Early-stage fusion and bone morphology process in anterior cervical discectomy and fusion: a comparison of autografts and allografts via quantitative computed tomography-based three-dimensional reconstruction

Introduction

Cervical degenerative disc disease (DDD) is a progressive condition characterized by intervertebral disc dehydration, annular fissures, and osteophyte formation, often accompanied by low inflammation and vascular invasion and usually leading to foraminal or spinal canal narrowing (1-3). These degenerative changes can result in neural compression and corresponding symptoms of radiculopathy or myelopathy (1,4). Cervical DDD is highly prevalent, especially in aging populations, and constitutes a major contributor to chronic neck pain, neurological dysfunction, and disability (5). The burden of cervical DDD is increasing globally, placing significant strain on healthcare systems and highlighting the need for effective surgical strategies. Anterior cervical discectomy and fusion (ACDF) is a widely recognized surgical intervention for treating cervical DDD, including cervical spondylotic radiculopathy (CSR) and cervical spondylotic myelopathy (CSM). Since its introduction by Smith and Robinson in 1958 (6), ACDF has become the gold standard for surgical treatment. However, achieving robust osseous fusion remains a critical challenge, as interbody fusion is essential for long-term success (7). Recent advancements in spinal surgery have primarily included the optimization of bone graft materials to enhance fusion rates and minimize complications (8,9). The use of in situ autografts, harvested from the cervical vertebrae, has garnered attention due to its potential to provide a rich source of osteogenic cells and growth factors (10).

Despite advancements in surgical techniques and biomaterials, the assessment of early fusion morphology and bone formation remains inadequate. Traditional imaging modalities, such as X-rays and conventional computed tomography (CT) scans, provide only indirect indicators of bone fusion, such as graft radiodensity or bridging across adjacent vertebrae. These methods lack the resolution and dimensional accuracy required to evaluate the dynamic progression of bone remodeling at different postoperative time points. Our previous study confirmed the feasibility of preoperative three-dimensional (3D) simulation in assessing available in situ bone graft volume (11), providing a foundation for personalized surgical planning. However, this approach primarily involved preoperative bone volume estimation and did not extend to postoperative fusion assessment.

To overcome the limitations of conventional imaging, CT-based 3D reconstruction technology has emerged as a powerful tool for assessing interbody fusion morphology. Unlike X-ray-based fusion scores, which only capture extragraft bone bridging (ExGBB) at a gross level (12), CT 3D reconstruction enables detailed volumetric analysis of osteogenesis, allowing for differentiation of fusion morphologies and bone formations. These distinct morphological patterns may provide crucial insights into early fusion stability and long-term clinical outcomes, such as subsidence risk, intervertebral height maintenance, and postoperative pain reduction.

Despite the increasing adoption of CT-based fusion assessment, no prior studies have systematically applied 3D reconstruction to quantitatively track both fusion volume and morphological evolution over time following ACDF (13). Our study introduced a dynamic imaging-based framework through use of CT 3D reconstruction to not only compare the fusion volume between autografts and allografts but also to define distinct osteogenic morphologies (stalactite, hourglass, and columnar) and monitor their temporal transitions. Furthermore, we investigated the correlation between early osteogenic features and key clinical outcomes, including subsidence, intervertebral height maintenance, and pain relief. By integrating quantitative morphometric analysis with clinical metrics, we aim to provide novel imaging biomarkers for improving decision-making in graft selection and postoperative management. We present this article in accordance with the STROBE reporting checklist (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-769/rc).

Methods

Study design

This retrospective study was approved by the Institutional Review Board of Guangdong Provincial People’s Hospital (No. KY-Q-2022-112-01) and conducted in accordance with the Declaration of Helsinki and its subsequent amendments. All patients provided written informed consent that included radiation risk disclosure. We retrospectively reviewed the medical records of patients who underwent single- or two-level ACDF with polyetheretherketone (PEEK) cages filled with either autografts or allografts between January 2021 and January 2022. The inclusion criteria were as follows: (I) diagnosis of CSR or CSM; (II) failure of conservative treatments; and (III) complete clinical and radiological follow-up data. Meanwhile, the exclusion criteria included the following: (I) age <18 years; (II) previous cervical fusion or concurrent posterior surgery; (III) cervical spine fracture; (IV) presence of tumor or infection; (V) postoperative follow-up <2 years; and (VI) incomplete imaging data. All surgeries were performed by two senior surgeons at a single medical center (Figure S1).

Surgical and bone graft fusion

The in situ autograft harvesting technique was derived from the preoperative planning and 3D simulation methodologies used in our previous work (11). The surgical technique employed was the standard Smith-Robinson approach for ACDF as previously reported (11). After radiological identification of the operative level, anterior exposure was achieved with a Caspar retractor. The anterior osteophytes were removed with a Kerrison rongeur or high-speed burr. The disc and cartilaginous endplates were completely excised until subchondral bleeding was observed. The posterior longitudinal ligament was resected, and the intervertebral foramen was decompressed with a high-speed burr and curette. An appropriately sized PEEK cage was filled with either autograft (harvested from the anterior lip of the proximal vertebral body and local osteophytes) or allograft (deep-frozen bone) and inserted into the disc space. The quantity of bone grafting in both groups was determined according to the extent to which the cage bone graft groove was filled. If the required amount of harvesting in situ autograft could not be obtained from the autologous bone group, the case was excluded from the study. All cases were stabilized with either a cervical plate and cage system or a Zero-P implant system. No patient was prescribed a cervical collar postoperatively.

CT 3D reconstruction and ExGBB measurement

All postoperative CT scans were performed with a low-dose protocol under the following parameters: tube voltage, 120 kVp; tube current, 320 mA; slice thickness, 1.0 mm; and pitch, 0.75. The scan field of view (FOV) was restricted to the operative cervical segments (typically C2–C7), which minimized unnecessary exposure to adjacent tissues. This resulted in an estimated effective dose ranging from a few to a dozen millisieverts, in compliance with national radiation standard (WS/T 637-2018, GB/T 16137-2021) (14,15). The total cumulative dose across all four scans remained well below the 100-mSv safety threshold defined by the International Commission on Radiological Protection (ICRP 103) (16). Where applicable, beam collimation and automated dose modulation were employed to reduce scatter, and shielding of nontargeted body regions was applied under scanner control.

High-resolution CT data were imported in Digital Imaging and Communications in Medicine (DICOM) format into Mimics software version 21.0 (Materialize, Leuven, Belgium). Threshold-based segmentation was performed under a Hounsfield unit (HU) range of 226–3071 to isolate osseous structures. Use of multiplanar reconstruction (MPR) allowed for precise anatomical orientation in the sagittal, coronal, and axial planes. Fusion bone was segmented semiautomatically with the region-growing algorithm and followed by manual refinement to exclude nonbridging structures such as osteophytes or ligament calcifications. To address metal-induced beam-hardening artifacts, CT attenuation profile correction and artifact-reduction filters were applied during image postprocessing. Moreover, these methods were combined to reduce the influence of metal artifacts and increase the accuracy of segmentation. The detailed processes of reducing metal artifacts are as follows: (I) for MPR, continuous bone cortex was observed in the coronal/sagittal position, with metal artifacts typically being discontinuous; (II) for windowing, the bone window highlighted bone detail and reduced metal artifacts; and (III) for artifact mapping, threshold segmentation (e.g., >3,000 HU to mark metal) was used to generate an artifact template and enhance the bone region in reverse. The final ExGBB volume was calculated through use of the volumetric analysis module in Mimics software (Figure 1).

Figure 1 CT-based 3D reconstruction images showing the cephalad vertebral body and osteogenic region. (A) Immediate postoperative period and (B) 3 months postoperation. (C) Volume measurement of the osteogenic region at 3 months. 3D, three-dimensional; CT, computed tomography.

Fusion morphology classification

Based on CT 3D sagittal reconstruction, the posterior fusion bone morphology was categorized into three distinct types: stalactite shape, a fusion pattern in which bone formation occurs from both the superior and inferior endplates, curving toward the center but without complete bridging; hourglass shape, a fusion pattern in which bone bridging is achieved, but with narrowing at the center, forming a waist-like shape; and columnar shape, a fully connected and uniform-width bone bridge extending across the intervertebral space. These morphological patterns were systematically recorded at 3, 6, 12, and 24 months, and their correlation with fusion stability, intervertebral height maintenance, and subsidence risk was analyzed (Figure 2).

Figure 2 Schematic representation of fusion morphology on CT sagittal images: (A) stalactite shape, (B) hourglass shape, and (C) columnar shape. These shapes represent different patterns of osteogenesis observed in this study. CT, computed tomography.

Clinical and radiological assessments fusion

Clinical outcomes were evaluated with the neck pain visual analog scale (VAS) and the modified Japanese Orthopaedic Association (mJOA) scores, collected preoperatively, postoperatively, and during follow-up visits. Radiological assessments included cervical sagittal vertical axis (cSVA), C2–7 lordosis, segmental height, segmental lordosis, interspinous motion (ISM), and subsidence. CT scans were performed at 3, 6, 12, and 24 months postoperation to evaluate fusion status via quantitative 3D reconstruction. The fusion status was scored based on the formation of ExGBB according to a five-point scale adapted from Brantigan’s methodology, with scores of 4 and 5 indicating complete fusion (17). The morphology of the newly formed bone posterior to the fusion apparatus on CT sagittal images was categorized as stalactite, hourglass, and columnar shape.

Statistical analysis

Statistical analysis was performed by a statistician using SPSS statistical software, version 25.0 (IBM Corp., Armonk, NY, USA). Categorical data are presented as the frequency (percentage) and were analyzed with the Chi-squared test. Numerical data that followed a parametric distribution are presented as the mean ± standard deviation, and those that followed a nonparametric distribution are presented as the median and interquartile range. A two-sample t-test was used to detect significant differences in numerical variables. The Wilcoxon rank-sum test was used to analyze ordinal data. P<0.05 indicated a statistically significant difference.

Results

Demographic and clinical outcomes

This study included 134 patients who underwent one- or two-level ACDF, with 80 patients receiving autografts (98 surgical segments) and 54 receiving allografts (63 surgical segments). Baseline characteristics such as age, sex, BMI, smoking status, preoperative symptoms, surgical levels, and preoperative VAS and mJOA scores were comparable between groups (P>0.05; Table S1). The mean follow-up duration was 27.6 months (range, 24–32 months). At 3, 6, 12, and 24 months postoperation, both groups showed significant improvements in VAS and mJOA scores as compared to preoperative baseline values (P<0.05). The autograft group exhibited significantly lower neck pain VAS scores at 3, 6, and 12 months (P<0.05), but at 24 months, the difference between groups was no longer significant (P>0.05; Table 1 and Table S2).

Radiological outcomes: disc height, segmental stability, and subsidence

Both groups showed significant improvements in mean disc height and segmental height postoperatively (P<0.05), with no significant differences between groups at any time point (P>0.05; Table S3). The subsidence rate was similar in both groups (autograft group: 38.8%; allograft group: 36.5%; P>0.05). No cases required reoperation, and no new radiographic foraminal stenosis was detected during follow-up. In addition, we observed a progressive increase in the fusion scores in both groups. At 3 months, the autograft group had higher fusion scores (2.90±0.31) than did the allograft group (2.67±0.52; P<0.05); at 6 months, this trend continued (3.71±0.57 vs. 3.18±0.41; P<0.05); and at 12 and 24 months, fusion scores were similar in both groups (P>0.05; Table S4). Representative postoperative CT images illustrating these differences are shown in Figures 3,4.

Figure 3 CT reconstruction images of a 44-year-old male patient undergoing C3–5 ACDF with autografts. (A-C) Three months postoperation: partial bone bridging (fusion score =3). (D-F) Six months postoperation: near-complete fusion (fusion score =4). (G-I) Twelve months postoperation: complete fusion (fusion score =5). ACDF, anterior cervical discectomy and fusion; CT, computed tomography.

Figure 4 CT reconstruction images of a 46-year-old female patient undergoing C5–6 ACDF with allograft. (A-C) Three months postoperation: early osteogenesis without complete bridging (fusion score =2). (D-F) Six months postoperation: partial bone bridging (fusion score =3). (G-I) Twelve months postoperation: near-complete fusion with a small translucent band (fusion score =4). ACDF, anterior cervical discectomy and fusion; CT, computed tomography.

Quantitative CT-based 3D reconstruction analysis

In this study, CT 3D reconstruction provided detailed insights into bone fusion volume over time. At 3 months, our results indicated that the autograft group had significantly higher fusion volumes (185.04±92.67 mm³) compared to the allograft group (143.54±60.41 mm³; P<0.05); at 6 months, this trend persisted (270.03±96.15 vs. 213.42±114.08 mm³; P<0.05); at 12 months, the fusion volumes remained higher in the autograft group (345.79±131.81 vs. 289.02±112.75 mm³, P<0.05); and at 24 months, the fusion volumes were comparable between the groups (P>0.05).

Fusion rates and osteogenic morphology

In our study, fusion rate and osteogenic morphology were evaluated at different time points. At 3 months, 11.2% of segments in the autograft group were fused, whereas no fusion was observed in the allograft group (P<0.05). At 6 months, the fusion rate increased to 46.9% in the autograft group and to 23.8% in the allograft group (P<0.05); at 12 months, the fusion rates reached 90.8% and 85.7%, respectively (P>0.05); and at 24 months, both groups exhibited similar fusion rates (94.9% vs. 92.1%; P>0.05). Regarding the morphological evolution, we found that at 3 months, all allograft segments exhibited stalactite morphology, while 87 autograft segments had stalactite shapes and 11 had hourglass shapes (P<0.05). By 6 months, autografts had more advanced morphologies, with 52 stalactite, 29 hourglass, and 17 columnar shapes, whereas allografts exhibited 48 stalactite, 13 hourglass, and only 2 columnar shapes (P<0.05). At 12 and 24 months, the autograft group had a higher proportion of columnar shapes, indicating a more stable fusion structure (Table 2).

Relationship between osteogenic volume and clinical outcomes

Higher osteogenic volume correlated with better intervertebral height maintenance and lower subsidence rates. At 3 months, segments with an osteogenic volume ≥150 mm³ had better height maintenance and lower subsidence rates. At 6 months, segments with osteogenic volume ≥250 mm³ showed continued benefits. At 12 and 24 months, osteogenic volume ≥400 mm³ was associated with stable intervertebral height and minimal subsidence (Table 3). We further analyzed the correlation of these parameters with pain reduction after surgery. Interestingly, the data indicated that VAS scores were inversely correlated with osteogenic volume. At 3 and 6 months, higher osteogenic volumes were associated with lower pain scores. At 12 months, this correlation was significant only in the allograft group (osteogenic volume ≥400 mm³), while at 24 months, no significant differences were observed (Table 4). The osteogenic morphology and the relationship between osteogenic volume changes and clinical outcomes at different postoperative follow-up time points are shown in Figure 5.

Figure 5 The evolution of the osteogenic morphology from stalactite, hourglass, to columnar and the relationship between osteogenic volume changes and clinical outcomes at different postoperative follow-up time points. *, P<0.05. VAS, visual analog score.

Discussion

Although the superiority of autografts in early fusion is not a novel observation per se, our study provides new insights by introducing a dynamic and volumetric perspective. We demonstrated that early fusion volume and structured morphology are predictive of improved biomechanical integrity and clinical outcomes, thus adding quantitative and practical value to the existing knowledge in this field. This study was the first of its kind to apply CT-based 3D reconstruction to quantitatively assess the fusion process following ACDF, providing novel insights into the differences between autografts and allografts in terms of osteogenic volume and fusion morphology. Our findings demonstrate that autografts exhibit superior early fusion rates and larger osteogenic volumes than do allografts, particularly in the first 6 months after operation. This early-stage advantage is clinically relevant, as greater osteogenic volume was correlated with improved intervertebral height maintenance, reduced subsidence, and greater pain relief. By 24 months, however, the fusion rates and volumes between the two groups were similar, suggesting that while autografts provide a more robust initial osteogenic response, allografts can achieve equivalent long-term fusion outcomes. These findings highlight the importance of understanding early fusion characteristics, as they may influence postoperative management strategies aimed at optimizing long-term stability and clinical outcomes.

Clinical implications of fusion morphology and volume

A few studies have reported that the fusion rates in the early postoperative period of either autogenous local bone or autogenous iliac bone are higher than those of allograft bone (18,19). Our study demonstrated that autografts exhibited superior early fusion rates and greater osteogenic volumes as compared to allografts. This distinction is clinically relevant because early fusion and robust osteogenesis are associated with reduced neck pain, better maintenance of intervertebral height, and decreased incidence of cage subsidence. These outcomes are crucial for optimizing patient recovery and minimizing postoperative complications. By identifying these benefits, our study provides surgeons with evidence-based guidance on graft selection, especially as it concerns the relative benefits of autografts and allografts.

The ability to quantify fusion volume and categorize fusion morphology provides deeper insights into the fusion process beyond traditional binary fusion assessments. In this study, osteogenic morphology evolved dynamically, with autografts showing a faster transition from stalactite to hourglass and columnar patterns. The higher prevalence of columnar fusion morphology in autografts at 6 and 12 months suggests that a more organized and structured bone formation pattern may contribute to enhanced biomechanical stability. This structured bone bridging pattern is likely a key factor in reducing micromotion and subsidence, which may explain the better clinical outcomes observed in the autograft group during the early postoperative period. The correlation between higher osteogenic volumes and reduced neck pain scores reinforces the idea that early, robust bone formation plays a role in facilitating functional recovery. These findings suggest that fusion morphology assessment should be integrated into routine fusion evaluation, as different fusion patterns may have distinct biomechanical implications for spinal stability and long-term outcomes. The introduction of distinct fusion morphology patterns (stalactite, hourglass, and columnar) provides an innovative lens through which fusion progression can be monitored and interpreted. These morphological indicators may serve as potential biomarkers for assessing fusion stability in future studies. However, we did not perform subgroup analysis based on implant type, and we acknowledged that this may be a study limitation. Future controlled studies are necessary to clarify how implant design may interact with bone graft properties in shaping fusion outcomes.

Advantages of CT-based 3D reconstruction over conventional imaging

Although traditional X-ray-based fusion scoring systems such as ExGBB provide valuable qualitative assessments, they lack the resolution needed to capture early osteogenesis and subtle changes in fusion morphology. Our study demonstrates that CT 3D reconstruction provides a superior assessment of fusion volume and morphology, allowing for a more precise and objective evaluation of fusion progression. The ability to classify fusion morphology into stalactite, hourglass, and columnar patterns adds another dimension to fusion assessment, enabling clinicians to track how fusion evolves over time and to identify cases in which fusion progression may be suboptimal. Furthermore, quantitative 3D analysis eliminates the subjectivity associated with traditional fusion grading, offering a more reproducible and standardized approach to fusion evaluation. By leveraging this technology, we can refine postoperative management strategies, ensuring that patients with suboptimal early fusion responses receive appropriate interventions to promote bone healing.

To our knowledge, few previous studies have specifically measured the volume of cervical fusion. CT has been used to conduct morphological analysis of lumbar intervertebral fusion, confirming the importance of ExGBB in fusion evaluation, but only the osteogenic area has been examined, with no elaboration on the osteogenic shape and volume (12,20). Metallic artifacts from plates or fusion devices can impede the accurate measurement of intradevice ossification volume on CT scans. In our study, we observed minimal ossification in the anterior region of the fusion device, likely due to the space occupied by the metal implant. Consequently, in a modification of the ExGBB (21,22), we excluded the osteogenesis of the anterior vertebral body from this study and introduced the volume of ossification on both the lateral and posterior regions of the fusion device as a novel metric for evaluating cervical fusion, thereby enabling quantitative assessment.

Furthermore, our study is one of the few to quantify the relationship between osteogenic volume and clinical outcomes. By demonstrating that larger osteogenic volumes correlate with better maintenance of intervertebral height and reduced neck pain, we have provided a quantitative basis for evaluating fusion success. This innovation allows for more objective assessments of fusion outcomes and can aid in standardizing postoperative care protocols.

Postoperative management and micromotion

The relationship between micromotion and fusion progression remains a critical factor in ACDF outcomes. In our study, postoperative cervical collars were not routinely used as per an institutional protocol emphasizing early mobilization. Although the surgeon was motivated to use the collar to improve fusion rates, this is not well supported in the literature, and the majority of related studies indicate there being no significant difference in fusion rates between patients with and without the collar (23,24). However, the impact of micromotion on early-stage osteogenesis remains complex. Excessive micromotion may compromise fusion stability (25), while controlled micromotion can stimulate osteogenesis by promoting mechanical loading at the bone-graft interface (26). The observed early fusion volume disparities between autografts and allografts may indicate differences in how these grafts respond to micromotion, with autografts potentially being more resilient to mechanical stress due to their biological properties. Future research should focus on optimizing implant design and surgical techniques to regulate micromotion, ensuring a balance between early mobilization and stable fusion formation.

Future directions

Our findings suggest several important directions for future research. Prospective, multicenter trials are needed to validate the relationship between fusion volume, morphology, and clinical outcomes, particularly in larger patient cohorts. Additionally, studies examining implant designs and surgical techniques that optimize micromotion regulation could provide valuable insights into improving fusion efficiency. Advances in artificial intelligence-driven 3D reconstruction may further enhance fusion assessment, allowing for the automated analysis of fusion volume and morphology that can identify high-risk patients requiring reoperation early in the postoperative period. By building on the findings of this study, future research can help establish standardized, objective criteria for fusion evaluation, ultimately improving surgical decision-making and postoperative care in patients requiring ACDF.

Limitations

This study involved several limitations that should be acknowledged. First, the retrospective design and relatively small sample size may limit the generalizability of our findings. Second, the surgical instrumentation varied between patients based on surgeon preference, with half receiving cervical plates and cages and the other half receiving Zero-P cages. This variation might have influenced the evaluation of imaging indicators and affected the early fusion rates and osteogenesis. Although the radiation dose of the patients receiving CT in this study was within the safe range (16), the radiation amount was large and unsuitable for large-scale studies. Finally, the morphological classification (stalactite, hourglass, and columnar) proposed in this study was not validated through interobserver reliability analysis. Further studies are needed to confirm its reproducibility and potential as a standardized fusion grading system.

Conclusions

Quantitative CT-based 3D reconstruction provides a precise and dynamic method for assessing the bone fusion process in patients undergoing ACDF, enabling detailed visualization of morphological changes throughout the different postoperative stages. This study demonstrates that autografts facilitate earlier and more robust fusion than do allografts, leading to superior clinical outcomes, including improved intervertebral height maintenance, reduced subsidence, and enhanced pain relief. The ability to quantitatively evaluate fusion volume and morphology via 3D reconstruction highlights the importance of integrating advanced imaging techniques into clinical practice to refine fusion assessment and guide postoperative management. These findings underscore the critical role of graft selection in optimizing fusion efficacy and patient recovery, while also establishing a foundation for future research aimed at improving spinal fusion strategies through enhanced imaging and biomechanical analysis.

Acknowledgments

The authors express their gratitude towards Zujun Ouyang and Jiajian Chen (members of Sailner Digital Medical Technology Co., Ltd.) for technical support.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-769/rc

Data Sharing Statement: Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-769/dss

Funding: This work was supported by National Natural Science Foundation of China (Nos. 82472533, 82102636, 82201360), Guangzhou Municipal Science and Technology Project (Nos. 2024A04J10010, 2025A04J4741), Basic and Applied Basic Research Foundation of Guangdong Province (No. 2023B1515120078), and Foundation of Guangdong Provincial Key Laboratory of Digital Medicine and Biomechanics (No. MB202307).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-769/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. This retrospective study was approved by the Institutional Review Board of Guangdong Provincial People’s Hospital (No. KY-Q-2022-112-01), all patients provided written informed consent that included radiation risk disclosure.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Davies BM, Mowforth OD, Smith EK, Kotter MR. Degenerative cervical myelopathy. BMJ 2018;360:k186. [Crossref] [PubMed]
2. Wojdasiewicz P, Poniatowski ŁA, Kotela A, Skoda M, Pyzlak M, Stangret A, Kotela I, Szukiewicz D. Comparative Analysis of the Occurrence and Role of CX3CL1 (Fractalkine) and Its Receptor CX3CR1 in Hemophilic Arthropathy and Osteoarthritis. J Immunol Res 2020;2020:2932696. [Crossref] [PubMed]
3. Kubaszewski Ł, Wojdasiewicz P, Rożek M, Słowińska IE, Romanowska-Próchnicka K, Słowiński R, Poniatowski ŁA, Gasik R. Syndromes with chronic non-bacterial osteomyelitis in the spine. Reumatologia 2015;53:328-36. [Crossref] [PubMed]
4. Davies BM, Munro CF, Kotter MR. A Novel Insight Into the Challenges of Diagnosing Degenerative Cervical Myelopathy Using Web-Based Symptom Checkers. J Med Internet Res 2019;21:e10868. [Crossref] [PubMed]
5. Alvin MD, Qureshi S, Klineberg E, Riew KD, Fischer DJ, Norvell DC, Mroz TE. Cervical degenerative disease: systematic review of economic analyses. Spine (Phila Pa 1976) 2014;39:S53-64. [Crossref] [PubMed]
6. SMITH GW. ROBINSON RA. The treatment of certain cervical-spine disorders by anterior removal of the intervertebral disc and interbody fusion. J Bone Joint Surg Am 1958;40-A:607-24.
7. Li J, Zheng Q, Guo X, Zeng X, Zou Z, Liu Y, Hao S. Anterior surgical options for the treatment of cervical spondylotic myelopathy in a long-term follow-up study. Arch Orthop Trauma Surg 2013;133:745-51. [Crossref] [PubMed]
8. Park S, Lee DH, Hwang S, Oh S, Hwang DY, Cho JH, Hwang CJ, Lee CS. Feasibility of local bone dust as a graft material in anterior cervical discectomy and fusion. J Neurosurg Spine 2019;31:480-5. [Crossref] [PubMed]
9. Ma F, Xu S, Liao Y, Tang Q, Tang C, Wang Q, Zhong D. Using a mixture of local bone dust and morselized bone as graft materials in single- and double-level ACDF. BMC Musculoskelet Disord 2021;22:510. [Crossref] [PubMed]
10. Min WK, Bae JS, Park BC, Jeon IH, Jin HK, Son MJ, Park EK, Kim SY. Proliferation and osteoblastic differentiation of bone marrow stem cells: comparison of vertebral body and iliac crest. Eur Spine J 2010;19:1753-60. [Crossref] [PubMed]
11. Chen C, Chen Y, Ye Y, Liang G, Ye W, Yang Y, Chang Y. Preoperative three-dimensional simulation and clinical evaluation of in-situ bone harvesting in anterior cervical discectomy and fusion surgery. Quant Imaging Med Surg 2025;15:1741-52. [Crossref] [PubMed]
12. Seo DK, Kim MJ, Roh SW, Jeon SR. Morphological analysis of interbody fusion following posterior lumbar interbody fusion with cages using computed tomography. Medicine (Baltimore) 2017;96:e7816. [Crossref] [PubMed]
13. Obermueller T, Wagner A, Kogler L, Joerger AK, Lange N, Lehmberg J, Meyer B, Shiban E. Radiographic measurements of cervical alignment, fusion and subsidence after ACDF surgery and their impact on clinical outcome. Acta Neurochir (Wien) 2020;162:89-99. [Crossref] [PubMed]
14. Methods for Estimation of Examinee’s Organ Doses in X-ray Diagnosis. National Standard of the People’s Republic of China. Beijing, China: Standardization Administration of the People's Republic of China; 2021.
15. National Health Commission of the People's Republic of China. Diagnostic reference levels for adults in X-ray computed tomography. Beijing, China: National Health Commission of the People's Republic of China; 2018.
16. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103. Ann ICRP 2007;37:1-332. [Crossref] [PubMed]
17. Brantigan JW, Steffee AD. A carbon fiber implant to aid interbody lumbar fusion. Two-year clinical results in the first 26 patients. Spine (Phila Pa 1976) 1993;18:2106-7. [Crossref] [PubMed]
18. Park JS, Park SJ, Lee CS, Chung SS, Park HJ. Is allograft a more reliable treatment option than autograft in 2-level anterior cervical discectomy and fusion with plate fixation? Medicine (Baltimore) 2019;98:e16621. [Crossref] [PubMed]
19. Kanna RM, Perambuduri AS, Shetty AP, Rajasekaran S. A Randomized Control Trial Comparing Local Autografts and Allografts in Single Level Anterior Cervical Discectomy and Fusion Using a Stand-Alone Cage. Asian Spine J 2021;15:817-24. [Crossref] [PubMed]
20. Lee J, Lee DH, Jung CW, Song KS. The Significance of Extra-Cage Bridging Bone via Radiographic Lumbar Interbody Fusion Criterion. Global Spine J 2023;13:113-21. [Crossref] [PubMed]
21. Riew KD, Yang JJ, Chang DG, Park SM, Yeom JS, Lee JS, Jang EC, Song KS. What is the most accurate radiographic criterion to determine anterior cervical fusion? Spine J 2019;19:469-75. [Crossref] [PubMed]
22. Song KS, Chaiwat P, Kim HJ, Mesfin A, Park SM, Riew KD. Anterior cervical fusion assessment using reconstructed computed tomographic scans: surgical confirmation of 254 segments. Spine (Phila Pa 1976) 2013;38:2171-7. [Crossref] [PubMed]
23. McKeon JF, Alvarez PM, Castaneda DM, Emili U, Kirven J, Belmonte AD, Singh V. Cervical Collar Use Following Cervical Spine Surgery: A Systematic Review. JBJS Rev 2024; [Crossref]
24. Ricciardi L, Scerrati A, Olivi A, Sturiale CL, De Bonis P, Montano N. The role of cervical collar in functional restoration and fusion after anterior cervical discectomy and fusion without plating on single or double levels: a systematic review and meta-analysis. Eur Spine J 2020;29:955-60. [Crossref] [PubMed]
25. Kohli N, Stoddart JC, van Arkel RJ. The limit of tolerable micromotion for implant osseointegration: a systematic review. Sci Rep 2021;11:10797. [Crossref] [PubMed]
26. Ledet EH, Sanders GP, DiRisio DJ, Glennon JC. Load-sharing through elastic micro-motion accelerates bone formation and interbody fusion. Spine J 2018;18:1222-30. [Crossref] [PubMed]