A meta-analysis comparing the results of cervical disc arthroplasty with anterior cervical discectomy and fusion (ACDF) for the treatment of symptomatic cervical disc disease

Anterior Cervical Decompression and Fusion for Neck Pain in Patients with Cervical Spondylosis: Pooled Results of Three Prospective Cohort Studies

INTRODUCTION

Currently, there is a lack of large-scale prospective cohort data to explore the response of neck pain to anterior cervical decompression and fusion (ACDF). The aim of this study was to investigate whether patients with neck pain can achieve consistent neck pain relief following ACDF regardless of preoperative neurological symptoms and number of surgical segments.

MATERIALS AND METHODS

The study was a pooled analysis of 3 multicenter prospective cohort studies. Patients with cervical radiculopathy and/or myelopathy with significant neck pain (visual analog scale [VAS] ≥ 4) who underwent ACDF were included. Neck pain VAS scores (VAS-neck) were collected at preoperative and postoperative follow-up time points (3 months, 6 months, and 1 year). Subgroup analyses were conducted for patients with radiculopathy, myelopathy, or myeloradiculopathy, as well as for single- versus multi-segment ACDF.

RESULTS

A total of 237 patients were confirmed. Patients showed significant improvement in VAS-neck at all follow-up time points compared with baseline (P < 0.001 for each). In the first year after surgery, VAS-neck were reduced by 3.3 points (57.0%) on average, and the rates of achieving minimum clinically important difference and patient acceptable symptom state were 72.2% and 73.8%, respectively. Meanwhile, one year after surgery, there was no significant difference in ΔVAS-neck, recovery rate, minimum clinically important difference, and patient acceptable symptom state attainment rate between the radiculopathy, myelopathy and myeloradiculopathy groups, and the same trend was observed between the single-segment and multi-segment groups.

CONCLUSIONS

This study found that ACDF significantly improved neck pain in patients with cervical spondylosis, regardless of preoperative neurological symptoms and number of surgical segments.

Impact of Preoperative Symptom Duration on Patient-Reported Outcomes Following Cervical Disc Replacement for Cervical Radiculopathy

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To determine the impact of preoperative symptom duration on postoperative functional outcomes after cervical disc replacement (CDR) for radiculopathy.

SUMMARY OF BACKGROUND DATA

CDR has emerged as a reliable and efficacious treatment option for degenerative cervical spine pathologies. The relationship between preoperative symptom duration and outcomes after CDR is not well established.

METHODS

Patients with radiculopathy without myelopathy who underwent primary 1- or 2-level CDRs were included and divided into shorter (<6 mo) and prolonged (≥6 mo) cohorts based on preoperative symptom duration. Patient-reported outcome measures (PROMs) included neck disability index (NDI), visual analog scale (VAS) neck and arm. Changes in PROM scores and minimal clinically important difference (MCID) rates were calculated. Analyses were conducted on the early (within 3 mo) and late (6 mo-2 y) postoperative periods.

RESULTS

A total of 201 patients (43.6±8.7 y, 33.3% female) were included. In both early and late postoperative periods, the shorter preoperative symptom duration cohort experienced significantly greater change from preoperative PROM scores compared with the prolonged symptom duration cohort for NDI, VAS-Neck, and VAS-Arm. The shorter symptom duration cohort achieved MCID in the early postoperative period at a significantly higher rate for NDI (78.9% vs. 54.9%, P =0.001), VAS-Neck (87.0% vs. 56.0%, P <0.001), and VAS-Arm (90.5% vs. 70.7%, P =0.002). Prolonged preoperative symptom duration (≥6 mo) was identified as an independent risk factor for failure to achieve MCID at the latest timepoint for NDI (OR: 2.9, 95% CI: 1.2-6.9, P =0.016), VAS-Neck (OR: 9.8, 95% CI: 3.7-26.0, P <0.001), and VAS-Arm (OR: 7.5, 95% CI: 2.5-22.5, P <0.001).

CONCLUSIONS

Our study demonstrates improved patient-reported outcomes for those with shorter preoperative symptom duration undergoing CDR for radiculopathy, suggesting delayed surgical intervention may result in poorer outcomes and greater postoperative disability.

LEVEL OF EVIDENCE

Level III.

Compensatory strategies of dysphagia after anterior cervical spinal surgery: A case report

RATIONALE

Dysphagia after anterior cervical discectomy and fusion (ACDF) is a common postoperative complication. However, information regarding rehabilitation strategies for postoperative dysphagia is limited. Herein, we report a compensatory strategy for treating dysphagia after ACDF.

PATIENT CONCERNS

A 65-year-old Asian male presented with left arm pain and weakness for more than 1 month. Magnetic resonance imaging of the cervical spine revealed degenerative disc lesions and spinal stenosis at the C3 to C7 levels. The patient underwent ACDF at the C3 to C5 levels and artificial disc replacement at the C5 to C7 levels by right side approach. After surgery, the patient complained of difficulty swallowing. A video fluoroscopic swallowing study (VFSS) detected swallowing dysfunction in the pharyngeal phase, revealing an asymmetric pharyngeal residue in the anterior-posterior view.

DIAGNOSIS

The patient was diagnosed with dysphagia after ACDF.

INTERVENTIONS

Based on the VFSS findings, the patient underwent swallowing rehabilitation therapy and compensatory techniques, such as head rotation to the weak right side and head tilting to the robust left side.

OUTCOMES

After 2 months of rehabilitation with compensatory techniques, food moved smoothly towards the robust side, and the subjective symptoms of dysphagia improved.

LESSONS

Consequently, swallowing function post-ACDF surgery must be assessed; if unilateral dysphagia is detected, compensatory techniques may prove beneficial. This case study showed that, based on the objective findings of the VFSS, an effective swallowing compensation strategy can be established and applied to patients with postoperative dysphagia.

Cervical Disc Arthroplasty (CDA) versus Anterior Cervical Discectomy and Fusion (ACDF) for Two-Level Cervical Disc Degenerative Disease: An Updated Systematic Review and Meta-Analysis

Background: Anterior cervical discectomy and fusion (ACDF) and cervical disc arthroplasty (CDA) are both considered to be efficacious surgical procedures for treating cervical spondylosis in patients with or without compression myelopathy. This updated systematic review and meta-analysis aimed to compare the outcomes of these procedures for the treatment of cervical degenerative disc disease (DDD) at two contiguous levels. Methods: The PubMed, EMBASE, and Cochrane CENTRAL databases were searched up to 1 May 2023. Studies comparing the outcomes between CDA and ACDF in patients with two-level cervical DDD were eligible for inclusion. Primary outcomes were surgical success rates and secondary surgery rates. Secondary outcomes were scores on the Neck Disability Index (NDI) and Visual Analogue Scale (VAS) for neck and arm pain, as well as the Japanese Orthopaedic Association (JOA) score for the severity of cervical compression myelopathy and complication rates. Results: In total, eight studies (two RCTs, four retrospective studies, and two prospective studies) with a total of 1155 patients (CDA: 598; ACDF: 557) were included. Pooled results revealed that CDA was associated with a significantly higher overall success rate (OR, 2.710, 95% CI: 1.949-3.770) and lower secondary surgery rate (OR, 0.254, 95% CI: 0.169-0.382) compared to ACDF. In addition, complication rates were significantly lower in the CDA group than in the ACDF group (OR, 0.548, 95% CI: 0.326 to 0.919). CDA was also associated with significantly greater improvements in neck pain VAS than ACDF. No significant differences were found in improvements in the arm VAS, NDI, and JOA scores between the two procedures. Conclusions: CDA may provide better postoperative outcomes for surgical success, secondary surgery, pain reduction, and postoperative complications than ACDF for treating patients with two-level cervical DDD.

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

STUDY DESIGN

Observational cohort study.

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Risk factors for failure to achieve minimal clinically important difference following cervical disc replacement

BACKGROUND CONTEXT

While cervical disc replacement (CDR) has been emerging as a reliable and efficacious treatment option for degenerative cervical spine pathology, not all patients undergoing CDR will achieve minimal clinically important difference (MCID) in patient-reported outcome measures (PROMs) postoperatively-risk factors for failure to achieve MCID in PROMs following CDR have not been established.

PURPOSE

To identify risk factors for failure to achieve MCID in Neck Disability Index (NDI, Visual Analog Scale (VAS) neck and arm following primary 1- or 2-level CDRs in the early and late postoperative periods.

STUDY DESIGN

Retrospective review of prospectively collected data.

PATIENT SAMPLE

Patients who had undergone primary 1- or 2-level CDR for the treatment of degenerative cervical pathology at a single institution with a minimum follow-up of 6 weeks between 2017 and 2022.

OUTCOME MEASURES

Patient-reported outcomes: Neck disability index (NDI), Visual analog scale (VAS) neck and arm, MCID.

METHODS

Minimal clinically important difference achievement rates for NDI, VAS-Neck, and VAS-Arm within early (within 3 months) and late (6 months to 2 years) postoperative periods were assessed based on previously established thresholds. Multivariate logistic regressions were performed for each PROM and evaluation period, with failure to achieve MCID assigned as the outcome variable, to establish models to identify risk factors for failure to achieve MCID and predictors for achievement of MCID. Predictor variables included in the analyses featured demographics, comorbidities, diagnoses/symptoms, and perioperative characteristics.

RESULTS

A total of 154 patients met the inclusion criteria. The majority of patients achieved MCID for NDI, VAS-Neck, and VAS-Arm for both early and late postoperative periods-79% achieved MCID for at least one of the PROMs in the early postoperative period, while 80% achieved MCID for at least one of the PROMs in the late postoperative period. Predominant neck pain was identified as a risk factor for failure to achieve MCID for NDI in the early (OR: 3.13 [1.10-8.87], p-value: .032) and late (OR: 5.01 [1.31-19.12], p-value: .018) postoperative periods, and VAS-Arm for the late postoperative period (OR: 36.63 [3.78-354.56], p-value: .002). Myelopathy was identified as a risk factor for failure to achieve MCID for VAS-Neck in the early postoperative period (OR: 3.40 [1.08-10.66], p-value: .036). Anxiety was identified as a risk factor for failure to achieve MCID for VAS-Neck in the late postoperative period (OR: 6.51 [1.91-22.18], p-value: .003). CDR at levels C5C7 was identified as a risk factor for failure to achieve MCID in NDI for the late postoperative period (OR: 9.74 [1.43-66.34], p-value: .020).

CONCLUSIONS

Our study identified several risk factors for failure to achieve MCID in common PROMs following CDR including predominant neck pain, myelopathy, anxiety, and CDR at levels C5-C7. These findings may help inform the approach to counseling patients on outcomes of CDR as the evidence suggests that those with the risk factors above may not improve as reliably after CDR.

Cervical Disc Arthroplasty Usage Has Leveled Out From 2010 to 2021

STUDY DESIGN

Descriptive epidemiologic study.

OBJECTIVE

To compare trends in utilization and predictive factors for single-level cervical disc arthroplasty (CDA) relative to anterior cervical discectomy and fusion (ACDF) over the years.

BACKGROUND

CDA is an alternative to ACDF for the treatment of cervical spine pathologies. With both procedures performed for similar indications, controversy on best practices exists.

MATERIALS AND METHODS

Patients who underwent single-level CDA or ACDF were identified in the 2010 through 2021 PearlDiver M151Ortho data set. The yearly number of CDAs performed and proportionality was assessed. Predictive patient factors for undergoing CDA as opposed to ACDF were determined. Kaplan Meyer survival analysis with an endpoint of cervical spine reoperation compared 5-year outcomes between CDA and ACDF.

RESULTS

From 2010 to 2021, 19,301 single-level CDAs and 181,476 single-level ACDFs were identified. The proportional utilization of CDA relative to ACDF increased from 4.00% in 2010 to 14.15% in 2018 ( P < 0.0001), after which there was a plateau between 2018 and 2021 where proportional utilization was 14.47% ( P = 0.4654). Multivariate analysis identified several predictors of undergoing CDA rather than ACDF, including: younger age [odds ratio (OR) per decade decrease: 1.72], having surgery performed in the Midwest, Northeast, or West (relative to South, OR: 1.16, 1.13, 2.26, respectively), having Commercial insurance (relative to Medicare, OR: 1.75), and having surgery performed by an orthopedic surgeon (relative to a neurological surgeon, OR: 1.54) ( P < 0.0001 for each). There was no statistically significant difference in 5-year survival to further cervical spine surgery between CDA and ACDF at 5 years (97.6% vs. 97.7%, P = 0.4249).

CONCLUSIONS

Although the use of CDA relative to ACDF rose from 2010 to 2018, its use has subsequently plateaued between 2018 and 2021 and remained a relatively low percentage of the single-level anterior cervical surgeries performed (14.47% in 2021). The causes for such changes in the trend are unclear.

Clinical Effectiveness of Artificial Disc Replacement in Comparison With Anterior Cervical Discectomy and Fusion in the Patients With Cervical Myelopathy: Systematic Review and Meta-analysis

OBJECTIVE

Cervical myelopathy (CM) describes the compressive cervical spinal cord state, often accompanied by serious clinical condition, by herniated disc or hypertrophied spurs or ligament. Anterior cervical discectomy and fusion (ACDF) has been frequently employed as conventional surgical solution for this CM despite its inherent biomechanical handicap. Alternatively, an artificial disc replacement (ADR) preserves cervical motion while still decompressing the spinal canal and neural foramen. This analysis elaborated to clarify the potential benefits of ADR application to CM over ACDF from the conglomerated results of the past references.

METHODS

A literature search was performed using MEDLINE, Embase, Cochrane review, and KMbase databases from the studies published until March 2023. Six studies (3 randomized controlled study [RCTs] and 3 non-RCTs) were included in a qualitative and quantitative synthesis. Data were extracted and analyzed using a random effects model to obtain effect size and its statistical significance. Quality assessment and evidence level were established in accordance with the GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology.

RESULTS

Among 6 studies, 2 studies showed that ADR group achieved significantly better clinical improvement than the ACDF group, while the rest 4 studies revealed no significant difference. A meta-analysis showed better clinical outcomes with or without statistical significance. The level of evidence was low because of inconsistency and imprecision.

CONCLUSION

ADR was superior or at least, not inferior to ACDF in terms of functional recovery. However, its application to the CM patients is merely empowered with weak strength due to low level of evidence.

Clinical and imaging outcomes of self-locking stand-alone cages and anterior cage-with-plate in three-level anterior cervical discectomy and fusion: a retrospective comparative study

BACKGROUND

Anterior cervical discectomy and fusion has been considered standard management for cervical myelopathy and radiculopathy. However, the option of using self-locking stand-alone cages or cage-with-plate in three-level anterior cervical discectomy and fusion still remains controversial. The aim of this study was to evaluate the clinical and imaging outcomes of the two procedures in multilevel anterior cervical discectomy and fusion.

METHODS

Sixty-seven patients who underwent three-level anterior cervical discectomy and fusion were enrolled in this study, of which 31 patients underwent surgery using self-locking stand-alone cages (group cage) and 36 patients using cage-with-plate (group plate). For the evaluation of clinical outcomes, modified Japanese Orthopedic Association scores, visual analogue scale for neck pain, neck disability index, Odom's criteria and dysphagia status were measured. Imaging outcomes were evaluated by cervical sagittal angle, fusion segmental Cobb's angle, fusion segmental height, range of motion, cage subsidence rate, fusion rate and adjacent segment degeneration. Statistical analyses were performed using the SPSS software (version 19.0).

RESULTS

Both groups showed improvement in modified Japanese Orthopedic Association scores, visual analogue scale for neck pain and neck disability index, after surgery, and there was no significant difference between the groups. The occurrence rate of dysphagia is significantly lower in the group cage compared with the group plate (p < 0.05). The postoperative cervical sagittal angle, fusion segmental Cobb's angle, fusion segmental height and cage subsidence rate in the group plate were significantly superior to that in the group cage (p < 0.05). However, the rate of adjacent segment degeneration was significantly lower in the group cage compared with the group plate (p < 0.05). Both groups showed no significant difference in terms of fusion rate (p > 0.05).

CONCLUSIONS

The self-locking stand-alone cages are effective, reliable and safe in anterior cervical discectomy and fusion for the treatment of cervical myelopathy and radiculopathy. Self-locking stand-alone cages showed a significantly lower rate of dysphagia and adjacent segment degeneration, while anterior cervical cage-with-plate could provide stronger postoperative stability and maintain better cervical spine alignment.

Biomechanical analysis of single- and double-level cervical disc arthroplasty using finite element modeling

Recently, many different types of artificial discs have been introduced to persevere the biomechanical behavior of the cervical spine. This study compares the biomechanical behavior of single- and double-level cervical disc arthroplasty, that is "Prestige LP and Mobi-C" on the index and adjacent segment. A three-dimension finite element model of C2-C7 was developed and validated. In single-level prostheses, the Prestige LP or Mobi-C was implanted in the segment C5-C6, while the double-level arthroplasty was integrated at both segments C4-C5 and C5-C6 in the FE model. The intact FE and prosthesis-modified models were constrained from the inferior endplate of the vertebra C7 and applied a compressive load of 73.6 N with a moment load of 1 Nm on the odontoid process of the vertebra C2 to produce flexion/extension, lateral bending, and axial rotation. The prosthesis-modified model's range of motion and intradiscal pressure were determined and compared to the intact model. Also examined the impact of the prostheses on the stress at the bone-implant interface. The range of motion of the implanted segments in both single- and double-levels arthroplasty was increased while that of the adjacent segment of implanted segments decreased. The intradiscal pressure in both levels of arthroplasty was greater than in the intact model. In conclusion, Mobi-C's cervical prostheses could better preserve the normal range of motion and maintain intradiscal pressure than the Prestige LP.

Reoperation rates and patient-reported outcomes of single and two-level anterior cervical discectomy and fusion

INTRODUCTION

The purposes of this study were to identify the 2 year rate of reoperation and determine patient-reported outcomes after elective one- and two-level anterior cervical discectomy and fusion (ACDF) with structural allograft and anterior plating using indications similar to cervical disc arthroplasty.

MATERIALS AND METHODS

A retrospective chart review was performed on 116 consecutive one- and two-level primary ACDF for adult degenerative disease with structural allograft and anterior plating in one surgeon's practice. Patient-reported visual analog score (VAS), Oswestry disability index (ODI) and radiographs, collected prospectively on all operative patients preoperatively and postoperatively at 6 weeks, 3 months, 6 months, 1 year, and 2 years were reviewed. Patient demographics and reoperation rates were obtained from the chart.

RESULTS

One hundred and four patients were identified with a final reoperation rate of 2.9% at a mean final follow-up 2 years (95% CI 17.2-29.0). No reoperations occurred within 90 days. After 1 year, three patients required reoperation. The mean patient-reported outcomes improved (VAS, 6.6 preoperatively to 3.0 at final follow-up and ODI, 24.3 preoperatively to 12.3 at final follow-up). These improvements were statistically significant (p < 0.01). No significant patient risk factors for reoperation were found.

CONCLUSIONS

The rate of reoperation for one- and two-level anterior cervical discectomy and fusion at follow-up was found to be lower than those previously published in the literature quoted for CDA. Arthrodesis continues to demonstrate improvements in patient-reported outcomes.

A Retrospective Comparative Study of Long-Term Outcomes Following Cervical Total Disc Replacement Versus Anterior Cervical Discectomy and Fusion

Introduction The traditional treatment for patients with radiculopathy and myelopathy caused by degenerative disc disease was anterior cervical discectomy and fusion (ACDF). However, a documented complication of ACDF is adjacent segment degeneration (ASD). An alternative that was developed was total disc replacement (TDR). The aim of this study was to determine and compare the short- and medium-to-long-term outcomes after a TDR or ACDF. Methods A retrospective review of 154 patients who had single and two-level ACDFs and 90 TDRs performed by a single surgeon between 2011 and 2017 was conducted. Parameters for comparisons include both radiological evaluation and patient-reported outcome measures (PROMS) at six weeks, one year, and two years postoperatively. The Neck Disability Index (NDI) and the visual analogue scale (VAS) for neck and arm pain are used to evaluate pain, function, patient satisfaction, and overall clinical success. Results TDR and ACDF showed significant improvement in NDI and VAS when compared to pre- and post-operatively at both six weeks (p<0.05 & P=0.032, respectively) and two years (p<0.05 & 0=0.026, respectively). TDR vs. ACDF showed no significant difference (p<0.05). VAS scores after ACDF showed improvement from 13.41 to 3.94 at two years (p<0.001). TDR showed similar scores of 12.5 to 3.55 (p<0.001). The radiological fusion rate at 12 or 24 months showed no significant difference between the two groups. There were two cases that required re-operation after ACDF (1.2%), and two that required TDR (2.2%). Conclusion Both TDR and ACDF lead to clinically significant improvements in pain and function scores. We did not find a statistically significant difference in NDI and VAS in the neck and arm. The results are in agreement with others' assessments of these two treatment modalities. Our conclusions supplement the literature about these operative options for degenerative disc disease of the cervical spine and are a useful addition to the armamentarium in the assessment of patients with degenerative pathology of the c-spine.

A Bibliometric Analysis of the Top 100 Cited Articles in Anterior Cervical Discectomy and Fusion

Study design

A bibliometric analysis.

Objective

To identify and analyze the top 100 cited articles in anterior cervical discectomy and fusion.

Summary of Background Data

Anterior cervical discectomy and fusion (ACDF) is one of the most routine surgical procedures in spine surgery. Many surgeons and academics have researched ACDF thoroughly and published numerous articles. However, there is no relevant bibliometric analysis. Therefore, our study aims to identify and analyze the top 100 cited articles in ACDF to identify the research trends.

Methods

We searched the Web of Science (WOS) Core Collection database with restrictions and identified the top 100 cited publications in ACDF for analysis.

Results

The citation counts of the top 100 cited publications ranged from 37 to 361 (mean 67.42). All studies were published between 2008 and 2019, with 2013 and 2015 the most prolific years. The journals Spine and Journal of Neurosurgery-Spine provided the majority of the articles. Overall, the 100 articles came from 12 countries, with the United States being the top producer, followed by China and South Korea. The most frequent keywords were "spine", "anterior cervical discectomy and fusion", "interbody fusion", 'arthrodesis', "follow-up", "decompression", and "ACDF".

Conclusion

ACDF has been regarded as a classical gold standard in anterior cervical surgery, and the emergence of new surgical procedures has not affected its status. Cervical disc arthroplasty still needs further research and development. As the first bibliometric analysis of ACDF, this bibliometric study is meant to provide guidance for clinicians and scholars to research the development trend of this field.

Comparison of anterior cervical discectomy and fusion versus artificial disc replacement for cervical spondylotic myelopathy: a meta-analysis

OBJECTIVE

Anterior cervical discectomy and fusion (ACDF) has long been regarded as a gold standard in the treatment of cervical myelopathy. Subsequently, cervical artificial disc replacement (c-ADR) was developed and provides the advantage of motion preservation at the level of the intervertebral disc surgical site, which may also reduce stress at adjacent levels. The goal of this study was to compare clinical and functional outcomes in patients undergoing ACDF with those in patients undergoing c-ADR for cervical spondylotic myelopathy (CSM).

METHODS

A systematic literature review and meta-analysis were performed using the Embase, PubMed, and Cochrane Central Register of Controlled Trials databases from database inception to November 21, 2021. The authors compared Neck Disability Index (NDI), SF-36, and Japanese Orthopaedic Association (JOA) scores; complication rates; and reoperation rates for these two surgical procedures in CSM patients. The Mantel-Haenszel method and variance-weighted means were used to analyze outcomes after identifying articles that met study inclusion criteria.

RESULTS

More surgical time was consumed in the c-ADR surgery (p = 0.04). Shorter hospital stays were noted in patients who had undergone c-ADR (p = 0.04). Patients who had undergone c-ADR tended to have better NDI scores (p = 0.02) and SF-36 scores (p = 0.001). Comparable outcomes in terms of JOA scores (p = 0.24) and neurological success rate (p = 0.12) were noted after the surgery. There was no significant between-group difference in the overall complication rates (c-ADR: 18% vs ACDF: 25%, p = 0.17). However, patients in the ACDF group had a higher reoperation rate than patients in the c-ADR group (4.6% vs 1.5%, p = 0.02).

CONCLUSIONS

At the midterm follow-up after treatment of CSM, better functional outcomes as reflected by NDI and SF-36 scores were noted in the c-ADR group than those in the ACDF group. c-ADR had the advantage of retaining range of motion at the level of the intervertebral disc surgical site without causing more complications. A large sample size with long-term follow-up studies may be required to confirm these findings in the future.

Prospective, multicenter study of 2-level cervical arthroplasty with a PEEK-on-ceramic artificial disc

OBJECTIVE

The purpose of this study was to evaluate the safety and efficacy of a PEEK-on-ceramic cervical total disc replacement (cTDR) device for the treatment of 2-level cervical disc disease with radiculopathy and/or myelopathy.

METHODS

The study was a prospective, nonrandomized, historically controlled FDA investigational device exemption trial evaluating the Simplify Cervical Artificial Disc for use at 2 levels. The anterior cervical discectomy and fusion (ACDF) control group was derived from a propensity score-matched (using subclassification) cohort of patients who participated in an earlier prospective trial in which similar indications were used. The follow-up duration was 24 months. The primary outcome was a 4-point composite success classification. Other validated clinical and radiographic assessments were also evaluated.

RESULTS

The investigational group (n = 182) was compared with patients who underwent ACDF (n = 170) in a historical control group using propensity score analysis. The overall composite success rate was statistically significantly greater in the cTDR group compared with the ACDF group (86.7% vs 77.1%; p < 0.05). The mean Neck Disability Index scores improved significantly in both groups, with cTDR significantly lower at some follow-up points. At the 24-month follow-up, a minimum 15-point improvement in Neck Disability Index scores was achieved in 92.9% of the cTDR group and 83.5% of the ACDF group (p > 0.05). In both groups, neck and arm pain scores improved significantly (p < 0.05) by 6 weeks and improvement was maintained throughout follow-up. Segmental range of motion was maintained at both treated segments in the cTDR group. MRI performed in the cTDR group at 24 months postoperatively found minimal changes in facet joint degeneration. The rate of subsequent surgical intervention was 2.2% in the cTDR group and 8.8% in the ACDF group.

CONCLUSIONS

This study adds to the growing body of literature supporting cTDR for 2-level cervical disc disease with radiculopathy or myelopathy. cTDR showed a superior overall success rate compared to ACDF, while maintaining motion. These results support that the Simplify disc is a viable alternative to ACDF in appropriately selected patients with 2-level cervical spondylosis.

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

INTRODUCTION

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

METHODS AND ANALYSIS

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

DISCUSSION

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

TRIAL REGISTRATION

ClinicalTrials.gov NCT04623593. Registered on 29 September 2020.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Anterior Cervical Discectomy and Fusion Versus Cervical Disc Arthroplasty: A Comparison of National Trends and Outcomes

OBJECTIVE

Anterior cervical discectomy and fusion (ACDF) has been considered the standard treatment for degenerative cervical disc disease; however, recent trials have shown comparable outcomes with cervical disc arthroplasty (CDA). This study aimed to observe disparities in treatment paradigms of single-level cervical disc diseases and compare inpatient outcomes between procedures.

METHODS

A retrospective cohort of patients treated for single-level cervical disc herniation or degeneration without myelopathy was queried from the Nationwide Inpatient Sample spanning 2012-2015. Multivariate logistic regression was performed to assess the effects of demographics, temporality of admission, and hospital characteristics on odds of receiving CDA versus ACDF. Propensity-score matching was performed to compare cost, length of stay (LOS), non-home discharge, and inpatient complications.

RESULTS

In total, 1028 CDAs and 44,374 ACDFs were performed for single-level cervical disc disease during 2012-2015. Matched comparison showed that while non-home discharges were not different between CDA and ACDF (P = 0.248), patients who received CDA had a 0.19-day shorter LOS (P < 0.001) and $4694 greater total cost (P < 0.001). There were no statistically significant differences in inpatient complication rates. Multivariate analysis showed that patients in the 26th-50th percentile, 51st-75th percentile, and 76th-100th percentile of median household income had greater odds of CDA compared with patients in the 0-25th percentile (odds ratio [OR] 1.35, P = 0.003; OR 1.31, P = 0.013; OR 1.34, P = 0.011, respectively). Patients with private insurance had greater odds of receiving CDA compared with patients on Medicare (OR 1.91, P < 0.001).

CONCLUSIONS

CDA was associated with shorter LOS but greater costs compared with ACDF. Patients with greater median income and private insurance were more likely to receive CDA.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Trends in Spinal Surgery Performed by American Board of Orthopaedic Surgery Part II Candidates (2008 to 2017)

INTRODUCTION

The American Board of Orthopaedic Surgery (ABOS) Part II Oral Examination is typically taken two calendar years after fellowship completion. Despite previous studies using ABOS Part II Oral Examination data in other subspecialties, types of cases performed by spine surgeons in initial independent practice have not been well-studied. Such data may help trainees anticipate case composition observed in early practice and allow spine fellowship programs to understand emerging trends.

METHODS

We retrospectively reviewed surgical cases submitted to the ABOS by candidates taking the Part II Oral Examination between 2008 and 2017 whose designated subspecialty was spine. A hierarchical, restrictive algorithm was used to determine procedures based on candidate-reported International Classification of Diseases 9th/10th Revision and Current Procedural Terminology codes. Adjusted multivariable Poisson regression analyses were used to assess changes in procedure incidence rates over time.

RESULTS

We identified 37,539 cases, averaging 3,754 cases/yr, and an average of 49 cases per candidate per 6-month collection period. The most common procedures were lumbar diskectomy (22% of all procedures), posterolateral spinal fusion (PSF) (19%), and anterior cervical diskectomy and fusion (ACDF) (17%). Rates of ACDF and cervical disk arthroplasty significantly increased over time (incidence rate ratios of 1.41 and 23.3 times higher, respectively, at the end of the study period), whereas rates of cervical foraminotomy, lumbar diskectomy, PSF, and structural autograft use decreased (incidence rate ratios of 0.35, 0.84, 0.55, and 0.30). Rates of anterior lumbar interbody fusion/lateral lumbar interbody fusion and transforaminal lumbar interbody fusion did not significantly change over the study period.

DISCUSSION

Recent spine fellowship graduates are performing more cervical disk arthroplasties and ACDFs while decreasingly using structural autograft as well as performing fewer PSFs and lumbar diskectomies. Techniques such as anterior lumbar interbody fusion/lateral lumbar interbody fusions and transforaminal lumbar interbody fusions have not changed significantly over the last decade.

LEVEL OF EVIDENCE

Level IV (retrospective case series study).

Surgical Interventions for Cervical Radiculopathy without Myelopathy: A Systematic Review and Meta-Analysis

BACKGROUND

The effectiveness of surgical interventions for cervical degenerative disorders has been investigated in multiple systematic reviews. Differences in study population (e.g., patients with myelopathy and/or radiculopathy) were often neglected. Therefore, the objective of this study was to investigate the effectiveness of surgical interventions for patients with symptoms of cervical radiculopathy without myelopathy by conducting a systematic review and meta-analysis based on randomized controlled trials (RCTs).

METHODS

A comprehensive systematic search was conducted in MEDLINE, Embase, and CENTRAL (Cochrane Central Register of Controlled Trials) to identify RCTs that investigated the effectiveness of surgical interventions using an anterior or posterior approach compared with other interventions for patients with pure cervical radiculopathy. Outcomes were success rates (Odom criteria, similar rating scales, or percentage of patients who improved), complication and reoperation rates, work status, disability (Neck Disability Index), and pain (arm and neck). The Cochrane risk-of-bias tool was used to assess the likelihood of the risk of bias. A random-effects model was used. Heterogeneity among study results (I2 ≥ 50% or p < 0.05) was explored by conducting subgroup analyses. Funnel plots were used to assess the likelihood of publication bias.

RESULTS

A total of 21 RCTs were included, comprising 1,567 patients. For all outcomes, among all surgical techniques, only 1 pooled estimate showed a significant effect on success rate, which was in favor of anterior cervical discectomy with fusion compared with anterior cervical discectomy without an intervertebral spacer (p = 0.02; risk ratio [RR] = 0.87; 95% confidence interval [CI] = 0.77 to 0.98). Complication rates were higher when autologous bone graft from the iliac crest was used as an intervertebral spacer (p < 0.01; RR = 3.40; 95% CI = 1.56 to 7.43), related to donor-site morbidity.

CONCLUSIONS

This meta-analysis demonstrated consistent results regarding clinical outcome for pure cervical radiculopathy among all studied interventions. Complication and reoperation rates were also similar, with the exception of higher complication rates in patients in whom autologous bone grafts were used. On the basis of clinical outcome and safety, there is no superior surgical intervention for pure cervical radiculopathy.

LEVEL OF EVIDENCE

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

Multilevel Cervical Disc Arthroplasty: Long-Term Outcomes at 3 and 4 Levels

BACKGROUND

Multilevel cervical degenerative disc disease in 2 or more segments poses treatment challenges. Anterior cervical discectomy and fusion is a viable treatment option, but one with high rates of adjacent segment disease and pseudoarthrosis. Cervical disc arthroplasty (CDA) is approved by the US Food and Drug Administration for the treatment of 1- and 2-level cervical pathology, with established long-term safety and effectiveness. Limited evidence exists for CDA at more than 2 levels. This study investigates the long-term outcomes of 3- and 4-level CDA out to 7 years.

METHODS

In a retrospective review of prospectively collected data, patient demographics and surgical characteristics were collected. Patient-reported outcomes (PROs) were collected preoperatively and at 6 weeks, 3 months, 6 months, and 12 months postoperatively, and annually thereafter, including: Neck Disability Index (NDI), numeric rating scales for neck pain and arm pain, the Veterans Rand 12-item Health Survey physical component summary (PCS) score and mental component summary (MCS) score, and patient satisfaction scores. Secondary surgery data were also collected. Predictive methods using mixed-effects regression models were used to analyze the data.

RESULTS

Data for 139 CDAs were available for evaluation (n = 116 three-level and n = 23 four-level). Statistical improvement was shown for all PRO scores at all postoperative intervals (P < .001). From preoperatively to 7 years postoperatively, mean NDI decreased from 57.9 to 31.3 (45.9% improvement), mean neck pain decreased from 15.6 to 7.9 (49.4% improvement), mean arm pain decreased from 12.2 to 5.6 (54.1% improvement), mean PCS increased from 29.2 to 41.4 (41.8% improvement), and mean MCS increased from 37.1 to 44.5 (19.9% improvement). Five (3.6%) 3-level patients underwent secondary surgery. Patient satisfaction exceeded 88% 7 years after surgery.

CONCLUSION

Statistical improvement in PROs, with a low rate of secondary surgeries out to 7 years, demonstrates that 3- and 4-level CDA may be performed safely and effectively in appropriately selected patients.

LEVEL OF EVIDENCE

4.

Biomechanical evaluation of adjacent segment degeneration after one- or two-level anterior cervical discectomy and fusion versus cervical disc arthroplasty: A finite element analysis

BACKGROUND AND OBJECTIVE

To compare the biomechanical changes of adjacent segment degeneration (ASD) after one- or two-level anterior cervical discectomy and fusion (ACDF) versus cervical disc arthroplasty (CDA).

METHODS

A three-dimensional finite element (FE) model of intact C2-C7 segments was constructed and validated. In the one-level surgery model, the cage with plate implant or Prestige LP cervical disc prosthesis were integrated at C5-C6 segment into the FE model; while in the two-level surgery model, the prostheses were integrated at both C4-C5 and C5-C6 segments into the FE model. A pure moment of 1.0 Nm combined with a follower load of 73.6 N were imposed on C2 to investigate the flexion-extension, lateral bending, and axial rotation of different segments in the FE model. The segmental range of motion (ROM) and intradiscal pressure of the surgery models were investigated and compared with the intact model.

RESULTS

In the one-level model of ACDF, the ROM at C5-C6 was decreased, the ROM and intradiscal pressure at C4-C5 and C6-C7 segments were increased. In the two-level model of ACDF, the ROM at C4-C5 and C5-C6 were decreased, the ROM and intradiscal pressure at C3-C4 and C6-C7 were increased. However, in both one- and two-level models of CDA, the ROM of surgery segments were preserved, avoiding the increase of the ROM and intradiscal pressure at the adjacent segments.

CONCLUSIONS

Abnormal ROM and intradiscal pressure at the adjacent segments may contribute to the higher risk of ASD after ACDF compared with CDA.

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

STUDY DESIGN

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

OBJECTIVE

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

SUMMARY OF BACKGROUND DATA

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

Objective

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

Methods

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

Results

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

Conclusion

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

Cervical disc arthroplasty versus anterior cervical discectomy and fusion: a meta-analysis of rates of adjacent-level surgery to 7-year follow-up

Background

Anterior cervical discectomy and fusion (ACDF) is an effective treatment for cervical spondylosis. A limitation of ACDF is the risk of adjacent-segment degeneration (ASD), owing to arthrodesis of a motion segment. Cervical disc arthroplasty (CDA) has hence garnered significant attention; yet, compelling evidence of reduction in ASD requiring surgery is lacking. This systematic review and meta-analysis sought to compare long-term longitudinal adjacent-level operation rates with CDA versus ACDF.

Methods

An electronic literature search was conducted. Eligible studies were multi-center randomized controlled trials (RCTs) comparing CDA with ACDF for one- or two-level symptomatic cervical spondylosis. The primary outcome was adjacent-level operation. Index-level reoperation was a secondary outcome. Outcomes were evaluated at 1-year intervals from the index operation to last reported follow-up by random-effects meta-analyses.

Results

Eleven RCTs met criteria. For one-level spondylosis, there was no difference in the rate of adjacent-level operation between CDA (2.3%) and ACDF (3.6%) at 2 years. However, a large difference favoring CDA became evident at 5 years and persisted at 7 years (4.3% vs. 10.8%, P<0.001). Significantly fewer patients who underwent CDA required index-level reoperation at all time points out to 7 years (5.2% vs. 12.7%, P<0.001). Similar to one-level operations, there was no significant difference in adjacent-level operations with two-level CDA (1.7%) versus two-level ACDF (3.4%) at 2 years. At 7 years, a significant difference favoring CDA became apparent (5.1% vs. 10.0%, P=0.014). Two-level CDA resulted in fewer index-level reoperations out to 7 years (4.2% vs. 13.5%, P<0.001).

Conclusions

In this meta-analysis, the short-term rate of adjacent-level operation was similar with CDA or ACDF. However, around 5 years, a statistically significant divergence emerged, where the rate of adjacent-level surgery rose steeply for ACDF. Index-level reoperations were less frequent with CDA in both the short- and long-term. These data indicate CDA may have a superior longevity to ACDF with regard to need for subsequent adjacent-level operation.

Cervical Total Disc Replacement and Heterotopic Ossification: A Review of Literature Outcomes and Biomechanics

Anterior cervical discectomy and fusion (ACDF) immobilizes surgical segments and can lead to the development of adjacent segment degeneration and adjacent segment disease. Thus, cervical total disc replacement (CTDR) has been developed with the aim to preserve the biomechanics of spine. However, heterotopic ossification (HO), a complication following CTDR, can reduce the segmental range of motion (ROM) and defects the motion-preservation benefit of CTDR. The pathological process of HO in CTDR remains unknown. HO has been suggested to be a self-defense mechanism in response to the non-physiological biomechanics of the cervical spine following CTDR. The current literature review is concerned with the association between the biomechanical factors and HO formation and the clinical significance of HO in CTDR. Endplate coverage, disc height, segmental angle, and center of rotation may be associated with the development of HO. The longer the follow-up, the higher the rate of ROM-limiting HO. Regardless of the loss of motion-preservation benefit of CTDR in patients with HO, CTDR confers patients with a motion-preservation period before the development of ROM-limiting HO. This may delay the development of adjacent segment degeneration compared with ACDF. Future clinical studies should explore the association between HO and changes in biomechanical factors of the cervical spine.

Cervical Discs as a Source of Neck Pain. An Analysis of the Evidence

OBJECTIVESBACKGROUND

Objectives To determine the extent and strength of evidence that supports the belief that cervical intervertebral discs are a source of neck pain.

DESIGN

Design The evidence from anatomical, laboratory, experimental, diagnostic, and treatment studies was summarized and analyzed for concept validity, face validity, content validity, and construct validity.

RESULTS

Results Evidence from basic sciences shows that cervical discs have a nociceptive innervation, and experimental studies show that they are capable of producing neck pain. Disc stimulation has been developed as a diagnostic test but has rarely been used in a disciplined fashion. The prevalence of cervical disc pain has not been properly established but appears to be low. No treatment has been established that reliably achieves complete relief of neck pain in substantial proportions of patients.

CONCLUSIONS

Conclusions Basic science evidence supports the concept of cervical disc pain, but epidemiologic and clinical evidence to vindicate the clinical application of the concept is poor or lacking.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

First Clinical Experience with a Carbon Fibre Reinforced PEEK Composite Plating System for Anterior Cervical Discectomy and Fusion

Carbon fibre reinforced polyether ether ketone (CFR-PEEK) is a suitable material to replace metal implants in orthopaedic surgery. The radiolucency of CFR-PEEK allows an optimal visualisation of the bone and soft tissue structures. We aimed to assess the performance and radiological and clinical outcomes of anterior cervical discectomy and fusion (ACDF) with CFR-PEEK anterior cervical plating (ACP) under first use clinical conditions. We retrospectively studied the prospectively-collected data of 42 patients who underwent ACDF with CFR-PEEK ACP between 2011 and 2016. We assessed clinical outcome (Odom's criteria, complications) and radiological parameters (global and segmental cervical lordosis, Bridwell score for fusion, adjacent segment degeneration) preoperatively, immediately post-operatively, and after a 12-month follow-up period. Patients' satisfaction was excellent, good, fair, and poor in 12, 19, 3, and 1 patients, respectively. Two patients developed dysphagia. No hardware failure occurred. Compared with preoperative radiographs, we observed a gain of global cervical lordosis and segmental lordosis (7.4 ± 10.1 and 5.6 ± 7.1 degrees, respectively) at the 12-month follow-up. Bridwell IF grades I, II, and III were observed in 22, 6, and 7 patients, respectively. The 12-month adjacent segment degeneration-free and adjacent segment disease-free survival rates were 93.1% and 96.3%, respectively. We observed a dysphagia rate of 5.7% and a reoperation rate of 4.8%. In conclusion, CFR-PEEK ACP shows positive outcomes in terms of implant safety, restoration of cervical lordosis, and functional recovery, and is suitable for ACDF.

Surgical Strategies to Prevent Adjacent Segment Disease in the Cervical Spine

The most popular approach to treating symptomatic cervical disk disease is anterior cervical discectomy and fusion. Although this procedure has significant long-term clinical success, it is associated with progressive adjacent segment degeneration with an annual incidence of ∼3%. Total disk arthroplasty was designed as an alternative to fusion that could preserve segmental motion at the operative level and potentially delay or prevent adjacent-level breakdown. The etiology of adjacent segment pathology (ASP) is multifactorial, and it is likely that most cases of ASP are unavoidable. When attempting to surgically prevent ASP, it is important to consider nonfusion alternatives, be judicious in one's level selection, and attempt to restore sagittal alignment. When ASP becomes a clinical problem, it is important to have an algorithm for how best to treat it.

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

Objectives

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

Methods

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

Results

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

Conclusion

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

Cervical Disk Arthroplasty

Anterior cervical diskectomy and fusion has been and remains the benchmark surgical management of cervical degenerative disk disease. However, an increased use of cervical disk arthroplasty (CDA) has been found in the past few years. The purported benefits of CDA included preserved motion, less adjacent-level degeneration, and less morbidity. Short-term results from randomized control trials clearly showed noninferiority of CDA compared with fusion. With long-term comparison data becoming available, results are equivalent and superior in many metrics compared, favoring CDA. Concerns remain regarding the best way to manage CDA failures. Nonetheless, appropriate patient selection and adherence to strict surgical technique make CDA a viable treatment.

Clinical Outcomes After Four-Level Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

Anterior cervical discectomy and fusion (ACDF) demonstrates reliable improvement in neurologic symptoms associated with anterior compression of the cervical spine. There is a paucity of data on outcomes following 4-level ACDFs. The purpose of this study was to evaluate clinical outcomes for patients undergoing 4-level ACDF.

METHODS

All 4-level ACDFs with at least 1-year clinical follow-up were identified. Clinical outcomes, including fusion rates, neurologic outcomes, and reoperation rates were determined.

RESULTS

Retrospective review of our institutional database revealed 25 patients who underwent 4-level ACDF with at least 1-year clinical follow-up. Average age was 57.5 years (range 38.2-75.0 years); 14 (56%) were male, and average body mass index was 30.2 kg/m² (range 19.9-43.4 kg/m²). Two (8%) required secondary cervical surgery at an average of 94.5 days postoperatively while the remaining 23 did not with an average follow-up of 19 months. Of 23 patients not requiring revision surgery, 16 (69%) patients fused by definition of less than 1 mm of spinous process motion per fused level in flexion and extension. Fifteen (65%) had at least one muscle group with one grade of weakness preoperatively. Nineteen of these patients (83%) had improved to full strength while no patients lost muscle strength.

CONCLUSIONS

Review of our institution's experience demonstrated a low rate of revision cervical surgery for any reason of 8% at mean 19 months follow-up, and neurological examinations consistently improved, despite a high rate of radiographic nonunion (31%).

Cervical disc degeneration and neck pain

Cervical intervertebral disc has long been considered a common source of neck pain. However, the pain caused by the disc itself has not been clearly defined so far, and its diagnosis and treatment has always been controversial. Degenerative cervical disc has a rich supply of nerve fibers, is prone to inflammatory reactions, and is susceptible to pain that can be provoked by disc stimulation or distention, and can be eliminated by block. Overwhelming clinical evidence demonstrates that neck pain in patients with degenerative cervical radiculopathy or myelopathy can be subsided rapidly by anterior cervical surgery, further indicating that this neck pain stems from the pathology of cervical disc itself. Cervical discography is advocated as the only test that connects disease to symptoms, but the procedure remains controversial. If strict criteria and technique are maintained, discography can discriminate painful, symptomatic discs from nonpainful, asymptomatic discs. Discogenic neck pain alone without cervical disc herniation or cervical spondylosis accounts for a large proportion of chronic neck pain. For these patients who continue to have refractory neck pain and fail to respond to conservative treatment, anterior cervical fusion surgery or artificial cervical disc replacement may be a better choice, and preoperative cervical discography can guarantee the excellent surgical results. Existing basic and clinical studies have scientifically shown that cervical intervertebral disc degeneration can lead to neck pain.

Chromium and Nickel Concentrations in Subjects with a Stainless Steel Metal-on-Metal Cervical Disc Arthroplasty: Results from a Prospective Longitudinal Study with 7 Years Follow-Up

Background

Cervical disc arthroplasty (CDA) has emerged as an alternative to anterior cervical discectomy and fusion for degenerative cervical disc disease. The artificial discs provide intervertebral motion using multicomponent articulation and thus tend to generate particulate debris and soluble metal ions. Limited information is available on the long-term metal concentrations and associated systemic adverse events observed in metal-on-metal CDA. Serum chromium (Cr) and nickel (Ni) concentrations were assessed in patients implanted with ball-in-trough stainless steel-based cervical disc through 7 years.

Methods

A prospective, nonrandomized longitudinal study was conducted that included 25 patients following rigorous exclusion criteria that included no previous permanent metal implants and no professional exposure to metal particles. Blood serum Cr and Ni concentrations were assayed preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months postoperatively using high-resolution inductively coupled plasma-mass spectrometry. Longitudinal statistical comparisons were made using the Friedman test with statistical significance at P < .05.

Results

Median serum concentrations determined preoperatively and at 3, 6, 12, 24, 36, 60, and 84 months postoperatively were 0.074, 0.106, 0.132, 0.170, 0.172, 0.274, 0.192, and 0.203 ng/mL for Cr and 0.085, 0.178, 0.222, 0.175, 0.205, 0.284, 0.181, and 0.194 ng/mL for Ni. The serum Cr concentrations were statistically higher for all postoperative time periods compared to preoperative concentration (Friedman P <.01), whereas serum Ni concentration was statistically higher at the 84-month postoperative time period than the preoperative concentration (Friedman P <.01) and then the concentration at 3, 12, 24, and 60 months postoperatively (Friedman P < .03).

Conclusions

The Cr concentrations detected at all postoperative times were statistically higher than preoperative concentrations, whereas Ni concentration was statistically higher than the preoperative concentration only at 84 months.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Comparison of Multilevel Cervical Disc Replacement and Multilevel Anterior Discectomy and Fusion: A Systematic Review of Biomechanical and Clinical Evidence

OBJECTIVE

The aim of this study was to comprehensively compare the clinical and biomechanical efficiency of anterior cervical discectomy and fusion (ACDF) with anterior cervical disc replacement (ACDR) for treatment of multilevel cervical disc disease using a meta-analysis and systematical review.

METHODS

A literature search was performed using PubMed, MEDLINE, EMBASE, and the Cochrane Library for articles published between January 1960 and December 2017. Both clinical and biomechanical parameters were analyzed. Statistical tests were conducted by Revman 5.3. Nineteen studies including 10 clinical studies and 9 biomechanical studies were filtered out.

RESULTS

The pooled results for clinical efficiency showed that no significant difference was observed in blood loss (P = 0.09; mean difference [MD], 7.38; confidence interval [CI], -1.16 to 15.91), hospital stay (P = 0.33; MD, -0.25; CI, -0.76 to 0.26), Japanese Orthopaedic Association scores (P = 0.63; MD, -0.11; CI, -0.57 to 0.34), visual analog scale (P = 0.08; MD, -0.50; CI, -1.06 to 0.05), and Neck Disability Index (P = 0.33; MD, -0.55; CI, -1.65 to 0.56) between the 2 groups. Compared with ACDF, ACDR did show increased surgical time (P = 0.03; MD, 31.42; CI, 2.71-60.14). On the other hand, ACDR showed increased index range of motion (ROM) (P < 0.00001; MD, 13.83; CI, 9.28-18.39), lower rates of adjacent segment disease (ASD) (P = 0.001; odds ratio [OR], 0.27; CI, 0.13-0.59), complications (P = 0.006; OR, 0.62; CI, 0.45-0.87), and rate of subsequent surgery (P < 0.00001; OR, 0.25; CI, 0.14-0.44). As for biomechanical performance, ACDR maintained index ROM and avoided compensation in adjacent ROM and tissue pressure.

CONCLUSIONS

Multilevel ACDR may be an effective and safe alternative to ACDF in terms of clinical and biomechanical performance. However, further multicenter and prospective studies should be conducted to obtain a stronger and more reliable conclusion.

A comparison of a self-locking stand-alone cage and anterior cervical plate for ACDF: Minimum 3-year assessment of radiographic and clinical outcomes

OBJECTIVES

The self-locking stand-alone cage has been clinically applied in treating cervical degenerative disc disease (CDDD). However, no long-term clinical and radiographic studies have been performed so far. This retrospective study was designed to analyze and compare the efficacy and outcomes of anterior cervical discectomy and fusion (ACDF) using self-locking stand-alone cages and cages with the anterior cervical plating system.

PATIENTS AND METHODS

A total of 98 consecutive patients were recruited in this study. Patients in the cage group were given stand-alone self-locking cages, and patients in the plate group were treated with cages and anterior plate fixation. The operative time, intraoperative blood loss and complications were recorded. Clinical outcomes were evaluated using the JOA scoring system, Neck Disability Index and Odom's criteria. The cervical lordosis, subsidence and cervical fusion status were assessed by X-ray and computed tomography.

RESULTS

The mean follow-up period was 39.7 months in the cage group and 42.2 months in the plate group. The operative time, intraoperative blood loss, postoperative dysphagia, sore throat and adjacent segment degeneration in the cage group were significantly less than those in the plate group (p < 0.05). All the patients in both groups achieved complete interbody fusion. Postoperative JOA and NDI scores in both groups were obviously improved compared with the preoperative ones. The postoperative cervical lordosis was effectively restored in both groups.

CONCLUSIONS

The self-locking stand-alone cage for ACDF could effectively restore the cervical physiological curvature, cause few complications, and lead to satisfactory outcomes. Therefore, it could be used as an effective and reliable treatment for the CDDD.

Adverse Events Following Cervical Disc Arthroplasty: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Comparison between cervical disc arthroplasty and conservative treatment for patients with single level cervical radiculopathy at C5/6

BACKGROUND

Cervical radiculopathy is a common disease that affects millions of people. Patients usually are managed by conservative therapy and surgical treatments.

OBJECTIVE

To compare the clinical outcomes between cervical disc arthroplasty (CDA) and conservative management for patients with single level cervical radiculopathy at C5/6.

METHODS

Seventy-two patients with cervical radiculopathy that only affect C5/6 joints were included and thirty-two of them received CDA surgery, and forty patients were treated with conservative management. All the patients were followed up around 4 years. Cervical curvature, cervical range of motion (CROM), horizontal displacement of cervical spine, and intervertebral gap were measured by radiological examination.

RESULTS

All the patients have comparable disease severity based on pre-surgical radiological assessments. At the 4-year follow-up examination, patients with CDA surgery had less CROM at C5/6 level, while greater CROM at C4/5 level, than control group. Similarly, the horizontal displacement in CDA group decreased at C5/6 vertebrae, and increased at C4/5 level at the 4-year follow-up examination. The intervertebral gaps of patients in CDA group were larger than control group at one-year and last follow-up examination.

CONCLUSION

CDA surgery stabilized C5/6 vertebrae and increased the CROM and horizontal displacement of upper adjacent C4/5 vertebrae.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

A Prospective Study of Interbody Fat Graft Application With the Anterior Contralateral Cervical Microdiscectomy to Preserve Segmental Mobility

BACKGROUND

Any surgical procedure aims at protecting mobile segments at the operated level, and the sagittal balance of the columna vertebralis. Interbody fusion has become an often applied technique in anterior cervical discectomy.

OBJECTIVE

To indicate that a minimally invasive technique in which we use interbody fat graft placement showed great results and effectiveness, especially in patients who were suffering from cervical paramedian disc herniation.

METHODS

In this study, 432 patients were observed from 2000 to 2013. All these consecutive patients had paramedian disc herniation. The initial 239 patients (group 1) underwent microdiscectomy without graft placement, whereas the remaining 193 patients (group 2) had a microdiscectomy with interbody fat graft insertion. The Neck Disability Index (NDI) and Short Form-36 (SF-36) were used to evaluate clinical outcomes. They were followed up for 5.3 years (range 2-13 years).

RESULTS

Spontaneous radiological fusion was noticed in 12% of group 1 patients and none of the group 2 patients. It has been observed that the mean overall cervical curvature (C2-7) angles and segmental lordosis did not change significantly in late follow-up findings. During both early and late follow-ups, all patients indicated a decreasing NDI score, but in late follow-up, an improving SF-36 score.

CONCLUSION

This surgical technique provides good direct decompression and preserves mobility at the treated level, while preventing disc collapse.

There is no increased risk of adjacent segment disease at the cervicothoracic junction following an anterior cervical discectomy and fusion to C7

BACKGROUND CONTEXT

Anterior cervical discectomy and fusion (ACDF) is a very common operative intervention for the treatment of cervical spine degenerative disease in those who have failed non-operative measures. However, studies examining long-term follow-up on patients who underwent ACDF reveal evidence of radiographic and clinical degenerative disc disease at the levels adjacent to the fusion construct. Consistent with other junctional regions of the spine, the cervicothoracic junction (CTJ) has significant morphologic variations. As a result, the CTJ undergoes significant static and dynamic stress. Given these findings, there has been some thought that ACDF down to C7 may experience additional risks for adjacent segment degeneration/disease (ASD) when compared with ASDFs that are cephalad to C7.

PURPOSE

The goal of this study is to evaluate the rate of radiographic and clinical ASD in patients who have undergone single- or multilevel ACDF, down to C7.

STUDY DESIGN

This is a retrospective cohort study.

PATIENT SAMPLE

The sample included consecutive patients from a single orthopedic surgeon at one quaternary referral medical center who underwent an ACDF between January 2008 and November 2014. Indications for surgery included radiculopathy, myelopathy, or myeloradiculopathy in the setting of failed conservative treatments. Patients were excluded if they had an ACDF of which the caudal level was cephalad to C7 or if they had undergone a previous cervical fusion.

OUTCOME MEASURES

Radiographic diagnosis of ASD was determined by the presence of disc space narrowing >50%, new or enlarged osteophytes, end plate sclerosis, or increased calcification of the anterior longitudinal ligament (ALL). Postoperatively, data were collected on the presence of new radicular or myelopathic symptoms indicative of pathology at C7-T1, indicating a diagnosis of clinical ASD.

METHODS

Demographic information was collected for all patients, which included age, sex, body mass index, smoking status, and Charleston Comorbidity Index (CCI). Several radiographic parameters were measured preoperatively, immediately postoperatively, and at the last follow-up: C2-C7 lordosis, sagittal vertical axis (SVA), thoracic inlet angle (TIA), and T1 slope C2-C7 lordosis were measured using the Cobb angle between the inferior end plate of C2 to the inferior end plate of C7. Radiographic and clinical factors associated with ASD were analyzed postoperatively.

RESULTS

Four patients (4.8%) presented with clinical evidence of ASD, all of whom also showed signs of radiographic ASD and improved with conservative measures. No patients underwent reoperation for ASD at the C7-T1 junction. Thirty patients (36.1%) presented radiographic evidence of ASD. These were generally older (54.4 vs. 48.4 years; p=.014). There were neither significant differences in radiographic parameters nor between single- versus multilevel ACDFs and the development of ASD.

CONCLUSIONS

The cervicothoracic junction may present with vulnerability to ASD given the junctional biomechanics. However, this study provides evidence that an ACDF with the caudal level of C7 does not incur additional risk of ASD, showing similar outcomes to ACDFs at other levels.

Factors Affecting the Nonlinear Force Versus Distraction Height Curves in an In Vitro C5-C6 Anterior Cervical Distraction Model

STUDY DESIGN

In vitro biomechanical study of cervical intervertebral distraction.

OBJECTIVE

To investigate the forces required for distraction to different heights in an in vitro C5-C6 anterior cervical distraction model, focusing on the influence of the intervertebral disk, posterior longitudinal ligament (PLL), and ligamentum flavum (LF).

SUMMARY OF BACKGROUND DATA

No previous studies have reported on the forces required for distraction to various heights or the factors resisting distraction in anterior cervical discectomy and fusion.

MATERIALS AND METHODS

Anterior cervical distraction at C5-C6 was performed in 6 cadaveric specimens using a biomechanical testing machine, under 4 conditions: A, before disk removal; B, after disk removal; C, after disk and PLL removal; and D, after disk and PLL removal and cutting of the LF. Distraction was performed from 0 to 10 mm at a constant velocity (5 mm/min). Force and distraction height were recorded automatically.

RESULTS

The force required increased with distraction height under all 4 conditions. There was a sudden increase in force required at 6-7 mm under conditions B and C, but not D. Under condition A, distraction to 5 mm required a force of 268.3±38.87 N. Under conditions B and C, distraction to 6 mm required <15 N, and further distraction required dramatically increased force, with distraction to 10 mm requiring 115.4±10.67 and 68.4±9.67 N, respectively. Under condition D, no marked increase in force was recorded.

CONCLUSIONS

Distraction of the intervertebral space was much easier after disk removal. An intact LF caused a sudden marked increase in the force required for distraction, possibly indicating the point at which the LF was fully stretched. This increase in resistance may help to determine the optimal distraction height to avoid stress to the endplate spacer.

Cervical Disk Replacement With Discover Versus Fusion in a Single-Level Cervical Disk Disease: A Prospective Single-Center Randomized Trial With a Minimum 2-Year Follow-up

STUDY DESIGN

Prospective randomized study.

OBJECTIVE

To compare the clinical outcome after Discover arthroplasty versus anterior cervical discectomy and fusion (ACDF) in patients treated for symptomatic single-level cervical disk disease.

SUMMARY OF BACKGROUND DATA

ACDF is still the gold standard for surgical treatment of cervical spine degenerative disk disease. However, results of many studies suggest that it may cause degenerative changes at levels immediately above and below the fusion, known as adjacent segment degenerative disease. Cervical arthroplasty has recently been introduced as an alternative to standard procedure of ACDF. It showed decreased surgical morbidity, decreased complications from postoperative immobilization, and an earlier return to previous level of function.

MATERIALS AND METHODS

A total of 105 consecutive patients with single-level cervical disk disease, producing radiculopathy and/or myelopathy were randomly divided into groups to undergo ACDF or Discover arthroplasty. All patients were evaluated with preoperative and postoperative serial radiographic studies and clinically, using Neck Disability Index, Visual Analog Scale and neurological status at 3, 6, 12, and 24 months.

RESULTS

The results of our study indicate that cervical arthroplasty using Discover Artificial Cervical Disc provides favorable clinical and radiologic outcomes in a follow-up period of 24 months. There has been significant improvement in clinical parameters, Visual Analog Scale and Neck Disability Index, at 3, 6, 12, and 24 months in arthroplasty group comparing to control group.

CONCLUSION

The Discover artificial cervical disc replacement offers favorable outcome compared with ACDF for a single-level cervical disk disease at short-term and long-term follow-up.

Development of a Remodeled Caspar Retractor and Its Application in the Measurement of Distractive Resistance in an In Vitro Anterior Cervical Distraction Model

STUDY DESIGN

In vitro biomechanical study of the cervical intervertebral distraction using a remodeled Caspar retractor.

OBJECTIVE

To investigate the torques required for distraction to different heights in an in vitro C3-C4 anterior cervical distraction model using a remodeled Caspar retractor, focusing on the influence of the intervertebral disk, posterior longitudinal ligament (PLL), and ligamentum flavum (LF).

SUMMARY OF BACKGROUND DATA

No previous studies have reported on the torques required for distraction to various heights or the factors resisting distraction in anterior cervical discectomy and fusion.

METHODS

Anterior cervical distractions at C3-C4 was performed in 6 cadaveric specimens using a remodeled Caspar retractor, under 4 conditions: A, before disk removal; B, after disk removal; C, after disk and PLL removal; and D, after disk and PLL removal and cutting of the LF. Distraction was performed for 5 teeth, and distractive torque of each tooth was recorded.

RESULTS

The torque increased with distraction height under all conditions. There was a sudden increase in torque at the fourth tooth under conditions B and C, but not D. Under condition A, distraction to the third tooth required 84.8±13.3 cN m. Under conditions B and C, distraction to the third tooth required <13 cN m, and further distraction required dramatically increased torque. Under condition D, no marked increase in torque was recorded.

CONCLUSIONS

Distraction of the intervertebral space was much easier after disk removal. An intact LF caused a sudden marked increase in the force required for distraction, possibly indicating the point at which the LF was fully stretched. This increase in resistance may help to determine the optimal distraction height to avoid excessive stress to the endplate spacer. The remodeled Caspar retractor in the present study may provide a feasible and convenient method for intraoperative measurement of distractive resistance.

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

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