Risk factors of second surgery for adjacent segment disease following anterior cervical discectomy and fusion: A 16-year cohort study

Comparative analysis of risk factors associated with degeneration of adjacent segments: zero-profile anchored spacer vs. anterior cervical plate and cage construct

Objective

Anterior cervical discectomy and fusion (ACDF) is an established treatment for cervical degenerative disc disease, but cervical spine surgery may affect sagittal alignment parameters and induce adjacent segment degeneration (ASD). This study aimed to determine the risk factors for developing ASD following anterior cervical plate and cage (ACPC) compared with the use of zero-profile anchored spacer (ROI-C).

Methods

A retrospective contrastive study included 105 patients who underwent ACPC or ROI-C between January 2014 and October 2019 at our treatment centre. There were 50 cases in the ROI-C group and 55 patients in the ACPC group. Clinical and radiological results and the incidence of ASD were assessed after surgery. All patients were further divided into the ASD and non-ASD groups for subgroup analysis.

Results

At each follow-up time, there was no statistically significant in radiographic parameters between the two groups. The overall ASD rate was higher in the ACPC group than in the ROI-C group (65.5% vs. 44.0%, p = 0.027). The low preoperative Cobb angle, low preoperative segment angle (SA), and loss of Cobb (ΔCobb) were significantly correlated with ASD. However, clinical outcomes were not associated with ASD at any postoperative follow-up visit.

Conclusion

Equally good therapeutic effects were achieved with both the ROI-C and ACPC. The occurrence of ASD was considerably higher in the ACPC group than in the ROI-C group. The preoperative Cobb angle, preoperative SA, and ΔCobb were the most associated with an increase in the risk of ASD.

Biomechanical Analysis of Hybrid Artificial Discs or Zero-Profile Devices for Treating 1-Level Adjacent Segment Degeneration in ACDF Revision Surgery

OBJECTIVE

Cervical hybrid surgery optimizes the use of cervical disc arthroplasty (CDA) and zero-profile (ZOP) devices in anterior cervical discectomy and fusion (ACDF) but lacks uniform combination and biomechanical standards, especially in revision surgery (RS). This study aimed to investigate the biomechanical characteristics of adjacent segments of the different hybrid RS constructs in ACDF RS.

METHODS

An intact 3-dimensional finite element model generated a normal cervical spine (C2-T1). This model was modified to the primary C5-6 ACDF model. Three RS models were created to treat C4-5 adjacent segment degeneration through implanting cages plus plates (Cage-Cage), ZOP devices (ZOP-Cage), or Bryan discs (CDA-Cage). A 1.0-Nm moment was applied to the primary C5-6 ACDF model to generate total C2-T1 range of motions (ROMs). Subsequently, a displacement load was applied to all RS models to match the total C2-T1 ROMs of the primary ACDF model.

RESULTS

The ZOP-Cage model showed lower biomechanical responses including ROM, intradiscal pressure, maximum von Mises stress in discs, and facet joint force in adjacent segments compared to the Cage-Cage model. The CDA-Cage model exhibited the lowest biomechanical responses and ROM ratio at adjacent segments among all RS models, closely approached or lower than those in the primary ACDF model in most motion directions. Additionally, the maximum von Mises stress on the C3-4 and C6-7 discs increased in the Cage-Cage and ZOP-Cage models but decreased in the CDA-Cage model when compared to the primary ACDF model.

CONCLUSION

The CDA-Cage construct had the lowest biomechanical responses with minimal kinematic change of adjacent segments. ZOP-Cage is the next best choice, especially if CDA is not suitable. This study provides a biomechanical reference for clinical hybrid RS decision-making to reduce the risk of ASD recurrence.

Stand-Alone Anchored Spacer vs Anterior Plate Construct in the Management of Adjacent Segment Disease after Anterior Cervical Discectomy and Fusion: A Systematic Review and Meta-Analysis of Comparative Studies

STUDY DESIGN

Systematic Review and Meta-Analysis.

OBJECTIVES

This study aimed to evaluate the clinical and radiological outcomes of surgically treated adjacent segment disease (ASDis) following ACDF with either anterior plate construct (APC) or stand-alone anchored spacers (SAAS).

METHOD

Multiple databases were searched until December 2022 for pertinent studies. The primary outcome was health-related quality of life outcomes [JOA, NDI, and VAS], whereas, the secondary outcomes included operative characteristics [estimated blood loss (EBL) and operative time (OT)], radiological outcomes [C2-C7 Cobb angle, disc height index (DHI) changes, fusion rate], and complications.

RESULTS

A total of 5 studies were included, comprising 210 patients who had been surgically treated for cervical ASDis. Among them, 113 received APC, and 97 received SAAS. Postoperative dysphagia was significantly higher in the APC group [47% vs 11%, OR = 7.7, 95% CI = 3.1-18.9, P < .05]. Similarly, operative time and blood loss were higher in the APC group compared to the SAAS group; [MD = 16.96, 95% CI = 7.87-26.06, P < .05] and [MD = 5.22, 95% CI = .35 - 10.09, P < .05], respectively. However, there was no difference in the rate of prolonged dysphagia and clinical outcomes in terms of JOA, NDI, and VAS. Furthermore, there was no difference in the radiological parameters including the C2-7 Cobb angle and DHI as well as the fusion rate.

CONCLUSION

Our meta-analysis demonstrated that both surgical techniques (APC and SAAS) are effective in treating ASDis. However, with low certainty of the evidence, considering patients are at high risk of dysphagia following revision cervical spine surgery SAAS may be the preferred choice.

Exploring the incidence and risk factors of reoperation for symptomatic adjacent segment disease following cervical decompression and fusion

Background

Patients with long-term follow-up after cervical decompression and fusion have often been noted to have development of adjacent segment degeneration with a smaller subset of these patients progressing to adjacent segment disease (ASD), which results in the development of new symptomatic radiculopathy or myelopathy referable to a site either directly above or below a prior fused segment. The cause of ASD is multifactorial often involving natural age-related progression of spondylosis, accelerated progression following cervical decompression and fusion, operative technique, and patient-related factors. The effect of age at the time of index cervical decompression and fusion on the need for reoperation for ASD is not fully understood. This study aims to establish underlying risk factors for the development of symptomatic cervical ASD following cervical decompression and fusion requiring reoperation in patients of various age groups.

Methods

A retrospective database review of patients aged 20 or greater with insurance claims of primary cervical decompression and fusion over the course of 11 years and 10 months (January 01, 2010-October 31, 2022) was conducted using an insurance claims database. The primary outcome was to evaluate the incidence of cervical ASD requiring reoperation amongst patients stratified by age at the time of their primary procedure. Secondary outcomes included an evaluation of various risk factors for ASD following cervical decompression and fusion including surgeon-controlled factors such as the number of levels fused and approach taken, patient cervical pathology including cervical disc disorder and cervical spondylosis, and underlying patient medical comorbidities including osteoporosis and vitamin D deficiency, and substance use.

Results

A total of 60,292 patient records were analyzed, where the overall reoperation incidence for symptomatic ASD was 6.57%, peaking at 8.12% among those aged 30 to 39 and decreasing with age. Regression analysis revealed ages lower than 50 years as more predictive for the development of symptomatic ASD requiring reoperation. Multivariate regression analysis identified predictive factors for reoperation, including age, Elixhauser Comorbidity Index (ECI), multiple-level surgery, cervical spondylosis, cervical disc disorder, osteoporosis, and vitamin D deficiency. Notably, these factors had a variable impact across various age groups, as revealed by subgroup analysis.

Conclusions

The incidence of reoperation secondary to symptomatic ASD is 6.57%, highest in those aged 30 to 39. The surgical approach had no significant impact on the need for reoperation, but multiple-level fusions posed a consistent risk in the development of symptomatic ASD requiring reoperation. Patient factors like degenerative disc disease, spondylosis, osteoporosis, and vitamin D deficiency were associated, urging further age-specific risk assessment and nonoperative intervention exploration.

Multilevel Cervical Disk Arthroplasty: Moving Beyond Two Levels

Cervical disk arthroplasty (CDA) is well-studied for 1-level and 2-level cervical pathology. There is an increasing trend towards its utilization for greater than 2-level disease as an alternative to the gold standard, anterior cervical discectomy and fusion (ACDF). The number of high-level, prospective studies or randomized trials regarding multilevel CDA is limited but continues to grow as the procedure gains popularity. In appropriately indicated patients with multilevel disease caused by disk herniations or spondylosis without extensive facet arthropathy, CDA shows promising results. Multilevel CDA should be avoided in patients with prior spinal trauma, significant degenerative spondylolisthesis with translation, arthrodesis without mobility, severely incompetent facet joints, ossification of the posterior longitudinal ligament, or kyphotic deformity. With overall similar risk profiles to ACDF but lower theoretical rates of pseudarthrosis and adjacent segment disease, multilevel CDA has been shown to preserve, or perhaps even increase, preoperative cervical range of motion. There are negligible differences in postoperative neck and arm pain, VAS scores, modified Japanese Orthopaedic Association scores, and Neck Disability Index scores when comparing multilevel CDA and ACDF. Despite current indications for multilevel CDA largely being based on single and 2-level data, careful patient selection is critical. Expansion of indications can be expected as literature continues to emerge regarding outcomes and complications in multilevel CDA, as well as with improvements in prosthesis design.

Comparative study of outcomes between allograft intervertebral disc transplantation and anterior cervical discectomy and fusion: a retrospective cohort study at least 5 years of follow-up

PURPOSE

Adjacent segment degeneration (ASDeg) after anterior cervical discectomy and fusion (ACDF) seriously affects the long-term efficacy of the operation. Therefore, our team has done a lot of research on allograft intervertebral disc transplantation (AIDT) to prove its feasibility and safety. This study will compare the efficacy between AIDT and ACDF in the treatment of cervical spondylosis.

METHODS

All patients who received ACDF or AIDT in our hospital from 2000 to 2016 and followed up for at least 5 years were recruited and divided into ACDF and AIDT groups. The clinical outcomes including functional scores and radiological data of both groups were collected and compared preoperatively and postoperatively at 1 week, 3 months, 6 months, 12 months, 24 months, 60 months and last follow-up. Functional scores included Japanese Orthopedic Association score (JOA), Neck Disability Index (NDI), Visual Analog Scale of Neck (N-VAS) and Arms (A-VAS) pain, the Short Form Health Survey-36 (SF-36) and imaging dates including digital radiographs in the lateral, hyperextension and flexion positions to assess the stability, sagittal balance and mobility of the cervical spine and magnetic resonance imaging (MRI) scans to assess the degeneration of adjacent segment.

RESULTS

There were 68 patients with 25 in AIDT group and 43 in ACDF group. Satisfactory clinical results were obtained in both groups, but the long-term NDI score and N-VAS score in the AIDT group were better. The AIDT obtained the same stability and sagittal balance of the cervical spine as fusion surgery. The range of motion of adjacent segments can be restored to the preoperative level after transplantation, but this increases significantly after ACDF. There were significant differences in the superior adjacent segment range of motion (SROM) between two groups at 12 months (P = 0.039), 24 months (P = 0.035), 60 months (P = 0.039) and the last follow-up (P = 0.011). The inferior adjacent segment range of motion (IROM) and SROM had a similar trend in the two groups. The ratio value of the greyscale (RVG) of adjacent segments showed a downward trend. At the last follow-up, the RVG decreased more significantly in the ACDF group. At the last follow-up, there was a significant difference in the incidence of ASDeg between the two groups (P = 0.000). And the incidence of adjacent segment disease (ASDis) is 22.86% in the ACDF group.

CONCLUSION

The allograft intervertebral disc transplantation may be as an alternative technique to traditional anterior cervical discectomy and fusion for the management of cervical degenerative diseases. For the more, the results showed it would improve cervical kinematics and reduce the incidence of adjacent segment degeneration.

Prevalence and Risk Factors for Cervical Adjacent Segment Disease and Analysis of the Clinical Effect of Revision Surgery: A Minimum of 5 Years' Follow-Up

STUDY DESIGN

A retrospective study was performed.

OBJECTIVE

To investigate the prevalence and risk factors for adjacent segment disease (ASD) after anterior cervical discectomy and fusion (ACDF) and the clinical efficacy of revision surgery.

METHOD

A total of 219 patients treated with ACDF were analyzed retrospectively. Demographic characteristics, including age, sex, body mass index (BMI) and bone mineral density (BMD), and radiographic measurements, including C2-C7 cervical sagittal vertical axis (cSVA), T1 slope (T1S), thoracic inlet angle (TIA) and C2-C7 Cobb angle, were analyzed. Modified Japanese Orthopaedic Association (mJOA) score and visual analog scale (VAS) score were used to evaluate patient function. Parameters were analyzed with Student's t test, and potential risk factors for ASD were further analyzed with multivariate logistic regression analysis.

RESULTS

The incidence of ASD after ACDF surgeries was 21%. The severity of osteoporosis, BMI and C2-C7 cSVA were significantly higher in the ASD group than in the NASD group (P < .05). The preoperative and postoperative TIAs were lower in the ASD group (P < .05). Multivariate logistic regression analysis showed that a high BMI, severe osteoporosis and a high C2-C7 cSVA were risk factors for ASD after ACDF (P < .05). The postoperative TIA and postoperative T1S were also correlated with ASD (P < .05).

CONCLUSION

Patients with a high BMI, severe osteoporosis, and a large C2-C7 cSVA after ACDF have a higher risk of ASD, while a large T1S and TIA may be protective factors. In addition, revision surgery can restore cervical spine balance in patients with ASD and promote better clinical outcomes.

Biomechanical evaluation of a novel biomimetic artificial intervertebral disc in canine cervical cadaveric spines

Background Context

Cervical disc replacement (CDR) aims to restore motion of the treated level to reduce the risk of adjacent segment disease (ASD) compared with spinal fusion. However, first-generation articulating devices are unable to mimic the complex deformation kinematics of a natural disc. Thus, a biomimetic artificial intervertebral CDR (bioAID), containing a hydroxyethylmethacrylate (HEMA)-sodium methacrylate (NaMA) hydrogel core representing the nucleus pulposus, an ultra-high-molecular-weight-polyethylene fiber jacket as annulus fibrosus, and titanium endplates with pins for primary mechanical fixation, was developed.

Purpose

To assess the initial biomechanical effect of the bioAID on the kinematic behavior of the canine spine, an ex vivo biomechanical study in 6-degrees-of-freedom was performed.

Study Design

A canine cadaveric biomechanical study.

Methods

Six cadaveric canine specimens (C3-C6) were tested in flexion-extension (FE), lateral bending (LB) axial rotation (AR) using a spine tester in three conditions: intact, after C4-C5 disc replacement with bioAID, and after C4-C5 interbody fusion. A hybrid protocol was used where first the intact spines were subjected to a pure moment of ±1 Nm, whereafter the treated spines were subjected to the full range of motion (ROM) of the intact condition. 3D segmental motions at all levels were measured while recording the reaction torsion. Biomechanical parameters studied included ROM, neutral zone (NZ), and intradiscal pressure (IDP) at the adjacent cranial level (C3-C4).

Results

The bioAID retained the sigmoid shape of the moment-rotation curves with a NZ similar to the intact condition in LB and FE. Additionally, the normalized ROMs at the bioAID-treated level were statistically equivalent to intact during FE and AR while slightly decreased in LB. At the two adjacent levels, ROMs showed similar values for the intact compared to the bioAID for FE and AR and an increase in LB. In contrast, levels adjacent to the fused segment showed an increased motion in FE and LB as compensation for the loss of motion at the treated level. The IDP at the adjacent C3-C4 level after implantation of bioAID was close to intact values. After fusion, increased IDP was found compared with intact but did not reach statistical significance.

Conclusion

This study indicates that the bioAID can mimic the kinematic behavior of the replaced intervertebral disc and preserves that for the adjacent levels better than fusion. As a result, CDR using the novel bioAID is a promising alternative treatment for replacing severely degenerated intervertebral discs.

Multilevel cervical disc arthroplasty: a review of optimal surgical management and future directions

OBJECTIVE

Cervical disc arthroplasty (CDA) has been recognized as a popular option for cervical radiculopathy or myelopathy caused by disc problems that require surgery. There have been prospective randomized controlled trials comparing CDA to anterior cervical discectomy and fusion (ACDF) for 1- and 2-level disc herniations. However, the indications for CDA have been extended beyond the strict criteria of these clinical trials after widespread real-world experiences in the past decade. This article provides a bibliometric analysis with a review of the literature to understand the current trends of clinical practice and research on CDA.

METHODS

The PubMed database was searched using the keywords pertaining to CDA in human studies that were published before August 2022. Analyses of the bibliometrics, including the types of papers, levels of evidence, countries, and the number of disc levels involved were conducted. Moreover, a systematic review of the contents with the emphasis on the current practice of multilevel CDA and complex cervical disc problems was performed.

RESULTS

A total of 957 articles published during the span of 22 years were analyzed. Nearly one-quarter of the articles (232, 24.2%) were categorized as level I evidence, and 33.0% were categorized as levels I or II. These studies clearly demonstrated the viability and effectiveness of CDA regarding clinical and radiological outcomes, including neurological improvement, maintenance, and preservation of segmental mobility with relatively low risks for several years postoperation. Also, there have been more papers published during the last decade focusing on multilevel CDA and fewer involving the comparison of ACDF. Overall, there was a clustering of CDA papers published from the US and East Asian countries. Based on substantial clinical data of CDA for 1- and 2-level disc diseases, the practice and research of CDA show a trend toward multilevel and complex disease conditions.

CONCLUSIONS

CDA is an established surgical management procedure for 1- and 2-level cervical disc herniation and spondylosis. The success of motion preservation by CDA-with low rates of complications-has outscored ACDF in patients without deformity. For more than 2-level disc diseases, the surgery shows a trend toward multiple CDA or hybrid ACDF-CDA according to individual evaluation for each level of degeneration.

Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion with Plate Fixation: A Systematic Review and Meta-Analysis

BACKGROUND

Adjacent segment disease (ASD) following anterior cervical discectomy and fusion with plating (ACDF-P) may yield a poor prognosis or reoperation. This review aimed to summarize risk factors for radiographic ASD (RASD) and clinical ASD (CASD) after ACDF-P.

METHODS

Six electronic databases were searched from inception to October 30, 2021. Four reviewers independently screened titles, abstracts, and full-text articles to identify relevant studies. Methodological quality of the included studies was evaluated. Meta-analyses for risk factors were conducted, if possible.

RESULTS

Sixteen cohort and 3 case-control studies (3,563 participants) were included. These studies showed low (n = 2), moderate (n = 9), and high (n = 8) risk of bias. One risk factor for RASD was pooled for 2 meta-analyses based on the follow-up period. Four different risk factors for CASD at ≥4 years were pooled for meta-analyses. Limited evidence showed that multi-level fusion, greater asymmetry in total or functional cross-sectional area of the cervical paraspinal muscle, and preoperative degeneration in a greater number of segments were associated with a higher RASD incidence <4 years after ACDF-P. In contrast, no significant risk factors were identified for CASD <4 years after ACDF-P. At ≥4 years after ACDF-P, limited evidence supported that both cephalad and caudal plate-to-disc distances of <5 mm were associated with a higher RASD incidence, and very limited evidence supported that developmental canal stenosis, preoperative RASD, unfused C5-C6 or C6-C7 adjacent segments, use of autogenous bone graft, and spondylosis-related ACDF-P were associated with a higher CASD incidence.

CONCLUSIONS

Although several risk factors for RASD and CASD development after ACDF-P were identified, the supporting evidence was very limited to limited. Future prospective studies should extend the existing knowledge by more robustly identifying risk factors for RASD and CASD after ACDF-P to inform clinical practice.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

In Vivo Evidence of Early Instability and Late Stabilization in Motion Segments Immediately Superior to Anterior Cervical Arthrodesis

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

The aim was to identify patient factors that affect adjacent segment kinematics after anterior cervical discectomy and fusion (ACDF) as measured by biplane radiography.

SUMMARY OF BACKGROUND DATA

The etiology of adjacent segment disease (ASD) may be multifactorial. Previous studies have investigated associations between patient factors and ASD, although few attempted to link patient factors with mechanical changes in the spine that may explain ASD development. Previous studies manually measured intervertebral motion from static flexion/extension radiographs, however, manual measurements are unreliable, and those studies failed to measure intervertebral motion during rotation.

METHODS

Patients had continuous cervical spine flexion/extension and axial rotation movements captured at 30 images per second in a dynamic biplane radiography system preoperatively and 1 year after ACDF. Digitally reconstructed radiographs generated from subject-specific computed tomography scans were matched to the biplane radiographs using a validated tracking process. Dynamic kinematics and preoperative disc height were calculated from this tracking process. Preoperative magnetic resonance imagings were evaluated for disc bulge. Patient age, sex, body mass index, smoking status, diabetes, psychiatric history, presence of an inciting event, and length of symptoms were collected. Multivariate linear regression was performed to identify patient factors associated with 1-year postoperative changes in adjacent segment kinematics.

RESULTS

Sixty-three patients completed preoperative and postoperative testing. Superior adjacent segment disc height and disc bulge predicted the change in superior adjacent segment range of motion after surgery. Inferior adjacent segment disc bulge, smoking history, and the use of psychiatric medications predicted the change in inferior adjacent segment flexion/extension range of motion after surgery.

CONCLUSIONS

Preexisting adjacent segment disc degeneration, as indicated by disc height and disc bulge, was associated with reduced adjacent segment motion after ACDF, while lack of preexisting adjacent disc degeneration was associated with increased adjacent segment motion after ACDF. These findings provide in vivo evidence supporting early instability and late stabilization in the pathophysiology of disc degeneration.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Short Review/Perspective on Adjacent Segment Disease (ASD) Following Cervical Fusion Versus Arthroplasty

Background:

Although the incidence of radiographic Adjacent Segment Disease (ASD) following anterior cervical diskectomy/fusion (ACDF) or cervical disc arthroplasty (CDA) typically ranges from 2-4%/year, reportedly fewer patients are symptomatic, and even fewer require secondary surgery.

Methods:

Multiple studies have documented a 2-4% incidence of radiographic ASD following either ACDF or CDA per year. However, fewer are symptomatic from ASD, and even fewer require additional surgery/reoperations.

Results:

In a meta-analysis (2016) involving 83 papers, the incidence of radiographic ASD per year was 2.79%, but symptomatic disease was present in just 1.43% of patients with only 0.24% requiring secondary surgery. In another study (2019) involving 38,149 patients undergoing ACDF, 2.9% (1092 patients; 0.62% per year) had radiographic ASD within an average of 4.66 postoperative years; the younger the patient at the index surgery, the higher the reoperation rate (i.e. < 40 years of age 4.56 X reoperations vs. <70 at 2.1 X reoperations). In a meta-analysis of 32 articles focusing on ASD 12–24 months following CDA, adjacent segment degeneration (ASDeg) occurred in 5.15% of patients, but adjacent segment disease (AS Dis) was noted in just 0.2%/ year. Further, AS degeneration occurred in 7.4% of patients after 1-level vs. 15.6% following 2 level fusions, confirming that CDA’s “motion-sparing” design did not produce the “anticipated” beneficial results.

Conclusion:

The incidence of radiographic ASD ranges from 2-4% per year for ACDF and CDA. Additionally, both demonstrate lesser frequencies of symptomatic ASD, and the need for secondary surgery. Further, doubling the frequency of ASD following 2 vs. 1-level CDA, should prompt surgeons to limit surgery to only essential levels.

Impact of Depression on Patient Reported Outcomes Following Primary Versus Revision ACDF

STUDY DESIGN

Retrospective cohort.

OBJECTIVE

To assess the relationship of depressive symptoms with patient reported outcome measures (PROMs) in patients undergoing either primary or revision anterior cervical discectomy and fusion (ACDF) procedures.

SUMMARY OF BACKGROUND

Depression has been associated with poorer outcomes following ACDF. However, research examining the relationship between depression and PROMs in revision ACDF procedures is limited.

METHODS

A prospective database was retrospectively reviewed for primary or revision, single- or multilevel ACDF procedures from 2016 to 2019. Patients lacking preoperative Patient Health Questionnaire-9 (PHQ-9) surveys were excluded. Demographic and perioperative characteristics were recorded and analyzed using Fisher's exact test or t test. Patient-reported outcome measures were collected preoperatively and postoperatively. Postoperative improvement from baseline scores (ΔPROM) was calculated at all postoperative timepoints. Differences in mean PROM and ΔPROM between groups and changes from baseline PROM scores within groups were assessed using Student's t test. Linear regression analyzed the impact of preoperative PHQ-9 on ΔPROM.

RESULTS

A total of 143 patients (121 primary and 22 revision) were included. Significant differences between groups were demonstrated at the preoperative timepoint for Neck Disability Index (NDI) (P = 0.022). ΔPROM values did not significantly differ between groups. Regression analysis revealed significant relationships between preoperative PHQ-9 and ΔPHQ-9 at all timepoints, ΔVAS neck at 6-weeks and 6-months, ΔVAS arm at 6-months, and ΔNDI at 6-weeks and 6-months for the primary group (all P < 0.05). Regression analysis revealed no significant associations for the revision group.

CONCLUSION

Primary or revision ACDF procedures did not significantly differ in depressive symptoms through 1-year. Primary ACDF patients significantly improved in all PROMs through all timepoints, while revision patients had limited improvement in PROMs. Preoperative depression may have a stronger association on postoperative outcomes for primary procedures.Level of Evidence: 3.

Cervical disc arthroplasty for Klippel-Feil syndrome

OBJECTIVE

Klippel-Feil syndrome (KFS) is a congenital musculoskeletal condition characterized by improper segmentation of the cervical spine. This study aimed to evaluate outcomes of KFS patients who underwent cervical disc arthroplasty (CDA).

METHODS

Consecutive patients who underwent anterior cervical surgery were retrospectively reviewed. Those patients with KFS who received discectomy adjacent to the congenitally fused vertebral segments were extracted and grouped into either the fusion or the CDA group. Clinical and radiological evaluations included visual analog scales, Neck Disability Index (NDI), Japanese Orthopedic Association (JOA) scores, C2-7 range of motion (ROM), C2-7 Cobb angle, C2-7 sagittal vertical axis (SVA), and T1-slope.

RESULTS

Among 2320 patients, there were 41 with KFS (prevalence = 1.77%), who were younger than the entire cohort (53.3 vs 56.4 years). Thirty KFS patients had adjacent discs and were grouped into the CDA and fusion groups (14 vs 16). Type-I KFS with C3-4 involvement was the most common for both groups (92.8% vs 81.2% with 57% vs 50%, respectively). Post-operation, both groups demonstrated improvement of all the patient reported outcomes. The C2-7 ROM significantly decreased in the fusion group than that of pre-operation (12.8 ± 6° vs 28.1 ± 11.5°). In contrast, the CDA group successfully preserved C2-7 and segmental ROM without additional complications.

CONCLUSIONS

KFS is rare (prevalence = 1.77%) among cervical spine surgery patients, and it rarely affects the overall cervical spinal alignment, except that it decreases segmental mobility. CDA is a feasible option for KFS because it not only avoids long-segment fusion but also preserves segmental and global mobility.

A Novel Technique of Endoscopic Anterior Transcorporeal Approach with Channel Repair for Adjacent Segment Disease After Anterior Cervical Discectomy and Fusion

OBJECTIVE

To first report the application of percutaneous full-endoscopic anterior transcorporeal cervical discectomy (PEATCD) with channel repair for a patient with adjacent segment disease (ASD) after anterior cervical discectomy and fusion.

METHODS

PEATCD with channel repair was performed for a patient with ASD at the cranial level adjacent to previous fusion at the C5-C6 level. The pre- and postoperative clinical symptoms were evaluated with Japanese Orthopedic Association and visual analog scale (VAS). The radiological examinations included magnetic resonance imaging, computed tomography, and plain radiographs, which were used to evaluate the cervical alignment, stability, intraoperative decompression, and bony channel.

RESULTS

The procedure was successfully completed within 70 minutes. The drainage tube was unnecessary. No surgery-related complications were recorded. The postoperative neck pain immediately improved to VAS 3 from preoperative VAS 6. The Japanese Orthopedic Association scores also took a turn for the better gradually from preoperative 10 to final 16 (improvement rate 85.7%). The muscle power recovered completely, and the Hoffman sign turned to negative during follow-up periods. Magnetic resonance imaging 1 week postoperatively showed a total removal of the herniation. The bony channel was almost disappeared on computed tomography images 3 months postoperatively. During postoperative periods, no relapse, channel collapse, bone plug migration, or instability was observed.

CONCLUSION

As a novel and supplemental procedure for ASD after anterior cervical discectomy and fusion, PEATCD combines the advantages of transcorporeal approach and endoscopy together, which decreases iatrogenic damage to disc, preserves the cervical motion segment, and reduces surgical trauma. As the limitations of 1 case show, the effectiveness and reliability of PEATCD for patients with ASD should be verified in further studies.

Occurrence, Risk Factors, and Time Trends for Late Reoperations due to Degenerative Cervical Spine Disease: A Finnish National Register Study of 19 377 Patients Operated on Between 1999 and 2015

BACKGROUND

Surgery for degenerative cervical spine disease has escalated since the 1990s. Fusion has become the mainstay of surgery despite concerns regarding adjacent segment degeneration. The patient-specific trends in reoperations have not been studied previously.

OBJECTIVE

To analyze the occurrence, risk factors, and trends in reoperations in a long-term follow-up of all the patients operated for degenerative cervical spine disease in Finland between 1999 and 2015.

METHODS

The patients were retrospectively identified from the Hospital Discharge Registry. Reoperations were traced individually; only reoperations occurring >365 d after the primary operation were included. Time trends in reoperations and the risk factors were analyzed by regression analysis.

RESULTS

Of the 19 377 identified patients, 9.2% underwent a late reoperation at a median of 3.6 yr after the primary operation. The annual risk of reoperation was 2.4% at 2 yr, 6.6% at 5 yr, 11.1% at 10 yr, and 14.2% at 15 yr. Seventy-five percent of the late reoperations occurred within 6.5 yr of the primary operation. Foraminal stenosis, the anterior cervical decompression and fusion (ACDF) technique, male gender, weak opiate use, and young age were the most important risk factors for reoperation. There was no increase in the risk of reoperations over the follow-up period.

CONCLUSION

The risk of reoperation was stable between 1999 and 2015. The reoperation risk was highest during the first 6 postoperative years and then declined. Patients with foraminal stenosis had the highest risk of reoperation, especially when ACDF was performed.

Utility of the 5-Item Modified Frailty Index for Predicting Adverse Outcomes Following Elective Anterior Cervical Discectomy and Fusion

BACKGROUND

Frailty is an increasingly studied tool for preoperative risk stratification, but its prognostic value for anterior cervical discectomy and fusion (ACDF) patients is unclear. We sought to evaluate the association of the 5-item modified Frailty Index (5i-mFI) with 30-day adverse outcomes following ACDF and its predictive performance compared with other common metrics.

METHODS

The National Surgical Quality Improvement Program was queried from 2016-2018 for patients undergoing elective ACDF for degenerative diseases. Outcomes of interest included 30-day complications, extended length of stay (LOS), non-home discharge, and unplanned readmissions. Unadjusted/adjusted odds ratios were calculated. The discriminatory performance of the 5i-mFI compared with age, American Society of Anesthesiologists (ASA) classification, and body mass index was computed using the area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 23,754 patients were identified. On adjusted analysis, an index of 1 was significantly associated with extended LOS, non-home discharge, and unplanned readmissions (P < 0.001, P = 0.023, P = 0.003, respectively), but not complications (all P > 0.05). An index ≥2 was significantly associated with each outcome (all P < 0.001). The 5i-mFI was found to have a significantly higher AUC than body mass index for each outcome, a similar AUC compared with ASA classification and age for complications and unplanned readmissions, and a significantly lower AUC than ASA classification and age for extended LOS and non-home discharge.

CONCLUSIONS

The 5i-mFI was found to be significantly associated with 30-day adverse outcomes following ACDF but had similar or lesser predictive performance compared with more universally available and easily implemented metrics, such as ASA classification and age.

Comparison between repeat anterior and posterior decompression and fusion in the treatment of two-level symptomatic adjacent segment disease after anterior cervical arthrodesis

BACKGROUND

Two-level symptomatic adjacent segment disease (ASD) is rarely reported, but remains a challenge after anterior cervical arthrodesis. The purpose of this study was to compare the clinical and radiological outcomes of repeat anterior and posterior decompression and fusion procedures for two-level symptomatic ASD.

METHODS

Thirty-two patients with two-level symptomatic ASD were retrospectively reviewed and underwent repeat anterior cervical discectomy and fusion (ACDF) or posterior decompression and fusion (PDF). Clinical outcomes (JOA, NDI, and VAS scores), perioperative parameters (blood loss, operation time, and length of hospital stay), radiological parameters (cervical lordosis and ROM), and complications were compared.

RESULTS

Eighteen patients underwent ACDF, and 14 patients underwent PDF. Patients who underwent PDF were older, more frequently presented with myelopathic deficits, and were fused at more levels. Patients who underwent ACDF experienced significantly shorter surgery time (p < 0.001), lower blood loss (p < 0.001), and reduced hospital stay (p = 0.002). Both groups exhibited significant increases in JOA scores and decreases in NDI and both neck pain and arm pain VAS scores (p < 0.05), but patients who underwent PDF had significantly higher NDI scores (p = 0.012), neck pain VAS scores (p = 0.019), loss of cervical lordosis (p < 0.001), and loss of ROM (p = 0.001). Three patients developed dysphagia in the ACDF group, and two patients had C5 root palsy and one had hematoma in the PDF group. Recurrent ASD after the second operation occurred in two patients in the ACDF group but no patients in the PDF group.

CONCLUSIONS

For patients with two-level symptomatic ASD, both anterior and posterior decompression and fusion were effective for improving the neurological function. For patients with radicular symptoms, ACDF had less surgical trauma, better restoration of lordosis, and less postoperative neck pain, but higher chance of recurrent ASD. PDF was an effective surgical option for older patients with myelopathy developing in adjacent segments.

Radiological and clinical outcomes of 3-level cervical disc arthroplasty

OBJECTIVE

One- and two-level cervical disc arthroplasty (CDA) has been compared to anterior cervical discectomy and fusion (ACDF) in several large-scale, prospective, randomized trials that have demonstrated similar clinical outcomes. However, whether these results would be similar when treating 3-level disc herniation and/or spondylosis has remained unanswered. This study aimed to investigate the differences between 3-level CDA and ACDF.

METHODS

A series of 50 patients who underwent 3-level CDA at C3-7 was retrospectively reviewed and compared with another series of 50 patients (age- and sex-matched controls) who underwent ACDF at C3-7. Clinical outcomes were measured using the visual analog scale (VAS) for neck and arm pain, the modified Japanese Orthopaedic Association (mJOA) scale, and the Neck Disability Index (NDI). Radiological outcomes included range of motion (ROM) at the index levels. Every patient was evaluated by CT for the presence of fusion in the ACDF group. Also, complication profiles were investigated.

RESULTS

The demographics and levels of distribution in both groups were very similar. During the follow-up period of 24 months, clinical outcomes improved (overall and respectively in each group) for both the CDA and ACDF patients when compared with the patients' preoperative condition. There were essentially few differences between the two groups in terms of neck and arm pain VAS scores, mJOA scores, and NDI scores preoperatively and at 3, 6, 12, and 24 months postoperatively. After the 3-level surgery, the CDA group had an increased mean ROM of approximately 3.4°, at 25.2° ± 8.84°, compared to their preoperative ROM (21.8° ± 7.20°) (p = 0.001), whereas the ACDF group had little mobility (22.8° ± 5.90° before and 1.0° ± 1.28° after surgery; p < 0.001). The mean operative time, estimated blood loss, and complication profiles were similar for both groups.

CONCLUSIONS

In this selectively matched retrospective study, clinical outcomes after 3-level CDA and ACDF were similar during the 2-year follow-up period. CDA not only successfully preserved but slightly increased the mobility at the 3 index levels. However, the safety and efficacy of 3-level CDA requires more long-term data for validatation.