Zero-P: a new zero-profile cage-plate device for single and multilevel ACDF. A single institution series with four years maximum follow-up and review of the literature on zero-profile devices

Does Bone Preservation at the Anterior Edge of the Vertebral Body Affect the Subsidence of Zero-Profile Cages After Anterior Cervical Discectomy and Fusion?

OBJECTIVE

The purpose of this study was to investigate whether the preservation of the anterior edge of the vertebral body affects the cage subsidence and clinical outcomes after anterior cervical discectomy and fusion (ACDF) using zero-profile cages.

METHODS

We retrospectively analyzed 86 patients who underwent 1-3 levels of ACDF using zero-profile cages between December 2017 and June 2023. According to whether the anterior edge was protected, the patients were divided into an intact group and a defect group. Cage subsidence was defined as a ≥2 mm decrease in vertebral height at follow-up compared with measurement on postoperative day 2. The patients' radiological parameters and clinical outcomes were also analyzed.

RESULTS

The subsidence rate was 17.02% (8/47) in the intact group and 41.03% (16/39) in the defect group (P = 0.014). At the last follow-up, all patients in both groups achieved complete intervertebral fusion. The cervical lordosis of the 2 groups was effectively restored after surgery, and the visual analog scale and Neck Disability Indexscores of the 2 groups were significantly improved. Multivariate logistic regression analysis showed that the protective factor for zero-profile cage subsidence was bone protection at the anterior edge of the vertebral body (odds ratio = 0.270; 95% confidence interval = 0.091-0.804), and the risk factor was related to the height of the preoperative surgical segment (odds ratio = 2.285; 95% confidence interval = 1.395-3.743).

CONCLUSIONS

For patients who undergo ACDF with zero-profile cages, especially those with a higher surgical segment, bone protection at the anterior edge of the vertebral body can effectively reduce the risk of zero-profile cage subsidence, but there is no difference in the final clinical effect.

Clinical and Radiological Outcomes of Anchored Stand-Alone Cage Compared to Conventional Plating in Multilevel Anterior Cervical Discectomy and Fusion: A Systematic Review

Multilevel cervical degenerative disc disease (cDDD) is typically treated through anterior cervical discectomy and fusion (ACDF). Traditionally, the plate-cage construct (PCC) has been utilized, though alternatives such as the locking stand-alone cage (LSC) have become popular. This systematic review aims to assess differences in clinical and radiological outcomes between LSC and PCC methods in the ACDF management of multilevel cDDD by aggregating existing literature. A comprehensive search of five electronic databases (PubMed, Medline, Ovid, Embase, and Cochrane) was conducted from 2015 to 2022 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The comparative studies were assessed using the Methodological Index for Non-randomized Studies (MINORS) criteria and the two randomized controlled trials (RCTs) were assessed using the Jadad scale for RCT. Eight studies met the inclusion criteria, comprising a total cohort of 516 contiguous multilevel cDDD cases treated via ACDF, with 254 (49%) managed with PCC and 262 (51%) treated with LSC. The comparative outcomes assessed included the rate of subsidence and the rate of postoperative dysphagia. The LSC approach exhibited a higher incidence of cage subsidence compared to PCC. Conversely, dysphagia was observed more frequently in patients receiving PCC compared to those treated with LSC. Clinical outcomes and functional scores did not reveal significant differences. Clinical measures such as the Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), visual analog scale (VAS), and Odom's and Robinson's criteria revealed no significant differences between treatment groups in seven of the studies. However, one of the included studies reported a statistically significant improvement in the LSC group for VAS and Odom's criteria. The incidence of cage subsidence in ACDF surgery varies depending on the cage type employed. Among the reviewed studies, the LSC group exhibited a higher incidence of subsidence compared to the PCC group, with the exception of one study that reported no cases of subsidence. Variability in subsidence rates across studies may be attributed to differences in surgical techniques, patient demographics, and follow-up periods. Further research is necessary to investigate associated risk factors and to develop strategies aimed at minimizing this complication in ACDF procedures.

[Clinical outcomes of 3D-printing stand-alone artificial vertebral body in anterior cervical surgeries]

OBJECTIVE

To explore the short-term outcomes of 3D-printing stand-alone artificial vertebral body (AVB) in the surgical procedure of anterior cervical corpectomy and fusion (ACCF).

METHODS

Following the proposal of IDEAL (idea, development, exploration, assessment, and long-term follow-up) framework, we designed and conducted this single-armed, retrospective cohort study. The patients with cervical spondylotic myelopathy were recruited, and these patients exclusively received the surgical procedure of single-level ACCF in our single center. After the process of corpectomy, the size was tailored using different trials and the most suitable stand-alone AVB was then implanted. This AVB was manufactured by the fashion of 3D-printing. Two pairs of screws were inserted in an inclined way into the adjacent vertebral bodies, to stabilize the AVB. The participants were regularly followed-up after the operation. Their clinical data were thoroughly reviewed. We assessed the neurological status according to Japanese Orthopedic Association (JOA) scale. We determined the fusion based on imaging examination six months after the operation. The recorded clinical data were analyzed using specific software and they presented in suitable styles. Paired t test was employed in comparison analysis.

RESULTS

In total, there were eleven patients being recruited eventually. The patients were all followed up over six months after the operation. The mean age of the cohort was (57.2±10.2) years. The mean operation time was (76.1±23.1) min and the median bleeding volume was 150 (100, 200) mL. The postoperative course was uneventful for all the cases. Dysphagia, emergent hematoma, and deterioration of neurological function did not occur. Mean JOA scores were 13.2±2.2 before the operation and 16.3±0.8 at the final follow-up, which were significantly different (P < 0.001). The mean recovery rate of neurological function was 85.9%. By comparing the imaging examinations postoperatively and six months after the operation, we found that the average subsidence length was (1.2±1.1) mm, and that there was only one cases (9.1%) of the severe subsidence (>3 mm). We observed significant improvement of cervical lordosis after the operation (P=0.013). All the cases obtained solid fusion.

CONCLUSION

3D-printing stand-alone AVB presented favorable short-term outcome in one-level ACCF in this study. The fusion rate of this zero-profile prosthesis was satisfactory and the complication rate was relatively low.

Biomechanical analysis of the door-shaped titanium plate in single-level anterior cervical discectomy and fusion

BACKGROUND

Analyse and discuss the immediate stability of the cervical spine after anterior cervical discectomy and fusion using a door-shaped titanium plate and compare it with the traditional titanium plate, to provide biomechanical evidence for the rationality and effectiveness of the door-shaped titanium plate in clinical applications.

METHODS

Ten adult goat C4/5 vertebral bodies were obtained, and models were prepared using denture base resin. Biomechanical experiments were performed on the specimens before internal fixation. MTS was used to conduct non-destructive biomechanical loading tests in six directions, including flexion, extension, left-right bending, and left-right torsion, recording the range of motion (ROM) and neutral zone (NZ) of each specimen. The specimens were then randomly divided into two groups: the study group was fixed with a door-shaped titanium plate, and the control group was fixed with a traditional titanium plate. ROM and NZ in each direction were measured again. After measurements, both groups were subjected to 0.5 Hz torsion loading with a torque of 2 N m for a total of 3000 cycles, followed by measuring ROM and NZ in six directions once more.

RESULTS

Compared to before fixation, ROM and NZ in both groups significantly decreased in all six directions after fixation, with statistical significance (P < 0.05); after fixation, the study group showed slightly lower values for various mechanical reference parameters compared to the control group, with no statistical significance (P > 0.05); after 3000 torsional loads, both internal fixation groups showed increased ROM and NZ compared to after fixation but to a lower extent, and no screw or titanium plate loosening was observed. Compared to before fixation, the differences were still statistically significant (P < 0.05), with the study group having slightly lower ROM and NZ values in all directions compared to the control group, with no statistical significance (P > 0.05).

CONCLUSION

The door-shaped titanium plate exhibits mechanical properties similar to the traditional titanium plate in all directions, and its smaller size and simpler surgical operation can be used for anterior cervical endoscopic surgery, reducing surgical trauma. It is clinically feasible and deserves further research and promotion.

Biomechanical performance of the novel assembled uncovertebral joint fusion cage in single-level anterior cervical discectomy and fusion: A finite element analysis

Introduction: Anterior cervical discectomy and fusion (ACDF) is widely accepted as the gold standard surgical procedure for treating cervical radiculopathy and myelopathy. However, there is concern about the low fusion rate in the early period after ACDF surgery using the Zero-P fusion cage. We creatively designed an assembled uncoupled joint fusion device to improve the fusion rate and solve the implantation difficulties. This study aimed to assess the biomechanical performance of the assembled uncovertebral joint fusion cage in single-level ACDF and compare it with the Zero-P device.

Methods: A three-dimensional finite element (FE) of a healthy cervical spine (C2−C7) was constructed and validated. In the one-level surgery model, either an assembled uncovertebral joint fusion cage or a zero-profile device was implanted at the C5–C6 segment of the model. A pure moment of 1.0 Nm combined with a follower load of 75 N was imposed at C2 to determine flexion, extension, lateral bending, and axial rotation. The segmental range of motion (ROM), facet contact force (FCF), maximum intradiscal pressure (IDP), and screw−bone stress were determined and compared with those of the zero-profile device.

Results: The results showed that the ROMs of the fused levels in both models were nearly zero, while the motions of the unfused segments were unevenly increased. The FCF at adjacent segments in the assembled uncovertebral joint fusion cage group was less than that that of the Zero-P group. The IDP at the adjacent segments and screw–bone stress were slightly higher in the assembled uncovertebral joint fusion cage group than in those of the Zero-P group. Stress on the cage was mainly concentrated on both sides of the wings, reaching 13.4–20.4 Mpa in the assembled uncovertebral joint fusion cage group.

Conclusion: The assembled uncovertebral joint fusion cage provided strong immobilization, similar to the Zero-P device. When compared with the Zero-P group, the assembled uncovertebral joint fusion cage achieved similar resultant values regarding FCF, IDP, and screw–bone stress. Moreover, the assembled uncovertebral joint fusion cage effectively achieved early bone formation and fusion, probably due to proper stress distributions in the wings of both sides.

The clinical efficacy of anterior cervical discectomy and fusion with ROI-C device vs. plate-cage in managing traumatic central cord syndrome

Purpose

To assess the efficacy and complications of anterior cervical discectomy and fusion (ACDF) with ROI-C device vs. conventional anterior plate and cage system (APCS) in managing traumatic central cord syndrome (TCCS).

Methods

A total of 37 patients diagnosed with TCCS who underwent ACDF with ROI-C implant and APCS were recruited in this retrospective study from June 2012 to February 2020. Radiological parameters and clinical results were recorded and compared through follow-up time. Characteristics of patients and complications were also recorded.

Results

All patients tolerated the procedure well. The average follow-up time was 25.00 ± 7.99 months in the ROI-C group, and 21.29 ± 7.41 months in the APCS group. The blood loss and operation time were significantly lower in the ROI-C group than in the APCS group. Radiological parameters and clinical results were all improved postoperatively and maintained at the final follow-up. Fusion was achieved in all patients. ROI-C group had a lower incidence of postoperative dysphagia than the APCS group. Only 1 case of ALD was observed at the final follow-up in the APCS group.

Conclusions

Both ROI-C device and APCS demonstrated satisfactory clinical effects and safety in managing symptomatic single-level traumatic central cord syndrome with underlying instability. Both techniques could improve and maintain cervical lordosis and disc height. ROI-C device was related to a lower incidence of postoperative dysphagia, shorter operation time, and less blood loss.

Trends of single-level anterior cervical discectomy and fusion documentation after the 2015 Centers for Medicare & Medicaid Services coding audit

OBJECTIVE

With the use of anterior cervical discectomy and fusion (ACDF) expected to rise by 13.3% from 2020 to 2040, the increased usage of interbody cages with integral anterior fixation prompted a Centers for Medicare & Medicaid Services (CMS) review, which resulted in coding changes affecting anterior instrumentation documentation. CMS determined that Current Procedural Terminology (CPT) code 22845 should not be used to report integrated instrumentation (plate) with an interbody device, and if additional anterior instrumentation (e.g., plates and screws) is placed with an integrated interbody device, then a 59 modifier should be used. There is sparse literature examining the trends of ACDF without and with additional anterior instrumentation after the 2015 CMS audit. Therefore, this study aimed to evaluate the trends of single-level subaxial ACDF utilization from 2011 to 2019 to determine whether the 2015 CMS audit influenced the documented usage of additional anterior instrumentation.

METHODS

A retrospective cohort study was performed using the commercially available database PearlDiver. Patient records were queried from 2011 to 2019 for single-level subaxial ACDF without (CPT code 22551) and with (CPT codes 22551 + 22845) instrumentation. Cochran-Armitage trend analyses were performed to evaluate the hypothesis that ACDF with additional anterior instrumentation decreased over the given time period.

RESULTS

Between 2011 and 2019, the total number of single-level ACDFs decreased from 6202 to 4402. From 2011 to 2015, an average of 6240 patients per year underwent single-level subaxial ACDF; of those, 950 patients (15.2%) had ACDF without instrumentation and 5290 patients (84.8%) had ACDF with instrumentation. In 2016, the total number of single-level subaxial ACDFs decreased to 5525, with 1006 patients (18.2%) receiving no instrumentation and 4519 patients (81.8%) receiving instrumentation. From 2017 to 2019, an average of 4283 patients per year underwent a single-level subaxial ACDF; of these, 1280 (29.9%) had no instrumentation and 3003 (70.1%) had instrumentation (all p < 0.0001).

CONCLUSIONS

From 2015 to 2019, single-level ACDF without instrumentation significantly increased by 91.5% and ACDF with anterior instrumentation significantly decreased by 18.1%. The 2015 CMS audit of interbody cages and anterior instrumentation coding (CPT code 22845) may account for the decreased documentation of anterior instrumentation in the 9-year period. Understanding CMS auditing could help surgeons perceive changes in practice patterns that may lead to a more thorough evaluation of patient outcomes, cost, and overall value.

An update of interbody cages for spine fusion surgeries: from shape design to materials

INTRODUCTION

Discectomy and interbody fusion are widely used in the treatment of intervertebral disc-related diseases. Among them, the interbody cage plays a significant role. However, the complications related to the interbody cage, such as nonunion or pseudoarthrosis, subsidence, loosening, and prolapse of the cage, cannot be ignored. By changing the design and material of the interbody fusion cage, a better fusion effect can be obtained, the incidence of appeal complications can be reduced, and the quality of life of patients after interbody fusion can be improved.

AREAS COVERED

This study reviewed the research progress of cage design and material and discussed the methods of cage design and material to promote intervertebral fusion.

EXPERT OPINION

Current treatment of cervical and lumbar degenerative disease requires interbody fusion to maintain decompression and to promote fusion and reduce the incidence of fusion failure through improvements in implant material, design, internal structure, and function. However, interbody fusion is not an optimal solution for treating vertebral instability.Abbreviations: ACDF, Anterior cervical discectomy and fusion; ALIF, anterior lumbar interbody fusion; Axi-aLIF, axial lumbar interbody fusion; BAK fusion cage, Bagby and Kuslich fusion cage; CADR, cervical artificial disc replacement; DBM, decalcified bone matrix; HA, hydroxyapatite; LLIF/XLIF, lateral or extreme lateral interbody fusion; MIS-TLIF, minimally invasive transforaminal lumbar interbody fusion; OLIF/ATP, oblique lumbar interbody fusion/anterior to psoas; PEEK, Poly-ether-ether-ketone; PLIF, posterior lumbar interbody fusion; ROI-C, Zero-profile Anchored Spacer; ROM, range of motion; SLM, selective melting forming; TLIF, transforaminal lumbar interbody fusion or.

Zero-profile implant versus conventional cage-plate construct in anterior cervical discectomy and fusion for the treatment of single-level degenerative cervical spondylosis: a systematic review and meta-analysis

BACKGROUND

The clinical outcomes of single-level anterior cervical discectomy and fusion (ACDF) with the Zero-profile (Zero-p) were evaluated in comparison with the anterior cervical cage-plate construct (CPC).

METHODS

We performed a systematic search covering PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Science, Medline, China National Knowledge Infrastructure (NCKI), Wan Fang Database, and Wei Pu Database. Articles focused on single-level ACDF or data of the single - level that can be extracted were included, and articles that did not directly compare Zero-p and CPC were excluded. Twenty-seven studies were included with a total of 1866 patients, 931 in the Zero-p group and 935 in the CPC group. All outcomes were analyzed using Review Manager 5.4.

RESULTS

The meta-analysis outcomes indicated that operative time (WMD = - 12.47, 95% CI (- 16.89, - 8.05), P < 0.00001), intraoperative blood loss (WMD = - 13.30, 95% CI (- 18.83, - 7.78), P < 0.00001), risk of adjacent segment degeneration (ASD) (OR 0.31, 95% CI (0.20, 0.48), P < 0.0001), risk of dysphagia of short-term (OR 0.40, 95% CI (0.30, 0.54), P < 0.0001), medium-term (OR 0.31, 95% CI (0.20, 0.49), P < 0.0001), and long-term (OR 0.29, 95% CI (0.17, 0.51), P < 0.0001) of Zero-p group were significantly lower. The JOA score of Zero-p group at the final follow-up was significantly higher (WMD = - 0.17, 95% CI (- 0.32, - 0.03), P = 0.02). There were no significant differences in length of stay (LOS), Neck Disability Index (NDI), Visual Analogue Score (VAS), fusion rate, segmental Cobb angle, cervical Cobb angle, prevertebral soft tissue thickness (PSTT), SF-36, subsidence, implant failure, and hoarseness between the two groups. This study was registered with PROSPERO, CRD42022347146.

CONCLUSION

Zero-p group reduced operative time, intraoperative blood loss, JOA score at follow-up and reduced the incidence of dysphagia and postoperative ASD, but the two devices had the same efficacy in restoring the cervical curvature, preventing the cage subsidence, and in postoperative VAS, NDI, LOS, PSTT, SF-36, fusion rate, implant failure, and hoarseness in single-level ACDF. The use of Zero-p in single-level ACDF was recommended.

Is the Zero-P Spacer Suitable for 3-Level Anterior Cervical Discectomy and Fusion Surgery in Terms of Sagittal Alignment Reconstruction: A Comparison Study with Traditional Plate and Cage System

The Zero-P spacer was primarily developed aiming to reduce the morbidity associated with the traditional anterior cervical plate. During the past decade, many authors have reported the use of Zero-P spacers for anterior cervical discectomy and fusion (ACDF) of one or two segments. Nevertheless, there is still a paucity of knowledge on the safety and feasibility of using Zero-P spacers for 3-level fixation. The objective of this study was to investigate the clinical and radiological outcomes, with a focus on the sagittal alignment reconstruction of 3-level ACDF surgery using Zero-P spacers versus those using a traditional plate and cage system. From Sep 2013 to Aug 2016, a total of 44 patients who received 3-level ACDF surgery due to cervical spondylotic myelopathy were recruited. The Zero-P spacer was used in 23 patients (group ZP) and the traditional plate and cage system in 21 (group PC). Clinical outcomes were analyzed by Neck Disability Index (NDI) and Japanese Orthopedic Association (JOA) scores, and dysphagia was evaluated using the Bazaz score. Radiological outcomes, including fusion rate, adjacent segment degeneration (ASD), and especially changes in cervical sagittal alignment, were analyzed. The NDI and JOA scores did not differ significantly between the two groups postoperatively (p > 0.05); however, there was significantly less dysphagia in patients using Zero-P spacers at the 3- and 6-month follow-up (p < 0.05). At the 24-month follow-up, the fusion rate and ASD were similar between the two groups (p > 0.05). Interestingly, patients using Zero-P spacers had a significantly lower postoperative C2-7 Cobb angle and fused segment Cobb angle, compared to those using a traditional plate and cage system (p < 0.05); meanwhile, the fused segment disc wedge was also found to be significantly smaller in patients using Zero-P spacers after surgery (p < 0.05). Moreover, we further divided patients into subgroups according to their cervical lordosis. In patients with a preoperative C2-7 Cobb angle ≤ 10°, significantly less cervical and local lordosis, as well as disc wedge, were seen in group ZP after surgery (p < 0.05), while in others with a preoperative C2-7 Cobb angle > 10°, no significant difference in postoperative changes of the cervical sagittal alignment was seen between group ZP and group PC (p > 0.05). Zero-P spacers used in 3-level ACDF surgery could provide equivalent clinical outcomes and a lower rate of postoperative dysphagia, compared to the traditional plate and cage system. However, our results showed that it was inferior to the cervical plate in terms of sagittal alignment reconstruction for 3-level fixation. We recommend applying Zero-P spacers for 3-level ACDF in patients with good preoperative cervical lordosis (C2-7 Cobb angle > 10°), in order to restore and maintain physiological curvature of the cervical spine postoperatively.

Anterior cervical plating combined with zero-profile anchored spacer for the treatment of cervical facet dislocation in elderly patients

OBJECTIVE

The purpose of this study was to evaluate the efficacy of anterior cervical plating combined with zero-profile (Z-P) anchored spacer for the treatment of cervical facet dislocation in elderly patients.

METHODS

This is a retrospective study. Twelve elderly patients (from 57 to 77 years old, averaged 65 years) with unilateral or bilateral facet dislocation of sub-axial cervical spine from September 2015 to September 2019 surgically treated at the authors' hospital were enrolled in this study. The patients with osteoporosis or osteopenia were all surgically treated by anterior-only procedure using cervical plating combined with zero-profile anchored spacer after closed manual reduction under general anesthesia and spinal cord monitoring. The operation times (OT), estimated blood loss (EBL), perioperative complications, were recorded. The clinical evaluation included visual analogue scales (VAS) and the American Spinal Injury Association (ASIA) scale. The radiographic evaluation included kyphotic angle (KA) and disc height (DH) and the fusion rate.

RESULTS

Anterior discectomy, interbody fusion and fixation were performed in all patients after the disloctions were reduced by manual maneuver. The average OT was 66 minutes, with a range from 45 to 110 minutes. The EBL averaged 42 ml per surgical procedure, with a range from 20 to 60 ml. The VAS, ASIA, KA were improved significantly after surgery (P<0.05). The average follow-up time was 24.2 months, with a range from 12 to 38 months. There were no statistical differences between the immediately post-op KA and KA at the last follow-up (P>0.05). No disc space subsidence was observed statistically (P<0.05) Interbody fusion was obtained in all patients. Two patient experienced slight difficulty in swallowing, which were improved 6 weeks later. There were no hardware failure, no segmental instability, no wound infection or other complications.

CONCLUSIONS

Manual reduction with spinal cord monitoring under general anesthesia is a safe and efficient option and the anterior cervical plating combined with Z-P spacer could achieve reliable fixation for the patients with cervical facet dislocation in the elderly patients with osteoporosis or osteopenia.

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.

Zero-Profile Anchored Spacer (ROI-C) in the Treatment of Cervical Adjacent Segment Disease

Background  Self-locking stand-alone cages have increasingly been used in anterior cervical discectomy and fusion (ACDF) cervical degenerative disc disease. We studied clinical and radiological outcomes of patients who underwent zero-profile anchored spacer (ROI-C)–assisted ACDF without anterior plate fixation in cervical adjacent segment disease.

Materials and Methods  Fifteen patients suffering from cervical adjacent segment disease with various symptoms, such as radiculopathy, myelopathy, or both, were retrospectively evaluated. The cervical adjacent segment disease was confirmed by plain radiographs and magnetic resonance imaging. The patients underwent radiological evaluation to assess cervical curvature, intervertebral height, fusion, and subsidence. Clinical assessment was graded using a visual analog scale, Modified Japanese Orthopedic Association score, and the Neck Disability Index.

Results  There were 19 levels of operation. Single-level ACDF was performed in 11 patients and two level in 4 patients. In the postoperative period, our study revealed significant improvement in the clinical outcome. The cervical curvature and intervertebral height were significantly improved at 12-months follow-up ( p  < 0.05). The fusion rate was 100%, whereas subsidence occurred in 5.3% but produced no symptoms. Of the 19 operated segment, 2 (5.3%) from 38 VerteBRIDGE plates had breakage. There was only one case of mild dysphagia, which resolved in less than 2 weeks.

Conclusion  This study indicates that zero-profile anchored spacer (ROI-C) in the treatment of cervical adjacent segment disease provides improvement of clinical outcomes, restoration of lordosis, high fusion rate, and low incidence of dysphagia. However, subsidence and breakage of VerteBRIDGE plate occurred in 5.3% cases, but did not cause clinical symptoms.

Efficacy and safety of anterior cervical discectomy and fusion (ACDF) through mini-incision and posterior laminoplasty (LAMP) for treatment of long-level cervical spondylosis: a retrospective cohort study

BACKGROUND

The efficacy and safety of anterior cervical discectomy and fusion (ACDF) through mini-incision and posterior laminoplasty for long-level cervical spondylosis were investigated.

METHOD

From January 2018 to September 2019, clinical patients data with 3-4 segments (C3-7) cervical spondylotic radiculopathy, cervical spondylotic myelopathy, or mixed cervical spondylosis who received ACDF (42 cases) throughwith mini-incision or LAMP (36 cases) treatment were retrospectively collected and analyzed. The operative time, bleeding volume, incisive length, and hospital stay were recorded. Moreover, the intervertebral height, functional segment height, cervical lordosis, cervical hyperextension and hyperflexion range-of-motion (ROM) and ROM in all directions of the cervical spine before and after the operation were measured. Additionally, all relevant postoperative complications were also recorded. Then, the therapeutic effects of both surgical methods were investigated.

RESULTS

Patients in the ACDF group had less bleeding, shorter incision, and fewer hospitalization days than the LAMP group. There was no significant difference in JOA, VAS score of the upper limb, NDI score after surgery between two groups. Postoperative intervertebral height and functional segment height in the ACDF group were significantly higher than those before the operation, and postoperative functional segment height of the ACDF group was significantly higher than that of the LAMP group. Moreover, the postoperative cervical lordosis angle in the ACDF group was significantly larger than the LAMP group. There was no significant difference between preoperative and postoperative ROM in all directions of the cervical spine for the two groups.

CONCLUSIONS

Both ACDF through mini-incision and LAMP are effective treatments for long-level cervical spondylosis. However, ACDF through mini-incision shows minor trauma, less bleeding, fast recovery, and it is beneficial for cervical lordosis reconstruction.

Clinical Outcomes between Stand-Alone Zero-Profile Spacers and Cervical Plate with Cage Fixation for Anterior Cervical Discectomy and Fusion: A Retrospective Analysis of 166 Patients

Stand-alone (SA) zero-profile implants are an alternative to cervical plating (CP) in anterior cervical discectomy and fusion (ACDF). In this study, we investigate differences in surgical outcomes between SA and CP in ACDF. We conducted a retrospective analysis of 166 patients with myelopathy and/or radiculopathy who had ACDF with SA or CP from Jan 2013-Dec 2016. We measured surgical outcomes including Bazaz dysphagia score at 3 months, Nurick grade at last follow-up, and length of hospital stay. 166 patients (92F/74M) were reviewed. 92 presented with radiculopathy (55%), 37 with myelopathy (22%), and 37 with myeloradiculopathy (22%). The average operative time with CP was longer than SA (194 ± 69 vs. 126 ± 46 min) (p < 0.001), as was the average length of hospital stay (2.1 ± 2 vs. 1.5 ± 1 days) (p = 0.006). At 3 months, 82 patients (49.4%) had a follow-up for dysphagia, with 3 patients reporting mild dysphagia and none reporting moderate or severe dysphagia. Nurick grade at last follow-up for the myelopathy and myeloradiculopathy cohorts improved in 63 patients (85%). Prolonged length of stay was associated with reduced odds of having an optimal outcome by 0.50 (CI = 0.35-0.85, p = 0.003). Overall, we demonstrate that there is no significant difference in neurological outcome or rates of dysphagia between SA and CP, and that both lead to overall improvement of symptoms based on Nurick grading. However, we also show that the SA group has shorter length of hospital stay and operative time compared to CP.

Change in the postoperative intervertebral space height and its impact on clinical and radiological outcomes after ACDF surgery using a zero-profile device: a single-Centre retrospective study of 138 cases

BACKGROUND

The effects of postoperative intervertebral height (IH) changes on the clinical and radiological outcomes after anterior cervical decompression and fusion (ACDF) surgery using a zero-profile device remain unclear.

METHODS

We retrospectively reviewed patients who had undergone ACDF using a zero-profile device from March 2012 to February 2016 at our institution. Based on the postoperative IH variation, the patients were divided into group A with postoperative IH 0 to 2 mm, group B with postoperative IH 2 to 4 mm, and group C with postoperative IH greater than 4 mm. Clinical efficacy was evaluated using JOA, VAS, and NDI scores in the groups. Imaging parameters including the IH, cervical lordosis, fusion rate, intervertebral foramen (IVF) diameter and complications such as subsidence, dysphagia, and ASD were also compared across the three groups.

RESULTS

The average IH increased significantly from 6.72 mm preoperatively to 10.46 mm 1 week after surgery, and then gradually decreased to 7.48 mm at the final follow-up. The fusion rate was 61.90% in group A, 63.23% in group B, 53.57% in group C at 3 months, 73.81% in group A, 79.41% in group B, 67.86% in group C at 6 months, 90.48% in group A, 95.59% in group B, 92.86% in group C 1 year after surgery, and at the last follow-up, the fusion rate of three groups was all 100%. The IVF diameter was 6.52 ± 1.80 mm in group A, 9.55 ± 2.36 mm in group B, and 9.34 ± 1.62 mm in group C. ASD at the superior and inferior levels affected 11.90 and 16.67% patients in group A, 5.88 and 7.38% in group B, and 14.28 and 10.71% in group C. Regarding the 3 groups, the subsidence rates were 7.14, 4.41, and 14.29%, respectively.

CONCLUSIONS

No clear correlation was found between IH changes and clinical efficacy within a year of surgery. However, the IH may affect various complications after ACDF. If postoperative IH changes are maintained at 2 to 4 mm after a year, a satisfactory imaging parameters and relatively low complications may be achieved after ACDF surgery using a zero-profile device.

A biomechanical analysis of four anterior cervical techniques to treating multilevel cervical spondylotic myelopathy: a finite element study

BACKGROUND

The decision to treat multilevel cervical spondylotic myelopathy (MCSM) remains controversial. The purpose of this study is to compare the biomechanical characteristics of the intervertebral discs at the adjacent segments and internal fixation, and to provide scientific experimental evidence for surgical treatment of MCSM.

METHODS

An intact C2-C7 cervical spine model was developed and validated. Four additional models were developed from the fusion model, including multilevel anterior cervical discectomy and fusion (mACDF), anterior cervical corpectomy and fusion (ACCF), hybrid decompression and fusion (HDF), and mACDF with cage alone (mACDF-CA). Biomechanical characteristics on the plate and the disc of adjacent levels (C2/3, C6/7) were comparatively analyzed.

RESULTS

Of the four models, stress on the upper (C2/3) adjacent intervertebral disc was the lowest in the mACDF-CA group and highest in the ACCF group. Stress on the intervertebral discs at adjacent segments was higher for the upper C2/3 than the lower C6/7 intervertebral disc. In all models, the mACDF-CA group had the lowest stress on the intervertebral disc, while the ACCF group had the highest stress. In the three surgical models with titanium plate fixation (mACDF, ACCF, and HDF), the ACCF group had the highest stress at the titanium plate-screw interface, while the mACDF group had the lowest stress.

CONCLUSION

Among the four anterior cervical reconstructive techniques for MCSM, mACDF-CA makes little effect on the adjacent disc stress, which might reduce the incidence of adjacent segment degeneration (ASD) after fusion. However, the accompanying risk of the increased incidence of cage subsidence should never be neglected.

Results of Four-Level Anterior Cervical Discectomy and Fusion Using Stand-Alone Interbody Titanium Cages

Study Design

This is a retrospective study with a minimum follow-up of 2 years.

Purpose

The aim of this study is to assess the long-term outcomes after performing the four-level anterior cervical discectomy and fusion (ACDF) in the treatment of degenerative cervical spine disease using stand-alone titanium cages.

Overview of Literature

Over the last decades, a rapid increase in the use of stand-alone cages for ACDF has been observed. However, research on their application in the treatment of four-level diseases is insufficient.

Methods

In this study, 130 patients presenting with symptomatic cervical spondylosis who underwent four-level ACDF using stand-alone cages in our institution between 2008 and 2016 were assessed. Fifty-two patients were women and 78 men with a mean age of 60.5 years. Their clinical and radiological outcomes were assessed. The results of the Neck Disability Index (NDI) and Visual Analog Scale as well as bony fusion were evaluated, and the revisions were analyzed. All of the patients underwent the four-level microscopic ACDF using the same titanium rectangular cage.

Results

The mean follow-up was 47±11.4 months. A fusion of all four levels was achieved in 80.72% of the patients. In 25 patients (19.23%), an incomplete bony bridging was observed in at least one fusion level at the final follow-up. However, only two patients (1.5%) were symptomatic and underwent revision. The mean NDI improved significantly from 39.4±9.3 at presentation to 8.3±6.6 at the final follow-up. Cervical lordosis improved significantly from a mean of 5.5° preoperatively to a mean of 15° postoperatively. Cage sinking and loss of segment height during healing had a mean of 3 mm.

Conclusions

Overall, the application of four-level ACDF using titanium cages in a stand-alone technique has been proven to be a safe and effective treatment method for degenerative disease. In a large cohort, a high rate of good long-term clinical and radiological results was achieved.

Pseudarthrosis in anterior cervical discectomy and fusion with a self-locking, stand-alone cage filled with hydroxyapatite: a retrospective study with clinical and radiological outcomes of 98 levels with a minimum 2-year follow-up

OBJECTIVE

The goal of this study was to evaluate the incidence of pseudarthrosis after the treatment of cervical degenerative disc disease (CDDD) with anterior cervical discectomy and fusion (ACDF) in which self-locking, stand-alone intervertebral cages filled with hydroxyapatite were used.

METHODS

The authors performed a retrospective cohort study of 49 patients who underwent 1- to 3-level ACDF with self-locking, stand-alone intervertebral cages without plates, with a minimum 2 years of follow-up. The following data were extracted from radiological and clinical charts: age, sex, time and type of pre- and postoperative signs and symptoms, pain status (visual analog scale [VAS]), functional status (Neck Disability Index [NDI]), history of smoking, bone quality (bone densitometry), and complications. Pseudarthrosis was diagnosed by a blinded neuroradiologist using CT scans. Clinical improvement was assessed using pre- and postoperative comparison of VAS and NDI scores. The Wilcoxon test for paired tests was used to evaluate statistical significance using a p value of < 0.05.

RESULTS

Three patients (6%) developed symptomatic pseudarthrosis requiring reoperation, with only 1 patient showing clinical worsening due to pseudarthrosis, while the other 2 with pseudarthrosis had associated disc disease at an adjacent level. The rate of symptomatic pseudarthrosis according to the number of operated levels was 0% for 1 level, 8.7% (2/23 patients) for 2 levels, and 7.7% (1/13 patients) for 3 levels. The total pseudarthrosis rate (including both symptomatic and asymptomatic patients) was 16.4%. Considering the clinical outcomes, there was a significant improvement of 75.6% in neck pain and 95.7% in arm pain, as well as a 64.9% improvement in NDI scores. Complications were observed in 18.4% of patients, with adjacent-level degenerative disease being the most prevalent at 14.3%.

CONCLUSIONS

ACDF with self-locking, stand-alone cages filled with a hydroxyapatite graft can be used for the surgical treatment of 1- to 3-level CDDD with clinical and radiological outcomes significantly improved after a minimum 2-year follow-up period. Comparative studies are necessary.

Dysphagia rates in single- and multiple-level anterior cervical discectomy and fusion surgery: a meta-analysis

Background

To conduct a meta-analysis to assess dysphagia complicating single-level and multiple-level (≥2) anterior cervical discectomy and fusion (ACDF) surgery.

Methods

Electronic searches were performed using four electronic databases from their inception to December 2017. Relevant studies reporting the rate of dysphagia as an endpoint for patients undergoing ACDF for degenerative disease, myelopathy, cervical canal stenosis or ossification of the posterior longitudinal ligament were identified according to prior inclusion and exclusion criteria. Statistical analysis was performed using a fixed effect model. P-scores were used to rank the levels of ACDF based on the rate of dysphagia. I² was used to explore heterogeneity.

Results

Ten studies were identified and included in the systematic review and meta-analysis, with a total of 4,018 patients identified; 2,362 patients underwent single-level ACDF, while 1,656 underwent multiple level (≥2 ACDF). The mean age ranged from 49.45 to 57.77 years. Mean follow-up time ranged from 2 days to 27.3 months. Overall, meta-analysis demonstrated a statistically significant higher dysphagia rate for multiple-level ACDF (6.6%) than for single-level ACDF (4%) (P heterogeneity =0.151, OR =1.42, 95% CI: 1.05-1.91, I²=32%).

Conclusions

Dysphagia is a relatively common complication in the early postoperative period following ACDF and may cause patients significant discomfort and distress. This meta-analysis demonstrates a higher rate of dysphagia with multiple-level ACDF than with single-level ACDF at a period of 12-24 months.

Incidence of Subsidence of Seven Intervertebral Devices in Anterior Cervical Discectomy and Fusion: A Network Meta-Analysis

BACKGROUND

Subsidence is an incapacitating complication in anterior cervical discectomy and fusion (ACDF). However, the debate over which of the intervertebral devices is associated with lower incidence of subsidence remains to be settled.

METHODS

Seven dominant techniques comprising cage with plate (CP), iliac bone graft with plate (IP), Zero-profile cage with screws (Zero-P), ROI-C cages with clips (ROI-C), polyether ether ketone cage alone (PCA), iliac crest autogenous graft (ICAG), and titanium cage alone (TCA) were examined. The incidences of subsidence in the different groups were calculated and compared.

RESULTS

A total of 30 studies with 2264 patients were identified. Overall, the CP group presented the lowest incidence of subsidence, and its incidence was significantly lower than that in the Zero-P group, the PCA group, the ICAG group, and the TCA group (P < 0.05). The incidence of subsidence in the IP group was significantly lower than that in the PCA group, the ICAG group, and the TCA group (P < 0.05). In single-level ACDF, the CP group presented the lowest incidence of subsidence, and its incidence was significantly lower than that in the PCA group and the TCA group (P < 0.05). No difference was found between single-level and multilevel ACDF and the incidence of subsidence was higher in those undergoing single-level ACDF.

CONCLUSIONS

CP and IP resulted in a lower rate of subsidence than cage alone or ICAG. Zero-P and ROI-C cages led to similar subsidence rates with plate. All types of intervertebral device can be applied to both single-level and multilevel ACDF with comparable subsidence rate.

Is the bone fusion affected by Modic-2 changes in single-level anterior cervical discectomy and fusion?

To explore the impact of Modic changes (MCs) on bone fusion after single-level anterior cervical discectomy and fusion (ACDF) with a zero-profile implant (the Zero-P implant system).From November 2014 to November 2017, a total of 116 patients who underwent single-level ACDF with the Zero-P implant were divided into two groups according to MRI showing type 2 MCs (MC2) or no MCs (i.e., the MC2 group and the NMC group, respectively). A total of 92 (79.3%) patients were classified into the NMC group, and 24 (20.7%) patients were classified into the MC2 group. The clinical outcomes and fusion rates were retrospectively evaluated between the 2 groups preoperatively and postoperatively at 3, 6, and 12 months, and the final follow-up.The Japanese Orthopedic Association (JOA) scores and the visual analogue scale (VAS) scores of neck pain were significantly improved compared to the preoperative scores in both the NMC and MC2 groups (P < .05). However, there were no differences in JOA or VAS scores between the 2 groups (P > .05). The fusion rates of the NMC and MC2 groups at 3, 6, and 12 months postoperatively, and the final follow-up were 33.7% and 12.5%, 77.2% and 54.2%, 89.1% and 87.5%, and 97.8% and 95.8%, respectively. The fusion rates were significantly lower at 3 and 6 months after surgery in the MC2 group than in the NMC group (P < .05).The presence of MC2 did not affect the clinical outcome but delayed the fusion time following ACDF with the Zero-P implant system.Level of Evidence is Level 3.

A Biomechanical Evaluation of a Next-Generation Integrated and Modular ACDF Device Possessing Full-Plate, Half-Plate, and No-Profile Fixation Iterations

STUDY DESIGN

In vitro biomechanical study.

OBJECTIVES

The objective of this in vitro biomechanical range-of-motion (ROM) study was to evaluate spinal segmental stability following fixation with a novel anterior cervical discectomy and fusion (ACDF) device ("novel device") that possesses integrated and modular no-profile, half-plate, and full-plate fixation capabilities.

METHODS

Human cadaveric (n = 18, C3-T1) specimens were divided into 3 groups (n = 6/group). Each group would receive one novel device iteration. Specimen terminal ends were potted. Each specimen was first tested in an intact state, followed by anterior discectomy (C5/C6) and iterative instrumentation. Testing order: (1) novel device (group 1, no-profile; group 2, half-plate; group 3, full-plate); (2) novel device (all groups) with lateral mass screws (LMS); (3) traditional ACDF plate + cage; (4) traditional ACDF plate + cage + LMS. A 2 N·m moment was applied in flexion/extension (FE), lateral bending (LB), and axial rotation (AR) via a kinematic testing machine. Segmental ROM was tracked and normalized to intact conditions. Comparative statistical analyses were performed.

RESULTS

Key findings: (1) the novel half- and full-plate constructs provided comparable reduction in FE and LB ROM to that of traditional plated ACDF (P ≥ .05); (2) the novel full-plate construct significantly exceeded all other anterior-only constructs (P ≤ .05) in AR ROM reduction; and (3) the novel half-plate construct significantly exceeded the no-profile construct in FE (P < .05).

CONCLUSIONS

The novel ACDF device may be a versatile alternative to traditional no-profile and independent plating techniques, as it provides comparable ROM reduction in all principle motion directions, across all device iterations.

Correlation Between Different Interbody Grafts and Pseudarthrosis After Anterior Cervical Discectomy and Fusion Compared with Control Group: Systematic Review

BACKGROUND

Cervical spine degenerative disease is one of the main causes of myelopathy. Anterior cervical discectomy and fusion (ACDF) is the most common surgical procedure used to treat cervical myelopathy. Therefore, it is important to study pseudarthrosis rates after ACDF and correlate them with the graft used.

METHODS

We performed a systematic review to evaluate the relationship between pseudarthrosis after ACDF and the interbody graft used.

RESULTS

A total of 3732 patients were evaluated in 46 studies. The mean age of the included patients was 51.5 ± 4.18 years (range, 42-59.6 years). ACDF is most often perforemd as single-level surgery and the level most impaired is C5-C6. The use of titanium cages, zero profile, recombinant human bone morphogenetic protein 2, and carbon cages was seen as a protective factor for pseudarthrosis compared with the autograft group (control group); with an odds ratio of 0.29, 0.51, 0.03, and 0.3, respectively; the results were statistically relevant. The use of polyetheretherketone, poly(methyl methacrylate), and trabecular metal was a risk factor for development of pseudarthrosis compared with the control group, with an odds ratio of 1.7, 8.7, and 6.8, respectively; the results were statistically relevant. Radiologic follow-up was an important factor for the pseudarthrosis rate; paradoxically, a short follow-up (<1 year) had lower rates of pseudarthrosis and follow-up >2 years increased the chance of finding pseudarthrosis.

CONCLUSIONS

Different types of grafts lead to a significant difference in pseudarthrosis rates. Follow-up time is also an important factor that affects the rate of pseudarthrosis after ACDF.

Three-Dimensional, High-Definition Exoscopic Anterior Cervical Discectomy and Fusion: A Valid Alternative to Microscope-Assisted Surgery

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) remains one of the most commonly taught procedures during residency and one of the most frequently performed by neurosurgeons. Neurosurgeons use microscopes to perform surgery and to train other surgeons. Although the microscope provides excellent illumination and magnification, its use will be limited to 2 people: the surgeon and the assistant. Consequently, the scrub nurse and residents watching 2-dimensional images on monitors will have a reduced perception of the surgical field depth and anatomical details. The exoscope has been introduced as an alternative to microscopes and endoscopes. We used a 3-dimensional (3D), high-definition exoscope (3D Vitom [Karl Storz, Tuttlingen, Germany]) in 2 patients undergoing 2-level ACDF for cervical myeloradiculopathy.

METHODS

The exoscope was used during soft tissue dissection, discectomy, osteophytectomy, and cage insertion. Microsurgical drilling of the posterior osteophytes, which will usually require adequate magnification and proper microscope angulation, was also performed using the exoscope.

RESULTS

The exoscope provided a 3D view of the surgical field similar to that provided by a microscope and allowed us to effectively and safely perform the required surgical steps. The main advantage of 3D exoscope-assisted surgery, compared with microscope-assisted surgery, is the possibility to generate videos with a similar view and image quality as perceived by the surgeon. Therefore, the didactic capabilities of exoscopic videos are greater than those provided by microscopic videos. Exoscopes are also smaller compared with microscopes, allowing for comfortable use from the early surgical steps to device implantation.

CONCLUSION

We believe that exoscope-assisted surgery could become a safe and effective alternative to microscope-assisted surgery in ACDF.

[Minimally invasive fusion in patients with multilevel cervical spinal stenosis: case report and literature review]

Age-related degenerative changes in osseocartilaginous structures of the cervical spine are found in 50% of middle-aged population that is able to work. Although most cases are asymptomatic, such changes as herniated intervertebral disks, marginal osteophyte formation, hypertrophied joint and ligaments are the reason for neurological symptoms and cause neck pain, radiculopathy, and myelopathy. Surgical access to the cervical vertebrae and options for spinal decompression have long been known and standardized. There are also many methods (both anterior and posterior ones) for fixing the operated segments. This article describes minimally invasive anterior fusion used for patients with multilevel cervical spinal stenosis using zero-profile cages with a blocking mechanism. Statistical analysis of clinical efficacy of this treatment was also performed. It demonstrates that advantages of the chosen decompression and fixation method are as follows: it is minimally invasive and ensures that surgical trauma is minimal, so patients recover quickly.

Predictive Factors of Postoperative Dysphagia in Single-Level Anterior Cervical Discectomy and Fusion

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVE

To investigate if zero profile devices offer an advantage over traditional plate/cage constructs for dysphagia rates in single level anterior cervical discectomy and fusion (ACDF).

SUMMARY OF BACKGROUND DATA

Dysphagia rates following ACDF have been reported to be as high as 83%, most cases are self-limiting, but chronic dysphagia can continue in up to 35% of patients. Zero profile devices were developed to limit dysphagia, and other plate specific complications, however the literature is currently divided regarding their efficacy.

METHODS

Dysphagia was assessed by swallowing quality of life (SWAL-QOL) scores preoperatively, at 6 weeks and 12 weeks. Patient reported outcome measures (PROMs) including visual analog scale (VAS) and Neck Disability Index (NDI) were collected preoperatively, at 6 weeks and at 6 months. Univariate and multivariate regression analysis was conducted with SWAL-QOL score as the dependent variable.

RESULTS

Sixty-four patients were included, 41 received a zero profile device, and 23 received plate-graft construct. Both groups were similar regarding patient demographics, except operative time, with the zero-profile group having a shorter procedure time than the cage-plate group (44.88 ± 6.54 vs. 54.43 ± 14.71 min, P = 0.001). At all timepoints dysphagia rates were similar between the groups. Regression analysis confirmed preoperative SWAL-QOL and operative time were the only significant variables. PROMs were also similar between groups at all time points, except VAS neck at 6 months, which was lower in the plate-graft group (1.05 ± 1.48 vs. 3.43 ± 3.21, P = 0.007).

CONCLUSION

Operative time and preoperative SWAL-QOL scores are predictive of dysphagia in single level ACDF. Zero profile devices had a significantly shorter operative time, and may provide a benefit in dysphagia rates in this regard.

LEVEL OF EVIDENCE

3.

The use of anterior cervical interbody spacer with integrated fixation screws for management of cervical disc disease

INTRODUCTION

Integrated cage and screw designs were introduced for anterior cervical discectomy and fusion (ACDF) and allegedly are superior to anterior plating due to their minimal anterior profile.

METHODS

A descriptive study was designed as a prospective case series of 25 patients (30 operated discs) with cervical disc disease treated with a zero-profile cage, and followed up for an average of 16 months (range 12 -18 months). Functional assessment was done with the Neck Disability Index (NDI) and Visual analog scale (VAS) scores for arm and neck pain. Furthermore, Nurick's classification system for myelopathy based on gait abnormalities was documented. Radiological fusion was confirmed with plain X-rays and when indicated with a CT scan at 12 months postoperatively. Dysphagia was classified according to the Bazaz criteria.

RESULTS

VAS for neck and arm pain, NDI, and Nurick Score immediately improved postoperatively and remained so at 12-month follow-up. Fusion was achieved in 19 patients (95%) at six months and in 20 patients (100%) of the single-level group at one year. At six months 80% (four patients) and at 12 months 100% (five patients) showed complete union in the double-level group. No evidence of cage subsidence was noted radiographically.

DISCUSSION

The favorable lordosis and fusion rates of the low-profile integrated device are consistent with ACDF using anterior plating. Additionally, improved pain and an acceptable rate of dysphagia support the use of integrated interbody spacers for use in ACDF procedures.

Retropharyngeal Granulation: Delayed Complication of Anterior Cervical Diskectomy and Fusion in C2-3

BACKGROUND

A 26-year-old man presented with acute quadriparesis owing to a traffic accident. A computed tomography scan revealed a hangman fracture and locking of the left facet joint at C2-3. Magnetic resonance imaging showed a high signal change of the spinal cord on T2-weighted image and hemorrhage in the C2-3 level.

CASE DESCRIPTION

An emergency closed reduction after anterior cervical diskectomy and fusion were performed for spinal stability and decompression of the dural sac. Five months postoperatively, C1-2-3 posterior wiring using an iliac bone graft with the Brook method was performed due to nonunion of C2-3. After using the posterior cervical approach, the patient began complaining about the difficulty in swallowing. A 5 × 2 × 1-cm-sized posterior pharyngeal wall mass was detected on an endoscopic examination. Despite conservative management, the retropharyngeal mass progressed and dysphagia worsened, so the retropharyngeal wall granulation mass was resected by a laryngologist. Despite removal of the granulation mass, dysphagia and throat discomfort persisted for about 2 years. The plate and screws were removed considering their possible correlation with the granulation tissue. One month after plate removal, the retropharyngeal granulation tissue resolved almost spontaneously. At the last follow-up, the radiologic examination showed well-fused C1-2-3 with good alignment. The patient had no residual neurologic deficits or dysphagia.

CONCLUSIONS

Retropharyngeal granulation can occur as a late complication associated with plate fixation after anterior cervical diskectomy and fusion. Recurrent retropharyngeal wall granulation caused by plate irritation might only be resolved after plate and screw removal.

Comparison of radiological outcomes and complications between single-level and multilevel anterior cervical discectomy and fusion (ACDF) by using a polyetheretherketone (PEEK) cage-plate fusion system

This study aimed to compare the differences in radiological outcomes and complications between single- and multilevel anterior cervical discectomy and fusion (ACDF) by using a polyetheretherketone (PEEK) cage-plate fusion system.Fifty-seven patients who underwent ACDF via the PEEK cage-plate fusion system were enrolled and subjected to ≥6 months of follow-up. The patients were divided into 4 groups according to different cage-plate implantation levels: 1-level group (n = 17), 2-level group (n = 24), 3-level group (n = 12), and 4-level group (n = 4). Fusion time, changes in segment and global lordotic angle, subsidence rate, and changes in disc and adjacent segmental disc height were subjected to radiological evaluation.The fusion period of multilevel ACDF was longer than that of single-level ACDF. The fusion period of the 3-level (4.09 ± 0.94, P = .004) and 4-level (5.25 ± 0.89, P = .004) group was also significantly longer than that of the 1-level group. The mean lordotic angle in all of the groups was changed in the immediate postoperative period and in the final follow-up. The cage subsidence rates were 11.76% (2/17) in the 1-level group, 20.83% (5/24) in the 2-level group, and 2/12 (16.67%) in the 3-level group. No subsidence occurred in the 4-level groups. Changes in the lower adjacent segmental disc height were significantly increased in multilevel ACDF compared with those in single-level ACDF.Despite the longer fusion time, the outcomes of the proposed system were even better with the greater number of treatment levels by using PEEK cage-plate fusion system. Changes in the lower adjacent segmental disc height should also prolong follow-up duration to investigate the symptomatic adjacent segment degeneration in multilevel ACDF.

Clinical outcomes of locking stand-alone cage versus anterior plate construct in two-level anterior cervical discectomy and fusion: a systematic review and meta-analysis

BACKGROUND

Two-level cervical degenerative disc disease (cDDD) can be effectively treated by anterior cervical discectomy and fusion (ACDF) similarly to single-level cDDD. Traditionally an anterior plate construct (APC) approach has been utilized, but ACDF without plate with a locking stand-alone cage (LSC) approach has emerged as an alternative option. The aim of this study was to compare the clinical outcome of LSC and APC in contiguous two-level ACDF used to treat cDDD the current literature.

METHODS

Searches of seven electronic databases from inception to March 2018 were conducted following preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Extracted data were analysed using meta-analysis of proportions.

RESULTS

The nine observational studies that satisfied all criteria described a pooled cohort of 687 contiguous two-level cDDD cases managed by ACDF, with 302 (44%) and 385 (56%) managed by LSC and APC approaches, respectively. When compared with APC, LSC was associated with significantly increased subsidence likelihood (OR 2.75; p < 0.001), greater disc height (MD 0.60 mm; p = 0.04) and reduced cervical lordosis (MD - 2.52°; p = 0.04) at last follow-up. Operative outcomes, fusion rates, functional scores and postoperative dysphagia rates were comparable.

CONCLUSION

Although significant radiological differences were most evident, the comparability between LSC and APC in contiguous two-level ACDF with respect to all other clinical outcomes does not implicate one approach as clearly superior to the other in two-level ACDF. Larger, randomized studies with longer follow-up are required to delineate outcomes further to validate the findings of this study. These slides can be retrieved under Electronic Supplementary Material.

Radiological Fusion Criteria of Postoperative Anterior Cervical Discectomy and Fusion: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

Diagnosis of pseudarthrosis after anterior cervical fusion is difficult, and often depends on the surgeon's subjective assessment because recommended radiographic criteria are lacking. This review evaluated the available evidence for confirming fusion after anterior cervical surgery.

METHODS

Articles describing assessment of anterior cervical fusion were retrieved from MEDLINE and SCOPUS. The assessment methods and fusion rates at 1 and 2 years were evaluated to identify reliable radiographical criteria.

RESULTS

Ten fusion criteria were described. The 4 most common were presence of bridging trabecular bone between the endplates, absence of a radiolucent gap between the graft and endplate, absence of or minimal motion between adjacent vertebral bodies on flexion-extension radiographs, and absence of or minimal motion between the spinous processes on flexion-extension radiographs. The mean fusion rates were 90.2% at 1 year and 94.7% at 2 years. The fusion rate at 2 years had significant independence (P = .048).

CONCLUSIONS

The most common fusion criteria, bridging trabecular bone between the endplates and absence of a radiolucent gap between the graft and endplate, are subjective. We recommend using <1 mm of motion between spinous processes on extension and flexion to confirm fusion.

Diagnosing Pseudoarthrosis After Anterior Cervical Discectomy and Fusion

Radiographic confirmation of fusion after anterior cervical discectomy and fusion (ACDF) surgery is a critical aspect of determining surgical success. However, there is a lack of established diagnostic radiographic parameters for pseudoarthrosis. The purpose of this study is to summarize the findings of previous studies, review the advantages and disadvantages of frequently employed diagnostic criteria, and present our recommended protocol of fusion assessment. This study identified randomized controlled trials, case-control studies, and prospective and retrospective cohort studies reporting on spinal fusion and how successful fusion after ACDF. Among the 39 articles reviewed, bridging bone across the operated levels on static radiographs was the most commonly used criteria to confirm fusion (31 of 39, 79%). Dynamic flexion-extension radiographs were used to assess for interspinous movement (ISM) (22 of 39, 56.4%) and change in Cobb angle (12 of 39, 30.8%). Computed tomography (CT) based findings (21 of 39, 53.8%) were employed in ambiguous cases with improved sensitivity and specificity. Reconstructed CT scans were used to assess for intragraft bridging bone and extragraft bridging bone (ExGBB). ExGBB were proved to have the highest diagnostic sensitivity and specificity for pseudoarthrosis detection when compared to all other radiographic criteria. The ISM <1 mm on dynamic flexion-extension radiographs had high diagnostic sensitivity and specificity as well. After our reviewing, we recommend using dynamic lateral flexion-extension cervical spine radiographs at 150% magnificationin which the interspinous motion <1 mm and superjacent interspinous motion ≥4 mm confirms fusion. In ambiguous cases, we recommend using reconstructed CT scans to evaluate for ExGBB.

Can the Zero-Profile Implant Be Used for Anterior Cervical Discectomy and Fusion in Traumatic Subaxial Disc Injury? A Preliminary, Retrospective Study

Objective

The zero-profile implant (Zero-P) is accepted for use in anterior cervical fusion for the treatment of degenerative cervical disease. However, evidence pertaining to its efficiency and safety in traumatic cervical injury is largely insufficient. This study aimed to compare the overall outcomes of patients who underwent Zero-P for traumatic cervical disc injury.

Methods

Data from a total of 53 consecutive patients who underwent surgery for traumatic or degenerative cervical disc disease using the Zero-P were reviewed. Seventeen patients (group A) had traumatic cervical disc injury and the remaining 36 (group B) had degenerative cervical disc herniation. The fusion and subsidence rates and Cobb angle were measured retrospectively from plain radiographs. The patients’ clinical outcomes were evaluated using the Japanese Orthopedic Association (JOA) score and Odom’s criteria.

Results

The C2–7 Cobb and operative segmental angles increased by 3.45±7.61 and 2.94±4.59 in group A; and 2.46±7.31 and 2.88±5.49 in group B over 12 postoperative months, respectively. The subsidence and fusion rate was 35.0% and 95.0% in group A; and 36.6% and 95.1% in group B, respectively. None of the parameters differed significantly between groups. The clinical outcomes were similar in both groups in terms of increasing the JOA score and producing a grade higher than “good” using Odom’s criteria.

Conclusion

The application of Zero-P in patients with traumatic cervical disc injury was found to be acceptable when compared with the clinical and radiological outcomes of degenerative cervical spondylosis.

Anterior Techniques in Managing Cervical Disc Disease

Surgical treatment may be indicated for select patients with cervical disc disease, whether it is cervical disc herniation or spondylosis due to degenerative changes, acute cervical injury due to trauma, or other underlying cervical pathology. Currently, there are various surgical techniques, including anterior, posterior, or combined approaches, in addition to new interventions being utilized in practice. Ideally, the surgical approach should be selected in consideration of each patient’s clinical presentation, imaging findings, and overall medical comorbidities on an individual basis. But the unique advantages and disadvantages of each surgical technique often complicate the therapy choice in managing cervical disc diseases. Although anterior cervical discectomy and fusion (ACDF) is the most widely accepted procedure performed for both single and multi-level cervical disc diseases, there are multiple modifications to this technique. Surgeons have access to different types of plates, screws, and cages and can adopt newer advances in the field such as stand-alone and minimally invasive techniques when indicated. In short, no consensus exists in terms of a single approach that is preferred for all patients. This article aims to review the standard of care for management of cervical disc disease with a focus on the surgical techniques and, in particular, the anterior approach, exploring the various surgical options within this technique.

Single anterior cervical discectomy and fusion (ACDF) using self- locking stand-alone polyetheretherketone (PEEK) cage: evaluation of pain and health-related quality of life

BACKGROUND

Anterior cervical discectomy and fusion (ACDF) constitutes the conventional treatment of cervical disc herniation due to degenerative disc disease (DDD). ACDF with plating presents a variety of complications postoperatively and stand-alone cages are thought to be a promising alternative. The aim of this study was firstly, to analyze prospectively collected data from a sample of patients treated with single ACDF using C-Plus self-locking stand-alone PEEK cage system, without the use of plates or screws, in order to evaluate pain levels of patients, utilizing Neck and Arm Pain scale as an expression of visual analogue scale (VAS). Secondly, we aimed to evaluate health-related quality of life, via the short-form 36 (SF-36) and Neck Disability Index (NDI).

METHODS

Thirty-six patients (19 male and 17 female) with mean age 49.6±7 years old who underwent successful single ACDF using self-locking stand-alone PEEK cage for symptomatic cervical DDD were selected for the study. Neck and Arm pain, as well as SF-36 and NDI were estimated preoperatively and 1, 3, 6, and 12 months postoperatively. Patients underwent preoperative and postoperative clinical, neurological and radiological evaluation.

RESULTS

The clinical and radiological outcomes were satisfactory after a minimum 1-year follow-up. All results were statistically important (P<0.05), excluding improvement in NDI measured between 6 and 12 months. SF-36, Neck Pain, as well as Arm Pain featured gradual and constant improvement during follow-up, with best scores presenting at 12 months after surgery, while NDI reached its best at 6 months postoperatively.

CONCLUSIONS

Generally, all scores showed improvement postoperatively during the different phases of the follow-up. Subsequently, ACDF using C-Plus cervical cage constitutes an effective method for cervical disc herniation treatment, in terms of postoperative improvement on pain levels and health-related quality of life and a safe alternative to the conventional method of treatment for cervical DDD.

Cervical Burst Fracture in a Patient with Contiguous 2-Level Cervical Stand-Alone Cages

BACKGROUND

Cervical stand-alone interbody cages have seen increasingly wider use over the plate-and-screw construct in single-level anterior cervical discectomy and fusion (ACDF) in the treatment of cervical disc herniation and degenerative spondylotic conditions. Despite positive clinical outcomes, the efficacy and safety of using these devices in contiguous multilevel ACDF has remained controversial. This report discusses a burst fracture seen as a complication in multilevel cervical stand-alone cage use.

CASE DESCRIPTION

A 39-year-old woman with a history of C5-C6 and C6-C7 ACDF with contiguous stand-alone interbody cages 2 years prior, presented with recurrent arm and neck pain with myelopathy. Computed tomography scan revealed a burst fracture of the C6 vertebral body with retropulsion of fragments compressing the spinal cord.

CONCLUSIONS

This case suggests that use of cervical stand-alone cages in contiguous levels may cause late complications despite good instrumentation and illustrates the need for more careful consideration of technique selection in multilevel ACDF.

Pulled-out locking screw re-screwed spontaneously in anterior cervical decompression and fusion with the zero-profile implant system: A case report

RATIONALE

The zero-profile, standalone device (Zero-P, Synthes GmbH, Switzerland) has been reported to be an effective and safe treatment method with similar clinical outcomes compared with plate. Instrumental complications concerning Zero-P have been little reported. Considering the rarity, we present this amazing case to share with our spinal surgeons and instrument specialists.

PATIENT CONCERNS

A 46-year-old man patient presented to our hospital with neck and shoulders pain for 23 years, numbness and weak-ness of right hand for 6 months.

DIAGNOSES

Hypoesthesia in the right C6 and C7 roots distribution, myodynamia weakness of the right little finger was detected from physical examination. Two-level anterior cervical decompression and fusion (ACDF) using the Zero-P was performed via a classic right Smith-Robinson approach after induction of general anesthesia. Three months postoperative x-rays showed a good position of the implant. Six months postoperative x-rays showed a locking screw at the segment C6/7 pulled out. The patient was diagnosed as screw pullout after ACDF.

INTERVENTIONS

The patient was treated conservatively with regular follow-up as he was asymptomatic and no evidence of esophageal perforation was detected.

OUTCOMES

The patient was followed again and 24 months postoperative x-rays also showed the pulled-out locking screw had re-screwed spontaneously. The patient was noticed that a revision surgery was needed if symptoms occur. At present bony union is not reached but he is still asymptomatic.

LESSONS

Pulled-out screws re-screwed spontaneously are rare but it does occur. Insertion angle may affect the stability of the Zero-P device, and the repeated micro-motion may be the critical reason of the screw pull-out and re-screwing. The management of screws pull-out after ACDF remains individualized and a revision surgery is not necessary for every patient. Conservative treatment such as orthosis and regular follow-ups may be suitable for some asymptomatic patients.

A Clinical Comparison of Anterior Cervical Plates Versus Stand-Alone Intervertebral Fusion Devices for Single-Level Anterior Cervical Discectomy and Fusion Procedures

OBJECTIVE

To compare radiologic and clinical outcomes, including rates of dysphagia and dysphonia, using a no-profile stand-alone intervertebral spacer with integrated screw fixation versus an anterior cervical plate and spacer construct for single-level anterior cervical discectomy and fusion (ACDF) procedures.

METHODS

This multicenter, randomized, prospective study included 54 patients with degenerative disc disease requiring ACDF at a single level at C3-C7. Twenty-six patients underwent single-level ACDF with stand-alone spacers, and 28 with plate fixation and spacers. Analyses were based on comparison of perioperative outcomes, radiologic and clinical metrics, and incidence of dysphagia and/or dysphonia.

RESULTS

Mean patient age was 48.8 ± 10.1years (53.7% female). No significant differences were observed between groups in operative time (101.8 ± 34.4 minutes, 114.4 ± 31.5 minutes), estimated blood loss (44.8 ± 76.5 mL, 82.5 ± 195.1 mL), or length of hospital stay (1.2 ± 0.6 days, 1.3 ± 0.6 days). Mean visual analog scale pain scores and Neck Disability Index scores improved significantly from preoperative to last follow-up (10.8 ± 2.6 months) in both groups (P < 0.05). Mean Voice Handicap Index and Eating Assessment Tool scores improved significantly from discharge to last follow-up in both groups (P < 0.05). From discharge to 6 months, the stand-alone spacers group consistently demonstrated greater improvement in Voice Handicap Index. Preoperative intervertebral disc and neuroforaminal heights increased significantly across treatment groups (P < 0.01), and no cases required surgical revision at index or adjacent levels.

CONCLUSIONS

Anterior cervical discectomy and fusion with stand-alone spacers resulted in similar clinical and radiologic outcomes as compared with plate and spacers and may help minimize postoperative dysphonia.

Zero-profile anchored cage reduces risk of postoperative dysphagia compared with cage with plate fixation after anterior cervical discectomy and fusion

PURPOSE

To compare the rate of postoperative dysphagia between zero-profile anchored cage fixation (ZPC group) and cage with plate fixation (CP group) after anterior cervical discectomy and fusion (ACDF).

METHODS

A meta-analysis of cohort studies between zero-profile anchored cage and conventional cage with plate fixation after ACDF for the treatment of cervical diseases from 2008 to May 2016. An extensive search of studies was performed in PubMed, Medline, Embase, Cochrane library and Google Scholar. Dysphagia rate was extracted. Data analysis was conducted with RevMan 5.2.

RESULTS

Sixteen trials involving 1066 patients were included in this meta-analysis. The results suggested that the ZPC group were associated with lower incidences of dysphagia than the CP group at postoperative immediately, 2 weeks, 2, 3, 6 and 12 months. In subgroup analysis, although significant differences were only found in the mild dysphagia at 3 and 6 months postoperatively and in the moderate dysphagia at 2 weeks after surgery; the ZPC group had a lower rate of postoperative dysphagia than the CCP group in short, medium and long term follow-up periods.

CONCLUSIONS

Zero-profile anchored cage had a lower risk of postoperative dysphagia than cage with plate.

Surgical Outcomes of Anterior Cervical Fusion Using Deminaralized Bone Matrix as Stand-Alone Graft Material: Single Arm, Pilot Study

Objective

To investigate the safety and efficacy of demineralized bone matrix (DBM) as a bone graft substitute for anterior cervical discectomy and fusion (ACDF) surgery.

Methods

Twenty consecutive patients treated with ACDF using stand-alone polyestheretherketone (PEEK) cages (Zero-P) with DBM(CGDBM100) were prospectively evaluated with a minimum of 6 months of follow-up. Radiologic efficacy was evaluated with a 6-point scoring method for osseous fusion using plain radiograph and computed tomogrpahy scans. Clinical efficacy was evaluated using the visual analogue scale (VAS), Owestry disability index (ODI), and short-form health questionnaire-36. The safety of the bone graft substitute was assessed with vital sign monitoring and a survey measuring complications at each follow-up visit.

Results

There were significant improvements in VAS and ODI scores at a mean 6-month follow-up. Six months after surgery, solid fusion was achieved in all patients. Mean score on the 6-point scoring system was 5.1, and bony formation was found to score at least 4 points in all patients. There was no case with implant-related complications such as cage failure or migration, and no complications associated with the use of CGDBM100.

Conclusion

ACDF using CGDBM100 demonstrated good clinical and radiologic outcomes. The fusion rate was comparable with the published results of traditional ACDF. Therefore, the results of this study suggest that the use of a PEEK cage packed with DBM for ACDF is a safe and effective alternative to the gold standard of autologous iliac bone graft.

Outcomes Evaluation of Zero-Profile Devices Compared to Stand-Alone PEEK Cages for the Treatment of Three- and Four-Level Cervical Disc Disease

Background: Anterior cervical discectomy and fusion (ACDF) is a well-accepted treatment option for patients with cervical spine disease. Three- and four-level discectomies are known to be associated with a higher complication rate and lower fusion rate than single-level surgery. This study was performed to evaluate and compare zero-profile fixation and stand-alone PEEK cages for three- and four-level ACDF.

Methods: Two cohorts of patients who underwent ACDF for the treatment of three- and four-level disease were compared. Thirty-three patients underwent implantation of zero-profile devices that included titanium screw fixation (Group A). Thirty-five patients underwent implantation of stand-alone PEEK cages without any form of screw fixation (Group B).

Results: In Group A, twenty-seven patients underwent a three-level and six patients a four-level ACDF, with a total of 105 levels. In Group B, thirty patients underwent a three-level and five patients underwent a four-level ACDF, with a total number of 110 levels. In Group A, the mean preoperative visual analog scale score (VAS) for arm pain was 6.4 (range 3-8), and the mean postoperative VAS for arm pain decreased to 2.5 (range 1-7). In group B, the mean preoperative VAS of arm pain was 7.1 (range 3-10), and the mean postoperative VAS of arm pain decreased to 2 (range 0-4). In Group A, four patients (12%) developed dysphagia, and in Group B, three patients (9%) developed dysphagia. 

Conclusions: This study found zero-profile instrumentation and PEEK cages to be both safe and effective for patients who underwent three- and four-level ACDF, comparable to reported series using plate devices. Rates of dysphagia for the cohort were much lower than reports using plate devices. Zero-profile segmental fixation devices and PEEK cages may be considered as viable alternatives over plate fixation for patients requiring multi-level anterior cervical fusion surgery.