Cervical canal stenosis and adjacent segment degeneration after anterior cervical arthrodesis

Development and validation of a predictive model for the risk of symptomatic adjacent segmental degeneration after anterior cervical discectomy and fusion

Background

To investigate the risk factors for symptomatic adjacent segment degeneration (ASD) 5 years after anterior cervical discectomy and fusion (ACDF) and develop and evaluate predictive models.

Methods

A total of 655 patients who underwent ACDF were randomly assigned to the training set (n = 393) or validation set (n = 262) at a ratio of 6:4. Independent predictors of ASD were selected by LASSO regression and logistic regression analysis. A calibration curve, ROC curve and DCA curve were used to evaluate the model performance.

Results

LASSO regression combined with logistic regression analysis revealed that age, cervical canal stenosis, smaller T1S and smaller cervical lordosis (CL) were risk factors for ASD 5 years after surgery. Nomographic analysis using appeal factors was used to predict the risk of ASD. The area under the ROC curve was 0.711 (95% CI: 0.643-0.780) in the training set and 0.701 (95% CI: 0.618-0.785) in the validation set. The calibration curve showed no significant bias in either set. The DCA indicated that using the nomogram to predict the risk of ASD would be more accurate when the risk threshold probability was 12-53% in the training set and 6-43% in the validation set.

Conclusion

Age, cervical spinal stenosis, a smaller T1S, and a smaller CL are independent risk factors for ASD 5 years after ACDF surgery. Based on these four indicators, we constructed a new clinical prediction model that has a certain predictive effect and is conducive to clinical decision-making and treatment planning.

Does Spinal Cord-Canal Mismatch Adversely Affect the Clinical Outcomes of Anterior Cervical Discectomy and Fusion for the Treatment of Cervical Myelopathy?

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

To clarify whether clinical outcomes of anterior cervical discectomy and fusion (ACDF), is affected by presence of spinal canal-cord mismatch (SCCM).

SUMMARY OF BACKGROUND DATA

SCCM is considered a factor that would moderately influence surgeons to perform posterior surgery since it could widen the spinal canal, while an anterior approach could only remove degenerative pathologies grown into the spinal canal.

MATERIALS AND METHODS

We retrospectively reviewed 186 patients who underwent ACDF and had been followed-up for more than two years. Patients with spinal cord occupation ratio (SCOR) of ≥0.7 were classified into the SCCM group, while those with a SCOR of <0.7 were included in the no-SCCM group. Patient demographics, cervical sagittal parameters, neck pain visual analog scale (VAS), arm pain VAS, and Japanese Orthopedic Association (JOA) score were assessed. JOA score was the primary outcome of the study.

RESULTS

One hundred and forty-seven patients (79.0%) were included into the no-SCCM group, while 39 patients (21.0%) were classified into the SCCM group. Postoperative radiographic parameters including C2-C7 lordosis, C2-C7 sagittal vertical axis, and range of motion did not significantly differ between the two groups. Neck pain VAS, arm pain VAS, and JOA score (no-SCCM group, from 13.7±2.5 to 14.6±2.3, P <0.001; SCCM group, from 13.8±1.6 to 15.0±2.0, P <0.001) significantly improved after the operation in both groups, and results were not significantly different between the two groups. Furthermore, SCOR was not significantly associated with JOA recovery rate at two years postoperatively in linear regression analysis.

CONCLUSION

Clinical and radiographic outcomes of ACDF were not affected by the presence of SCCM. Furthermore, SCOR was not significantly associated with neurological recovery at two years of follow-up. Therefore, ACDF can be safely and effectively applied for treating cervical myelopathy, regardless of the presence of SCCM, when other factors favor the anterior approach.

LEVEL OF EVIDENCE

Level III.

Radiographic Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion (ACDF): A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVES

To assess the radiographic risk factors for adjacent segment disease (ASD) following anterior cervical discectomy and fusion (ACDF) for degenerative cervical spine pathologies.

METHODS

PubMed, Embase and the Cochrane Library databases were searched up to December 2023. The primary inclusion criteria were degenerative spinal conditions treated with ACDF, comparing radiological parameters in patients with and without postoperative ASD. The radiographic parameters included intervertebral disc height, cervical sagittal alignment, sagittal segmental alignment, range of motion, segmental height, T1 slope, sagittal vertical axis (SVA), thoracic inlet angle (TIA), and plate to disc distance (PPD). Risk of bias was assessed for all studies. The Cochrane Review Manager was utilized to perform the meta-analysis.

RESULTS

From 7044 articles, 13 retrospective studies were included in the final analysis. Three studies had "not serious" bias and the other 10 studies had serious or very serious bias. The total number of patients in the included studies was 1799 patients. Five studies included single-level ACDF, 2 studies included multi-level ACDF, and 6 studies included single or multi-level ACDF. On meta-analysis, the significant risk factors associated with ASD development were reduced postoperative cervical lordosis (mean difference [MD] = 3.35°, P = .002), reduced last-follow-up cervical lordosis (MD = -3.02°, P = .0003), increased preoperative to postoperative cervical sagittal alignment change (MD = -3.68°, P = .03), and the presence of developmental cervical canal stenosis (Odds ratio [OR] = 4.17, P < .001).

CONCLUSIONS

Decreased postoperative cervical lordosis, greater change in cervical sagittal alignment and developmental cervical canal stenosis were associated with an increased risk of ASD following ACDF.

Artificial Intelligence in Neurosurgery: A State-of-the-Art Review from Past to Future

In recent years, there has been a significant surge in discussions surrounding artificial intelligence (AI), along with a corresponding increase in its practical applications in various facets of everyday life, including the medical industry. Notably, even in the highly specialized realm of neurosurgery, AI has been utilized for differential diagnosis, pre-operative evaluation, and improving surgical precision. Many of these applications have begun to mitigate risks of intraoperative and postoperative complications and post-operative care. This article aims to present an overview of the principal published papers on the significant themes of tumor, spine, epilepsy, and vascular issues, wherein AI has been applied to assess its potential applications within neurosurgery. The method involved identifying high-cited seminal papers using PubMed and Google Scholar, conducting a comprehensive review of various study types, and summarizing machine learning applications to enhance understanding among clinicians for future utilization. Recent studies demonstrate that machine learning (ML) holds significant potential in neuro-oncological care, spine surgery, epilepsy management, and other neurosurgical applications. ML techniques have proven effective in tumor identification, surgical outcomes prediction, seizure outcome prediction, aneurysm prediction, and more, highlighting its broad impact and potential in improving patient management and outcomes in neurosurgery. This review will encompass the current state of research, as well as predictions for the future of AI within neurosurgery.

Contribution of dynamic cervical MRI to surgical planning for degenerative cervical myelopathy: Revision rate and clinical outcomes at 5 years' postoperative

INTRODUCTION

Cervical MRI is the gold standard for surgical planning of degenerative cervical myelopathy; however, the symptomatic postoperative recurrence rate is high in the medium and long terms (9.1% to 10.7%) and may bring into question the quality of the preoperative surgical plan. The objective of this study was to evaluate cervical spinal stenosis and intramedullary hyperintensity with dynamic cervical MRI to determine the recurrence rate and clinical improvement in a cohort of patients who had dynamic cervical MRI incorporated into their surgical plan.

METHODS

This was a prospective, single-center study. Upon enrolment and at each follow-up visit, patients completed the mJOA score, NDI, cervical pain on visual analog scale (VAS) and radicular pain on VAS. Every enrolled patient underwent dynamic cervical MRI (in neutral, flexion and extension positions). Five levels were measured in the three positions, resulting in 915 levels for analysis.

RESULTS

Sixty-one patients were included. Eighty-four levels had an intramedullary hyperintensity in neutral position, 93 in extension and 112 in flexion. The mean sagittal diameter varied the most at C4-C5, going from 7.13mm (SD 2.32) on average in neutral to 6.30mm (SD 2.22) in extension and 8.29mm (SD 2.10) in flexion, a variation of -12% and +16%, respectively. A Mühle grade≥2 was found in 134 levels in neutral position versus 189 in extension and 110 in flexion. None of the patients had worse neurological symptoms following the dynamic cervical MRI. The mean postoperative follow-up was 4.4 years (SD 0.88). Two patients (3.1%) required surgical revision because the implants had shifted. One patient developed symptomatic adjacent segment disease.

CONCLUSION

Preoperative surgical planning that incorporates dynamic cervical MRI before the surgical treatment of degenerative cervical myelopathy appears to be a safe and reliable method and one that helps reduce symptoms in the long term.

LEVEL OF EVIDENCE

IV.

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

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

Comparison of Adjacent Segment Degeneration, Cervical Alignment, and Clinical Outcomes After One- and Multilevel Anterior Cervical Discectomy and Fusion

Objective

This study aimed to assess the influence of a fused segment on cervical range of motion (ROM) and adjacent segmental kinematics and determine whether increasing number of fusion levels causes accelerated adjacent segment degeneration (ASD) after anterior cervical discectomy and fusion (ACDF).

Methods

A total of 165 patients treated with ACDF were recruited for assessment, and they were divided into 3 groups based on the number of fusion levels. Radiological measurements and clinical outcomes included visual analogue scale (VAS) and Neck Disability Index (NDI) assessed preoperatively and at ≥2 years of follow-up.

Results

ASD occurred in 41 of 165 patients who underwent ACDF (1-level, 12 of 78 [15.38%]; 2-level, 14 of 49 [28.57%]; 3-level, 15 of 38 [39.47%]; p=0.015) at final follow-up (mean, 31.9 months). Significant differences were found in reduction of global ROM based on the number of fusion levels (p<0.001). The upper adjacent segment ROM increased over time (p=0.004); however, lower segment ROM did not. Three-level ACDF did not obtain greater amounts of lordosis than did 1- or 2-level ACDF (p=0.003). Postoperative neck VAS scores and NDI were significantly higher for 3-level ACDF than for 1- or 2-level ACDF (p=0.033 and p=0.001).

Conclusion

ASD occurred predominantly in multilevel cervical fusion, more frequently in the upper segment of the prior fusion and as the number of fusion levels increased. Patients who underwent multilevel fusion had greater reduction of global ROM and increased compensatory motion at the upper adjacent segment. Three-level ACDF did not appear to restore cervical lordosis significantly compared with 1- or 2-level arthrodesis.

Symptomatic adjacent segment disease after single-lever anterior cervical discectomy and fusion: Incidence and risk factors

The purpose of this study was to determine the incidence and risk factors of symptomatic adjacent segment disease (ASD) following single-lever anterior cervical discectomy and fusion (ACDF) for cervical degenerative diseases.From January 2000 to December 2010, a total of 582 patients with cervical radiculopathy and myelopathy who had undergone single-lever ACDF surgery in the authors' institution were reviewed retrospectively. Patients who had a revision surgery for symptomatic ASD were selected for this study. The authors analyzed the incidence for ASD after single-lever ACDF. And univariate analysis and logistic regression analysis were performed to identify the risk factors of ASD.Among the 582 patients, 36 patients received subsequent surgical management for ASD after initial single-lever ACDF for an overall prevalence of 6.2%. The average onset time of ASD was 8.5 (2-15) years. The univariate analysis showed that there were no significant differences in sex, duration of disease, BMI, DM, smoking, operative levels, and follow-up period (P > .05) between the 2 groups with and without ASD. There were statistically significant differences in age at the time of operation (χ = 4.361, P = .037), and developmental canal stenosis (χ = 4.181, P = .041) between patients with and without ASD. The variables of age at the time of operation and developmental canal stenosis were included in a logistic regression model. The logistic regression analysis revealed that age at the time of operation ≤50 years (P = .045, OR = 3.015, 95% CI = 1.024-8.882) and developmental canal stenosis (P = .042, OR = 2.797, 95% CI = 1.039-7.527) were the risk factors for ASD after single-lever ACDF.In the present study, the incidence of symptomatic ASD after single-lever ACDF was 6.2%. And the age at the time of operation ≤50 years and developmental canal stenosis were the risk factors for ASD. The patients ≤50 years old at the time of operation or with developmental canal stenosis are more likely to develop ASD after surgery, and the risk of reoperation will increase.

Survivorship Analysis of Clinical Adjacent-Segment Pathology After Single-Level Cervical Fusion

Background

Clinical adjacent-segment pathology (CASP) is an important problem after anterior cervical surgery. The purpose of this study was to predict prevalence of CASP and determine the possible risk factors for CASP after single-level anterior cervical discectomy and fusion surgery.

Material/Methods

We retrospectively reviewed a series of patients who underwent single-level cervical discectomy and fusion surgery (ACDF). Both basic and radiographic data of patients were collected. Life-table method and Kaplan-Meier analysis were used to calculate prevalence of CASP and disease-free survival rate. Cox analysis was performed to determine the predictive factors for it.

Results

A total of 256 patients were included in this study. The mean length of follow-up was 70.64 months. Among them, 31 patients were diagnosed as having CASP during follow-up. Nineteen of them were at the cephalad adjacent segment, and the other 12 were at the caudal segment. After ACDF procedures, 10.01% of patients developed new symptoms of CASP within 5 years, and the incidence increased to 23.89% after 10 years. The incidence rate of CASP was an average of 2.46% per year. Multivariate Cox regression analysis showed that congenital stenosis (hazard ratio [HR], 3.250; 95% confidence interval [CI], 1.538–6.867) and degeneration of adjacent segment (HR, 2.681; 95% CI, 1.259–5.709) were correlated with the incidence of CASP.

Conclusions

Patients with congenital stenosis and pre-existing degenerative changes of adjacent segments had a higher risk of developing CASP after single-level anterior cervical discectomy and fusion.

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

BACKGROUND CONTEXT

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

PURPOSE

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

STUDY DESIGN

This is a retrospective cohort study.

PATIENT SAMPLE

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

OUTCOME MEASURES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Clinical outcome following anterior cervical discectomy and fusion with and without anterior cervical plating for the treatment of cervical disc herniation-a 25-year follow-up study

Extreme long-term clinical outcome studies following anterior cervical discectomy and fusion (ACDF) with an autologous iliac crest with and without Caspar plating (ACDF + CP) for the treatment of radiculopathy caused by cervical disc herniation (CDH) are extremely rare. Hospital records of patients who underwent ACDF or ACDF + CP for the treatment of CDH at least 17 years ago were reviewed. Information about diagnosis, surgery, pre- and postoperative clinical process, and repeated procedure was analyzed. At final follow-up, patients were reviewed with a standardized questionnaire including the current neurological status, Neck Disability Index (NDI), Odom's criteria, a modified EQ-5D, and limitations in quality of life. One hundred twenty-two patients with a mean follow-up of 25 years were evaluated. ACDF was performed in 80 and ACDF + CP in 42 patients, respectively. At final follow-up, 81.1% of patients were free of radicular pain and had no repeated procedure. According to Odom's criteria, 86.1% of good to excellent functional recovery was noted. The mean NDI and EQ-5D was 14% and 5 points, respectively. There was no significant difference in the assessed clinical outcome parameters between patients treated with ACDF and ACDF + CP. The rate for repeated procedure due to degenerative cervical disorders was 10.7 and 7.4% due to symptomatic adjacent segment disease with 25 years. ACDF and ACDF + CP achieved a high rate radicular pain relief (89.3%) and clinical success (86.1%) for the treatment of CDH within a 25 years follow-up. No statistical difference concerning clinical outcome and rate of repeated procedure was detected.

Is cervical disc arthroplasty good for congenital cervical stenosis?

OBJECTIVE

Cervical disc arthroplasty (CDA) has been demonstrated to be as safe and effective as anterior cervical discectomy and fusion (ACDF) in the management of 1- and 2-level degenerative disc disease (DDD). However, there has been a lack of data to address the fundamental discrepancy between the two surgeries (CDA vs ACDF), and preservation versus elimination of motion, in the management of cervical myelopathy associated with congenital cervical stenosis (CCS). Although younger patients tend to benefit more from motion preservation, it is uncertain if CCS caused by multilevel DDD can be treated safely with CDA.

METHODS

Consecutive patients who underwent 3-level anterior cervical discectomy were retrospectively reviewed. Inclusion criteria were age less than 50 years, CCS (Pavlov ratio ≤ 0.82), symptomatic myelopathy correlated with DDD, and stenosis limited to 3 levels of the subaxial cervical (C3–7) spine. Exclusion criteria were ossification of the posterior longitudinal ligament, previous posterior decompression surgery (e.g., laminoplasty or laminectomy), osteoporosis, previous trauma, or other rheumatic diseases that might have caused the cervical myelopathy. All these patients who underwent 3-level discectomy were divided into 2 groups according to the strategies of management: preservation or elimination of motion (the hybrid-CDA group and the ACDF group). The hybrid-CDA group underwent 2-level CDA plus 1-level ACDF, whereas the ACDF group underwent 3-level ACDF. Clinical assessment was measured by the visual analog scales (VAS) for neck and arm pain, Japanese Orthopaedic Association (JOA) scores, and Nurick grades. Radiographic outcomes were measured using dynamic radiographs for evaluation of range of motion (ROM).

RESULTS

Thirty-seven patients, with a mean (± SD) age of 44.57 ± 5.10 years, were included in the final analysis. There was a male predominance in this series (78.4%, 29 male patients), and the mean follow-up duration was 2.37 ± 1.60 years. There were 20 patients in the hybrid-CDA group, and 17 in the ACDF group. Both groups demonstrated similar clinical improvement at 2 years' follow-up. These patients with 3-level stenosis experienced significant improvement after either type of surgery (hybrid-CDA and ACDF). There were no significant differences between the 2 groups at each of the follow-up visits postoperatively. The preoperative ROM over the operated subaxial levels was similar between both groups (21.9° vs 21.67°; p = 0.94). Postoperatively, the hybrid-CDA group had significantly greater ROM (10.65° vs 2.19°; p < 0.001) than the ACDF group. Complications, adverse events, and reoperations in both groups were similarly low.

CONCLUSIONS

Hybrid-CDA yielded similar clinical improvement to 3-level ACDF in patients with myelopathy caused by CCS. In this relatively young group of patients, hybrid-CDA demonstrated significantly more ROM than 3-level ACDF without adjacent-segment disease (ASD) at 2 years' follow-up. Therefore, hybrid-CDA appears to be an acceptable option in the management of CCS. The strategy of motion preservation yielded similar improvements of cervical myelopathy to motion elimination (i.e., ACDF) in patients with CCS, while the theoretical benefit of reducing ASD required further validation.

Prevalence of adjacent segment disease following cervical spine surgery: A PRISMA-compliant systematic review and meta-analysis

Prevalence estimates of adjacent segment degeneration (ASD) following cervical spine surgery varied greatly in current studies. We conducted a systematic review and meta-analysis to summarize the point prevalence of ASD after cervical spine surgery.

METHODS

Comprehensive electronic searches of PubMed, Embase, Web of Knowledge, and Cochrane Library databases were conducted to identify any study published from initial state to January 2016. Those reporting the prevalence of ASD after cervical surgery were included. A random-effects model was used to estimate the prevalence of radiographic ASD, symptomatic ASD, and reoperation ASD. Univariate meta-regression analyses were conducted to explore the potential associations between prevalence and length of follow-up. All analyses were performed using R version 3.2.3 (R Foundation for Statistical Computing).

RESULTS

A total of 83 studies were included in the meta-analysis. The prevalence of radiographic ASD, symptomatic ASD, and reoperation ASD after cervical surgery was 28.28% (95% confidence interval [CI], 20.96-36.96), 13.34% (95% CI, 11.06-16.00), and 5.78% (95% CI, 4.99-6.69), respectively, in a general analysis. It was found 2.79%, 1.43%, and 0.24% additions per year of follow-up in the incidence of radiographic ASD, symptomatic ASD, and reoperation ASD, respectively.

CONCLUSION

This meta-analysis provides some details about the prevalence of radiographic ASD, symptomatic ASD, and reoperation ASD after cervical spine surgery. However, the results of this meta-analysis should be interpreted with caution because of the heterogeneity among the studies.

Anterior Cervical Corpectomy Non-Fusion Model Produced by a Novel Implant

BACKGROUND

Anterior cervical corpectomy and fusion are frequently used in the treatment of cervical spinal disease. However, the range of motion (ROM) of the operative level is unavoidably lost due to fusion. This study aims to establish an anterior cervical corpectomy goat non-fusion model and to evaluate the ROM of adjacent and operative levels.

MATERIAL/METHODS

Six adult-male goats (in vivo group) and twelve adult-male goat cervical spine specimens (randomly divided equally into intact group or in vitro group) were included. The non-fusion model was established by implanting a novel implant at C4 level. Imagiological examinations for the in vivo group were performed to inspect the position of the implant and spinal cord status. Specimens were harvested six months after the operation. Biomechanical testing was conducted to obtain the ROM in flexion-extension, lateral bending, and axial rotation at upper adjacent level (C(2-3)), operative levels (C(3-4) and C(4-5)) and at C(2-5). Specimens in the intact group were first tested as intact and then tested as fixed and became the fixation group.

RESULTS

Imagiological examinations revealed that the position of the implant and the spinal cord status were good. The specimens in the in vivo and in vitro groups had significantly decreased C(2-3) ROM, increased C(3-4) and C(4-5) ROM and similar C(2-5) ROM compared with the fixation group.

CONCLUSIONS

This study presents a novel method for potential non-fusion treatment strategies for cervical spinal disease. However, improvement of this model and additional studies are needed.