Safety and effectiveness of bone allografts in anterior cervical discectomy and fusion surgery

Do the Choice of Fusion Construct With and Without Autograft Influence the Fusion and Complication Rates in Patients Undergoing 1 or 2-Level Anterior Cervical Discectomy and Fusion Surgery? A PRISMA-Compliant Network Meta-Analysis

STUDY DESIGN

Network meta-analysis.

OBJECTIVES

To compare the fusion outcome and complications of different 1 or 2-level anterior cervical decompression and fusion (ACDF) constructs performed with and without the application of autografts.

METHODS

We performed an independent and duplicate search in electronic databases including PubMed, Embase, Web of Science, Cochrane, and Scopus for relevant articles published between 2000 and 2020. We included comparative studies reporting fusion rate and complications with and without the use of autografts in ACDF across 5 different fusion constructs. A network meta-analysis was performed in Stata, categorized based on the type of fusion constructs utilized. Fusion constructs were ranked based on p-score approach and surface under cumulative ranking curve (SUCRA) scores. The confidence of results from the analysis was appraised with Cochrane's CINeMA approach.

RESULTS

A total of 2216 patients from 22-studies including 6 Randomized Controlled Trials (RCTs) and 16 non-RCTs were included in network analysis. The mean age of included patients was 49.3 (±3.62) years. Based on our meta-analysis, we could conclude that use of autograft in 1- or 2-level ACDF did not affect the fusion and mechanical implant-related complications. The final fusion and mechanical complication rates were also not significantly different across the different fusion constructs. The use of plated constructs was associated with a significant increase in post-ACDF dysphagia rates [OR 3.42; 95%CI (.01,2.45)], as compared to stand-alone constructs analysed.

CONCLUSION

The choice of fusion constructs and use of autografts does not significantly affect the fusion and overall complication rates following 1 or 2-level ACDF surgery.

Subsidence Performance of the Bioactive Glass-Ceramic (CaO-SiO2-P2O5-B2O3) Spacer in Terms of Modulus of Elasticity and Contact Area: Mechanical Test and Finite Element Analysis

OBJECTIVE

The objective of this study is to evaluate the subsidence performance of a bioactive glass-ceramic (CaO-SiO2-P2O5-B2O3) spacer in terms of its modulus of elasticity and contact area using mechanical tests and finite element analysis.

METHODS

Three spacer three-dimensional models (Polyether ether ketone [PEEK]-C: PEEK spacer with a small contact area; PEEK-NF: PEEK spacer with a large contact area; and Bioactive glass [BGS]-NF: bioactive glass-ceramic spacer with a large contact area) are constructed and placed between bone blocks for compression analysis. The stress distribution, peak von Mises stress, and reaction force generated in the bone block are predicted by applying a compressive load. Subsidence tests are conducted for three spacer models in accordance with ASTM F2267. Three types of blocks measuring 8, 10, and 15 pounds per cubic foot are used to account for the various bone qualities of patients. A statistical analysis of the results is conducted using a one-way Analysis of variance and post hoc analysis (Tukey's Honestly Significant Difference) by measuring the stiffness and yield load.

RESULTS

The stress distribution, peak von Mises stress, and reaction force predicted via the finite element analysis are the highest for PEEK-C, whereas they are similar for PEEK-NF and BGS-NF. Results of mechanical tests show that the stiffness and yield load of PEEK-C are the lowest, whereas those of PEEK-NF and BGS-NF are similar.

CONCLUSIONS

The main factor affecting subsidence performance is the contact area. Therefore, bioactive glass-ceramic spacers exhibit a larger contact area and better subsidence performance than conventional spacers.

Effects of Structural Allograft versus Polyetheretherketone Cage in Patients Undergoing Spinal Fusion Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

Inter body spacers have been widely used in patients undergoing spinal fusion surgery; however, it is not clear whether one implant shows superior clinical outcomes compared with the other. This systematic review and meta-analysis comprehensively evaluated the radiologic outcomes and patient-reported outcomes of structural allograft versus polyetheretherketone (PEEK) implants in patients undergoing spinal fusion surgery.

METHODS

Extensive literature searches were conducted on online databases, including MEDLINE, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and Cochrane Library, until January 2023. The present study adheres to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, and the Newcastle-Ottawa Scale and Cochrane Collaboration Risk of Bias tool were used to assess the quality of the included studies.

RESULTS

Fifteen studies, encompassing 8020 patients, met the eligibility criteria. The results indicate that structural allografts show a higher fusion rate compared with PEEK implants (odds ratio [OR], 1.88; 95% confidence interval [CI], 1.05-3.37; P ＝0.03; I2 = 71%). In addition, the structural allograft group also had a lower pseudarthrosis rate (OR, 0.40; 95% CI, 0.20-0.80; P = 0.009; I2 = 75%) and reoperation rate (OR, 0.46; 95% CI, 0.26-0.81; P = 0.007; I2 = 38%).

CONCLUSIONS

Our systematic review and meta-analysis show that structural allograft has a higher fusion rate compared with PEEK implants in patients undergoing spinal fusion surgery. In addition, structural allograft has a lower pseudarthrosis rate and reoperation rate.

Uncovertebral Joint Fusion Versus End Plate Space Fusion in Anterior Cervical Spine Surgery: A Prospective Randomized Controlled Trial

BACKGROUND

The uncovertebral joint is a potential region for anterior cervical fusion. Currently, we are aware of no clinical trials on human uncovertebral joint fusion (UJF). The purpose of this study was to compare the time it took to achieve osseous union/fusion and the clinical efficacy of UJF to end plate space fusion (ESF)-i.e., traditional anterior cervical discectomy and fusion (ACDF)-in anterior cervical surgery.

METHODS

Patients with single-level cervical spondylosis were recruited from April 2021 through October 2022 and randomly divided into the UJF and ESF groups, with 40 patients in each group. Autologous iliac bone was used for bone grafting in both groups. The primary outcome was the early fusion rate at 3 months postoperatively. Secondary outcomes included the prevalence of complications and patient-reported outcome measures (PROMs), including the Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), and visual analog scale (VAS) scores for arm and neck pain.

RESULTS

A total of 74 patients (92.5%) with an average age of 49.8 years (range, 26 to 65 years) completed the trial and were included in the analysis. There was no significant difference between the 2 groups at baseline. The operative duration and intraoperative blood loss were also comparable between the 2 groups. The fusion rate in the UJF group was significantly higher than that in the ESF group at 3 months (66.7% compared with 13.2%, p < 0.0001) and 6 months (94.1% compared with 66.7%, p = 0.006) after the operation. No significant difference was found in the fusion rate between the 2 groups 12 months postoperatively. Overall, the PROMs significantly improved after surgery in both groups and did not differ significantly between the groups at any follow-up time point. The prevalence of complications was not significantly different between the 2 groups.

CONCLUSIONS

In our study of anterior cervical fusion surgery, we found that the early fusion rate after UJF was significantly higher than that after ESF.

LEVEL OF EVIDENCE

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

Clinical Outcomes and Cost Profiles for Cage and Allograft Anterior Cervical Discectomy and Fusion Procedures in the Adult Population: A Propensity Score-Matched Study

STUDY DESIGN

Retrospective cohort study.

PURPOSE

To characterize the postoperative outcomes and economic costs of anterior cervical discectomy and fusion (ACDF) procedures using synthetic biomechanical intervertebral cage (BC) and structural allograft (SA) implants.

OVERVIEW OF LITERATURE

ACDF is a common spine procedure that typically uses an SA or BC for the cervical fusion. Previous studies that compared the outcomes between the two implants were limited by small sample sizes, short-term postoperative outcomes, and procedures with single-level fusion.

METHODS

Adult patients who underwent an ACDF procedure in 2007-2016 were included. Patient records were extracted from MarketScan, a national registry that captures person-specific clinical utilization, expenditures, and enrollments across millions of inpatient, outpatient, and prescription drug services. Propensity-score matching (PSM) was employed to match the patient cohorts across demographic characteristics, comorbidities, and treatments.

RESULTS

Of 110,911 patients, 65,151 (58.7%) received BC implants while 45,760 (41.3%) received SA implants. Patients who underwent BC surgeries had slightly higher reoperation rates within 1 year after the index ACDF procedure (3.3% vs. 3.0%, p=0.004), higher postoperative complication rates (4.9% vs. 4.6%, p=0.022), and higher 90-day readmission rates (4.9% vs. 4.4%, p =0.001). After PSM, the postoperative complication rates did not vary between the two cohorts (4.8% vs. 4.6%, p=0.369), although dysphagia (2.2% vs. 1.8%, p<0.001) and infection (0.3% vs. 0.2%, p=0.007) rates remained higher for the BC group. Other outcome differences, including readmission and reoperation, decreased. Physician's fees remained high for BC implantation procedures.

CONCLUSIONS

We found marginal differences in clinical outcomes between BC and SA ACDF interventions in the largest published database cohort of adult ACDF surgeries. After adjusting for group-level differences in comorbidity burden and demographic characteristics, BC and SA ACDF surgeries showed similar clinical outcomes. Physician's fees, however, were higher for BC implantation procedures.

A Five-Year Cost-Utility Analysis Comparing Synthetic Cage Versus Allograft Use in Anterior Cervical Discectomy and Fusion Surgery for Cervical Spondylotic Myelopathy

STUDY DESIGN

Retrospective cost-utility analysis.

OBJECTIVE

To conduct a cost-analysis comparing synthetic cage (SC) versus allograft (Allo) over a five-year time horizon.

SUMMARY OF BACKGROUND DATA

SC and Allo are two commonly used interbody choices for anterior cervical discectomy and fusion (ACDF) surgery. Previous analyses comparative analyses have reached mixed conclusions regarding their cost-effectiveness, yet recent estimates provide high-quality evidence.

MATERIALS AND METHODS

A decision-analysis model comparing the use of Allo versus SC was developed for a hypothetical 60-year-old patient with cervical spondylotic myelopathy undergoing single-level ACDF surgery. A comprehensive literature review was performed to estimate probabilities, costs (2020 USD) and quality-adjusted life years (QALYs) gained over a five-year period. A probabilistic sensitivity analysis using a Monte Carlo simulation of 1000 patients was carried out to calculate incremental cost-effectiveness ratio and net monetary benefits. One-way deterministic sensitivity analysis was performed to estimate the contribution of individual parameters to uncertainty in the model.

RESULTS

The use of Allo was favored in 81.6% of the iterations at a societal willing-to-pay threshold of 50,000 USD/QALY. Allo dominated (higher net QALYs and lower net costs) in 67.8% of the iterations. The incremental net monetary benefits in the Allo group was 2650 USD at a willing-to-pay threshold of 50,000 USD/QALY. One-way deterministic sensitivity analysis revealed that the cost of the index surgery was the only factor which significantly contributed to uncertainty.

CONCLUSION

Cost-utility analysis suggests that Allo maybe a more cost-effective option compared with SCs in adult patients undergoing ACDF for cervical spondylotic myelopathy.

Design and mechanical properties of cervical fusion cage based on porous entangled metal rubber material

Titanium and its alloys are one of the mainstream materials for the manufacture of intervertebral cages. With the application on clinical, the problems of elastic modulus is relatively high, subsidence of adjacent vertebral implants and stress shielding after surgery have gradually exposed. In this paper, metal rubber made from titanium alloy wire was used to prepare cervical fusion cage (CFC), which was a porous material with buffering and vibration damping properties. The C5/C6 segment of the goat cervical vertebra was used as the research object. The shape parameters of the CFC were determined by combining the three-dimensional model data of the cervical vertebra and the structural characteristics of the natural intervertebral disc. The force of CFC under different working conditions were simulated and analyzed by finite element simulation. Then three kinds of metal rubber core (MRC) were prepared by medical titanium alloy wire (TC4), and their mechanical properties and fatigue strength were experimentally studied. With the increases of density, the mechanical properties of MRC improved. The variation range of the loss factor η under different amplitudes and frequencies were 20% and 16.3%, respectively. After one million vibrations, the wear rate was 0.131 g/MC; after five million vibrations, the wear rate was 0.158 g/MC, which was similar to the existing clinical prosthesis wear rate. The MRC has sufficient mechanical strength. Compared with the existing clinical prostheses, it has a longer service life and has broad application prospects.

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.

Long segment spinal reconstruction of C3-T1 utilizing single strut fibula free flap following debridement and corpectomy for chronic osteomyelitis

Cervical vertebral osteomyelitis (CVO) is a complex destructive pathology that presents as a significant challenge to reconstructive surgeons. Advanced cases of CVO involving neurologic deficits, spinal column instability, or refractory infection require surgical intervention with bony debridement and decompression followed by spinal reconstruction, realignment, and stabilization. Reconstruction of the spine is typically performed through an anterior approach with or without posterior instrumentation. Restoration of the anterior spinal column can be performed with titanium or PEEK cages, allograft bone or vascularized autograft bone. Anterior spine reconstruction using vascularized osseous free flaps has been well documented in the medical literature; however, to our knowledge, we report the largest osteomyelitic anterior cervical spine defect that has been reconstructed using a single strut osseous free flap. This was a complex case of cervical osteomyelitis in a patient with prior C4-C7 anterior cervical corpectomy and fusion who presented with instrumentation failure and septicemia. Anterior column reconstruction required a vascularized fibular strut spanning six vertebral levels from C3-T1, as well as a trapezius myocutaneous pedicled flap for posterior soft tissue coverage.

Allograft Versus Autograft in Anterior Cervical Discectomy and Fusion: A Propensity-Matched Analysis

Objective

To compare the 30-day complication rate associated with allograft versus autograft in anterior cervical discectomy and fusion (ACDF) and to determine preoperative factors that may influence complication rate.

Methods

The American College of Surgeons National Surgical Quality Improvement Program database was retrospectively queried from 2014 to 2017 for all procedures with CPT codes for ACDF (22551). Patients undergoing ACDF with either autograft or allograft were matched by propensity scores based on age, sex, body mass index, and comorbidities. The incidence of adverse events in the 30-day postoperative period was compared.

Results

A total of 21,588 patients met the inclusion and exclusion criteria. Following the 10:1 propensity match, 17,061 remained in the study (1,551 autograft and 15,510 allograft). The overall adverse event rate was 3.18%; 3.48% for autograft and 3.15% for allograft (P=0.494). Autograft had a significantly greater incidence of extended length of stay (>2 d) (LOS) (48.9% vs 34.8%; P<0.001). Multivariate analysis suggested that autograft selection was associated with extended LOS (OR 1.4; 95% CI 1.3-1.5).

Conclusion

The results of this study provide information regarding how graft selection can relate to extended hospital LOS and influence postoperative complications. Extended LOS may be associated with worse patient outcomes and increase the overall cost of care. Further study should be performed to determine which patients would benefit from autograft versus allograft with regards to long-term outcomes, in consideration of these increased short-term complications.

Prospective comparison of dysphagia following anterior cervical discectomy and fusion (ACDF) with and without rhBMP-2

BACKGROUND CONTEXT

Previous studies have called into question the safety of using rhBMP-2 in anterior cervical fusion due to the possibility of airway compromise and dysphagia. A retrospective chart review identified a significant increase in the severity of dysphagia after II-level ACDF with rhBMP-2 compared to patients who did not receive rhBMP-2. To date, this topic has not been studied prospectively.

PURPOSE

Compare the incidence of dysphagia following anterior cervical discectomy and fusion (ACDF) when recombinant human bone morphogenetic protein-2 (rhBMP-2) is used with allograft compared to allograft alone.

STUDY DESIGN

Prospective cohort study.

PATIENT SAMPLE

A total of 114 patients completed a baseline SWAL-QOL survey and met the inclusion criteria. Thirty-nine patients underwent I- or II-level ACDF with allograft plus 0.5mg rhBMP-2/level. 44 patients underwent ACDF with allograft alone. Thirty-one patients undergoing a lumbar decompression were enrolled in a third cohort to control for dysphagia secondary to intubation.

OUTCOME MEASURES

The primary outcome measure was the 14-point SWAL-QOL dysphagia questionnaire. Other patient factors obtained from anesthesia and operative records were examined to evaluate their potential relationship to postoperative dysphagia.

METHODS

The 14-point SWAL-QOL questionnaire was administered at multiple time points (pre-op, post-op 7 days, 6 weeks, 6 months, and at least 1 year). Multivariable repeated-measures analysis was applied to data.

RESULTS

Baseline adjusted SWAL-QOL means 7 days after surgery were significantly different between the three study groups. These differences resolved by 6 weeks postoperative, beyond which point there were no differences. At final follow-up, baseline adjusted SWAL-QOL means at 1 year were similar for the three study groups.

CONCLUSIONS

This single-center study of anterior cervical surgery demonstrated that the addition of rhBMP-2 to an ACDF increased postoperative dysphagia at 7 days after surgery, but these patients recover to levels comparable to those who underwent ACDF without rhBMP-2 or lumbar surgery within 6 weeks.

Structural Allograft Versus Synthetic Interbody Cage for Anterior Cervical Discectomy and Fusion: A Comparison of 1-Year Outcomes From a National Database

STUDY DESIGN

Observational cohort study.

OBJECTIVE

To compare 1-year perioperative complications between structural allograft (SA) and synthetic cage (SC) for anterior cervical discectomy and fusion (ACDF) using a national database.

METHODS

The TriNetX Research Network was retrospectively queried. Patients undergoing initial single or multilevel ACDF surgery between October 1, 2015 and April 30, 2019 were propensity score matched based on age and comorbidities. The rates of 1-year revision ACDF surgery and reported diagnoses of pseudoarthrosis, surgical site infection (SSI), and dysphagia were compared between structural allograft and synthetic cage techniques.

RESULTS

A comparison of 1-year outcomes between propensity score matched cohorts was conducted on 3056 patients undergoing single-level ACDF and 3510 patients undergoing multilevel ACDF. In single-level ACDF patients, there was no difference in 1-year revision ACDF surgery (P = .573), reported diagnoses of pseudoarthrosis (P = .413), SSI (P = .620), or dysphagia (P = .529) between SA and SC groups. In multilevel ACDF patients, there was a higher rate of revision surgery (SA 3.8% vs SC 7.3%, odds ratio = 1.982, P < .001) in the SC group, and a higher rate of dysphagia in the SA group (SA 15.9% vs SC 12.9%).

CONCLUSION

While the overall revision and complication rate for single-level ACDF remains low despite interbody graft selection, SC implant selection may result in higher rates of revision surgery in multilevel procedures despite yielding lower rates of dysphagia. Further prospective study is warranted.

Comparison of the differentiation abilities of bone marrow-derived mesenchymal stem cells and adipose-derived mesenchymal stem cells toward nucleus pulposus-like cells in three-dimensional culture

Nucleus pulposus cell (NPC) transplantation can be a potential therapeutic approach for intervertebral disc degeneration (IDD). However, low cell viability has restricted the therapeutic capacity of NPCs, and sources of natural NPCs are limited. Bone marrow-derived mesenchymal stem cells (BMSCs) and adipose-derived mesenchymal stem cells (ADSCs) can be differentiated toward NPC-like cells. However, it is unknown whether there are differences in the abilities of these two cell types to differentiate into NPC-like cells, or which cell type exhibits the best differentiation ability. The present study compared the abilities of BMSCs and ADSCs to differentiate toward NPC-like cells with or without a 3D culture system to lay a foundation for stem cell transplantation therapy for IDD. BMSCs were isolated from the rat whole bone marrow cell using the repeated adherent culture method. ADSCs were isolated from rat adipose tissues in the subcutaneous inguinal region using the enzyme digestion method. Cells were identified using flow cytometry. Cell viability was assessed via Cell Counting Kit-8 assays, and reverse transcription-quantitative PCR and western blotting were carried out to evaluate the expression of NPC markers and chondrocyte-specific genes. Glycosaminoglycans (GAGs) and proteoglycans were examined via Alcian blue and safranin O staining, respectively. ADSCs in 3D culture displayed the highest cell proliferative ability, compared with the 2D culture system and BMSC culture. In addition, ADSCs in 3D culture exhibited increased GAG and proteoglycan synthesis than BMSCs. Compared with BMSCs in 3D culture, ADSCs in 3D culture exhibited higher mRNA and protein expression of NPC marker genes (hypoxia-inducible factor 1-α, glucose transporter 1) and chondrocyte-specific genes (Sox-9, aggrecan and type II collagen). The present findings indicated that ADSCs exhibited a better ability to differentiate into NPC-like cells in 3D culture compared with BMSCs, which may be of value for the regeneration of intervertebral discs using cell transplantation therapy.

Clinical and radiographic outcomes using third-generation bioactive glass as a bone graft substitute for multi-level anterior cervical discectomy and fusion-a retrospective case series study

Background

Bioactive glasses have unique bone forming properties that have been used as a bone graft substitute for anterior cervical discectomy and fusions (ACDFs). Bone graft substitutes are used for achieving fusion while simultaneously avoiding donor site morbidity of iliac crest autograft. In this study, our principal intention is to assess the clinical and radiographic outcomes in patients with multi-level cervical disc disease undergoing ACDF using a third-generation bioactive glass as a bone graft substitute.

Methods

A retrospective case series study was performed of patients who underwent primary multi-level instrumented fusions for degenerative cervical disc disease with bioactive glass bone graft substitute between May 2016 and December 2017 by a single fellowship-trained spine surgeon. All patients were treated with a porous PEEK interbody spacer and with a third-generation bioactive glass synthetic bone graft substitute. Patients were assessed pre-operatively, immediately following surgery, and at 3, 6, 12, and 24 months. Accepted standard outcome measures were applied to evaluate preoperative and postoperative metrics, including Visual Analog Scale neck pain and arm pain, and Neck Disability Index. Dynamic lateral radiographs were used to assess sagittal alignment, disc space height, arthrodesis status, osseous integration, and implant migration. Sagittal plane angulation was measured by Cobb's criteria.

Results

Thirty-nine patients underwent multi-level instrumented fusions: seventeen (43%) were two-level; 12 (31%) were three-level; 9 (23%) were four-level; and 1 (3%) was five-levels. All patients were followed for a minimum of 6 months for mean of 16.0 months (range, 6 to 36 months); none were lost to follow-up. Significant improvements from preoperative scores in Neck Disability Index scores as well as neck and arm visual analog scale pain scores were realized. All patients either maintained or improved their neurological status. Radiographically, all patients were fused by 6 months postoperatively and showed improvement in fusion segment lordosis (Pre-Post and Pre-Final P<0.001), C2-C7 lordosis angle (Pre-Post and Pre-Final P<0.001), T1 slope (Pre-Post P=0.01, Pre-Final P=0.07) and maintenance of disc height (Post-Final P=0.02). There were no adverse events, infections, or reoperations.

Conclusions

Third-generation bioactive glass synthetic graft is a viable alternative to allograft or autograft in the setting of multi-level instrumented fusions for achieving improved clinical and radiographic outcomes.

Synthetic Cages Associated With Increased Rates of Revision Surgery and Higher Costs Compared to Allograft in ACDF in the Nonelderly Patient

Objective

The aim of this study was to compare all-cause reoperation rates and costs in nonelderly patients treated with anterior cervical discectomy and fusion (ACDF) with structural allograft versus synthetic cages for degenerative pathology.

Methods

We queried a private claims database to identify adult patients (≤ 65 years) who underwent single-level ACDF in a hospital setting using either structural allograft or a synthetic cage (polyetheretherketone, metal, or hybrid device), from 2010 to 2016. The rate of all-cause reoperations at 2 years were compared between the 2 groups. Index hospitalization costs and 90-day complication rates were also compared. Significance was set at p < 0.05.

Results

A total of 26,754 patients were included in the study. 11,514 patients (43%) underwent ACDF with structural allograft and 15,240 (57%) underwent ACDF with a synthetic cage. The patients in the allograft group were younger and more likely to be male. There was no significant difference between the 2 groups with respect to 90-day complications including: wound dehiscence, dysphagia, dysphonia, and hematoma/seroma. In the 2-year postoperative period, the synthetic cage group had a significantly higher rate of allcause reoperation compared to the allograft group (9.1% vs. 8.0%, p = 0.002). Index hospitalization costs were significantly higher in the synthetic cage group compared to those in the allograft group ($23,475 vs. $20,836, p < 0.001).

Conclusion

Structural allograft is associated with lower all-cause reoperation rates and lower index costs in nonelderly patients undergoing ACDF surgery for degenerative pathology. It is important to understand this data as we transition toward value-based care.

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.

A Randomized Control Trial Comparing Local Autografts and Allografts in Single Level Anterior Cervical Discectomy and Fusion Using a StandAlone Cage

Study Design

Randomized controlled trial.

Purpose

To compare the functional and radiological outcomes of anterior cervical discectomy and fusion (ACDF) using local graft and allograft

Overview of Literature

The choice of bone grafts for ACDF varies among different types: iliac crest, allograft, and substitutes. Availability, cost, and donor site morbidity are potential disadvantages. Local osteophyte grafts are then advantageous and shows to have good fusion.

Methods

We randomly sampled participants requiring a single level ACDF for degenerative conditions (n=27) between allograft (n=13) and local graft (n=14) groups. Follow-up of patients occurred at 6 weeks, 3 months, 6 months, and 1 year using Numerical Pain Rating Scale (NPRS) scores for arm and neck pain, Neck Disability Index (NDI), 2-item Short Form Health Survey (SF-12), and lateral disk height. We then assessed radiological fusion using computed tomography (CT) scan at 12 months, and graded as F− (no fusion), F (fusion seen through the cage), F+ (fusion seen through the cage, with bridging bone at one lateral edge), and F++ (fusion seen through cage with bridging bone bilaterally).

Results

There were no significant differences in the age, sex, duration of intervention, blood loss, and hospital stay between the two groups (p>0.05). Both groups showed significant improvements in all functional outcome scores including NPRS for arm and neck pain, NDI, and SF-12 at each visit (p<0.01). We observed a marked improvement in disk height in both groups (p<0.05), but at 1 year of follow-up, there was a significant though slight subsidence (p=0.47). CT at 1 year showed no non-unions. We recorded F, F+, and F++ grades of fusion in 23.2%, 38.4%, and 38.4% in allograft group and 28.6%, 42.8%, and 28.6% in local graft group, respectively, though no significant differences observed (p=0.73).

Conclusions

Marginal osteophytes are effective as graft inside cages for ACDF, since they provide similar radiological outcomes, and equivalent improvements in functional outcomes, as compared to allografts.

Comparing the efficacy of syngeneic iliac and femoral allografts with iliac crest autograft in a rat model of lumbar spinal fusion

BACKGROUND

Despite widespread use of femoral-sourced allografts in clinical spinal fusion procedures and the increasing interest in using femoral reamer-irrigator-aspirator (RIA) autograft in clinical bone grafting, few studies have examined the efficacy of femoral grafts compared to iliac crest grafts in spinal fusion. The objective of this study was to directly compare the use of autologous iliac crest with syngeneic femoral and iliac allograft bone in the rat model of lumbar spinal fusion.

METHODS

Single-level bilateral posterolateral intertransverse process lumbar spinal fusion surgery was performed on Lewis rats divided into three experimental groups: iliac crest autograft, syngeneic iliac crest allograft, and syngeneic femoral allograft bone. Eight weeks postoperatively, fusion was evaluated via microCT analysis, manual palpation, and histology. In vitro analysis of the colony-forming and osteogenic capacity of bone marrow cells derived from rat femurs and hips was also performed to determine whether there was a correlation with the fusion efficacy of these graft sources.

RESULTS

Although no differences were observed between groups in CT fusion mass volumes, iliac allografts displayed an increased number of radiographically fused fusion masses and a higher rate of bilateral fusion via manual palpation. Histologically, hip-derived grafts showed better integration with host bone than femur derived ones, likely associated with the higher concentration of osteogenic progenitor cells observed in hip-derived bone marrow.

CONCLUSIONS

This study demonstrates the feasibility of using syngeneic allograft bone in place of autograft bone within inbred rat fusion models and highlights the need for further study of femoral-derived grafts in fusion.

New Strategies in Enhancing Spinal Fusion

The biologic steps involved in creating a bony fusion between adjacent segments of the spine are a complex and highly coordinated series of events. There have been significant advancements in bone grafts and bone graft substitutes in order to augment spinal fusion. While autologous bone grafting remains the gold standard, allograft bone grafting, synthetic bone graft substitutes, and bone graft enhancers are appropriate in certain clinical situations. This article provides an overview of the basic biology of spinal fusion and strategies for enhancing fusion through innovations in bone graft material.

A novel anterior decompression technique for kyphosis line (K-line) ossification of posterior longitudinal ligament (OPLL): vertebral body sliding osteotomy

Background

Conventional anterior cervical corpectomy and fusion (ACCF) for cervical ossification of the posterior longitudinal ligament (OPLL) is associated with a high incidence of surgery-related complications. A novel anterior decompression technique [vertebral body sliding osteotomy (VBSO)] has been developed to prevent such complications and achieve effective anterior decompression for severe OPLL patients. The purpose of this study was to describe the procedure of novel surgical technique and to evaluate the long-term surgical outcomes.

Methods

Between 2012 and 2014, 24 patients underwent VBSO for treatment of cervical myelopathy caused by severe OPLL. Operation time, estimated blood loss (EBL), neurologic outcomes and perioperative complications were investigated. Various radiographic parameters such as the preoperative canal occupying ratio, postoperative canal widening, and preoperative and postoperative cervical sagittal alignment were also measured. Minimum follow-up was 24 months.

Results

The mean Japanese Orthopaedic Association score for cervical myelopathy (C-JOA score) improved from 12.4±2.9 preoperatively to 16.0±1.4 at the final follow-up (P<0.05). The mean recovery rate of the C-JOA score at the final follow-up was 68.65%±17.80%. The mean operating time was 130.7±21.0 minutes and the EBL was 176.3±38.0 mL. There were no perioperative complications. Pseudarthrosis was detected in two cases at 12 months postoperatively. The average spinal canal compromised ratio by OPLL decreased from 64.0%±15.0% preoperatively to 15.5%±12.2% postoperatively (P<0.05), with an average postoperative canal widening of 5.15±1.39 mm.

Conclusions

Novel anterior decompression technique termed VBSO may be an effective and safe surgical option for anterior decompression surgery in patients with severe cervical OPLL. Since, VBSO does not involve a direct manipulation of the OPLL mass or dissection of the interspace between the OPLL and dura mater, this may significantly decrease the incidence of surgery-related complications, operation time, and intraoperative blood loss.

Comparison of the effectiveness and safety of bioactive glass ceramic to allograft bone for anterior cervical discectomy and fusion with anterior plate fixation

Recently, a bioactive glass ceramic (BGC) has been developed for use as intervertebral cages for anterior cervical discectomy and fusion (ACDF). However, the effectiveness and safety of BGC cages remain to be evaluated. We completed a retrospective comparison of the radiological and clinical outcomes of 36 patients (52 levels) who underwent ACDF with a BGC cage and 35 patients (54 levels) using allograft bone. The following variables were compared between the two groups: the visual analog (VAS) neck and arm pain score and the neck disability index (NDI), measured before surgery and 1 year after; the change in Cobb's angle, between the C2 and C7 vertebrae, the global sagittal angle, and disc height compared from before surgery to 1 year after; and the rate of spinal fusion and cage subsidence at 1 and 2 years after surgery. The VAS and NDI scores were not different between the two groups. Similarly, the spinal fusion rate was not different between the BGC and allograft bone group at 1 year (73% and 87%, respectively; p = 0.07) and 2 years (94% and 91%, respectively; p = 0.54) after surgery. However, the rate of cage subsidence was higher in the allograft bone (43%) than the BGC (19%) group (p = 0.03), as was the rate of instrument-related failure (p = 0.028), with a specifically higher incidence of implant fracture or failure in the allograft bone group (p = 0.025). Overall, our findings indicate that BGC cages provide a feasible and safe alternative to allograft bone for ACDF.

Anterior cervical discectomy and fusion performed using structural allograft or polyetheretherketone: pseudarthrosis and revision surgery rates with minimum 2-year follow-up

OBJECTIVE

Both structural allograft and PEEK have been used for anterior cervical discectomy and fusion (ACDF). There are reports that PEEK has a higher pseudarthrosis rate than structural allograft. The authors compared pseudarthrosis, revision, subsidence, and loss of lordosis rates in patients with PEEK and structural allograft.

METHODS

The authors performed a retrospective review of patients who were treated with ACDF at their hospital between 2005 and 2017. Inclusion criteria were adult patients with either PEEK or structural allograft, anterior plate fixation, and a minimum 2-year follow-up. Exclusion criteria were hybrid PEEK and allograft cases, additional posterior surgery, adjacent corpectomies, infection, tumor, stand-alone or integrated screw and cage devices, bone morphogenetic protein use, or lack of a minimum 2-year follow-up. Demographic variables, number of treated levels, interbody type (PEEK cage vs structural allograft), graft packing material, pseudarthrosis rates, revision surgery rates, subsidence, and cervical lordosis changes were collected. These data were analyzed by Pearson's chi-square test (or Fisher's exact test, according to the sample size and expected value) and Student t-test.

RESULTS

A total of 168 patients (264 levels total, mean follow-up time 39.5 ± 24.0 months) were analyzed. Sixty-one patients had PEEK, and 107 patients had structural allograft. Pseudarthrosis rates for 1-level fusions were 5.4% (PEEK) and 3.4% (allograft) (p > 0.05); 2-level fusions were 7.1% (PEEK) and 8.1% (allograft) (p > 0.05); and ≥ 3-level fusions were 10% (PEEK) and 11.1% (allograft) (p > 0.05). There was no statistical difference in the subsidence magnitude between PEEK and allograft in 1-, 2-, and ≥ 3-level ACDF (p > 0.05). Postoperative lordosis loss was not different between cohorts for 1- and 2-level surgeries.

CONCLUSIONS

In 1- and 2-level ACDF with plating involving the same number of fusion levels, there was no statistically significant difference in the pseudarthrosis rate, revision surgery rate, subsidence, and lordosis loss between PEEK cages and structural allograft.

Finnish Trial on Practices of Anterior Cervical Decompression and Fusion (FACADE): a protocol for a prospective randomised non-inferiority trial comparing outpatient versus inpatient care

INTRODUCTION

Although a great majority of patients with cervical radiculopathy syndrome can successfully be treated non-operatively, a considerable proportion experience persistent symptoms, severe enough to require neurosurgical intervention. During the past decade, cervical spine procedures have increasingly been performed on an outpatient basis and retrospective database analyses have shown this to be feasible and safe. However, there are no randomised controlled studies comparing outpatient care with inpatient care, particularly with emphasis on the patients' perception of symptom relief and their ability to return to normal daily activities and work.

METHODS AND ANALYSIS

This is a prospective, randomised, controlled, parallel group non-inferiority trial comparing the traditional hospital surveillance (inpatient, patients staying in the hospital for 1-3 nights after surgery) with outpatient care (discharge on the day of the surgery, usually within 6-8 hours after procedure) in patients who have undergone anterior cervical decompression and fusion procedure. To determine whether early discharge (outpatient care) is non-inferior to inpatient care, we will randomise 104 patients to these two groups and follow them for 6 months using the Neck Disability Index (NDI) as the primary outcome. We expect that early discharge is not significantly worse than the current care in terms of change in NDI. Non-inferiority will be declared if the mean improvement for outpatient care is no worse than the mean improvement for inpatient care, by a margin of 17.3%. We hypothesise that a shorter hospital stay results in more rapid return to normal daily activities, shorter duration of sick leave and decreased secondary costs to healthcare system. Secondary outcomes in our study are arm pain and neck pain using the Numeric Rating Scale, operative success (Odom's criteria), patient's satisfaction to treatment, general quality of life (EQ-5D-5L), Work Ability Score, sickness absence days, return to previous leisure activities and complications.

ETHICS AND DISSEMINATION

The study was approved by the institutional review board of the Helsinki and Uusimaa Hospital District on 6 June 2019 (1540/2019) and duly registered at ClinicalTrials.gov. We will disseminate the findings of this study through peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

NCT03979443.

i-Factor™ Bone Graft vs Autograft in Anterior Cervical Discectomy and Fusion: 2-Year Follow-up of the Randomized Single-Blinded Food and Drug Administration Investigational Device Exemption Study

BACKGROUND

i-Factor™ Bone Graft (Cerapedics Inc, Westminster, Colorado) is a composite bone substitute material consisting of P-15 synthetic collagen fragment adsorbed onto anorganic bone mineral suspended in an inert biocompatible hydrogel carrier. A pivotal, noninferiority, US FDA Investigational Device Exemption study demonstrated the benefits of i-Factor™ compared to local autograft bone in single-level anterior cervical discectomy and fusion at 1-yr postoperative.

OBJECTIVE

To report 2-yr follow-up.

METHODS

Subjects randomly received either autograft (n = 154) or i-Factor™ (n = 165) in a cortical ring allograft and followed using radiological, clinical, and patient-reported outcomes.

RESULTS

At 2 yr, the fusion rate was 97.30% and 94.44% in i-Factor™ and autograft subjects, respectively (P = .2513), and neurological success rate was 94.87% (i-Factor™) and 93.79% (autograft; P = .7869). Neck Disability Index improved 28.30 (i-Factor™) and 26.95 (autograft; P = .1448); Visual Analog Scale arm pain improved 5.43 (i-Factor™) and 4.97 (autograft) (p = .2763); Visual Analog Scale neck pain improved 4.78 (i-Factor™) and 4.41 (autograft; P = .1652), Short Form-36 (SF-36v2) Physical Component Score improved 10.23 (i-Factor™) and 10.18 (autograft; P = .4507), and SF36v2 Mental Component Score improved 7.88 (i-FactorTM) and 7.53 (autograft; P = .9872). The composite endpoint of overall success (fusion, Neck Disability Index improvement >15, neurological success, and absence of re-operations) was greater in i-Factor™ subjects compared to autograft subjects (69.83% and 56.35%, respectively, P = .0302). Twelve (7.45%) i-Factor™ subjects and 16 (10.53%) autograft subjects underwent re-operation (P = .3411). There were no allergic reactions associated with i-Factor™.

CONCLUSION

Use of i-Factor™ in anterior cervical discectomy and fusion is effective and safe, and results in similar outcomes compared to local autograft bone at 2 yr following surgery.

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.

Risk Factors of Allogenous Bone Graft Collapse in Two-Level Anterior Cervical Discectomy and Fusion

Objective

Anterior cervical discectomy and fusion (ACDF) is commonly used surgical procedure for cervical degenerative disease. Among the various intervertebral spacers, the use of allografts is increasing due to its advantages such as no harvest site complications and low rate of subsidence. Although subsidence is a rare complication, graft collapse is often observed in the follow-up period. Graft collapse is defined as a significant graft height loss without subsidence, which can lead to clinical deterioration due to foraminal re-stenosis or segmental kyphosis. However, studies about the collapse of allografts are very limited. In this study, we evaluated risk factors associated with graft collapse.

Methods

We retrospectively reviewed 33 patients who underwent two level ACDF with anterior plating using allogenous bone graft from January 2013 to June 2017. Various factors related to cervical sagittal alignment were measured preoperatively (PRE), postoperatively (POST), and last follow-up. The collapse was defined as the ratio of decrement from POST disc height to follow-up disc height. We also defined significant collapses as disc heights that were decreased by 30% or more after surgery. The intraoperative distraction was defined as the ratio of increment from PRE disc height to POST disc height.

Results

The subsidence rate was 4.5% and graft collapse rate was 28.8%. The pseudarthrosis rate was 16.7% and there was no association between pseudarthrosis and graft collapse. Among the collapse-related risk factors, pre-operative segmental angle (p=0.047) and intra-operative distraction (p=0.003) were significantly related to allograft collapse. The cut-off value of intraoperative distraction ≥37.3% was significantly associated with collapse (p=0.009; odds ratio, 4.622; 95% confidence interval, 1.470-14.531). The average time of events were as follows: collapse, 5.8±5.7 months; subsidence, 0.99±0.50 months; and instrument failure, 9.13±0.50 months.

Conclusion

We experienced a higher frequency rate of collapse than subsidence in ACDF using an allograft. Of the various preoperative factors, intra-operative distraction was the most predictable factor of the allograft collapse. This was especially true when the intraoperative distraction was more than 37%, in which case the occurrence of graft collapse increased 4.6 times. We also found that instrument failure occurs only after the allograft collapse.

Complications and Risk Factors Using Structural Allograft Versus Synthetic Cage: Analysis 17 783 Anterior Cervical Discectomy and Fusions Using a National Registry

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To determine the rates of perioperative complications in patients undergoing anterior cervical discectomy and fusion (ACDF) with allograft versus synthetic cage.

METHODS

A large national administrative health care database was queried for ACDF procedures performed between 2007 and 2014 using ICD-9 (International Statistical Classification of Diseases, 9th revision) and CPT (Current Procedural Terminology) codes. Cases that utilized structural allograft and synthetic cages were identified via CPT codes. Gender, age, frequency of obesity, cigarette use, diabetes, and number of levels fused were compared between the 2 cohorts using χ² test. Complications within 90 days were identified via ICD-9 codes and compared between the 2 cohorts. Revision rates within 2 years were noted.

RESULTS

A total of 10 648 ACDF cases using synthetic cages and 7135 ACDFs using structural allograft were identified. The demographics between the 2 cohorts were similar. Overall complication rate was 8.71% in the synthetic cage group compared with 7.76% in the structural allograft group (P < .01). Use of synthetic cage was associated with higher rate of respiratory complications, 0.57% compared with 0.31% in the structural allograft cohort (P = .03), while use of structural allograft was associated with a higher rate of dysphagia, 0.64% compared with 0.33% (P < .01). Revision rate at 2 years was 0.50% and 0.56% in the synthetic cage and allograft groups, respectively (P = .03).

CONCLUSIONS

This data suggests that synthetic cages are associated with a marginally higher overall rate of complications with similar revision rates.

Bone Graft Substitutes in Single- or Double-Level Anterior Cervical Discectomy and Fusion: A Systematic Review

STUDY DESIGN

Systematic review OBJECTIVE.: To undertake a systematic review of published literature to evaluate efficacy of bone graft substitutes on radiographic and clinical outcomes in single- or double-level anterior cervical discectomy and fusion (ACDF) for degenerative disease.

SUMMARY OF BACKGROUND DATA

ACDF is one of the most common spinal surgeries completed in the United States. Today bone graft substitutes including ceramic-based synthetic bone grafts, allografts, bone morphogenetic proteins (BMPs), mesenchymal stem cells, and bone marrow aspirate are widely used to enhance fusions; even though the efficacy of these substitutes is poorly defined. Critical evaluation of these products is necessary to optimize radiographic and clinical outcomes for ACDF in degenerative disease.

METHODS

A systematic literature review of 22 published articles was conducted. All articles reported results on patients who underwent a single- or double-level ACDF performed using a bone graft substitute and reported results on radiographic fusion rates at least 6 months after surgery.

RESULTS

All studies using BMP showed 100% fusion rate despite length of the study or whether additional bone graft substitutes were used. Use of only ceramic-based synthetics had the lowest fusion rate, 80.5%. Use of only mesenchymal stem cells resulted in an average fusion rate of 87.7%. When used alone, allograft resulted in an average fusion rate of 87.3%. This was significantly influenced by one outlier, Kim et al, which when removed, increased the fusion rate to 93.5%. Clinical outcomes were improved postoperatively irrespective of the graft used, although dysphagia was significantly greater in studies using BMP (P < 0.001).

CONCLUSION

Allograft alone has the lowest cost with similar fusion rates and clinical outcomes compared to other bone graft substitutes. Physicians should consider this when choosing to use bone graft substitutes for routine ACDFs.

LEVEL OF EVIDENCE

4.

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.

Comparison of Cortical Ring Allograft and Plate Fixation with Autologous Iliac Bone Graft for Anterior Cervical Discectomy and Fusion

Study Design

A retrospective cohort study.

Purpose

To compare the clinical and radiological outcomes of patients who underwent anterior cervical discectomy and fusion (ACDF) supplemented with plate fixation using allograft with those who underwent ACDF using tricortical iliac autograft.

Overview of Literature

As plate fixation is becoming popular, it is reported that ACDF using allograft may have similar outcomes compared with ACDF using autograft.

Methods

Forty-one patients who underwent ACDF supplemented with plate fixation were included in this study. We evaluated 24 patients who used cortical ring allograft filled with demineralized bone matrix (DBM) (group A) and 17 patients who used tricortical iliac autograft (group B). In radiological evaluations, fusion rate, subsidence of grafted material, cervical lordosis, fused segmental lordosis, and radiological adjacent segment degeneration (ASD) were observed and analyzed with preoperative and postoperative plain radiographs. Clinical outcomes were evaluated using the Neck Disability Index score, Odom criteria, and Visual Analog Scale score of neck and upper extremity pain. Radiological union was determined by dynamic radiographs using cutoff values of 1 mm of interspinous motion as the indication of pseudarthrosis.

Results

There was no significant difference in the fusion rate, graft subsidence, cervical lordosis, fused segmental lordosis, and ASD incidence between the groups. Operative time was shorter in group A (136 min) than in group B (141 min), but it was not significant (p>0.05). Blood loss was greater in group B (325 mL) than in group A (210 mL, p=0.013). There was no difference in the clinical outcomes before and after surgery.

Conclusions

In ACDF with plate fixation, cortical ring allograft filled with DBM group showed similar radiological and clinical outcomes compared with those of the autograft group. If the metal plate is reinforced, using cortical ring allograft could be a viable alternative to autograft.

Partial Vertebrae Resection Laterally to Harvest Supplemental Autograft Bone for Anterior Cervical Discectomy and Fusion: A Technical Note and Outcomes

PURPOSE

To evaluate the safety and effectiveness of partial vertebrae resection laterally through intervertebral space to harvest supplemental autograft bone for anterior cervical discectomy and fusion (ACDF).

METHODS

Patients who accepted 1-segment (n = 19, 38.2 months follow-up) or 2-segment (n = 17, 40.4 months follow-up) ACDF with supplemental autograft bone were included. Cervical lordosis (CL), segmental lordosis (SL), anterior segment height (ASH), and posterior segment height (PSH) on neutrally lateral radiography, and intervertebral fusion rate on computed tomography were measured. The operation time, intraoperative blood loss, Japanese Orthopedic Association score, visual analog scale around the neck or arm, Neck Disability Index, and complications were also recorded.

RESULTS

Mean operation time was 86.2 and 115.6 minutes, and the intraoperative blood loss was 41.7 and 79.4 mL in cases with 1-segment and 2-segment ACDF, respectively. At the final visit, the visual analog scale score and Neck Disability Index significantly decreased, and the Japanese Orthopedic Association score significantly increased. Significant increases were observed in the ASH, PSH, CL, and SL after 2-segment ACDF. Significant increases were observed in the CL and SL after 1-segment ACDF, but not in the ASH and PSH. All the ASH, PSH, CL, and SL kept unchanged at the final visit. All cases acquired definite intervertebral fusion, and the incidence of cage subsidence was 5.3% after 1-segment and 17.6% after 2-segment ACDF at the final visit.

CONCLUSIONS

Partial vertebrae resection laterally through the intervertebral space was a safe and effective method to harvest supplemental autograft bone for the ACDF.

A single center retrospective clinical evaluation of anterior cervical discectomy and fusion comparing allograft spacers to silicon nitride cages

BACKGROUND

Iliac crest autograft or allograft spacers have been traditionally utilized in anterior cervical discectomy and fusion (ACDF) to provide vertebral stabilization and enhanced osteogenesis. However, abiotic cages have largely replaced these allogenic sources due to host-site morbidities and disease transmission risks, respectively. Although devices made of polyetheretherketone (PEEK) or titanium-alloys (Ti) have gained wide popularity, they lack osteoinductive or conductive capabilities. In contrast, silicon nitride (Si3N4) is a relatively new implant material that also provides structural stability and yet purportedly offers osteopromotive and antimicrobial behavior. This study compared radiographic outcomes at ≥12 months of follow-up for osseous integration, fusion rate, time to fusion, and subsidence in ACDF patients with differing intervertebral spacers.

METHODS

Fifty-eight ACDF patients (108 segments) implanted with Si3N4 cages were compared to thirty-four similar ACDF patients (61 segments) implanted with fibular allograft spacers. Lateral radiographs (normal, flexion, and extension) were obtained at 3, 6, 12, and 24 months to assess osseous integration, the presence of bridging bone, the absence of peri-implant radiolucencies, subsidence, and fusion using both interspinous distance (ISD) and Cobb angle methods.

RESULTS

In patients with ≥12 months of follow-up, fusion for the allograft spacers and Si3N4 cages was 86.84% and 96.83%, respectively (ISD method, P=0.10), and 67.65% and 84.13%, respectively (Cobb angle method P=0.07), while osseointegration was 76.32% and 93.65%, respectively (P=0.02). The time to fusion significantly favored the Si3N4 cages (4.08 vs. 8.64 months (ISD method, P=0.01), and 6.76 vs. 11.74 months (Cobb angle method, P=0.04). The assessed time for full osseointegration was 7.83 and 19.24 months for Si3N4 and allograft, respectively (P=0.00). Average subsidence at 1-year follow-up was 0.51 and 2.71 mm for the Si3N4 and allograft cohorts, respectively (P=0.00).

CONCLUSIONS

In comparison to fibular allograft spacers, Si3N4 cages showed earlier osseointegration and fusion, higher fusion rates, and less subsidence.

Rare Intractable Cervicalgia Related to Exaggerated Disc Height Distraction : Report of Two Cases and Literature Review

We present two cases of unexpected postoperative intractable cervicalgia due to over-sized implant insertion during simple anterior cervical decompression and fusion (ACDF) or artificial disc replacement (ADR). These patients experienced severe cervicalgia mostly related to their neck motion even after standard cervical operations. In both cases, the restored disc heights after the operations were prominently greater than the preoperative disc heights. The patients had not responded to any of the conservative treatments, and unloading of these excessively distracted segments through ultimate revision surgery led to dramatic pain relief. This report emphasizes the increase in distractional forces that takes place after a standard ACDF or ADR, as well as the importance of a proper sized implant. It also includes the reviews of other biomechanical or clinical reports dealing with this issue, thereby cautioning the surgeons not to disregard these factors, which might have an adverse effect in patients with cervicalgia even after radiographically successful cervical procedures.

Vertebroplasty Using Allograft Bone Chips with Posterior Instrumented Fusion in the Treatment of Osteoporotic Vertebral Fractures with Neurological Deficits

Introduction

In general, osteoporotic vertebral fractures with neurological deficits require surgery. However, the ideal surgical method remains controversial. We evaluated the efficacy of combining posterior instrumented fusion and vertebroplasty using allograft bone chips.

Methods

Twelve patients (five men, seven women; age 68-84 years, mean age 75.9 years) with osteoporotic vertebral fractures with neurological deficits were reviewed retrospectively. They underwent posterior instrumented fusion and vertebroplasty, using allograft bone, at our institution between January 2007 and June 2016. We assessed the surgical results, radiologically and neurologically, after a mean follow-up of 37.3 months.

Results

The mean local kyphosis angle was 10° before surgery, −3.3° immediately after surgery, and 4.4° at follow-up. The average spinal canal compromise was 26.9% before surgery and 19.5% at follow-up. All patients achieved bony fusion and none needed additional surgery. All patients improved by at least one grade on the modified Frankel grading system.

Conclusions

Combining vertebroplasty, using allograft bone chips, and posterior instrumented fusion appears to be an effective option for osteoporotic vertebral fractures with neurological deficits.

Anterior Cervical Discectomy With Fusion Using a Local Source for Cancellous Autograft: A Biomechanical Analysis of Vertebral Body Stability in an Osteopenic Bone Model

BACKGROUND

Anterior cervical discectomy with fusion is an effective treatment for patients having cervical radiculopathy and myelopathy. To reduce morbidity associated with autograft taken from the iliac crest without sacrificing high fusion rates, a novel technique that harvests bone from the vertebral body adjacent to the operative disc space has been proposed. The effects of square and round bone graft harvest techniques on the mechanical stability of the osteopenic donor vertebrae are unknown. We analyzed the biomechanical implications of the technique by subjecting osteopenic models to uniaxial compression to compare yield strengths of surgically altered and unaltered specimens.

METHODS

Biomechanical grade polyurethane foam was cut into 60 different 12 mm × 17 mm × 20 mm blocks. The foam had a density of 10 pounds per cubic foot, simulating osteoporotic bone. Rectangular prism (4 mm × 4 mm × 6 mm) and cylindrical cores (r = 2 mm, h = 8 mm) were removed from 20 blocks per group. Twenty samples were left intact as a control group. Anterior plate screws were applied to the models and a Polyether ether ketone (PEEK) interbody spacer was placed on top. Samples underwent uniaxial compression at 0.1 mm/s until mechanical failure. Points of structural failure were determined using a 0.1% offset on a force-displacement curve and compared to determine the reductions in compressive strength.

RESULTS

The mean force eliciting structural failure for intact samples was 450.6 N. Average failure forces for rectangular prisms and cylindrical cores removed were 383.2 and 395.4 N, respectively. Removal of a rectangular prismatic core of the necessary volume resulted in a 15.0% reduction in compressive strength, while removal of a cylindrical core of comparable volume facilitated a reduction of 12.2%.

CONCLUSION

Local autograft harvested from adjacent vertebrae reduces morbidity associated with a second surgical site while minimally reducing the compressive strength of the donor vertebra in an osteopenic model, lending credence to the efficacy of this technique in elderly patient populations.

Anterior Cervical Infection: Presentation and Incidence of an Uncommon Postoperative Complication

STUDY DESIGN

Retrospective multi-institutional case series.

OBJECTIVE

The anterior cervical discectomy and fusion (ACDF) affords the surgeon the flexibility to treat a variety of cervical pathologies, with the majority being for degenerative and traumatic indications. Limited data in the literature describe the presentation and true incidence of postoperative surgical site infections.

METHODS

A retrospective multicenter case series study was conducted involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network, selected for their excellence in spine care and clinical research infrastructure and experience. Medical records for 17 625 patients who received cervical spine surgery (levels from C2 to C7) between January 1, 2005, and December 31, 2011, inclusive, were reviewed to identify the occurrence of 21 predefined treatment complications. Patients who underwent an ACDF were identified in the database and reviewed for the occurrence of postoperative anterior cervical infections.

RESULTS

A total of 8887 patients were identified from a retrospective database analysis of 21 centers providing data for postoperative anterior cervical infections (17/21, 81% response rate). A total of 6 postoperative infections after ACDF were identified for a mean rate of 0.07% (range 0% to 0.39%). The mean age of patients identified was 57.5 (SD = 11.6, 66.7% female). The mean body mass index was 22.02. Of the total infections, half were smokers (n = 3). Two patients presented with myelopathy, and 3 patients presented with radiculopathic-type complaints. The mean length of stay was 4.7 days. All patients were treated aggressively with surgery for management of this complication, with improvement in all patients. There were no mortalities.

CONCLUSION

The incidence of postoperative infection in ACDF is exceedingly low. The management has historically been urgent irrigation and debridement of the surgical site. However, due to the rarity of this occurrence, guidance for management is limited to retrospective series.

Allograft Bone Use in Pediatric Subaxial Cervical Spine Fusions

BACKGROUND

The use of freeze-dried allograft as a bone graft substitute for pediatric spine surgery is safe and efficacious in the thoracic and lumbar spines. Allograft bone use in segmental instrumented fusions in the subaxial cervical spine has not been well reported in the literature. We sought to describe our experience with allograft bone in this patient cohort, and to compare union rates to patients treated with autograft.

METHODS

Medical records were queried over a 10-year time period (2004 to 2014). Inclusion criteria were all pediatric patients (18 y old and below) who underwent subaxial cervical spine fusion with minimum follow-up of 24 months. Variables queried included demographics, type of graft material used, diagnosis, approach (anterior, posterior, combined), levels instrumented, placement of postoperative halo, surgical-related complications, and achievement of fusion.

RESULTS

A total of 26 patients qualified for inclusion (18 allograft, 8 autograft). No differences existed between the 2 groups regarding age, sex, or number of fused levels. In the allograft cohort, average age at initial surgery was 13.3 years (range, 5 to 18 y). The most common reasons for surgery included trauma (6), tumor (3), and syndrome-associated kyphosis (3). The average number of instrumented levels was 4 (range, 2 to 13). Four patients (22%) developed a postoperative surgical complication. There were 2 asymptomatic pseudarthroses not requiring revision. At a minimum of 24-month follow-up (average, 45 mo; range, 24 to 121 mo), the allograft group demonstrated a fusion rate of 88%, which was comparable with a fusion rate of 87% in the autograft group.

CONCLUSIONS

The use of allograft bone for pediatric subaxial instrumented cervical spine fusions is safe in a variety of conditions, with the same rate of fusion as autograft. Rates of complications are acceptable. To avoid donor-site morbidity from autogenous graft harvest, we recommend considering allograft bone in subaxial cervical spine fusions with modern segmental instrumentation.

LEVEL OF EVIDENCE

Level IV-case series; therapeutic.

Dysphagia Rates after Anterior Cervical Diskectomy and Fusion: A Systematic Review and Meta-Analysis

STUDY DESIGN

 Systematic review and meta-analysis.

OBJECTIVE

Anterior cervical diskectomy and fusion (ACDF) is an effective surgical option for patients with cervical radiculopathy, myelopathy, or deformity. Although ACDF is generally safe, dysphagia is a common complication. Despite its high incidence, prolonged postoperative dysphagia is poorly understood; its etiology remains relatively unknown, and its risk factors are widely debated.

METHODS

We searched MEDLINE, Scopus, Web of Science, and Embase for studies reporting complications for cervical diskectomy with plating. We recorded dysphagia events from all included studies and calculated effect summary values, 95% confidence intervals (CIs), Q values, and I² values.

RESULTS

Of the 7,780 retrieved articles, 14 met inclusion criteria. The overall dysphagia rate was 8.5% (95% CI 5.7 to 11.3%). The rate of moderate or severe dysphagia was 4.4% (0.4 to 8.4%). Follow-up times of <12, 12 to 24, and >24 months reported rates of 19.9% (6.0 to 33.7%), 7.0% (5.2 to 8.7%), and 7.6% (1.4 to 13.8%), respectively. Studies utilizing the Bazaz Dysphagia Score resulted in an increase in dysphagia diagnosis relative to studies with no outlined criteria (19.8%, 5.9 to 33.7% and 6.9%, 3.7 to 10.0%, respectively), indicating that the criteria used for dysphagia identification are critical. There was no difference in dysphagia rate with the use of autograft versus allograft.

CONCLUSIONS

This review represents a comprehensive estimation of the actual incidence of dysphagia across a heterogeneous group of surgeons, patients, and criteria. The classification scheme for dysphagia varied significantly within the literature. To ensure its diagnosis and identification, we recommend the use of a standardized, well-outlined method for dysphagia diagnosis.

Study protocol for a randomised controlled multicentre study: the Foraminotomy ACDF Cost-Effectiveness Trial (FACET) in patients with cervical radiculopathy

INTRODUCTION

Cervical radiculopathy due to discogenic or spondylotic stenosis of the neuroforamen can be surgically treated by an anterior discectomy with fusion (ACDF) or a posterior foraminotomy (FOR). Most surgeons prefer ACDF, although there are indications that FOR is as effective as ACDF, has a lower complication rate and is less expensive. A head-to-head comparison of the 2 surgical techniques in a randomised controlled trial has not yet been performed. The study objectives of the Foraminotomy ACDF Cost-Effectiveness Trial (FACET) study are to compare clinical outcomes, complication rates and cost-effectiveness of FOR to ACDF.

METHODS AND ANALYSIS

The FACET study is a prospective randomised controlled trial conducted in 7 medical centres in the Netherlands. The follow-up period is 2 years. The main inclusion criterion is a radiculopathy of the C4, C5, C6 or C7 nerve root, due to a single-level isolated cervical foraminal stenosis caused by a soft disc and/or osteophytic component, requiring operative decompression. A sample size of 308 patients is required to test the hypothesis of clinical non-inferiority of FOR versus ACDF. Primary outcomes are: 'operative success', the measured decrease in radiculopathy assessed by the visual analogue scale and 'patient success', assessed by the modified Odom's criteria. Secondary outcomes are: Work Ability Index (single-item WAI), quality of life (EuroQol 5 Dimensions 5 level Survey, EQ-5D-5L), Neck Disability Index (NDI) and complications. An economic evaluation will assess cost-effectiveness. In addition, a budget impact analysis will be performed.

ETHICS AND DISSEMINATION

Ethical approval was obtained from the Institutional Ethics Committee of the University Medical Center Groningen. Results of this study will be disseminated through national and international papers. The participants and relevant patient support groups will be informed about the results of the study.

TRIAL REGISTRATION NUMBER

NTR5536, pre-results.

Imaging Evaluation and Relative Significance in Cases of Cervical Disk Allografting: Radiographic Character After Total Disk Transplantation

STUDY DESIGN

The clinical and radiologic data of total disk allografting (TDA) cases were collected and analyzed to explore the correlation between neurological function improvements and imaging changes.

OBJECTIVE

The aim of the study was to assess the medium-term and long-term outcome and radiographic character after TDA, and, furthermore, to explore the significance of the changes of imaging signs after the transplantation.

SUMMARY OF BACKGROUND DATA

Spinal fusion may result in the adjacent segment degeneration. The anxiousness urged the necessity for the development of TDA to reduce the risk of adjacent segment degeneration. Both animal studies and recent clinical trials have shown promising results to support the use of intervertebral disk allograft as a natural mobile disk replacement.

METHODS

The conditions of 13 cases that underwent TDA after cervical discectomy were recorded in detail. Axial symptoms and neurological function in various periods were assessed, and, meanwhile, radiologic examination was performed for the comprehensive evaluation of the relevant indicators before and after surgery.

RESULTS

(1) There was significant improvement in the neurological function after TDA. Postoperatively, the Visual Analog Score of axial symptoms did not increase significantly. (2) Both the entire and local segment maintained a satisfactory curve after allografting. There was no obvious correlation between the neurological function recovery and the cervical curve. Besides, the motion of the cervical spine did not change postoperatively. (3) Postoperatively, the spinal cord area at the index level increased significantly, whereas the signal value of the transplanted disk decreased sharply.

CONCLUSIONS

(1) Disk allografting is one of the effective and safe methods in treating the diseases of cervical disk herniation. (2) Although some degeneration occurs in the transplanted disk, the allograft can still be alive and can successfully maintain and improve the biological characters of the cervical spine in both radiologic and practical aspects.