RESULTS

In total, 366 ACDF patients were included (50.8% male, mean age 51.4 ± 11.1 years). Over 18.7 ± 20.9 months of follow-up, 97 (26.5%) patients developed EO-ASD. The model demonstrated good discrimination and overall performance according to precision (EO-ASD: 0.70, non-ASD: 0.88), recall (EO-ASD: 0.73, non-ASD: 0.87), accuracy (0.82), F1-score (0.79), Brier score (0.203), and AUC (0.794), with C4/C5 posterior disc bulge, C4/C5 anterior disc bulge, C6 posterior superior osteophyte, presence of osteophytes, and C6/C7 anterior disc bulge identified as the most important predictive features.

CONCLUSIONS

Through an ML approach, the model identified risk factors and predicted development of EO-ASD following ACDF with good discrimination and overall performance. By addressing the shortcomings of traditional statistics, ML techniques can support discovery, clinical decision-making, and precision-based spine care.

The Clinical Relevance of the Cervical Disc Prosthesis: Combining Clinical Results of Two RCTs

STUDY DESIGN

Retrospective analysis was performed on data from 251 patients that were included in two randomized, double-blinded clinical trials comparing clinical results of anterior cervical discectomy and arthroplasty (ACDA) to anterior cervical discectomy and fusion (ACDF), and anterior cervical discectomy (ACD), for single-level disc herniation.

OBJECTIVE

This study aimed to investigate whether the ACDA procedure offers superior clinical results 2 years after surgery, to either ACDF or ACD without instrumentation, in the entire group of patients or in a particular subgroup of patients.

SUMMARY OF BACKGROUND DATA

The cervical disc prosthesis was introduced to provide superior clinical outcomes after ACD.

METHODS

Neck Disability Index (NDI), and subscales of the 36-item short-form health survey (SF-36) and McGill pain score were collected at baseline, 1 year and 2 years after surgery. Reoperations and complications were also evaluated. A preliminary subgroup analysis was performed for age, disc height, body mass index (BMI), smoking, and sex.

RESULTS

The NDI decreased comparably in all treatment arms to circa 50% of the baseline value and marginal mean NDI differences varied from 0.4 to 1.1 on a 100 point NDI scale, with confidence intervals never exceeding the 20-point minimal clinical important difference (MCID). Secondary outcome parameters showed comparable results. Preliminary subgroup analysis could not demonstrate clinically relevant differences in NDI between treatments after 2 years.

CONCLUSION

After combining data from two Randomized Controlled Trials it can be concluded that there is no clinical benefit for ACDA, when compared with ACDF or ACD 2 years after surgery. Preliminary subgroup analysis indicated outcomes were similar between treatment groups, and that no subgroup could be appointed that benefited more from either ACD, ACDF, or ACDA.Level of Evidence: 1.

Deep Learning for Adjacent Segment Disease at Preoperative MRI for Cervical Radiculopathy

Background Patients who undergo surgery for cervical radiculopathy are at risk for developing adjacent segment disease (ASD). Identifying patients who will develop ASD remains challenging for clinicians. Purpose To develop and validate a deep learning algorithm capable of predicting ASD by using only preoperative cervical MRI in patients undergoing single-level anterior cervical diskectomy and fusion (ACDF). Materials and Methods In this Health Insurance Portability and Accountability Act-compliant study, retrospective chart review was performed for 1244 patients undergoing single-level ACDF in two tertiary care centers. After application of inclusion and exclusion criteria, 344 patients were included, of whom 60% (n = 208) were used for training and 40% for validation (n = 43) and testing (n = 93). A deep learning-based prediction model with 48 convolutional layers was designed and trained by using preoperative T2-sagittal cervical MRI. To validate model performance, a neuroradiologist and neurosurgeon independently provided ASD predictions for the test set. Validation metrics included accuracy, areas under the curve, and F1 scores. The difference in proportion of wrongful predictions between the model and clinician was statistically tested by using the McNemar test. Results A total of 344 patients (median age, 48 years; interquartile range, 41-58 years; 182 women) were evaluated. The model predicted ASD on the 93 test images with an accuracy of 88 of 93 (95%; 95% CI: 90, 99), sensitivity of 12 of 15 (80%; 95% CI: 60, 100), and specificity of 76 of 78 (97%; 95% CI: 94, 100). The neuroradiologist and neurosurgeon provided predictions with lower accuracy (54 of 93; 58%; 95% CI: 48, 68), sensitivity (nine of 15; 60%; 95% CI: 35, 85), and specificity (45 of 78; 58%; 95% CI: 56, 77) compared with the algorithm. The McNemar test on the contingency table demonstrated that the proportion of wrongful predictions was significantly lower by the model (test statistic, 2.000; P < .001). Conclusion A deep learning algorithm that used only preoperative cervical T2-weighted MRI outperformed clinical experts at predicting adjacent segment disease in patients undergoing surgery for cervical radiculopathy. © RSNA, 2021 An earlier incorrect version appeared online. This article was corrected on September 22, 2021.

Differences in the Prevalence of Clinical Adjacent Segment Pathology among Continents after Anterior Cervical Fusion: Meta-Analysis of Randomized Controlled Trials

Development of adjacent segment pathology leading to secondary operation is a matter of concern after anterior cervical discectomy and fusion (ACDF). Some studies have reported anatomic difference between races, but no epidemiological data on prevalence of clinical adjacent segment pathology (cASP) among races or continents has been published. The purpose of this study was to compare the prevalence of cASP that underwent surgery after monosegmental ACDF among continents by meta-analysis. MEDLINE, EMBASE, and Cochrane Library with manual searching in key journals, reference lists, and the National Technical Information Service were searched from inception to December 2018. Twenty studies with a total of 2009 patients were included in the meta-analysis. We extracted the publication details, sample size, and prevalence of cASP that underwent surgery. A total of 15 papers from North America, three from Europe, and two from Asia met the inclusion criteria. A total number of 2009 patients underwent monosegmental ACDF, and 113 patients (5.62%) among them had cASP that underwent surgery. The rate of cASP that underwent surgery was 4.99% in the North America, 3.65% in the Europe, 6.34% in the Asia, and there were no statistically significant differences (p = 0.63). The current study using the method of meta-analysis revealed that there were no significant differences in the rate of cASP that underwent surgery after ACDF among the continents.

Longitudinal change of cervical artificial disc motion following replacement

We reviewed charts and radiologic studies of 30 patients operated upon by ADR with Mobi-C^® in single level since 2006. All patients had healthy cervical facet joints (less than or equal to grade 1 according to grading systems for cervical facet joint degeneration) preoperatively. We assessed clinical outcomes with NDI and VAS on neck and arm over follow-up and also measured ROM at implanted segment on dynamic radiographs during follow-up. The mean follow-up period was 42.4 ± 15.9 months. We then assessed the linearity of changes in ROM at implanted segment through linear mixed model. All patients showed significantly improved clinical outcomes. ROMs at implanted segment were maintained at slightly increased levels until 24 months postoperatively (P = 0.529). However, after 24 months, ROMs at implanted segment decreased significantly until last follow-up (P = 0.001). In addition, the decreasing pattern after 24 months showed a regular regression (P = 0.001). This decline was correlated with decline of extension angle at implanted segment. Based on this regular regression, we estimated that ROMs at implanted segments would be less than 2 degrees at 10.24 years postoperatively. Even though implanted segment maintains its motion for some length of time, we could assume that an artificial disc would have limited life expectancy correlated with the decline of extension angle.

Assessing the Effects of Publication Bias on Reported Outcomes of Cervical Disc Replacement and Anterior Cervical Discectomy and Fusion: A Meta-Epidemiologic Study

BACKGROUND

There have been several clinical trials as well as observational studies that have compared the outcomes of different cervical disc replacement (CDR) devices with anterior cervical disc replacement and fusion (ACDF). Although the results of these studies have provided sufficient evidence for the safety of CDR, there is still a lack of consensus in terms of longer-term outcomes, with studies providing equivocal results for the 2 procedures. In the current study, we used a novel methodology, a meta-epidemiologic study, to investigate the impact of study characteristics on the observed effects in the literature on CDR and ACDF.

METHODS

Data were abstracted from available meta-analyses regarding author, study author, year, intervention events, control events, and sample size, as well as year and geographic location of each study within the meta-analyses. We grouped the studies based on median year of publication as well as the region of the submitting author(s). Odds ratios, 95% confidence intervals (CIs), and standard errors of individual studies were calculated based on the number of events and sample size for each arm (ACDF or CDR). Further, results of outcomes from individual studies were pooled and a meta-analysis was conducted. Ratio of odds ratio (ROR) was used to assess the impact of each of these factors on estimates of the study for CDR versus ACDF.

RESULTS

A total of 13 meta-analyses were analyzed after exclusions. Using the results from 10 meta-analyses, we found that studies published before 2012 reported significantly lower odds of a reoperation after CDR (vs. ACDF), compared with studies published after 2012 (ROR, 0.51; 95% CI, 0.38-0.67; P < 0.001). We did not observe a significant impact of study year on difference in estimates between CDR and ACDF for adjacent segment disease (ROR, 0.99; 95% CI, 0.64-1.55; P = 0.465). The region of submitting author was also found to have no impact on results of published studies.

CONCLUSIONS

These results indicate that there may be a publication bias regarding the year of publication, with earlier studies reporting lower reoperation rates for CDR compared with ACDF.

Cervical Disc Replacement

Anterior cervical disc replacement (arthroplasty) has gained momentum over the past 2 decades. The ball-and-socket prosthesis design of arthroplasty has been shown to simulate normal motion in all 3 rotation planes at the level of surgery and replicates physiologic motion. Anterior cervical discectomy and fusion has been shown to be a safe and effective surgery over decades; cervical disc replacement counters some secondary effects owing to its preservation of segmental mobility, the potential to reduce adjacent segment degeneration, and the lack of plating or harvesting bone graft. The literature is growing in support of the success and longevity of arthroplasty.

Cervical radiculopathy: is a prosthesis preferred over fusion surgery? A systematic review

BACKGROUND

Meta-analyses on the comparison between fusion and prosthesis in the treatment of cervical radiculopathy mainly analyse studies including mixed patient populations: patients with radiculopathy with and without myelopathy. The outcome for patients with myelopathy is different compared to those without. Furthermore, apart from decompression of the spinal cord, restriction of motion is one of the cornerstones of the surgical treatment of spondylotic myelopathy. From this point of view, the results for arthroplasty might be suboptimal for this category of patients. Comparing clinical outcome in patients exclusively suffering from radiculopathy is therefore a more valid method to compare the true clinical effect of the prosthesis to that of fusion surgery.

AIM

The objective of this study was to compare clinical outcome of cervical arthroplasty (ACDA) to the clinical outcome of fusion (ACDF) after anterior cervical discectomy in patients exclusively suffering from radiculopathy, and to evaluate differences with mixed patient populations.

METHODS

A literature search was completed in PubMed, EMBASE, Web of Science, COCHRANE, CENTRAL and CINAHL using a sensitive search strategy. Studies were selected by predefined selection criteria (i.a.) patients exclusively suffering from cervical radiculopathy), and risk of bias was assessed using a validated Cochrane Checklist adjusted for this purpose. An additional overview of results was added from articles considering a mix of patients suffering from myelopathy with or without radiculopathy.

RESULTS

Eight studies were included that exclusively compared intervertebral devices in radiculopathy patients. Additionally, 29 articles concerning patients with myelopathy with or without radiculopathy were studied in a separate results table. All articles showed intermediate to high risk of bias. There was neither a difference in decrease in mean NDI score between the prosthesis (20.6 points) and the fusion (20.3 points) group, nor was there a clinically important difference in neck pain (VAS). Comparing these data to the mixed population data demonstrated comparable mean values, except for the 2-year follow-up NDI values in the prosthesis group: mixed group patients that received a prosthesis reported a mean NDI score of 15.6, indicating better clinical outcome than the radiculopathy patients that received a prosthesis though not reaching clinical importance.

CONCLUSIONS

ACDF and ACDA are comparably effective in treating cervical radiculopathy due to a herniated disc in radiculopathy patients. Comparing the 8 radiculopathy with the 29 mixed population studies demonstrated that no clinically relevant differences were present in clinical outcome between the two types of patients. These slides can be retrieved under Electronic Supplementary Material.

The NECK trial: Effectiveness of anterior cervical discectomy with or without interbody fusion and arthroplasty in the treatment of cervical disc herniation; a double-blinded randomized controlled trial

BACKGROUND

Motion preserving anterior cervical disc arthroplasty (ACDA) in patients with cervical radiculopathy was introduced to prevent symptomatic adjacent disc degeneration as compared with anterior cervical discectomy and fusion (ACDF). Prior reports suggest that ACDF is not more effective than anterior cervical discectomy (ACD) alone for the treatment of cervical radiculopathy.

PURPOSE

To evaluate whether patients with cervical radiculopathy due to a herniated disc benefit more from undergoing ACDA, ACDF, or ACD in terms of clinical outcome measured by the neck disability index (NDI).

STUDY DESIGN

Double-blinded randomized controlled trial.

METHODS

One hundred-nine patients with one level herniated disc were randomized to one of the following treatments: ACDA, ACDF with intervertebral cage, ACD without fusion. Clinical and radiological outcome was measured by NDI, Visual Analogue Scale (VAS) neck pain, VAS arm pain, SF36, EQ-5D, patients' self-reported perceived recovery, radiographic cervical curvature, and adjacent segment degeneration parameters at baseline and until two years after surgery. BBraun Medical paid €298.837 to cover the costs for research nurses.

RESULTS

The NDI declined from 41 to 47 points at baseline to 19 ± 15 in the ACD group, 19 ± 18 in the ACDF group, and 20 ± 22 in the ACDA group after surgery (p=.929). VAS arm and neck pain declined to half its baseline value and decreased below the critical value of 40 mm. Quality of life, measured by the EQ-5D, increased in all three groups. Adjacent segment degeneration parameters were comparable in all three groups as well. No statistical differences were demonstrated between the treatment groups.

CONCLUSIONS

The hypothesis that ACDA would lead to superior clinical outcome in comparison to ACDF or ACD could not be confirmed during a 2-year follow-up time period. Single level ACD without implanting an intervertebral device may be a reasonable alternative to ACDF or ACDA.

Radiological follow-up after implanting cervical disc prosthesis in anterior discectomy: a systematic review

OBJECTIVE

The objective of this study was to review current literature on the comparison of the radiological outcome of cervical arthroplasty with fusion after anterior discectomy for radiculopathy.

MATERIALS AND METHODS

A literature search was performed in PubMed, Embase, Web of Science, Cochrane, CENTRAL, and CINAHL using a sensitive search string combination. Studies were selected by predefined selection criteria (patients exclusively suffering from cervical radiculopathy), and risk of bias was assessed using a validated Cochrane checklist adjusted for this purpose. Additionally, an overview of results of articles published in 21 meta-analyses was added, considering a group of patients with myelopathy with or without radiculopathy.

RESULTS

Seven articles that compared intervertebral devices in patients with radiculopathy (excluding patients with myelopathy) were included in the study. Another 31 articles were studied as a mixed group, including patients with myelopathy and radiculopathy. Apart from three studies with low risk of bias, all other articles showed intermediate or high risk of bias. Heterotopic ossification was reported to be present in circa 10% of patients, seemingly predominant in patients with radiculopathy, with a very low level of evidence. Radiological signs of adjacent segment disease were present at baseline in 50% of patients, and there is a low level of evidence that this increased more (10%-20%) in the fusion group at long-term follow-up. However, this was only studied in the mixed study population, which is degenerative by diagnosis.

CONCLUSION

Although the cervical disc prosthesis was introduced to decrease adjacent level disease, convincing radiological evidence for this benefit is lacking. Heterotopic ossification as a complicating factor in the preservation of motion of the device is insufficiently studied. Regarding purely radiological outcomes, currently, no firm conclusion can be drawn for implanting cervical prosthesis versus performing fusion.

Secondary Surgery after Cervical Disc Arthroplasty versus Fusion for Cervical Degenerative Disc Disease: A Meta-analysis with Trial Sequential Analysis

The purpose of this meta-analysis was to explore whether cervical disc arthroplasty (CDA) was superior to anterior cervical discectomy and fusion (ACDF) in reducing secondary surgery. PubMed, EMBASE, and the Cochrane Library databases were systematically searched. Outcomes were reported as relative risk (RR) with the corresponding 95% confidence interval (CI). The pooled data was calculated using a random-effect model. We also used the trial sequential analysis (TSA) to further verify our results and obtain more moderate estimates. Twenty-one studies with 4208 patients were included in this meta-analysis. The results indicated that compared with ACDF, CDA had fewer frequency of secondary surgery at the index level (RR, 0.47; 95%CI, 0.36-0.63; P < 0.05) and adjacent level (RR, 0.48; 95%CI, 0.36-0.65; P < 0.05), and the differences were statistically significant. In addition, in terms of the overall frequency of secondary surgery at the index and adjacent level, CDA was also significantly superior to ACDF (RR, 0.49; 95%CI, 0.41-0.60; P < 0.05). TSA demonstrated that adequate and decisive evidence had been established. Regarding the frequency of secondary surgery, CDA was significantly superior to ACDF. It was supposed that CDA may be a better surgical intervention to reduce the rate of secondary surgery for patients with cervical degenerative disc disease.

Total disc replacement versus anterior cervical discectomy and fusion: a systematic review with meta-analysis of data from a total of 3160 patients across 14 randomized controlled trials with both short- and medium- to long-term outcomes

Aims

The aim of this study was to determine how the short- and medium- to long-term outcome measures after total disc replacement (TDR) compare with those of anterior cervical discectomy and fusion (ACDF), using a systematic review and meta-analysis.

Patients and Methods

Databases including Medline, Embase, and Scopus were searched. Inclusion criteria involved prospective randomized control trials (RCTs) reporting the surgical treatment of patients with symptomatic degenerative cervical disc disease. Two independent investigators extracted the data. The strength of evidence was assessed using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) criteria. The primary outcome measures were overall and neurological success, and these were included in the meta-analysis. Standardized patient-reported outcomes, including the incidence of further surgery and adjacent segment disease, were summarized and discussed.

Results

A total of 22 papers published from 14 RCTs were included, representing 3160 patients with follow-up of up to ten years. Meta-analysis indicated that TDR is superior to ACDF at two years and between four and seven years. In the short-term, patients who underwent TDR had better patient-reported outcomes than those who underwent ACDF, but at two years this was typically not significant. Results between four and seven years showed significant differences in Neck Disability Index (NDI), 36-Item Short-Form Health Survey (SF-36) physical component scores, dysphagia, and satisfaction, all favouring TDR. Most trials found significantly less adjacent segment disease after TDR at both two years (short-term) and between four and seven years (medium- to long-term).

Conclusion

TDR is as effective as ACDF and superior for some outcomes. Disc replacement reduces the risk of adjacent segment disease. Continued uncertainty remains about degeneration of the prosthesis. Long-term surveillance of patients who undergo TDR may allow its routine use. Cite this article: Bone Joint J 2018;100-B:991-1001.

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.

RSA in Spine: A Review

STUDY DESIGN

Systematic review of literature.

OBJECTIVES

This systematic review was conducted to investigate the accuracy of radiostereometric analysis (RSA), its assessment of spinal motion and disorders, and to investigate the limitations of this technique in spine assessment.

METHODS

Systematic review in all current literature to invesigate the role of RSA in spine.

RESULTS

The results of this review concluded that RSA is a very powerful tool to detect small changes between 2 rigid bodies such as a vertebral segment. The technique is described for animal and human studies for cervical and lumbar spine and can be used to analyze range of motion, inducible displacement, and fusion of segments. However, there are a few disadvantages with the technique; RSA percutaneous procedure needs to be performed to implant the markers (and cannot be used preoperatively), one needs a specific knowledge to handle data and interpret the results, and is relatively time consuming and expensive.

CONCLUSIONS

RSA should be looked at as a very powerful research instrument and there are many questions suitable for RSA studies.

The change of adjacent segment after cervical disc arthroplasty compared with anterior cervical discectomy and fusion: a meta-analysis of randomized controlled trials

BACKGROUND CONTEXT

Many meta-analyses have been performed to study the efficacy of cervical disc arthroplasty (CDA) compared with anterior cervical discectomy and fusion (ACDF); however, there are few data referring to adjacent segment within these meta-analyses, or investigators are unable to arrive at the same conclusion in the few meta-analyses about adjacent segment. With the increased concerns surrounding adjacent segment degeneration (ASDeg) and adjacent segment disease (ASDis) after anterior cervical surgery, it is necessary to perform a comprehensive meta-analysis to analyze adjacent segment parameters.

PURPOSE

To perform a comprehensive meta-analysis to elaborate adjacent segment motion, degeneration, disease, and reoperation of CDA compared with ACDF.

STUDY DESIGN

Meta-analysis of randomized controlled trials (RCTs).

METHODS

PubMed, Embase, and Cochrane Library were searched for RCTs comparing CDA and ACDF before May 2016. The analysis parameters included follow-up time, operative segments, adjacent segment motion, ASDeg, ASDis, and adjacent segment reoperation. The risk of bias scale was used to assess the papers. Subgroup analysis and sensitivity analysis were used to analyze the reason for high heterogeneity.

RESULTS

Twenty-nine RCTs fulfilled the inclusion criteria. Compared with ACDF, the rate of adjacent segment reoperation in the CDA group was significantly lower (p<.01), and the advantage of that group in reducing adjacent segment reoperation increases with increasing follow-up time by subgroup analysis. There was no statistically significant difference in ASDeg between CDA and ACDF within the 24-month follow-up period; however, the rate of ASDeg in CDA was significantly lower than that of ACDF with the increase in follow-up time (p<.01). There was no statistically significant difference in ASDis between CDA and ACDF (p>.05). Cervical disc arthroplasty provided a lower adjacent segment range of motion (ROM) than did ACDF, but the difference was not statistically significant.

CONCLUSIONS

Compared with ACDF, the advantages of CDA were lower ASDeg and adjacent segment reoperation. However, there was no statistically significant difference in ASDis and adjacent segment ROM.

Analysis of the Factors That Could Predict Segmental Range of Motion After Cervical Artificial Disk Replacement: A 7-Year Follow-up Study

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

To identify the potential preoperative factors and surgical technique factors that are associated with long-term range of motion (ROM) after surgery. Further, this article aimed to guide selection of patients with cervical artificial disk replacement and a fine surgical technique.

SUMMARY OF BACKGROUND DATA

Segmental ROM is the most important parameter concerning cervical kinematics after a cervical artificial disk replacement. There are few researches regarding the influencing factors on postoperative ROM, and consistent results have not yet been reported.

METHODS

The cohort comprised a total of 68 disks implanted into 57 patients who were retrospectively analyzed. The mean follow-up period was 84.1 months. Segmental ROM and other useful parameters were measured using lateral neutral, extension, and flexion radiographs, which were obtained preoperatively, 3 months after surgery, and at last follow-up. Preoperative CT and clinical assessment were also used. To find out associated factors, the patients were divided into 2 groups according to the segmental ROM at last follow-up.

RESULTS

After surgery, the clinical outcomes were satisfactory. The segmental ROM at last follow-up (7.8±4.3 degrees) was preserved without significant change from preoperative ROM (8.8±3.8 degrees). The patients who had a better segmental ROM after surgery were found to have a higher preoperative segmental ROM, a younger age, a better disk insertion angle, and disk insertion depth. These 4 factors were identified as independent risk factors (P=0.027, 0.017, 0.036, and 0.046, respectively) for long-term ROM.

CONCLUSIONS

The postoperative long-term, segmental ROM was well preserved and found to be affected by the preoperative segmental ROM, patient's age, disk insertion angle, and disk insertion depth.

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 Versus Anterior Cervical Discectomy and Fusion for Incidence of Symptomatic Adjacent Segment Disease: A Meta-Analysis of Prospective Randomized Controlled Trials

STUDY DESIGN

Meta-analysis of randomized controlled trials.

OBJECTIVE

To evaluate the reported rate of adjacent segment disease (ASD) of cervical disc arthroplasty (CDA) compared with anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

Motion-maintaining technologies such as CDA have developed rapidly because of the concern of ASD. Till date, however, it still has been under debate whether CDA is superior to ACDF regarding the incidence of ASD.

METHODS

We comprehensively searched PubMed, EMBASE, and Cochrane Central Register of Controlled Trails for prospective randomized controlled trials (RCTs) that reported the incidence of ASD between CDA and ACDF. The retrieved results were last updated on November 20, 2015 without language restrictions. Two independent authors selected qualified studies, assessed methodological quality, and extracted requisite data.

RESULTS

Fourteen relevant RCTs involving 3235 individuals with a follow-up period of 2 to 7 years were included in the meta-analysis (1696 in CDA group and 1539 in ACDF group). The outcomes indicated that CDA was superior to ACDF considering the lower rate of ASD (risk ratio, 0.57; 95% confidence interval, 0.37 to 0.87; P = 0.009). And compared with ACDF, there were significantly fewer adjacent segment reoperations in the CDA group (risk ratio, 0.47; confidence interval, 0.32 to 0.70; P = 0.0002). Subgroup analysis stratified by different types of disc prostheses was also performed.

CONCLUSION

CDA was superior to ACDF regarding fewer ASDs and relative reoperations on the basis of available evidence from a meta-analysis of 14 RCTs. CDA may be a better surgical procedure to reduce the incidence of ASD for patients with cervical disc disease compared with ACDF. Further well-designed studies should continue to pay attention to excellent patients with longer-term follow-up to evaluate the incidence of ASD of these two procedures.

LEVEL OF EVIDENCE

1.

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.

Treatment of degenerative cervical spondylosis with radiculopathy. Clinical practice guidelines endorsed by The Polish Society of Spinal Surgery

INTRODUCTION

Degenerative cervical spondylosis (DCS) with radiculopathy is the most common indication for cervical spine surgery despite favorable natural history. Advances in spinal surgery in conjunction with difficulties in measuring the outcomes caused the paucity of uniform guidelines for the surgical management of DCS.

AIMS

The aim of this paper is to develop guidelines for surgical treatment of DCS. For this purpose the available up-to-date literature relevant on the topic was critically reviewed.

METHODS AND RESULTS

Six questions regarding most important clinical questions encountered in the daily practice were formulated. They were answered based upon the systematic literature review, thus creating a set of guidelines. The guidelines were categorized into four tiers based on the level of evidence (I-III and X). They were designed to assist in the selection of optimal and effective treatment leading to the most successful outcome.

CONCLUSIONS

The evidence based medicine (EBM) is increasingly popular among spinal surgeons. It allows making unbiased, optimal clinical decisions, eliminating the detrimental effect of numerous conflicts of interest. The key role of opinion leaders as well as professional societies is to provide guidelines for practice based on available clinical evidence. The present work contains a set of guidelines for surgical treatment of DCS officially endorsed by the Polish Spine Surgery Society.

Mid- to Long-Term Outcomes of Cervical Disc Arthroplasty versus Anterior Cervical Discectomy and Fusion for Treatment of Symptomatic Cervical Disc Disease: A Systematic Review and Meta-Analysis of Eight Prospective Randomized Controlled Trials

PURPOSE

This study aimed to investigate the mid- to long-term outcomes of cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) for the treatment of 1-level or 2-level symptomatic cervical disc disease.

METHODS

Medline, Embase, and the Cochrane Central Register of Controlled Trials databases were searched to identify relevant randomized controlled trials that reported mid- to long-term outcomes (at least 48 months) of CDA versus ACDF. All data were analyzed by Review Manager 5.3 software. The relative risk (RR) and 95% confidence intervals (CIs) were calculated for dichotomous variables. The weighted mean difference (WMD) and 95%CIs were calculated for continuous variables. A random effect model was used for heterogeneous data; otherwise, a fixed effect model was used.

RESULTS

Eight prospective randomized controlled trials (RCTs) were retrieved in this meta-analysis, including 1317 and 1051 patients in CDA and ACDF groups, respectively. Patients after an ACDF had a significantly lower rate of follow-up than that after CDA. Pooled analysis showed patients in CDA group achieved significantly higher rates of overall success, Neck Disability Index (NDI) success, neurological success and significantly lower rates of implant/surgery-related serious adverse events and secondary procedure compared with that in ACDF group. The long-term functional outcomes (NDI, Visual Analog Scale (VAS) neck and arm pain scores, the Short Form 36 Health Survey physical component score (SF-36 PCS)), patient satisfaction and recommendation, and the incidence of superior adjacent segment degeneration also favored patients in CDA group with statistical difference. Regarding inferior adjacent segment degeneration, patients in CDA group had a lower rate without statistical significance.

CONCLUSIONS

This meta-analysis showed that cervical disc arthroplasty was superior over anterior discectomy and fusion for the treatment of symptomatic cervical disc disease in terms of overall success, NDI success, neurological success, implant/surgery-related serious adverse events, secondary procedure, functional outcomes, patient satisfaction and recommendation, and superior adjacent segment degeneration.

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.

An Updated Meta-Analysis Comparing Artificial Cervical Disc Arthroplasty (CDA) Versus Anterior Cervical Discectomy and Fusion (ACDF) for the Treatment of Cervical Degenerative Disc Disease (CDDD)

STUDY DESIGN

A meta-analysis of published randomized controlled Trials (RCTs).

OBJECTIVE

The aim of this study was to compare the efficacy and safety of cervical disc arthroplasty (CDA) with anterior cervical discectomy and fusion (ACDF) for the treatment of one-level cervical degenerative disc disease (CDDD).

SUMMARY OF BACKGROUND DATA

ACDF has been widely performed for the treatment of CDDD. However, the loss of motion at the operated level has been hypothesized to accelerated adjacent-level disc degeneration. CDA is designed to avoid the side effect of fusion. However, it is still uncertain whether CDA is more effective and safer than ACDF.

METHODS

We performed a meta-analysis of published RCTs to examine whether there was a superior clinical effects of CDA than ACDF. A PubMed database search through October 2014 was performed for relevant studies. We included RCTs that reported relevant data in the treatment of one-level CDDD, which were suitable for detailed extraction of data.

RESULTS

We identified 18 RCTs eligible for analysis. The results of the meta-analysis indicated longer operative times, more blood loss, lower neck and arm pain scores reported on a visual analog scale (VAS), better neurological success, greater motion at the operated level, fewer secondary surgical procedures in the CDA group than in the ACDF group (P < 0.05). The 2 groups had similar lengths of hospital stay, Neck Disability Index scores, and rates of adverse events (P > 0.05).

CONCLUSIONS

Findings of the present meta-analysis indicated that CDA was an effective and safe surgical procedure for the treatment of one-level CDDD, and CDA was found to be more superior than ACDF in terms of VAS neck and arm pain, neurological success, range of motion at the operated level, and secondary surgical procedures.

LEVEL OF EVIDENCE

1.

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.

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.

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.

Anterior surgical management of single-level cervical disc disease: a cost-effectiveness analysis

STUDY DESIGN

Cost-effectiveness analysis with decision analysis and meta-analysis.

OBJECTIVE

To determine the relative cost-effectiveness of anterior cervical discectomy with fusion (with autograft, allograft, or spacers), anterior cervical discectomy without fusion (ACD), and cervical disc replacement (CDR) for the treatment of 1-level cervical disc disease.

SUMMARY OF BACKGROUND DATA

There is debate as to the optimal anterior surgical strategy to treat single-level cervical disc disease. Surgical strategies include 3 techniques of anterior cervical discectomy with fusion (autograft, allograft, or spacer-assisted fusion), ACD, and CDR. Several controlled trials have compared these treatments but have yielded mixed results. Decision analysis provides a structure for making a quantitative comparison of the costs and outcomes of each treatment.

METHODS

A literature search was performed and yielded 156 case series that fulfilled our search criteria describing nearly 17,000 cases. Data were abstracted from these publications and pooled meta-analytically to estimate the incidence of various outcomes, including index-level and adjacent-level reoperation. A decision analytic model calculated the expected costs in US dollars and outcomes in quality-adjusted life years for a typical adult patient with 1-level cervical radiculopathy subjected to each of the 5 approaches.

RESULTS

At 5 years postoperatively, patients who had undergone ACD alone had significantly (P < 0.001) more quality-adjusted life years (4.885 ± 0.041) than those receiving other treatments. Patients with ACD also exhibited highly significant (P < 0.001) differences in costs, incurring the lowest societal costs ($16,558 ± $539). Follow-up data were inadequate for comparison beyond 5 years.

CONCLUSION

The results of our decision analytic model indicate advantages for ACD, both in effectiveness and costs, over other strategies. Thus, ACD is a cost-effective alternative to anterior cervical discectomy with fusion and CDR in patients with single-level cervical disc disease. Definitive conclusions about degenerative changes after ACD and adjacent-level disease after CDR await longer follow-up.

LEVEL OF EVIDENCE

4.

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.

Measurement of intervertebral cervical motion by means of dynamic x-ray image processing and data interpolation

Accurate measurement of intervertebral kinematics of the cervical spine can support the diagnosis of widespread diseases related to neck pain, such as chronic whiplash dysfunction, arthritis, and segmental degeneration. The natural inaccessibility of the spine, its complex anatomy, and the small range of motion only permit concise measurement in vivo. Low dose X-ray fluoroscopy allows time-continuous screening of cervical spine during patient's spontaneous motion. To obtain accurate motion measurements, each vertebra was tracked by means of image processing along a sequence of radiographic images. To obtain a time-continuous representation of motion and to reduce noise in the experimental data, smoothing spline interpolation was used. Estimation of intervertebral motion for cervical segments was obtained by processing patient's fluoroscopic sequence; intervertebral angle and displacement and the instantaneous centre of rotation were computed. The RMS value of fitting errors resulted in about 0.2 degree for rotation and 0.2 mm for displacements.

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.

A meta-analysis of cervical arthroplasty compared to anterior cervical discectomy and fusion for single-level cervical disc disease

There is no consensus on whether anterior cervical arthroplasty or anterior cervical discectomy and fusion (ACDF) is the optimal treatment for single-level cervical radiculopathy or myelopathy. We conducted a meta-analysis of randomized controlled trials to compare the safety and efficacy of anterior cervical arthroplasty with ACDF. Eight studies met the inclusion criteria. Overall, there were significant differences between these two treatment approaches in the arm visual analog scale (VAS) scores [mean difference (MD)=-4.86, 95% confidence interval (CI)=-6.42 to -3.30], neck VAS scores (MD=-7.90, 95% CI=-10.36 to -5.44), overall success rate [odds ratio (OR)=1.84, 95% CI=1.43 to 2.36], neurological success rate (OR=1.75, 95% CI=1.20 to 2.55), and incidence of reoperation [risk ratio (RR)=0.50, 95% CI=0.26 to 0.97]. However, there were no significant differences in the neck disability index (NDI) scores (MD=-3.81, 95% CI=-8.12 to 0.51), number of adverse events (RR=0.77, 95% CI=0.48 to 1.23), or radiological success rate (OR=0.87, 95% CI=0.36 to 2.09). Based on this meta-analysis, cervical arthroplasty is a safe and effective surgical procedure for treating single-level cervical radiculopathy or myelopathy.

Activ C cervical disc replacement for myelopathy

Background:

Cervical disc replacement is becoming an increasingly popular treatment option for cervical myelopathy. It retains motion at the affected segment, unlike anterior cervical discectomy and fusion. The aim of this study is to assess the outcomes of a series of patients who underwent Activ C disc replacement for cervical myelopathy.

Materials and Methods:

A series of patients at the above Trust with clinical and radiological evidence of cervical myelopathy who were suitable for cervical disc replacement from 2007 to 2009 were included. Implants were inserted by one of two consultant surgeons {IMS, MO’M}. Patients were assessed preoperatively and at six, 12 and 24 months, postoperatively, with a visual analogue score (VAS) for neck and arm pain severity and frequency, the Neck Disability Index questionnaire (NDI) and the Centre for Epidemiologic Studies Depression questionnaire (CES-D).

Results:

Ten patients underwent surgery between May 2007 and July 2009, 6 women, and 4 men. Average age was 54 years (40-64). Disc levels replaced were: four at C4-5; eight at C5-6; seven at C6-7. Three patients had one disc replaced, five patients had two discs replaced, and two patients had three discs replaced. The VAS for neck pain improved from 5.9 pre-operatively to 1.4-24 months postoperatively and the VAS arm pain improved from 5.4 to 2.6. The NDI improved from 51% preoperatively to 26.8% at 24 months postoperatively. The CES-D showed a slight increase from 19.5 preoperatively to 21.7 at 24 months, postoperatively.

Conclusion:

Cervical decompression and disc replacement improves pain and function in patients with cervical myelopathy. This benefit is maintained at 24 months post op, with no cases requiring revision.

Adjacent segment pathology following cervical motion-sparing procedures or devices compared with fusion surgery: a systematic review

STUDY DESIGN

A systematic review.

OBJECTIVE

To critically review and summarize the literature comparing motion preservation devices to fusion in the cervical spine to determine whether the use of these devices decreases the development of radiographical (RASP) or clinical adjacent segment pathology (CASP) compared with fusion.

SUMMARY OF BACKGROUND DATA

Historically, surgical treatment of symptomatic cervical disc disease presenting as radiculopathy and/or myelopathy with anterior cervical decompression and fusion has yielded excellent results. Controversy remains whether RASP and CASP requiring treatment is due to fusion-altered biomechanics and kinematics versus natural history.

METHODS

We conducted a systematic search in MEDLINE and the Cochrane Collaboration Library for literature published through February 2012 on human randomized control trials or cohort studies published in the English language containing abstracts to answer the following key questions: (1) Is there evidence that total disc replacement (TDR) is associated with a lower risk of RASP or CASP compared with fusion? (2) Is there evidence that other procedures that do not involve arthrodesis or other motion-sparing devices are associated with a lower risk of RASP or CASP compared with fusion? (3)Is one type of motion preservation device or procedure associated with a lower risk of RASP or CASP compared with others?

RESULTS

The initial literature search yielded 276 citations, of which 73 unique, potentially relevant citations that were evaluated against the inclusion/exclusion criteria set a priori. A total of 14 studies were selected for inclusion. For question 1, RASP was variably reported in studies that compared total disc replacement (TDR) to anterior cervical decompression and fusion (ACDF), and risk differences for reoperation due to CASP ranged from 1.0% to 4.8%, with no statistically significant differences between groups. For question 2, no studies comparing motion preservation devices to ACDF met our inclusion criteria. For question 3, one study comparing motion-sparing devices found the risk of RASP to be similar between groups.

CONCLUSION

A paucity of high-quality literature comparing motion-preserving devices or treatment methods to fusion or other motion-preserving techniques or devices (with RASP and/or CASP as an outcome using consistent definitions) exists. Independently funded, blinded long-term follow-up prospective studies would be able to delineate the true effects regarding incidence of RASP and CASP and treatment of CASP.

CONSENSUS STATEMENT

1. There is no significant difference in development of RASP and CASP after C-TDR versus ACDF at short- to mid-term follow-up.

LEVEL OF EVIDENCE

Moderate. Strength of Statement: Strong. Recommendation 1: No recommendation can be made from comparative literature of nonarthroplasty motion preservation device or techniques compared with fusion regarding the risk of RASP or CASP.

LEVEL OF EVIDENCE

Insufficient. Strength of Statement: Strong. Recommendation 2: No recommendation can be made from direct comparative literature of various motion preservation devices or techniques regarding the risk of RASP or CASP.

LEVEL OF EVIDENCE

Insufficient. Strength of Statement: Strong.

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.

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

OBJECTIVE

To evaluate the safety and effectiveness of cervical disc arthroplasty (CDA) versus anterior cervical discectomy and fusion (ACDF) for single-level symptomatic cervical disc disease.

METHODS

We identified eligible randomized controlled trials (RCTs) in PubMed (April 2011), EMBASE (April 2011) and Cochrane Central Register of Controlled Trials (April 2011). Data were collected and extracted by two reviewers independently. The methodological quality and clinical relevance of the included studies were assessed. Data analysis was conducted with RevMan 5.0.

RESULTS

Six RCTs involving 1,745 patients were included. The pooled analysis showed a higher prevalence of neurological and overall success [(P = 0.004, RR = 1.06, 95% CI = 1.02-1.10), (P = 0.0005, RR = 1.14, 95% CI = 1.06-1.22)], and a lower incidence of dysphagia and reoperation related to adjacent-segment degeneration [(P = 0.04, RR = 0.30, 95% CI = 0.09-0.97), (P = 0.03, RR = 0.46, 95% CI = 0.23-0.91)] with CDA compared to ACDF. However, there was no statistical difference in neck disability index (P = 0.92, SMD = 0.01, 95% CI = -0.25 to 0.27), neck and arm pain scores[(P = 0.33, SMD = -0.12, 95% CI = -0.37 to 0.13), (P = 0.54, SMD = 0.17, 95% CI = -0.36 to 0.70)], incidence of complications related to the implant or surgical procedure and reoperation related to primary surgery [(P = 0.32, RR = 0.76, 95% CI = 0.45-1.30), (P = 0.09, RR = 0.48, 95% CI = 0.20-1.12)].

CONCLUSION

Compared with ACDF, CDA carry a lower incidence of dysphagia complications and reoperation related to adjacent-segment degeneration, and a higher prevalence of neurological and overall success at 2 years postoperatively. As the poor quality of the included studies, it is still uncertain whether CDR is more effective and safer than ACDF treating single-level symptomatic cervical disc disease. Future large-scale RCTs with long-term follow-up are needed to provide clear evidence.

Cervical and lumbar spinal arthroplasty: clinical review

In contrast to cervical and lumbar fusion procedures, the principal aim of disk arthroplasty is to recapitulate the normal kinematics and biomechanics of the spinal segment affected. Following decompression of the neural elements, disk arthroplasty allows restoration of disk height and maintenance of spinal alignment. Based on clinical observations and biomechanical testing, the anticipated advantage of arthroplasty over standard arthrodesis techniques has been a proposed reduction in the development of symptomatic ALD. In this review of cervical and lumbar disk arthroplasty, we highlight the clinical results and experience with standard fusion techniques, incidence of ALD in the population of patients with surgical fusion, and indications for arthroplasty, as well as the biomechanical and clinical outcomes following arthroplasty. In addition, we introduce the devices currently available and provide a critical appraisal of the clinical evidence regarding arthroplasty procedures.

Systematic review and meta-analysis of randomized controlled trials: comparison of total disk replacement with anterior cervical decompression and fusion

The authors performed a systematic review and meta-analysis to evaluate whether there is a beneficial clinical effect of total disk replacement compared with anterior cervical diskectomy and fusion for the treatment of single-level symptomatic cervical disk disease. A comprehensive literature search of multiple databases, including PubMed (1966-2011), Cochrane Controlled Trials Register (CENTRAL; issue 1, 2011), and Embase (1984-2011), was conducted to identify studies that met the inclusion criteria. Methodologic quality was assessed and relevant data were retrieved, and if appropriate, meta-analysis was performed. Eight randomized controlled trials were identified; six of the 8 reported 24-month follow-up results. At 24 months, total disk replacement was demonstrated to be more beneficial for patients compared with anterior cervical diskectomy and fusion for the following outcomes: overall success rate (odds ratio [OR], 1.79; 95% confidence interval [CI], 1.37-2.33; P<.0001), overall reoperation rate (OR,.36; CI, .21-.61; P=0), reoperation rate for revision (OR, .12; CI, .02 to .64; P=.01), and visual analog scale neck pain scores (standard mean differences [SMD], -.48; CI, -.91 to -.05; P=.03). Other outcomes, including Neck Disability Index scores (SMD, -.02; CI, -.44 to .27; P=.67) and visual analog scale arm pain scores (SMD, -.21; CI, -.63 to .22; P=.34), demonstrated no differences between the 2 groups. For patients with single-level symptomatic cervical disk disease, total disk replacement was found to be more effective than anterior cervical diskectomy and fusion in the 2 outcomes of overall success rate and overall reoperation rate at 24 months. Long-term results also showed total disk replacement trended to be more effective than anterior cervical diskectomy and fusion in some aspects.

Cervical disc arthroplasty

This technology overview addressed four questions that compared the difference in outcomes between patients undergoing cervical disc arthroplasty with patients undergoing anterior cervical diskectomy fusion. Most studies did not either report or conduct the appropriate statistical analyses to examine predictive characteristics in patients with successful clinical outcomes. Most studies were inconclusive or unreliable regarding clinical outcomes and revision and/or complication rates in patients who present with neck and/or arm pain. No significant difference in the length of hospital stay was reported; however, two studies included in the overview reported that patients treated with cervical disc arthroplasty returned to work in significantly fewer days (range, 14 to 16 days) than did patients treated with anterior cervical diskectomy fusion.

Upper thoracic spine arthroplasty via the anterior approach

Significant progress has been made in lumbar and cervical disc replacement therapy. Several cervical disc prostheses have recently gained FDA approval. Although arthroplasty has not been previously described in the thoracic spine, selected patients with long-segment fusion to the level of C-7 have altered cervicothoracic and upper thoracic biomechanics and may benefit from motion-preservation therapy for T1-2 disc herniation. Currently, FDA-approved prostheses are indicated only for patients with single-level degenerative disc disease between C-3 and C-7 and no history of cervical arthrodesis. The authors describe a 52-year-old woman who had previously undergone C3-7 fusion and returned 4 years later with symptoms of C-8 myeloradiculopathy and radiological evidence of T1-2 degenerative disc disease. She underwent T1-2 arthroplasty in which a Prestige artificial cervical disc was placed via an anterior cervicothoracic approach. Motion at C7-T1 and T1-2 was preserved, and the patient made an excellent clinical recovery.