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Marwan Y, Jarragh A, Algarni N, Sheikh M, Alsaeed O. The Feasibility of Condylar Screws for Occipitocervical Fusion in Arabs: Computed Tomography-Based Morphometric Study. Global Spine J 2024:21925682241268093. [PMID: 39095957 DOI: 10.1177/21925682241268093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/04/2024] Open
Abstract
STUDY DESIGN Retrospective, cross-sectional study. OBJECTIVES Occipitocervical fusion is indicated for various conditions. Some techniques require placement of screws in the occipital condyle. The objective of this study was to analyze the morphometric features of the occipital condyle among Arabs. METHODS Computed tomography (CT)-based morphometric analysis of occipital condyles of 200 Arab skeletally mature patients (400 condyles) was done. Axial width of at least 8 mm and coronal height of at least 6.5 mm are the cutoff values for feasibility of condylar screw placement. RESULTS The mean age of the patients was 48.0 ± 18.3 years. Males were 53.5% (107) of the sample. The mean axial condylar width and length were 8.5 ± 1.5 mm and 20.3 ± 2.6 mm, respectively, while the mean axial screw angle was 35.9° ± 5.5° from midline. The mean sagittal condylar length and height were 16.1 ± 1.9 mm and 8.8 ± 1.5 mm, respectively. The mean condylar coronal height was 8.2 ± 1.4 mm. Based on axial width and coronal height measurements, 150 (37.5%) condyles could safely fit a 3.5 mm condylar screw. One hundred and four (55.9% female condyles) condyles cannot fit a screw in females, while 46 (21.5% male condyles) condyles cannot fit a screw in males. CONCLUSIONS Condylar screw for occipitocervical fusion is feasible for the majority of Arabs in our sample; however, this applies to slightly less than half of the female condyles. Detailed preoperative radiological planning is critical to avoid complications related to occipital condyle screw placement.
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Affiliation(s)
- Yousef Marwan
- Department of Surgery, College of Medicine, Health Sciences Centre, Kuwait University, Kuwait City, Kuwait
| | - Ali Jarragh
- Department of Surgery, College of Medicine, Health Sciences Centre, Kuwait University, Kuwait City, Kuwait
| | - Nizar Algarni
- Department of Orthopaedic Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Mehraj Sheikh
- Department of Radiology, College of Medicine, Health Sciences Centre, Kuwait University, Kuwait City, Kuwait
| | - Osama Alsaeed
- Department of Radiology, College of Medicine, Health Sciences Centre, Kuwait University, Kuwait City, Kuwait
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Huang Q, Yang X, Zheng D, Zhou Q, Li H, Peng L, Ye J, Qi S, Lu Y. Exploring the Pathogenesis of Atlanto-Occipital Instability in Chiari Malformation With Type II Basilar Invagination: A Systematic Morphological Study. Neurosurgery 2023; 92:837-853. [PMID: 36700733 PMCID: PMC9988292 DOI: 10.1227/neu.0000000000002284] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 09/30/2022] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Our previous study suggested that atlanto-occipital instability (AOI) is common in patients with type II basilar invagination (II-BI). OBJECTIVE To further understand the pathogenesis of AOI in Chiari malformations (CM) and CM + II-BI through systematic measurements of the bone structure surrounding the craniocervical junction. METHODS Computed tomography data from 185 adults (80 controls, 63 CM, and 42 CM + II-BI) were collected, and geometric models were established for parameter measurement. Canonical correlation analysis was used to evaluate the morphological and positional relationships of the atlanto-occipital joint (AOJ). RESULTS Among the 3 groups, the length and height of the condyle and superior portion of the lateral masses of the atlas (C1-LM) were smallest in CM + II-BI cases; the AOJ had the shallowest depth and the lowest curvature in the same group. AOJs were divided into 3 morphological types: type I, the typical ball-and-socket joint, mainly in the control group (100%); type II, the shallower joint, mainly in the CM group (92.9%); and type III, the abnormal flat-tilt joint, mainly in the CM + II-BI group (89.3%). Kinematic computed tomography revealed AOI in all III-AOJs (100%) and some II-AOJs (1.5%) but not in type I-AOJs (0%). Morphological parameters of the superior portion of C1-LM positively correlated with those of C0 and the clivus and significantly correlated with AOI. CONCLUSION Dysplasia of the condyle and superior portion of C1-LM exists in both CM and II-BI cases yet is more obvious in type II-BI. Unstable movement caused by AOJ deformation is another pathogenic factor in patients with CM + II-BI.
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Affiliation(s)
- Qinguo Huang
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Department of Neurosurgery, The Second Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Xiaoyu Yang
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Dongying Zheng
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Qiang Zhou
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Nanfang Neurology Research Institution, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Hong Li
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Nanfang Neurology Research Institution, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Lin Peng
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Junhua Ye
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Songtao Qi
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Nanfang Neurology Research Institution, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Nanfang Glioma Center, Guangzhou, China
| | - Yuntao Lu
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Nanfang Neurology Research Institution, Nanfang Hospital, Southern Medical University, Guangzhou, China
- Nanfang Glioma Center, Guangzhou, China
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Bernstein DN, Ikpeze TC, Foxx K, Omar A, Mesfin A. Anatomical Parameters for Occipital Condyle Screws: An Analysis of 500 Condyles Using CT Scans. Global Spine J 2022; 12:1475-1480. [PMID: 33472429 PMCID: PMC9393991 DOI: 10.1177/2192568220983311] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
STUDY DESIGN Retrospective observational study. OBJECTIVE To establish occipital condyle dimensions (length, width, height), as well as the medialization angle necessary for safe occipital condyle screw placement in occipitocervical fixation. METHODS Between 1/2014-6/2014, patients who presented to a single level 1 academic trauma center emergency room and received computed tomography (CT) imaging of the cervical spine as part of routine clinical care were identified. After excluding patients with cervical fractures, neoplastic disease, or infection, 500 condyles representing 250 patients were analyzed. Condyle length, height, and width (all reported in millimeters [mm]) were evaluated on the sagittal, coronal, and axial series, respectively. Medialization angle (reported in degrees) was evaluated on the axial series of CT imaging. Measurements were compared by sex and age. RESULTS The average condyle length, width, and height were 18.6 millimeters (mm) (range, 14.5-23.0 mm), 10.5 mm (range, 7.4-13.8 mm), and 11.3 mm (7.1-15.3 mm), respectively. Additionally, the average occipital condyle medialization angle was 23° (range, 14-32°). Occipital condyles of men were significantly longer, wider, and taller (all comparisons, p < 0.05). The medialization angle was significantly steeper for women than men (p < 0.05). No measurement differences were appreciated by age. CONCLUSION Our findings are similar to previous studies in the field; however, length appears slightly shorter. Further, measurement differences were appreciated by sex but not age. Thus, our measurement findings emphasize the importance of preoperative planning utilizing individual patient anatomy to ensure safe placement of occipital condyle screws for optimal outcomes.
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Affiliation(s)
- David N. Bernstein
- Department of Orthopaedics & Physical Performance, University of Rochester, Rochester, NY, USA
| | - Tochukwu C. Ikpeze
- Department of Orthopaedics & Physical Performance, University of Rochester, Rochester, NY, USA
| | - Kenneth Foxx
- Mercy Clinic Neurosurgery, Mercy Hospital Fort Smith, Fort Smith, AR, USA
| | - Adan Omar
- Department of Orthopaedics & Physical Performance, University of Rochester, Rochester, NY, USA
| | - Addisu Mesfin
- Department of Orthopaedics & Physical Performance, University of Rochester, Rochester, NY, USA,Addisu Mesfin, Department of Orthopaedics & Physical Performance, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave, Box 665, Rochester, NY 14642, USA.
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Chakraborty AR, Pelargos PE, Milton CK, Martin MD, Bauer AM, Dunn IF. Occipital condyle screw fixation after posterior decompression for Chiari malformation: Technical report and application. Surg Neurol Int 2021; 12:543. [PMID: 34877029 PMCID: PMC8645510 DOI: 10.25259/sni_26_2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 09/15/2021] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Surgical techniques for stabilization of the occipital cervical junction have traditionally consisted of screw-based techniques applied in conjunction with occipital plating and rods connected to subaxial instrumentation in the form of pars, pedicle, or lateral mass screws. In patients with type 1 Chiari malformation (CM-1) and evidence of occipital cervical junction instability who have undergone posterior decompression, the occipital condyle (OC) represents a potential alternative cranial fixation point. To date, this technique has only been described in pediatric case reports and morphometric cadaver studies. METHODS Patients underwent posterior fossa decompression for treatment of CM. Subsequently, patients received occipital cervical stabilization using OC screws. RESULTS Patients were successfully treated with no post-operative morbidity. Patient 2 was found to have pseudoarthrosis and underwent revision. Both patients continue to do well at 1-year follow-up. CONCLUSION Placement of the OC screw offers advantages over traditional plate-based occipital fixation in that bone removal for suboccipital decompression is not compromised by the need for hardware placement, screws are hidden underneath ample soft tissue in patients with thin skin which prevents erosion, and the OC consists of primarily cortical bone which provides for robust tricortical fixation. These cases demonstrate the novel application of the OC screw fixation technique to the treatment of occipital cervical junction instability in adult patients undergoing simultaneous posterior fossa decompression.
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Affiliation(s)
| | | | | | | | | | - Ian F. Dunn
- Department of Neurosurgery, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
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Wan M, Zong R, Xu HL, Qiao GY, Tong HY, Shang AJ, Yin YH, Yu XG. Feasibility of occipital condyle screw placement in patients with Chiari malformation type I: a computed tomography-based morphometric study. Acta Neurochir (Wien) 2021; 163:1569-1575. [PMID: 33462712 DOI: 10.1007/s00701-021-04714-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 01/11/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND The occipital condyle (OC) screw is an alternative technique for occipitocervical fixation that is especially suitable for revision surgery in patients with Chiari malformation type I (CMI). This study aimed to investigate the feasibility and safety of this technique in patients with CMI. METHODS The CT data of 73 CMI patients and 73 healthy controls were retrospectively analyzed. The dimensions of OCs, including length, width, height, sagittal angle, and screw length, were measured in the axial, sagittal, and coronal planes using CT images. The OC available height was measured in the reconstructed oblique parasagittal plane of the trajectory. RESULTS The mean length, width, and height of OCs in CMI patients were 17.79 ± 2.31 mm, 11.20 ± 1.28 mm, and 5.87 ± 1.29 mm, respectively. All OC dimensions were significantly smaller in CMI patients compared with healthy controls. The mean screw length and sagittal angle were 19.13 ± 1.97 mm and 33.94° ± 5.43°, respectively. The mean OC available height was 6.36 ± 1.59 mm. According to criteria based on OC available height and width, 52.1% (76/146) of OCs in CMI patients could safely accommodate a 3.5-mm-diameter screw. CONCLUSIONS The OC screw is feasible in approximately half of OCs in CMI patients. Careful morphometric analyses and personalized surgical plans are necessary for the success of this operation in CMI patients.
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Ramos-Dávila EM, Meléndez-Flores JD, Álvarez-Pérez R, Barrera-Flores FJ, Martínez-Cobos MC, Pinales-Razo R, Quiroga-Garza A, Zarate-Garza P, Sanchez-Gomez A, Guzman-Lopez S, Elizondo-Omaña RE. Occipital condyle screw fixation viability according to age and gender anatomy: A computed tomography-based analysis. Clin Neurol Neurosurg 2020; 200:106358. [PMID: 33223342 DOI: 10.1016/j.clineuro.2020.106358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/02/2020] [Accepted: 11/04/2020] [Indexed: 10/23/2022]
Abstract
OBJECTIVE To assess the Occipital condyle morphology in an all-age population of Northeastern Mexico, and determine age and gender related changes for surgical viability. METHODS A total of 175 consecutive HRCT scans were included and divided into 5 age groups. The condylar length, width, height, sagittal angle, anterior, posterior and medial intercondylar distances, and intercondylar angle of the OC were measured. RESULTS Mean condylar length, width, and height in total population were 20.58 mm, 9.42 mm, and 9.02 mm, respectively. Differences were observed in most morphometric parameters when comparing age groups. Significant intergender differences in total population were observed in most parameters, when individualizing each age group the height remained significant in all. The group with the least height measurement was aged 5-9 years, this however, could allow the OC screw (≥6.5 mm) placement. CONCLUSION Differences in most morphometric parameters of OC were observed between age groups and gender, particularly patients with 5-9 years. However, all groups presented a minimum height that allows the placement of a standard screw. A preoperative imaging study is always recommended due to the variability and complexity of the region.
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Affiliation(s)
| | | | - Ricardo Álvarez-Pérez
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Hospital Universitario "Dr. José Eleuterio González", Department of Radiology and Imaging, Monterrey, Mexico.
| | | | - Maria C Martínez-Cobos
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Hospital Universitario "Dr. José Eleuterio González", Department of Radiology and Imaging, Monterrey, Mexico.
| | - Ricardo Pinales-Razo
- Universidad Autónoma de Nuevo León, Facultad de Medicina, Hospital Universitario "Dr. José Eleuterio González", Department of Radiology and Imaging, Monterrey, Mexico.
| | | | - Patricio Zarate-Garza
- Human Anatomy Department, Faculty of Medicine, Universidad Autónoma, Monterrey, Mexico.
| | - Arnulfo Sanchez-Gomez
- Human Anatomy Department, Faculty of Medicine, Universidad Autónoma, Monterrey, Mexico.
| | - Santos Guzman-Lopez
- Human Anatomy Department, Faculty of Medicine, Universidad Autónoma, Monterrey, Mexico.
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Du YK, Li SY, Yang WJ, Wang XY, Bi YF, Dong J, Huang H, Gao F, Li GZ, Wei HW, Yang JK, Xi YM. Morphometric Trajectory Analysis for Occipital Condyle Screws. Orthop Surg 2020; 12:931-937. [PMID: 32495510 PMCID: PMC7307246 DOI: 10.1111/os.12700] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 03/31/2020] [Accepted: 04/20/2020] [Indexed: 11/30/2022] Open
Abstract
Objectives Occipitocervical fusion (OCF) is an effective treatment for instability of occipitocervical junction (OCJ). The occipital condyle screw serves as a novel surgical technique for occipitocervical fixation. However, the intraoperative procedures for the occipital condyle screw technique have relied on surgeons’ experience, so the pool of surgeons who are able to perform this surgery safely is limited. The present study aims to evaluate the feasibility and safety of the occipital condyle screw technique using human cadavers and to provide image anatomy for clinical application basis. Methods The scientific study comprised 10 fresh‐frozen cadaveric specimens from the anatomy department of Qingdao University. Placement of the occipital condyle screws (3.5 mm diameter and 20.0 mm length) was performed in the 10 fresh‐frozen cadaveric specimens with intact occipitocervical junctions, respectively. Occipitocervical CT was performed for all specimens and the DICOM data was obtained. Occipitocervical CT three‐dimensional (3D) reconstruction was performed for the cadavers. Morphometric analysis was performed on the bilateral occipitocervical junction of 10 cadaveric specimens based on the 3D reconstruction CT images. Detailed morphometric measurements of the 20 occipital condyles screws were conducted including the average length of the screw trajectory, inside and upper tilting angles of screws, distance to the hypoglossal canal, and to the medial wall of occipital condyle. Results Placement of the occipital condyle screws into the 20 occipital condyles of the 10 cadaveric specimens was performed successfully and the trajectory of implantation was satisfactory according to 3D CT reconstruction images, respectively. There was no obvious injury to the spinal cord, nerve root, and vertebral artery. The length of the bilateral screw trajectory was, respectively, 20.96 ± 0.91 mm (left) and 20.59 ± 0.77 mm (right) (t = 1.306, P > 0.05). The upper tilting angle of bilateral screws was, respectively, 11.24° ± 0.74° (left) and 11.11° ± 0.64° (right) (t = 0.681, P > 0.05). The inside tilting angle of bilateral screws was, respectively, 31.00° ± 1.32° (left) and 30.85° ± 1.27° (right) (t = 0.307, P > 0.05). The screw's distance to the bilateral hypoglossal canal was, respectively, 4.84 ± 0.54 mm (left) and 4.70 ± 0.54 mm (right) (t = 0.685, P > 0.05). The screw's distance to the medial wall of the bilateral occipital condyle was, respectively, 5.13 ± 0.77 mm (left) and 5.04 ± 0.71 mm (right) (t = 0.384, P > 0.05). Conclusion The occipital condyle screw technique can serve as a feasible and safe treatment for instability of the occipitocervical junction with meticulous preoperative planning of the screw entry point and direction based on individual differences. Morphometric trajectory analysis is also an effective way to evaluate the surgical procedure.
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Affiliation(s)
- Yu-Kun Du
- Department of Spinal Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Si-Yuan Li
- Department of Spinal Surgery, Shandong Provincial Third Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Wen-Jiu Yang
- Department of Spinal Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Xiang-Yang Wang
- Department of Orthopaedics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yi-Fang Bi
- The Sanatorium of Qingdao, Qingdao, China
| | - Jun Dong
- Department of Spinal Surgery, Shandong Provincial Hospital affiliated to Shandong University, Jinan, China
| | - Hui Huang
- Department of Spinal Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Feng Gao
- Department of Orthopaedics, Nanyang City Center Hospital
| | - Gui-Zhi Li
- Department of Spinal Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Hua-Wei Wei
- Department of Spinal Surgery, De Zhou People's Hospital, Dezhou, China
| | - Jian-Kun Yang
- Department of Spinal Surgery, Zhoukou Xiehe Orthopedic Hospital, Zhoukou, China
| | - Yong-Ming Xi
- Department of Spinal Surgery, The Affiliated Hospital of Qingdao University, Qingdao, China
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Atlanto-Occipital Transarticular Screw Fixation for the Treatment of Traumatic Occipitocervical Instability in the Pediatric Population. World Neurosurg 2020; 140:e81-e86. [PMID: 32344140 DOI: 10.1016/j.wneu.2020.04.129] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 04/16/2020] [Accepted: 04/18/2020] [Indexed: 11/21/2022]
Abstract
BACKGROUND Atlanto-occipital transarticular screw fixation (AOTSF) has rarely been reported for fixation of the craniovertebral junction (CVJ). METHODS A retrospective chart review of all pediatric patients (less than 18 years of age) with an attempt of AOTSF for fixation of traumatic CVJ instability was conducted. RESULTS A total of 4 patients (2 boys and 2 girls; ages 2, 3, 5, and 8 years) who suffered from acute traumatic CVJ instability managed during 2007-2018 underwent an attempted AOTSF. In 2 patients, this method was technically successful. In the other 2 instances, we were not able to engage the screw into the occipital condyle. These were converted to standard occipital plate, rod, and screw fixation. All were placed in a halo subsequently for a minimum of 3 months. Three patients were fused at last follow-up (range, 17-48 months). One patient after successful AOTSF did not fuse. There were no surgical complications or revision procedures. CONCLUSIONS AOTSF was feasible in half of pediatric patients suffering from traumatic CVJ instability. Therefore, intraoperative salvage options and strategies should be on hand readily. In the pediatric population, where bony anatomy may pose challenges to fixation, this technique may offer a viable first-line option in selected cases, despite the overall modest success rate.
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Occipital Condyle Screw Placement in Patients with Chiari Malformation: A Radiographic Feasibility Analysis and Cadaveric Demonstration. World Neurosurg 2020; 136:470-478. [PMID: 32204299 DOI: 10.1016/j.wneu.2020.01.150] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 01/15/2020] [Indexed: 11/23/2022]
Abstract
OBJECTIVE Patients who undergo decompression surgery for Chiari malformation frequently require occipitocervical fixation. This is typically performed with occipital plates, which may cause intracranial injuries due to multiple fixation points. We undertook this study to assess the feasibility of occipital condyle (OC) screw placement as an alternative method of occipitocervical fixation in this patient population. METHODS Using a cadaveric model with navigational assistance, we performed the complete surgical procedure for occipitocervical fixation with OC screws. We then performed a morphometric analysis using measurements from computed tomography scans of 49 patients (32 adult, 17 pediatric) who had undergone occipitocervical fusion with instrumentation following decompression surgery for Chiari malformation. Bilateral morphometric data were analyzed for the adult and pediatric subgroups separately, as well as for the overall group. RESULTS The surgical procedure was successfully performed in the cadaveric model, demonstrating the feasibility of the proposed method. Ninety-eight OCs were studied in the morphometric analysis, and 80 (81.6%) met our eligibility criteria for OC screw placement. However, in 14.1% of adult OCs and 26.5% of pediatric OCs studied, placement of condylar screws would have been challenging or unsafe, according to our criteria. CONCLUSIONS Our findings suggest that OC screws provide a useful option for occipitocervical fixation in a substantial proportion of patients with Chiari malformation. However, rigorous preoperative analysis would be essential to identify appropriate candidates for this technique and exclude those in whom it should not be attempted. Additional study is warranted.
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Gumussoy I, Duman SB. Morphometric analysis of occipital condyles using alternative imaging technique. Surg Radiol Anat 2019; 42:161-169. [PMID: 31549198 DOI: 10.1007/s00276-019-02344-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 09/14/2019] [Indexed: 02/07/2023]
Abstract
PURPOSE The occipital condyles (OCs) are crucial anatomical structures in the cranial base. To our knowledge, there is no cone beam computed tomography (CBCT)-based study on the morphometric analysis of OCs. The aim of this study was to evaluate the morphometric analysis of OCs using CBCT. METHODS CBCT images of 200 OCs from 100 patients of which 39 males and 61 females in the age group of 18-67 years were included in the study population. Linear and angular measurements of OCs were performed. RESULTS The average OC width, length, height, sagittal angle, and effective height were 10.3 ± 1.3 mm, 19.6 ± 2.0 mm, 9.1 ± 1.4 mm, 7.4 ± 1.7 mm, and 35.3 ± 5.2 mm. Condylar width and sagittal angle measurements were found significantly different between the right and left sides; and were not found significant difference between the right and left sides in the measurements of condylar height, length, and effective height. Also the average intercondylar anterior distance (ICAD), intercondylar posterior distance (ICPD), distance between the basion and the anterior apex of the occipital condyle (B-AAOC), distance between the basion and posterior apex of the occipital condyle (B-PAOC), distance between the opisthion and anterior apex of occipital condyle (O-AAOC), and distance between the opisthion and posterior apex of occipital condyle (O-PAOC) were 20.9 ± 1.5 mm, 44.0 ± 2.0 mm, 12.3 ± 1.9 mm, 34.5 ± 4.2 mm, 29.8 ± 1.7 mm, and 27.0 ± 2.1 mm. There was not significant difference in the morphometric measurements among age groups. All morphometric measurements showed a significant difference depending on gender. CONCLUSIONS The morphometric evaluation of OCs may be effectively examined using CBCT. Linear and angular measurements data of OCs in the present study may be used as a reference database for future morphometric and surgical investigations.
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Affiliation(s)
- Ismail Gumussoy
- Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Sakarya University, Sakarya, Turkey.
| | - Suayip B Duman
- Department of Dentomaxillofacial Radiology, Faculty of Dentistry, İnonu University, Malatya, Turkey
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Abstract
STUDY DESIGN A computed tomographic assessment. OBJECTIVE To establish morphometric data of sacral-2 alar iliac (S2AI) screw fixation in pediatric population. SUMMARY OF BACKGROUND DATA Studies on morphometric parameters of S2AI screw fixation are mostly based on adult population. The pediatric scoliosis also needs the S2AI screw fixation, however, without the previous morphometric information of among pediatric population. METHODS Computed tomography (CT) scans of 120 pediatric patients without spinal deformities are obtained and imported to Mimics software for 3D reconstruction. Then, a cylinder (radius of 3.25 mm) is drawn to imitate the screw trajectory of S2AI screw and adjusted to a maximum upward and downward angle to obtain the feasible region. Nine parameters of the S2AI screw are measured. Differences between age groups are compared and significant statistical correlations are carefully studied to determine the potentially important clinical relationships. RESULTS The mean values and standard deviations (SD) for nine parameters at the maximum upward and downward angles were determined. With age increased, the S2AI screw trajectory becomes more caudal in the coronal (44.03 ± 4.43°-53.15 ± 4.68°) and sagittal planes (50.33 ± 5.89°-57.69 ± 4.21°) and more lateral in the transverse plane (49.40 ± 5.90°-54.44 ± 2.99°), and all of the distance parameters include max-length, sacral distance, iliac width, S2 midline, iliac wing, and skin distance increased. Age has a more significant effect on other parameters than transverse angle and skin distance (P < 0.05). CONCLUSION The S2AI screw fixation could be used on pediatric population too, but the pediatric population had smaller size of pelvis than adults, surgeons should choose the smaller diameters and the shorter length of screws for pediatric population depends on their age. LEVEL OF EVIDENCE N/ A.
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Viers AG, Nguyen KD, Moon PX, Forseen SE, Heger IM. Pediatric occipital condyle morphometric analysis using computed tomography with evaluation for occipital condyle screw placement. J Neurosurg Pediatr 2019; 23:634-638. [PMID: 30835709 DOI: 10.3171/2019.1.peds18583] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 01/08/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Occipitocervical fusions in the pediatric population are rare but can be challenging because of the smaller anatomy. The procedure is even more exacting in patients with prior suboccipital craniectomy. A proposed method for occipitocervical fusion in such patients is the use of occipital condyle screws. There is very limited literature evaluating the pediatric occipital condyle for screw placement. The authors examined the occipital condyle in pediatric patients to determine if there was an age cutoff at which condylar screw placement is contraindicated. METHODS The authors performed a retrospective morphometric analysis of the occipital condyle in 518 pediatric patients aged 1 week-9 years old. Patients in their first decade of life whose occipital condyle was demonstrated on CT imaging in the period from 2009 to 2013 at the Augusta University Medical Center and Children's Hospital of Georgia were eligible for inclusion in this study. Exclusion criteria were an age older than 10 years; traumatic, inflammatory, congenital, or neoplastic lesions of the occipital condyles; and any previous surgery of the occipitocervical junction. Descriptive statistical analysis was performed including calculation of the mean, standard deviation, and confidence intervals for all measurements. Probability values were calculated using the Student t-test with statistical significance determined by p < 0.05. RESULTS Overall, male patients had statistically significantly larger occipital condyles than the female patients, but this difference was not clinically significant. There was no significant difference in left versus right occipital condyles. There were statistically significant differences between age groups with a general trend toward older children having larger occipital condyles. Overall, 20.65% of all patients evaluated had at least one measurement that would prevent occipital condyle screw placement including at least one patient in every age group. CONCLUSIONS Occipital condyle screw fixation is feasible in pediatric patients younger than 10 years. More importantly, all pediatric patients should undergo critical evaluation of the occipital condyle in the axial, sagittal, and coronal planes preoperatively to determine individual suitability for occipital condyle screw placement.
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Affiliation(s)
- Angela G Viers
- 1Department of Neurosurgery, Augusta University Medical Center, Augusta
| | - Khoi D Nguyen
- 1Department of Neurosurgery, Augusta University Medical Center, Augusta
| | - Perounsack X Moon
- 2Philadelphia College of Osteopathic Medicine Georgia Campus, Suwanee; and
| | - Scott E Forseen
- 3Department of Radiology and Imaging, Neuroradiology Section, Augusta, Georgia
| | - Ian M Heger
- 1Department of Neurosurgery, Augusta University Medical Center, Augusta
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Computed Tomography-Based Occipital Condyle Morphometry in an Indian Population to Assess the Feasibility of Condylar Screws for Occipitocervical Fusion. Asian Spine J 2017; 11:847-853. [PMID: 29279738 PMCID: PMC5738304 DOI: 10.4184/asj.2017.11.6.847] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/15/2017] [Accepted: 05/08/2017] [Indexed: 11/08/2022] Open
Abstract
Study Design A retrospective computed tomography (CT)-based morphometric study of 82 occipital condyles in the Indian population, focusing on critical morphometric dimensions with relation to placing condylar screws. Purpose This study focused on determining the feasibility of placing occipital condylar screws in an Indian population using CT anatomical morphometric data. Overview of Literature The occipital condylar screw is a novel technique being explored as one of the options in occipitocervical stabilization. Sex and ethnic variations in anatomical structures may restrict the feasibility of this technique in some populations. To the best of our knowledge, there are no CT-based data on an Indian population that assess the feasibility of occipital condylar screws. Methods We measured the dimensions of 82 occipital condyles in 41 adults on coronal, sagittal, and axial reconstructed CT images. The differences were noted between the right and left sides and also between males and females. Statistical analysis was performed using the t-test, with a p-value of <0.05 considered significant. Results Mean sagittal length and height were 17.2±1.7 mm and 9.1±1.5 mm, respectively. Mean condylar angle/screw angle was 38.0°±5.5° from midline, with mean condylar length and width of 19.6±2.6 mm and 9.5±1.0 mm, respectively. Average coronal height on the anterior and posterior hypoglossal canal was 10.8±1.4 mm and 9.0±1.4 mm, respectively. The values in females were significantly lower than those in males, except for screw angle and condylar width. Based on Lin et al.'s proposed criteria, eight of 82 condyles were not suitable for condylar screws. Conclusions Preliminary CT morphometry data of the occipital condyle shows that condylar screws are anatomically feasible in a large portion of the Indian population. However, because a small number of population may not be suitable for this technique, meticulous study of preoperative anatomy using detailed CT data is advised.
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Zhou J, Espinoza Orías AA, Kang X, He J, Zhang Z, Inoue N, An HS. CT-based morphometric analysis of the occipital condyle: focus on occipital condyle screw insertion. J Neurosurg Spine 2016; 25:572-579. [DOI: 10.3171/2016.4.spine151431] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE
The segmental occipital condyle screw (OCS) is an alternative fixation technique in occipitocervical fusion. A thorough morphological study of the occipital condyle (OC) is critical for OCS placement. The authors set out to introduce a more precise CT-based method for morphometric analysis of the OC as it pertains to the placement of the segmental OCS, and they describe a novel preoperative simulation method for screw placement. Two new clinically relevant parameters, the height available for the OCS and the warning depth, are proposed.
METHODS
CT data sets from 27 fresh-frozen human cadaveric occipitocervical spines were used. All measurements were performed using a commercially available 3D reconstruction software package. The length, width, and sagittal angle of the condyle were measured in the axial plane at the base of the OC. The height of the OC and the height available for the segmental OCS were measured in the reconstructed oblique sagittal plane, fitting the ideal trajectory of the OCS recommended in the literature. The placement of a 3.5-mm-diameter screw that had the longest length of bicortical purchase was simulated into the OC in the oblique sagittal plane, with the screw path not being blocked by the occiput and not violating the hypoglossal canal cranially or the atlantooccipital joint caudally. The length of the simulated screw was recorded. The warning depth was measured as the shortest distance from the entry point of the screw to the posterior border of the hypoglossal canal.
RESULTS
The mean length and width of the OC were found to be larger in males: 22.2 ± 1.7 mm and 12.1 ± 1.0 mm, respectively, overall (p < 0.0001 for both). The mean sagittal angle was 28.0° ± 4.9°. The height available for the OCS was significantly less than the height of the OC (6.2 ± 1.3 mm vs 9.4 ± 1.5 mm, p < 0.0001). The mean screw length (19.3 ± 1.9 mm) also presented significant sex-related differences: male greater than female (p = 0.0002). The mean warning depth was 7.5 ± 1.7 mm. In 7.4% of the samples, although the height of the OC was viable, the height available for the OCS was less than 4.5 mm, thus making screw placement impractical. For these cases, a new preoperative simulation method of the OCS placement was proposed. In 92.6% of the samples that could accommodate a 3.5-mm-diameter screw, 24.0% showed that the entry point of the simulated screw was covered by a small part of the C-1 posterosuperior joint rim.
CONCLUSIONS
The placement of the segmental OCS is feasible in most cases, but a thorough preoperative radiological analysis is essential and cannot be understated. The height available for the OCS is a more clinically relevant and precise parameter than the height of the OC to enable proper screw placement. The warning depth may be helpful for the placement of the OCS.
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Affiliation(s)
- Jinsong Zhou
- 1Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois
- 2Department of Orthopaedic Surgery, Chengdu Military General Hospital, Chengdu, Sichuan; and
| | | | - Xia Kang
- 2Department of Orthopaedic Surgery, Chengdu Military General Hospital, Chengdu, Sichuan; and
| | - Jade He
- 1Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Zhihai Zhang
- 3Department of Orthopaedic Surgery, Aviation General Hospital, China Medical University, Beijing, People's Republic of China
| | - Nozomu Inoue
- 1Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois
| | - Howard S. An
- 1Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois
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Lee HJ, Choi DY, Shin MH, Kim JT, Kim IS, Hong JT. Anatomical feasibility for safe occipital condyle screw fixation. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2016; 25:1674-82. [PMID: 26831538 DOI: 10.1007/s00586-016-4399-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 01/11/2016] [Accepted: 01/15/2016] [Indexed: 12/01/2022]
Abstract
PURPOSE The occipital condyle (OC) screw can be a viable alternative option for the occipito-cervical fixation. However, the risk of vertebral artery (VA) injury during the direct OC screw fixation has not been adequately assessed. The purpose of this study was to establish the course of the VA (V3) relative to the nearby osseous structures to estimate the feasibility of OC screw fixation and describe its anatomical relationship depending on patient's age and sex. METHODS A total of 387 three-dimensional computed tomographic angiograms (3D-CTA) were used and compared between two age groups. The vertebral artery diameter and two kinds of bony space were measured. The occipito-C1 arch space (O-C1S) and VA-occipital bone distance (VOD, six entry points) were measured on both sides. The feasibility of direct OC screw fixation can be represented by the VOD value; the minimum feasible value was determined to be 4 mm. Angular measurements (O-C1A and O-C2A) were also taken to assess their relationship to the bony space. RESULTS The mean value of the O-C1S ranged from 9.0 to 9.9 mm. The mean value of the VOD ranged from 3.2 to 3.5 mm, and the proportion of individuals for which direct OC screw fixation was considered feasible ranged from 32 to 42 % in both age groups and there was no significant difference between two age groups. The VOD value was not affected by laterality or by gender (P > 0.05). The mean kyphosis of the O-C1A (-5° ± 5.2°, range -22° to 8°) was significantly smaller in the young age group compared to the older age group (-7.6° ± 5.3°, range -26° to 2°). The mean lordosis of the O-C2A (12.4° ± 6.4°, range 3°-33°) was significantly higher in the young age group compared to the older age group (10.4° ± 6.4°, range 0°-36°). CONCLUSIONS The direct OC screw fixation was not possible in a considerable number of cases due to the limited space and the position of the VA regardless of age group. Only about one quarter (21-24 %) of all patients was affordable to place the direct OC screw bilaterally. There was more space available to place the direct OC screw when the angle of the upper cervical spine is more kyphotic.
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Affiliation(s)
- Ho Jin Lee
- Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Doo Yong Choi
- Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Myoung Hoon Shin
- Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Jong Tae Kim
- Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Il Sup Kim
- Department of Neurosurgery, St. Vincent Hospital, The Catholic University of Korea, 93-6 Ji-Dong, Paldal-gu, Suwon, 442-723, Korea
| | - Jae Taek Hong
- Department of Neurosurgery, St. Vincent Hospital, The Catholic University of Korea, 93-6 Ji-Dong, Paldal-gu, Suwon, 442-723, Korea.
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Wu AM, Shao ZX, Wang JS, Yang XD, Weng WQ, Wang XY, Xu HZ, Chi YL, Lin ZK. The accuracy of a method for printing three-dimensional spinal models. PLoS One 2015; 10:e0124291. [PMID: 25915641 PMCID: PMC4411119 DOI: 10.1371/journal.pone.0124291] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/11/2015] [Indexed: 11/19/2022] Open
Abstract
Background To study the morphology of the human spine and new spinal fixation methods, scientists require cadaveric specimens, which are dependent on donation. However, in most countries, the number of people willing to donate their body is low. A 3D printed model could be an alternative method for morphology research, but the accuracy of the morphology of a 3D printed model has not been determined. Methods Forty-five computed tomography (CT) scans of cervical, thoracic and lumbar spines were obtained, and 44 parameters of the cervical spine, 120 parameters of the thoracic spine, and 50 parameters of the lumbar spine were measured. The CT scan data in DICOM format were imported into Mimics software v10.01 for 3D reconstruction, and the data were saved in .STL format and imported to Cura software. After a 3D digital model was formed, it was saved in Gcode format and exported to a 3D printer for printing. After the 3D printed models were obtained, the above-referenced parameters were measured again. Results Paired t-tests were used to determine the significance, set to P<0.05, of all parameter data from the radiographic images and 3D printed models. Furthermore, 88.6% of all parameters of the cervical spine, 90% of all parameters of the thoracic spine, and 94% of all parameters of the lumbar spine had Intraclass Correlation Coefficient (ICC) values >0.800. The other ICC values were <0.800 and >0.600; none were <0.600. Conclusion In this study, we provide a protocol for printing accurate 3D spinal models for surgeons and researchers. The resulting 3D printed model is inexpensive and easily obtained for spinal fixation research.
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Affiliation(s)
- Ai-Min Wu
- Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# Xue Yuan Western Road, Wenzhou, Zhejiang, People’s Republic of China
| | - Zhen-Xuan Shao
- Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# Xue Yuan Western Road, Wenzhou, Zhejiang, People’s Republic of China
| | - Jian-Shun Wang
- Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# Xue Yuan Western Road, Wenzhou, Zhejiang, People’s Republic of China
| | - Xin-Dong Yang
- Department of Anatomy, Wenzhou Medical University, Higher Education Zone, Wenzhou, Zhejiang, People’s Republic of China
| | - Wan-Qing Weng
- Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# Xue Yuan Western Road, Wenzhou, Zhejiang, People’s Republic of China
| | - Xiang-Yang Wang
- Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# Xue Yuan Western Road, Wenzhou, Zhejiang, People’s Republic of China
| | - Hua-Zi Xu
- Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# Xue Yuan Western Road, Wenzhou, Zhejiang, People’s Republic of China
| | - Yong-Long Chi
- Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# Xue Yuan Western Road, Wenzhou, Zhejiang, People’s Republic of China
- * E-mail: (YLC); (ZKL)
| | - Zhong-Ke Lin
- Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, 109# Xue Yuan Western Road, Wenzhou, Zhejiang, People’s Republic of China
- * E-mail: (YLC); (ZKL)
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Lee HJ, Kim JT, Shin MH, Choi DY, Hong JT. Quantification of pediatric cervical spine growth at the cranio-vertebral junction. J Korean Neurosurg Soc 2015; 57:276-82. [PMID: 25932295 PMCID: PMC4414772 DOI: 10.3340/jkns.2015.57.4.276] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 12/18/2014] [Accepted: 12/24/2014] [Indexed: 11/27/2022] Open
Abstract
Objective The purpose of this study was to investigate morphological change at the craniovertebral junction (CVJ) region using computed tomography. Methods A total of 238 patients were included in this study, and mean age was 47.8±21.3 months. Spinal canal diameter, Power's ratio, McRae line, antero-posterior C1 ring height, atlantoaxial joint space, C2 growth, epidural space from the dens (M-PB-C2) and longitudinal distance (basion to C2 lower margin, B-C2) were measured. The mean value of each parameter was assessed for individual age groups. The cohorts were then divided into three larger age groups : infancy (I) (≤2 years), very early (VE) childhood (2-5 years) and early (E) childhood (5≥ years). Results Spinal canal diameter increased with age; however, this value did not increase with statistical significance after VE age. A significant age-related difference was found for all C2 body and odontoid parameters (p<0.05). Mean McRae line was 8.5, 8, and 7.5 mm in the I, VE, and E groups, respectively. The M-PB-C2 line showed up-and-down dynamic change during early pediatric periods. Conclusion Expansion of the spinal canal was restricted to the very early childhood period (less than 5 years) in the CVJ region; however, the C2 body and odontoid process increased continuously with age. The above results induced a dynamic change in the M-PB-C2 line. Although C2 longitudinal growth continued with age, the McRae line showed relatively little change.
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Affiliation(s)
- Ho Jin Lee
- Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Jong Tae Kim
- Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Myoung Hoon Shin
- Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Doo Yong Choi
- Department of Neurosurgery, Incheon St. Mary's Hospital, The Catholic University of Korea, Incheon, Korea
| | - Jae Taek Hong
- Department of Neurosurgery, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea
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Free-hand placement of occipital condyle screws: a cadaveric study. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2014; 23:2182-8. [DOI: 10.1007/s00586-014-3488-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 07/22/2014] [Accepted: 07/23/2014] [Indexed: 10/25/2022]
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