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Varghese JE, Rabi S, Joseph V, Jeyaseelan L, Prithishkumar IJ. Morphometric Analysis of the Neural Arch of C2 Vertebra in Indian Population. Neurol India 2024; 72:334-339. [PMID: 38691478 DOI: 10.4103/ni.ni_1033_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 04/09/2023] [Indexed: 05/03/2024]
Abstract
BACKGROUND AND OBJECTIVE The most common injuries to upper cervical spine are fractures of the second cervical vertebrae. The study aims to evaluate the morphometry of the neural arch of the second cervical vertebrae in the South Indian population. MATERIALS AND METHODS Sixty-three second cervical vertebrae of undetermined gender and age without any gross defect were used for the study. The dimensions of neural arch, including superior articular facet, inferior articular facet, pediculoisthmic component, lamina, spinous process, foramen transversarium, and vertebral foramen, were measured by two independent observers using digital vernier caliper accurate to 0.1 mm and the data was analyzed. Descriptive statistics were obtained for the variables. Paired t-test was done to compare the measurements between right and left sides. RESULTS There was no statistical difference between the right and left sides of the dimensions of superior articular facets, foramen transversarium, and the transverse diameter of inferior articular facet. The anteroposterior diameter of the inferior articular facets was more on the right side (P = 0.009). The width of the pediculoisthmic component in both the superior and inferior aspects was found to be less on the right side than that of the left (P = 0.006 and P = 0.031, respectively). The thickness in the middle one-third of laminae was optimum for bilateral safe screw insertion (≥4.0 mm) in 77% specimens. CONCLUSION In summary, measurements of the transverse diameter of superior articular facet and thickness of lamina differed significantly from those reported in literature. This should be kept in mind while doing neurosurgery procedures in the Indian population.
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Affiliation(s)
- Jija E Varghese
- Department of Anatomy, Christian Medical College, Vellore, Tamil Nadu, India
| | - Suganthy Rabi
- Department of Anatomy, Christian Medical College, Vellore, Tamil Nadu, India
| | - Vivek Joseph
- Department of Neurosurgery, Christian Medical College, Vellore, Tamil Nadu, India
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Schmidt C, Chaiyamoon A, Cardona JJ, Mathkour M, Scullen T, Iwanaga J, Kalyvas J, Carrera A, Reina F, Dumont AS, Tubbs RS. What is the C2 pedicle, pars interarticularis, and isthmus? Anatomical study and review of the literature regarding these confusing terms with proposal of new nomenclature. Acta Neurochir (Wien) 2023:10.1007/s00701-023-05655-x. [PMID: 37291431 DOI: 10.1007/s00701-023-05655-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 05/27/2023] [Indexed: 06/10/2023]
Abstract
INTRODUCTION The atypical anatomy of the C2 vertebra has led to terminological discrepancies within reports and studies in the literature regarding the location of its pedicle, pars interarticularis, and isthmus. These discrepancies not only limit the power of morphometric analyses, but they also confuse technical reports regarding operations involving C2, and thus confuse our ability to properly communicate this anatomy. Herein, we examine the variations in nomenclature regarding the pedicle, pars interarticularis, and isthmus of C2, and via an anatomical study, propose new terminology. METHODS The articular surface and underlying superior and inferior articular processes and adjacent transverse processes were removed from 15 C2 vertebrae (30 sides). Specifically, the areas regarded as the pedicle, pars interarticularis, and isthmus were evaluated. Morphometrics were performed. RESULTS Our results indicate that, anatomically, C2 has no "isthmus" and that a pars interarticularis for C2, when present, is very short. Deconstruction of the attached parts allowed for visualization of a bony arch extending from the anterior most aspect of the lamina to the body of C2. The arch is composed almost entirely of trabecular bone and without its attached parts, e.g., transverse process, really has no cortical bone laterally. CONCLUSIONS We propose a more accurate terminology, the pedicle, for pars/pedicle screw placement of C2. Such a term more accurately describes this unique structure of the C2 vertebra and would alleviate terminological confusion in the future literature on this topic.
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Affiliation(s)
| | - Arada Chaiyamoon
- Department of Anatomy, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
| | - Juan J Cardona
- Department of Neurosurgery, Tulane University School of Medicine, New Orleans, LA, USA
| | - Mansour Mathkour
- Department of Neurosurgery, Tulane University School of Medicine, New Orleans, LA, USA
- Department of Neurosurgery and Ochsner Neuroscience Institute, Ochsner Health System, New Orleans, LA, USA
| | - Tyler Scullen
- Department of Neurosurgery, Tulane University School of Medicine, New Orleans, LA, USA
- Department of Neurosurgery and Ochsner Neuroscience Institute, Ochsner Health System, New Orleans, LA, USA
| | - Joe Iwanaga
- Department of Neurosurgery, Tulane University School of Medicine, New Orleans, LA, USA
- Department of Structural & Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
- Department of Neurology, Tulane Center for Clinical Neurosciences, Tulane University School of Medicine, New Orleans, LA, USA
| | - James Kalyvas
- Department of Neurosurgery and Ochsner Neuroscience Institute, Ochsner Health System, New Orleans, LA, USA
| | - Ana Carrera
- Medical Sciences Department, Clinical Anatomy, Embryology and Neuroscience Research Group (NEOMA), Faculty of Medicine, University of Girona, Girona, Spain
| | - Francisco Reina
- Medical Sciences Department, Clinical Anatomy, Embryology and Neuroscience Research Group (NEOMA), Faculty of Medicine, University of Girona, Girona, Spain
| | - Aaron S Dumont
- Department of Neurosurgery, Tulane University School of Medicine, New Orleans, LA, USA
| | - R Shane Tubbs
- Department of Neurosurgery, Tulane University School of Medicine, New Orleans, LA, USA
- Department of Neurosurgery and Ochsner Neuroscience Institute, Ochsner Health System, New Orleans, LA, USA
- Department of Anatomical Sciences, St. George's University, St. George's, West Indies, Grenada
- Department of Surgery, Tulane University School of Medicine, New Orleans, LA, USA
- Department of Structural & Cellular Biology, Tulane University School of Medicine, New Orleans, LA, USA
- Department of Neurology, Tulane Center for Clinical Neurosciences, Tulane University School of Medicine, New Orleans, LA, USA
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Wu Y, Liang Z, Bao J, Wen L, Zhang L. Morphology analysis of the C2 pediculoisthmic component and feasibility of safe C2 pedicle screw placement: comparison of multiplanar reconstruction versus traditional radiographic methods. J Orthop Surg Res 2023; 18:252. [PMID: 36973803 PMCID: PMC10044384 DOI: 10.1186/s13018-023-03727-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 03/17/2023] [Indexed: 03/29/2023] Open
Abstract
BACKGROUND Preoperatively evaluating the feasibility of safe C2 pedicle screw placement is the key to avoiding iatrogenic vertebral artery injury. However, it has not been verified whether the conventional CT measurements of C2 pediculoisthmic component (PIC) are reliable and accurate, and the results may lack validity. The purpose of this study is to analyze the evaluative performance of conventional CT measurements and to create an accurate predictor of morphometrics of C2 PIC. METHODS A total of 304 C2 PICs were measured in 152 consecutive patients who underwent CT examination of the cervical spine between April 2020 and December 2020. We obtained the morphometric parameters of C2 PIC by measuring minimum PIC diameter (MPD) in CT multiplanar reconstruction versus conventional measurements of transverse PIC width (TPW), oblique PIC width (OPW) and definition of high-riding vertebral artery (HRVA). The outer diameter measured less than 4 mm in MPD was regarded as the standard of precluding safe C2 pedicle screw insertion. The evaluative performance of the conventional CT measurements was assessed, and the correlation between conventional CT measurements and measurements in CT multiplanar reconstruction was calculated. RESULTS The parameters in OPW and MPD were measured significantly larger than those in TPW, and the preclusion of C2 pedicle screw placement evaluated from TPW and HRVA was significantly higher than that evaluated from OPW and MPD. The sensitivity of TPW was 93.09%, and the specificity was 79.31%. The sensitivity and specificity of OPW were 97.82% and 82.76%. The sensitivity of HRVA was 88.36%, and the specificity was 96.55%. Strong agreement with the highest correlation coefficient (0.879) and determination coefficient (0.7720) suggested that the outer diameter of OPW could be useful for the precise prediction of MPD. CONCLUSIONS CT MPR allows accurate measurement of the narrowest section of the C2 PIC. The outer diameter of OPW could be simply measured and be useful for precise prediction of MPD, which makes C2 pedicle screw placement more safely than the conventional measurement of TPW and HRVA.
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Affiliation(s)
- YueLin Wu
- The Spine Department, Orthopaedic Center, Guangdong Second Provincial General Hospital, Guang Zhou, Guangdong Province, China
| | - ZhaoQuan Liang
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong Province, China
| | - JunHao Bao
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong Province, China
| | - Ling Wen
- The Spine Department, Orthopaedic Center, Guangdong Second Provincial General Hospital, Guang Zhou, Guangdong Province, China
| | - Li Zhang
- The Spine Department, Orthopaedic Center, Guangdong Second Provincial General Hospital, Guang Zhou, Guangdong Province, China.
- The Second School of Clinical Medicine, Southern Medical University, Guangzhou, Guangdong Province, China.
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Li G, Wang Q. Detailed observation of anatomical location and pattern in Hangman's fracture based on computed tomography three-dimensional reconstruction. J Orthop Surg Res 2023; 18:136. [PMID: 36823607 PMCID: PMC9948456 DOI: 10.1186/s13018-023-03622-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 02/15/2023] [Indexed: 02/25/2023] Open
Abstract
OBJECTIVE To observe the precise anatomical location and pattern of the fracture lines in Hangman's fracture. METHODS Three-dimensional computed CT images of 210 patients with Hangman's fracture were collected. According to the involvement of anatomical structures, the injuries were classified into facet joint injury and pure bony injury. The C2 ring was also divided into: anterior, middle, and posterior elements. The anatomical structures involvement and fracture patterns were observed. RESULT Total 520 anatomical structures injuries were involved in 210 patients Hangman's fractures, including 298 facet joints injuries (57.3%) and 222 bony injuries (42.7%). The most common facet joints injury was superior articular facet injury of C2, and the most common pure bony injury was pediculoisthmic component fracture. The injuries of anterior element (60.6%) were more common than that of middle (20.4%) or posterior (19.0%) element. One injury in anterior element on one side and another injury located in the anterior, middle or posterior element other side was the most common fracture pattern. Injury of middle element on one side with another injury located in the middle or posterior element could be also observed. CONCLUSION In Hangman's fractures, fracture lines could occur in any part of C2 ring. Facet joints injuries were more common than pure bony injuries, and the injuries of anterior element were also more common than that of middle or posterior element. The high prevalence of facet joints injuries means that most of Hangman's fractures may be involved with intra-articular injuries.
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Affiliation(s)
- Guangzhou Li
- Department of Orthopeadics (Spine Surgery), The Affiliated Hospital of Southwest Medical University, No. 25 Taiping Street, Luzhou, 646000, Sichuan Province, China
| | - Qing Wang
- Department of Orthopeadics (Spine Surgery), The Affiliated Hospital of Southwest Medical University, No. 25 Taiping Street, Luzhou, 646000, Sichuan Province, China.
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The anatomical features of axis ring fractures: A retrospective analysis of 217 cases. INTERDISCIPLINARY NEUROSURGERY 2022. [DOI: 10.1016/j.inat.2022.101619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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He Q, Cao J, Tian H, Chen B, Fan X, Wang S, Zhao Y, Wei J, Nie L, Pan X, Cheng L. The Classification of Axial Deformity in Patients with Basilar Invagination. Orthop Surg 2022; 14:3150-3158. [PMID: 36222216 PMCID: PMC9732616 DOI: 10.1111/os.13487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 07/21/2022] [Accepted: 08/10/2022] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVE To summarize the variation types of the axis in patients with basilar invagination (BI), then propose a classification scheme of the axis deformity. METHODS From December 2013 to September 2020, 92 patients (male 42, female 50) who were diagnosed with BI were studied retrospectively. Based on the imaging data of CT, the width and height of the axis pedicle and the sagittal diameter of the lateral mass were measured in each patient. According to the development of axis pedicle and lateral mass, the types of axis variation were summarized, and then the classification scheme of axis deformity was put forward. RESULTS All cases were analyzed and axis deformities were divided into four types. Type I: the axis is basically normal (53 cases, 57.6%). Type II: axis lateral mass is dysplasia (eight cases, 8.7%), which includes two subtypes: type IIA, the axis unilateral lateral mass is dysplasia (three cases); type IIB, the axis bilateral lateral masses are all dysplasia (five cases). Type III: axis pedicle is dysplasia (11 cases, 12%), which is subdivided into two subtypes: type IIIA, the axis unilateral pedicle is dysplasia (six cases); type IIIB, the axis bilateral pedicles are all dysplasia (five cases). Type IV: axis pedicle and lateral mass are all dysplasia (20 cases, 21.7%), this type contains the following four subtypes: type IVA, the unilateral axis pedicle and unilateral lateral mass (contralateral or ipsilateral) are all hypoplasia (four cases); type IVB, the unilateral axis pedicle and bilateral lateral masses are all hypoplasia (five cases); type IVC, the bilateral axis pedicles and unilateral lateral mass are all dysplasia (seven cases); type IVD, the bilateral axis pedicles and bilateral lateral masses are all dysplasia (four cases). The left and right abnormal lateral mass sagittal diameter (Type II) was (7.23 ± 1.39) mm and (5.96 ± 1.37) mm, respectively, the left and right abnormal pedicle width (Type III) was (2.61 ± 1.01) mm and (3.23 ± 0.66) mm, respectively, left and right abnormal pedicle height (Type III) was (5.43 ± 2.19) mm and (4.92 ± 1.76) mm, respectively. Moreover, the classification scheme has good repeatability and credibility. CONCLUSIONS The classification about axis deformity could provide personalized guidance for axis screw placement in the BI and other upper cervical surgery, and axis screw placement errors would be effectively avoided.
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Affiliation(s)
- Qiting He
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Jiankang Cao
- Department of Pain, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Huichao Tian
- Department of Orthopedic SurgeryLiaocheng People's HospitalLiaochengChina
| | - Bin Chen
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Xincheng Fan
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina,Department of Orthopedic SurgeryTaian City Central HospitalTaianChina
| | - Shaoyi Wang
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Yunpeng Zhao
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Jianlu Wei
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Lin Nie
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Xin Pan
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
| | - Lei Cheng
- Department of Orthopedic Surgery, Qilu Hospital of Shandong University, Cheeloo College of MedicineShandong UniversityJinanChina
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Classifying vertebral artery anatomy abnormality in children with skeletal dysplasia. Spine Deform 2021; 9:833-839. [PMID: 33403655 DOI: 10.1007/s43390-020-00264-5] [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] [Received: 06/18/2020] [Accepted: 11/23/2020] [Indexed: 10/22/2022]
Abstract
PURPOSE Skeletal dysplasia (SKD) have predictably abnormal occipitocervical skeletal anatomy, but a similar understanding of their vertebral artery anatomy is not known. Knowledge and classification of vertebral artery anatomy in SKD patients is important for safe surgical planning. We aimed to determine if predictably abnormal vertebral artery anatomy exists in pediatric SKD. METHODS We performed a retrospective review of CTAs of the neck for pediatric patients at a single institution from 2006 to 2018. CTAs in SKD and controls were reviewed independently in blinded fashion by two radiologists who classified dominance, vessel curvature at C2, direction at C3, and presence of fenestration and intersegmental artery. RESULTS 14 skeletal dysplasia patients were compared to 32 controls. The path of the vertebral artery at C2 foramen was no different between the cohorts or by side, right (p = 0.43) or left (p = 0.13), nor for medial or lateral exiting direction from C3 foramen on right (p = 0.82) or left (p = 0.60). Dominance was most commonly neutral in both groups (71% in SKD and 63% in controls). There were no fenestrated nor first intersegmental arteries in our cohort. CONCLUSION No systematic differences were detected between SKD and control patients with respect to vertebral artery anatomy. Nonetheless, surgically relevant variability was observed in both groups. Paying particular attention to the direction of exit at C3 and curvature at C2 with respect to the foramen and vessel dominance are important and easily classifiable abnormalities that both surgeons and radiologists can use to communicate and employ in pre-operative planning. LEVEL OF EVIDENCE III.
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Klepinowski T, Pala B, Cembik J, Sagan L. Prevalence of High-Riding Vertebral Artery: A Meta-Analysis of the Anatomical Variant Affecting Choice of Craniocervical Fusion Method and Its Outcome. World Neurosurg 2020; 143:e474-e481. [PMID: 32750514 DOI: 10.1016/j.wneu.2020.07.182] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 07/24/2020] [Accepted: 07/26/2020] [Indexed: 11/18/2022]
Abstract
OBJECTIVE A high-riding vertebral artery (HRVA) has been defined as a C2 isthmus height of ≤5 mm and/or internal height of ≤2 mm measured 3 mm lateral to the border of the spinal canal. Its reported prevalence has varied widely. If overlooked during the approach for craniocervical fusion, injury to the vertebral arteries can occur, affecting the outcome. The present meta-analysis aimed to provide the pooled prevalence of HRVAs. METHODS A comprehensive database search was conducted by 3 of us. Peer-reviewed studies that had followed the strict definition for HRVAs and had reported its prevalence were included. The risk of bias was assessed using the anatomical quality assessment tool. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed. The pooled prevalence was calculated using a random effects model. RESULTS The data from 20 studies with 3126 subjects (7496 sides) were analyzed. The overall pooled prevalence of ≥1 HRVA was 25.3% (95% confidence interval [CI], 19.6%-31.5%). The prevalence in those without the most important confounding factor, rheumatoid arthritis (RA), was 20.9% (95% CI, 16.5%-25.8%). Patients with RA had a prevalence of 42.9% (95% CI, 23.8%-63.1%). The difference between the non-RA and RA groups was statistically significant (P < 0.001, test of homogeneity, χ2). No geographical differences were noted (P = 0.20, test of homogeneity, χ2). Among those with HRVA, unilateral HRVA was present in 70.3% (95% CI, 65.2%-75.2%) and bilateral in 29.7% (95% CI, 24.8%-34.8%). No left or right side predilection was found (left, 50.8%; 95% CI, 33.8%-67.6%; right, 49.2%; 95% CI, 32.4%-66.2%). CONCLUSIONS Craniocervical fusion should be preceded by examination of the vertebral arteries at the level of C2 because the presence of HRVAs is common and might preclude the safe insertion of transarticular or transpedicular screws.
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Affiliation(s)
- Tomasz Klepinowski
- Department of Neurosurgery, Public Clinical Hospital No. 1, Pomeranian Medical University, Szczecin, Poland.
| | - Bartłomiej Pala
- Department of Neurosurgery, Public Clinical Hospital No. 1, Pomeranian Medical University, Szczecin, Poland
| | | | - Leszek Sagan
- Department of Neurosurgery, Public Clinical Hospital No. 1, Pomeranian Medical University, Szczecin, Poland
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Davidson CT, Bergin PF, Varney ET, Jones LC, Ward MS. Planning C2 pedicle screw placement with multiplanar reformatted cervical spine computed tomography. JOURNAL OF CRANIOVERTEBRAL JUNCTION AND SPINE 2019; 10:46-50. [PMID: 31000981 PMCID: PMC6469326 DOI: 10.4103/jcvjs.jcvjs_116_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
Object: Careful preoperative planning with thin-slice computed tomography (CT) scan is useful for hardware placement at C2. Prior studies have shown considerable variability in the proportion of C2 vertebrae considered safe for pedicle screw placement, depending on the imaging technique used. Our work sought to more carefully define that proportion using a refined imaging technique on a large number of submillimeter CT scans. Materials and Methods: We reviewed 150 submillimeter cervical spine studies randomly selected from CT scans performed at a Level 1 trauma center. OsiriX™ image analysis software was used to propagate a 5-mm cylinder through the plane of the pedicle on paracoronal reformatted CT scans. Hounsfield unit attenuation was used to determine whether the cylinder violated the pedicle. Binomial data were generated to determine the proportion of pedicles that would allow safe screw placement. Results: We analyzed 300 pedicles in 150 patients. Using a standard C2 pedicle starting point, 32% of pedicles were breached by the 5-mm diameter cylinder. When screw trajectory was adjusted by moving the cylinder to fit the pedicle isthmus, establishing an optimized starting point, only 14% of pedicles were breached. Average pedicle length was 27.3 mm for screws that would have crossed the isthmus versus 13.2 mm for screws that would have stopped short due to potential breach. Conclusions: Findings of the current work suggest that preoperative imaging analysis or navigation can be useful adjuncts when anatomical variants are present.
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Affiliation(s)
- Casey T Davidson
- Department of Orthopedic Surgery and Rehabilitation, University of Mississippi Medical Center, Jackson, MS, USA
| | - Patrick F Bergin
- Department of Orthopedic Surgery and Rehabilitation, University of Mississippi Medical Center, Jackson, MS, USA
| | - Elliot T Varney
- School of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - LaRita C Jones
- Department of Orthopedic Surgery and Rehabilitation, University of Mississippi Medical Center, Jackson, MS, USA
| | - Marion S Ward
- Department of Orthopedic Surgery and Rehabilitation, University of Mississippi Medical Center, Jackson, MS, USA
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Montemurro N, Perrini P, Mangini V, Galli M, Papini A. The Y-shaped trabecular bone structure in the odontoid process of the axis: a CT scan study in 54 healthy subjects and biomechanical considerations. J Neurosurg Spine 2019; 30:585-592. [PMID: 30717040 DOI: 10.3171/2018.9.spine18396] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Accepted: 09/26/2018] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Odontoid process fractures are very common in both young and geriatric patients. The axial trabecular architecture of the dens appears to be crucial for physiological and biomechanical function of the C1-2 joint. The aim of this study is to demonstrate the presence of a Y-shaped trabecular structure of the dens on axial CT and to describe its anatomical and biomechanical implications. METHODS Fifty-four C2 odontoid processes in healthy subjects were prospectively examined for the presence of a Y-shaped trabecular structure at the odontocentral synchondrosis level with a dental cone beam CT scan. Length, width, and axial area of the odontoid process were measured in all subjects. In addition, measurements of the one-third right anterior area of the Y-shaped structure were taken. RESULTS The Y-shaped trabecular structure was found in 79.6% of cases. Length and width of the odontoid process were 13.5 ± 0.6 mm and 11.2 ± 0.9 mm, respectively. The mean area of the odontoid process at the odontocentral synchondrosis was 93.5 ± 4.3 mm2, whereas the mean one-third right anterior area of the odontoid process at the same level was 29.3 ± 2.5 mm2. The mean area of the odontoid process and its length and width were similar in men and women (p > 0.05). No significant difference was found in the mean area of the odontoid process in people older than 65 years (94 ± 4.2 mm2) compared to people younger than 65 years (93.3 ± 4.4 mm2; p > 0.05). CONCLUSIONS The authors identified a new anatomical entity, named the Y-shaped trabecular structure of the odontoid process, on axial CT scans. This structure appears to be the result of bone transformation induced by the elevated dynamic loading at the C1-2 level. The presence of the Y-shaped structure provides new insights into biomechanical responses of C2 under physiological loading and traumatic conditions.
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Affiliation(s)
- Nicola Montemurro
- 1Unit of Neurosurgery, "Di Venere" City Hospital, ASL Bari
- 2Department of Basic Medical Sciences, Neurosciences and Sensory Organs, University of Bari
| | - Paolo Perrini
- 3Department of Neurosurgery, Azienda Ospedaliero Universitaria Pisana (AOUP), Pisa; and
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Anatomical considerations of C2 lamina for the placement of translaminar screw: a review of the literature. EUROPEAN JOURNAL OF ORTHOPAEDIC SURGERY AND TRAUMATOLOGY 2017; 28:343-349. [PMID: 29119372 DOI: 10.1007/s00590-017-2072-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 11/03/2017] [Indexed: 10/18/2022]
Abstract
PURPOSE The thorough knowledge of C2 lamina anatomy is essential for the avoidance of complications during screw fixation. We performed a review of the literature, aiming to detect what was found about anatomical feasibility of C2 translaminar fixation in different populations, along with possible recommendations for the avoidance of complications, and to detect whether factors such as race or gender could influence axis lamina anatomy and fixation feasibility. METHODS We performed a search in PubMed and Cochrane database of systematic reviews for studies which correlated axis lamina anatomy with fixation feasibility. We extracted data concerning measurements on C2 lamina, the methods and conclusions of the studies. RESULTS Twenty-six studies met our inclusion criteria. The studies mainly focused on Asian populations. Male gender was generally related to larger anatomical parameters of C2 lamina. The use of a C2 translaminar screw with a diameter of 3.5 mm was generally feasible, even in children, but there was disagreement about risk of vertebral artery injury. Computed tomography was most frequently recommended preoperatively. Three-dimensional reconstruction was suggested by some authors. CONCLUSION C2 lamina anatomy generally permitted screw fixation in most studies, but there was disagreement about risk of vertebral artery injury. Preoperative computed tomography was generally recommended, while, according to some authors, three-dimensional reconstruction could be essential. However, there is a relative lack of studies about non-Asian populations. More research could further illustrate the anatomy of C2 lamina, clarify the safety of axis fixation for more populations and perhaps modify preoperative imaging protocols.
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Menon KV, Taif S. Detailed description of anatomy of the fracture line in hangman's injury: a retrospective observational study on motor vehicle accident victims. Br J Radiol 2015; 89:20150847. [PMID: 26607649 DOI: 10.1259/bjr.20150847] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To study the precise location of fracture line in hangman's fracture to determine the fracture patterns, symmetry and involvement of different vertebral elements. METHODS 32 cases of hangman's fractures were retrospectively evaluated. All patients presented with motor vehicle accidents. CT scans were studied to accurately localize the fracture lines. Symmetry of fracture lines on both sides was assessed, and involvement of the vertebral bodies, lamina, facet joints and foramen transversarium was also determined. RESULTS 20 patients showed asymmetric fracture locations, 13 of them had a unilateral pedicle fracture and a contralateral pars fracture which comprised the most common injury pattern (40% of cases). Less frequent combinations for the two sides of asymmetric C2 ring disruption include pars-vertebral body (3 patients), pedicle-vertebral body (2 patients) and pedicle-lamina (2 patients). 12 patients showed symmetrical fractures (5 through the pars and 7 through the pedicles). Vertebral body and facet joint involvement were demonstrated in 15 (47%) and 16 (50%) cases, respectively. 18 cases had fractures extending into the foramen transversarium (56%). In total, 26 fracture lines primarily affected the pars (40%) and 31 affected the pedicles (49%). CONCLUSION Asymmetric hangman's fracture is more common with the usual pattern being fracture pedicle on one side and pars on the other followed by the symmetric bilateral pedicle and bilateral pars fractures. Fracture lines running into the transverse foramen and facet joints are very frequent as well as those involving the vertebral bodies. ADVANCES IN KNOWLEDGE There is controversy in literature regarding the fracture locations in hangman's injury owing to lack of studies that address this subject. This article is the first to describe precisely the anatomical locations and patterns of this injury.
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Affiliation(s)
- K Venugopal Menon
- 1 Orthopaedics Department, Khoula Hospital, Mina al Fahal, Muscat, Sultanate of Oman
| | - Sawsan Taif
- 2 Department of Radiology, Khoula Hospital, Mina al Fahal, Muscat, Sultanate of Oman
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C1-C3 Lateral Mass Screw-Rod Fixation and Fusion for C2 Pathologies and Hangman's Fractures. Asian Spine J 2014; 8:735-46. [PMID: 25558315 PMCID: PMC4278978 DOI: 10.4184/asj.2014.8.6.735] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/02/2014] [Accepted: 03/03/2014] [Indexed: 01/09/2023] Open
Abstract
Study Design Retrospective clinical study. Purpose We report our experience of eight patients treated with C1-C3 lateral mass rod-screw stabilization and fusion in the treatment of Hangman's fracture and other axis pathologies. Overview of Literature Different surgical approaches, both anterior and posterior, have been described for treating Hangman's fracture and other pathologies where surgery is indicated. Methods All patients who underwent surgical treatment for Hangman's fracture and axial pathology where C1-C3 lateral mass screw-rod stabilization and fusion done, following reduction of the fracture or removal of the pathology were included in this series. The recorded patient management data was retrospectively studied. Results There were 8 cases in total. All were male, with an average age of 40.75 years. Hangman's fracture occurred in 6 cases (75%), one with metastatic squamous cell carcinoma and the remaining with plasmocytoma. Among the Hangman's fractures 4 (66.66%) had no neuro-deficit. Reduction and bilateral C1-C3 lateral mass screw and rod fixation with posterior fusion by bone graft was performed in all cases. In 2 cases, a C2 body tumor was removed transorally. All patients with neuro-deficit fully recovered, except one who expired in the early post-operative period. Rest of all patients were leading a normal life till last follow up. Conclusions Although the number of cases was very small with a relatively short follow up period, C1 and C3 lateral mass screw-rod fixation followed by fusion showed promise as an effective and biomechanically sound way for the treatment of properly selected Hangman's fracture cases, and may also be suitable in other axial pathologies.
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Dalbayrak S, Yaman O, Yılmaz M. A new technique in the surgical treatment of Hangman's fractures: Neurospinal Academy (NSA) technique. JOURNAL OF CRANIOVERTEBRAL JUNCTION AND SPINE 2014; 4:59-63. [PMID: 24744563 PMCID: PMC3980557 DOI: 10.4103/0974-8237.128529] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Context: Treatment of Hangman's fractures is still controversial. Hangman's fractures Type II and IIA are usually treated with surgical procedures. Aim: This study aims at describing the Neurospinal Academy (NSA) technique as an attempt to achieve an approximation of the fracture line to the axis body, which may be used for Type II and IIA patients with severe displacement and angulation. Settings and Design: NSA technique both pars or pedicle screws are placed bicortically to ensure that anterior surface of C2 vertebral body will be crossed 1-2 mm. A rod is prepared in suitable length and curve to connect the two screws. For placing the rod, sufficient amount of bone is resected from the C2 spinous process. C2 vertebral body is pulled back by means of the screws that crossed the anterior surface of C2 vertebral body. Materials and Methods: Hangman II and IIA patient are treated with NSA technique. Result: Angulated and tilted C2 vertebral body was pulled back and approximated to posterior elements. Conclusions: In Hangman's fractures Type II and IIA with severe vertebral body and pedicle displacement, NSA technique is an effective and reliable treatment alternative for the approximation of posterior elements to the C2 vertebral body, which is tilted, angulated, and dislocated.
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Affiliation(s)
- Sedat Dalbayrak
- Department of Neurosurgery, Neurospinal Academy, Istanbul, Turkey
| | - Onur Yaman
- Clinic of Neurosurgery, Tepecik Education and Training Hospital, Izmir, Turkey
| | - Mesut Yılmaz
- Department of Neurosurgery, Neurospinal Academy, Istanbul, Turkey
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Su BW, Shimer AL, Chinthakunta S, Salloum K, Ames CP, Vaccaro AR, Bucklen B. Comparison of fatigue strength of C2 pedicle screws, C2 pars screws, and a hybrid construct in C1-C2 fixation. Spine (Phila Pa 1976) 2014; 39:E12-9. [PMID: 24108297 DOI: 10.1097/brs.0000000000000063] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A biomechanical study comparing the fatigue strength of different types of C2 fixation in a C1-C2 construct. OBJECTIVE To determine the pullout strength of a C2 pedicle screw and C2 pars screw after cyclical testing and differentiate differences in stiffness pre- and post-cyclical loading of 3 different C1-C2 fixations. SUMMARY OF BACKGROUND DATA Some surgeons use a short C2 pars screw in a C1-C2 construct, because it is less technically demanding and/or when the vertebral artery is high riding. Difference in construct stiffness between use of bilateral C2 pedicle screws, bilateral C2 pars screws, or a hybrid construct is unknown. METHODS Biomechanical testing was performed on 15 specimens. A bicortical C1 lateral mass screw was used in combination with 1 of 3 methods of C2 fixation: (1) bilateral long C2 pedicle screws (LL), (2) bilateral 14-mm C2 pars screws (SS), and (3) unilateral long C2 pedicle screw with a contralateral 14-mm C2 pars screw (LS). Each construct was subject to 16,000 cycles to simulate the immediate postoperative period. Changes in motion in flexion-extension, lateral bending, and axial rotation were calculated. This was followed by pullout testing. RESULTS The ability to limit range of motion significantly decreased after cyclical testing in flexion-extension, lateral bending, and axial rotation for all 3 groups. After loading, the LL and LS groups had less percentage of increase in motion in flexion-extension and lateral bending than the SS group. Overall, the average pullout strength of a pedicle screw was 92% stronger than a pars screw. CONCLUSION C2 pedicle screws have twice the pullout strength of C2 pars screws after cyclical loading. In cases in which the anatomy limits placement of bilateral C2 pedicle screws, a construct using a unilateral C2 pedicle screw with a contralateral short pars screw is a viable option and compares favorably with a bilateral C2 pedicle screw construct. LEVEL OF EVIDENCE N/A.
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Affiliation(s)
- Brian W Su
- *Mt. Tam Orthopedics and Spine Center, Marin General Hospital, Larkspur, CA †University of Virginia, Charlottesville, VA ‡Globus Medical Inc., Audubon, PA §UCSF Department of Neurosurgery, San Francisco, CA; and ¶Thomas Jefferson University, Rothman Institute, Philadelphia, PA
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Ould-Slimane M, Le Pape S, Leroux J, Foulongne E, Damade C, Dujardin F, Duparc F. CT analysis of C2 pedicles morphology and considerations of useful parameters for screwing. Surg Radiol Anat 2013; 36:537-42. [PMID: 24240816 DOI: 10.1007/s00276-013-1233-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 11/01/2013] [Indexed: 10/26/2022]
Abstract
INTRODUCTION Surgery of cervical spine steadily requires realizing posterior osteosynthesis. The anchoring of instrumentation in C2 steadily constitutes an important stake of prognosis. Pedicle screwing is one of the best options and remains associated with a low morbidity. The aim of this CT study is to provide, from a wide population, the descriptive anatomical parameters of C2 pedicles. The data enable this analysis of feasibility of C2 pedicles screwing. MATERIALS AND METHODS A continuous and retrospective series have explored 100 CT scans of the cervical spine without finding C2 fracture. The software OSIRIX v5.0.2 has been used. The dimensions of the pedicles in C2 as length, diameter, and distance from the vertebral foramens have been measured from the preset posterior entry point. Their orientation has been described in the axial and sagittal plan by the pedicle transverse angle, the sagittal angle and the pedicle-lamina angle used as a visible mark during the procedure. At least, the feasibility of pedicle screwing has been evaluated using a diameter criterion higher than 4 mm. RESULTS The dimensions analysis of 200 studied pedicles has found an average length as 26.18 mm, an average diameter as 5.18 mm and an average distance between the entry point and the vertebral foramen as 9.06 mm. Their orientations have an average PTA as 36.6° and a SA as 25.8°. The average of the PLA was 81.3. The screwing feasibility has been evaluated as 92.5 % in the whole series. CONCLUSION These morphological data come from a large series give some help for the C2 pedicle screwing preoperative planning. These lean on 3D measures but also on accessible mark during the procedure and despite the difference of the patient orientation. A CT preoperative planning of the pedicle screwing remains essential because more than 7 % of the pedicles have a diameter lower than 4 mm.
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Affiliation(s)
- Mourad Ould-Slimane
- Orthopaedic and Traumatologic Surgery Department, Rouen University Hospital, 1 Rue de Germont, 76031, Rouen Cedex, France,
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Wu ZH, Zheng Y, Yin QS, Ma XY, Yin YH. Anterior pedicle screw fixation of C2: an anatomic analysis of axis morphology and simulated surgical 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 2013; 23:356-61. [PMID: 24077897 DOI: 10.1007/s00586-013-3042-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 09/16/2013] [Accepted: 09/19/2013] [Indexed: 11/25/2022]
Abstract
STUDY DESIGN Human cadaveric study measuring the morphology of C2 vertebra, description of anterior placement of pedicle screw with post-fixation computed tomography (CT) analysis. OBJECTIVE To assess the potential feasibility and safety anterior placement of C2 pedicle screws. SUMMARY OF BACKGROUND DATA Posterior pedicle screw fixation has become an established technique for upper cervical reconstruction. To our knowledge few reports in the previous literature have described the placement of or anatomy related to anteriorly approach C2 pedicle screws. METHODS The morphology of 60 human C2 vertebrae was measured directly to assess the size, position, and relative approach angle of the pedicles from an anterior perspective. In an additional 20 cadaveric cervical spines, bilateral 3.5 mm titanium C2 pedicle screws were placed and analyzed for pedicle morphology and placement accuracy with thin cut, 1 mm axial CT. RESULTS The mean C2 pedicle width measured directly and by CT scan was 7.8 and 6.6 mm, and the average length of the right and left pedicle was 26.4 and 25 mm, respectively. The mean transverse angle (α) was 17.6° and 21.4°, whereas declination angle (β) anterior to posterior was 13.8° and 10.6°, respectively. CONCLUSIONS Quantitative data regarding C2 pedicle shape and location with respect to the anterior placement of pedicle screws have not been previously reported. This study indicates that anterior placement of 3.5 mm C2 pedicle screws through a transoral approach may be both feasible and safe and also provides an important anatomic analysis that may guide clinical application.
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Feasibility of atlantoaxial pedicle screws' placement in children 6-8 years of age: a cadaveric and tomographic study. J Pediatr Orthop B 2013; 22:399-403. [PMID: 23764758 DOI: 10.1097/bpb.0b013e32835f583e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
The aims of this study were to evaluate the linear and angular dimensions of children's atlantoaxial pedicle using cadavers combined with axial computed tomography (CT) and to examine the feasibility of placing atlantoaxial pedicle screws (3.5 mm diameter) on the vertebrae of children 6-8 years of age. Fourteen cadaveric specimens, ranging in age from 6 to 8 years, were dissected to obtain their atlantoaxial vertebrae. We manually measured 12 linear anatomic parameters related to the atlantoaxial pedicle, its lateral mass, and the posterior arch under the vertebral artery groove. CT axial scanning of the atlantoaxial region was performed on 32 healthy children ranging in age from 6 to 8 years. The length of the atlantoaxial pedicles and the angle between the pedicle axis and the midline of the vertebral body were measured on the atlantoaxial transverse CT imaging. It is feasible to place a 3.5 mm screw in the atlantoaxial pedicle of children ranging in age from 6 to 8 years when the appropriate entry point and trajectory of the screw are chosen.
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Burke LM, Yu WD, Ho A, Wagner T, O'Brien JR. Anatomical feasibility of C-2 pedicle screw fixation: the effect of variable angle interpolation of axial CT scans. J Neurosurg Spine 2013; 18:564-7. [PMID: 23540733 DOI: 10.3171/2013.2.spine12798] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Anatomical variability of the C-2 pedicle poses a challenge for C-2 fixation. The use of multidimensional CT scanning is not widely used but might be an asset to preoperative planning. Careful preoperative planning is imperative for instrumentation at C-2. Fine-cut, noncontrast CT scanning is a useful tool for delineating anatomy; however, the axis of the images is not always along the anatomical axis of the vertebra in question. The authors evaluated the suitability of C-2 pedicles for screw placement by using OsiriX (Pixmeo) software to change the gantry angle of CT angiograms to measure the anatomical dimensions of the C-2 pedicle. METHODS The authors conducted a retrospective review of CT angiograms of the head and neck from 47 trauma patients seen consecutively at George Washington University Hospital. For each patient, 3 independent observers determined length and width of each C-2 pedicle (94 samples) by using OsiriX. OsiriX is a DICOM viewer that enables navigation and visualization in multidimensional imaging, such as 3D imaging, which was used for this study. Sex-specific measurements were also determined. Vertebral anatomy was studied to determine whether aberrant anatomy would preclude pedicle fixation. Statistical analyses were performed. RESULTS Of the 47 patients, 27 were male. Overall mean C-2 pedicle widths and lengths were 8.272 ± 1.364 mm and 27.052 ± 3.471 mm, respectively. The average widths and lengths of the pedicle in female patients were 8.040 ± 1.262 mm and 27.241 ± 2.731 mm, respectively, and those in male patients were 8.444 ± 1.414 mm and 26.913 ± 3.933 mm, respectively. The sex difference was statistically significant for width (p = 0.012) but not for length (p = 0.41). On the basis of width, the percentages of pedicles that could tolerate a 3.5-mm and 4.0-mm screw were 98% and 97%, respectively. Vertebral anatomy precluded screw length greater than 14 mm for only 3 patients. CONCLUSIONS Using multidimensional CT or 3D imaging, the authors found that C-2 pedicles in over 90% of patients could tolerate 3.5-mm and 4.0-mm pedicle screws. Vertebral anatomy precluded use of screw lengths greater than 14 mm for only 3 (6%) of 47 patients. Therefore, the C-2 pedicle might be more tolerant of fixation than previously reported.
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Affiliation(s)
- Lauren M Burke
- Department of Orthopaedic Surgery, George Washington University, Washington, DC, USA
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20
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Elliott RE, Tanweer O, Boah A, Smith ML, Frempong-Boadu A. Comparison of safety and stability of C-2 pars and pedicle screws for atlantoaxial fusion: meta-analysis and review of the literature. J Neurosurg Spine 2012; 17:577-93. [PMID: 23039110 DOI: 10.3171/2012.9.spine111021] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECT Some centers report a lower incidence of vertebral artery (VA) injury with C-2 pars screws compared with pedicle screws without sacrificing construct stability, despite biomechanical studies suggesting greater load failures with C-2 pedicle screws. The authors reviewed published series describing C-2 pars and pedicle screw implantation and atlantoaxial fusions and compared the incidence of VA injury, screw malposition, and successful atlantoaxial fusion with each screw type. METHODS Online databases were searched for English-language articles between 1994 and April of 2011 describing the clinical and radiographic outcomes following posterior atlantoaxial fusion with C-1 lateral mass and either C-2 pars interarticularis or pedicle screws. Thirty-three studies describing 2975 C-2 pedicle screws and 11 studies describing 405 C-2 pars screws met inclusion criteria for the safety analysis. Seven studies describing 113 patients treated with C-2 pars screws and 20 studies describing 918 patients treated with C-2 pedicle screws met inclusion criteria for fusion analysis. Standard and formal meta-analysis techniques were used to compare outcomes. RESULTS All studies provided Class III evidence. Ten instances of VA injury occurred with C-2 pedicle screws (0.3%) and no VA injury occurred with pars screws. The point estimate of VA injury for C-2 pedicle screws was 1.09% (95% CI 0.73%-1.63%) and was similar to that of C-2 pars screws (1.48%, 95% CI 0.62%-3.52%). Similarly, there was no statistically significant difference in the rate of clinically significant screw malpositions (1.14% [95% CI 0.77%-1.69%) vs 1.69% [95% CI 0.73%-3.84%]). Radiographically identified screw malposition occurred in a higher proportion of C-2 pedicle screws compared with C-2 pars screws (6.0% [95% CI 3.7%-9.6%] vs 4.0% [95% CI 2.0%-7.6%], p < 0.0001). Pseudarthrosis occurred in a greater proportion of patients treated with C-2 pars screws (5 [4.4%] of 113) compared with those treated with C-2 pedicle screws (2 [0.22%] of 900). Point estimates with 95% confidence intervals show a slightly higher rate of successful atlantoaxial fusion in the pedicle screw cohort (97.8% [CI 96.0%-98.8%] vs 93.5% [CI 86.6%-97.0%]; p < 0.0001). Q-testing ruled out heterogeneity between the study groups. CONCLUSIONS With a thorough knowledge of axis anatomy, surgeons can place both C-2 pars and C-2 pedicle screws accurately with a small risk of VA injury or clinically significant malposition. There may be subtle trade-off of safety for rigidity when using axial pedicle instead of pars screws, and the decision to use either screw type must be made only after careful review of the preoperative CT imaging and must take into account the surgeon's expertise and the particular demands of the clinical scenario in any given case.
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A clinical morphologic study of the C2 pedicle and isthmus. 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 2012; 22:39-45. [PMID: 22890566 DOI: 10.1007/s00586-012-2417-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 05/15/2012] [Accepted: 06/18/2012] [Indexed: 10/28/2022]
Abstract
PURPOSE This anatomic, radiographic study investigated locational differences in the C2 pedicle and isthmus [pediculoisthmic component (PIC)] and characterized its narrowest section for clinical application in posterior C2 screw fixation. METHODS Structures surrounding the transverse foramina of 30 dry C2s and 10 C3s were compared morphologically. Spinal CT scans of 32 Chinese adults were subjected to volume rendering and multiplanar reconstruction to identify the narrowest C2 PIC, and correlative parameters were measured and analyzed. RESULTS Inferior C2 and C3 structures were morphologically similar. In superior view, the C2 superior facets lay on the transverse foramen and the upper portion between superior and inferior facets was flat (average mediolateral angle, 11.1° ± 2.4°). In inferior view, the posteroinferomedial portion of the C2 transverse foramen displayed a partially tubular structure (average mediolateral angle of projection, 42.6° ± 4.9°). Average height and width were 11.6 and 6.9 mm. The inner medullary cavity was elliptical and the middle site of endosteal diameter was 3.3 ± 1.9 mm. Medial internal cortical bone was significantly thicker than lateral bone (P < 0.01). CONCLUSIONS The PIC is located between superior and inferior C2 facets. The superior flat area is the isthmus and the inferomedial area connecting the inferior facet and vertebral body is the pedicle. The pedicle is partially tubular and projects posteromedially to the transverse foramen. The narrowest PIC section is the narrowest point of the C2 pedicle. Considering its thin lateral cortical bone, medial and superior pedicle screw placement and preoperative CT reconstruction are recommended.
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Abstract
STUDY DESIGN A systematic review of the published literature was conducted specifically looking at studies reporting linear dimension and angular projection data on the anatomy of the cervical pedicle (C1-C7) via radiography or direct measurement. OBJECTIVE This study aimed to report a more accurate set of dimension data and identify differences based on race and gender, increasing the sample size by aggregating similar data of prior studies measuring the cervical pedicle in Asian, European/American, male, and female populations. SUMMARY OF BACKGROUND DATA A wide variation in the reports of the dimensions and projections of the cervical pedicle exist partly due to the uniqueness of this structure as well as the effects of small sample sizes and variable races and genders of sample populations of previous studies. METHODS An extensive literature search was executed, and identified articles were reviewed. A comprehensive database was constructed for synthesis of the identified studies. Subgroups were determined based on the type of population (race, gender, location of study) and radiographic or direct cadaveric measurement. Descriptive statistics were used to analyze and compare these subgroups including: means, standard deviations, and Student t test with the Bonferroni adjustment. RESULTS In total, the current study reports on 33 studies with the measurements of 1311 partial and complete cervical spines. At a 95% confidence interval statistically significant differences between races were found only at C3 and C4 levels in the pedicle axis length. Male-to-female significant differences existed only at the pedicle axis length of C5 in the Asian population, while sex differences existed in the outer pedicle width and height of C3, C4, C5, C6, and C7 in the European/American population. CONCLUSION The current study has found that there is no statistical difference in measuring the cervical pedicle via radiography (CT) or directly. There are more significant differences comparing the cervical pedicles of males and females in the European/American population than exists in the Asian population (specifically in pedicle width and height). There are also significant differences at C3 and C4 cervical pedicle between the Asian and European/American population (specifically in the pedicle axis length and transverse angle).
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Hoh DJ, Liu CY, Wang MY. A radiographic computed tomography–based study to determine the ideal entry point, trajectory, and length for safe fixation using C-2 pars interarticularis screws. J Neurosurg Spine 2010; 12:602-12. [DOI: 10.3171/2009.12.spine09543] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Object
Effective methods for fixation of the axis include C1–2 transarticular and C-2 pedicle screw placement. Both techniques pose a risk of vertebral artery (VA) injury in patients with narrow pedicles or an enlarged, high-riding VA. Pars screws at C-2 avoid the pedicle, but can cause VA injury with excessively long screws. Therefore, the authors evaluated various entry points and trajectories to determine ideal pars screw lengths that avoid breaching the transverse foramen.
Methods
Both pars were studied on 50 CT scans (100 total). Various pars lengths were assessed using 2 entry points and 3 trajectories (6 measurements). Entry point A was the superior one-fourth of the lateral mass. Entry point B was 3-mm rostral to the inferior aspect of the lateral mass. Using entry points A and B, Trajectory 1 was the minimum distance to the transverse foramen; Trajectory 2 was the maximum distance to the transverse foramen; and Trajectory 3 was the steepest angle to the pars/C-2 superior facet junction without transverse foramen breach.
Results
The mean patient age was 46 ± 17 years, and 84% of the CT scans reviewed were obtained in men. There was no significant difference in right or left measurements. Entry point B demonstrated greater pars lengths for each trajectory compared with entry point A (p < 0.0001). For both entry points, Trajectory 3 provided the greatest pars length. Using Trajectory 3 with entry point B, 84, 95, and 99% had a pars length that measured ≥ 18, 16, and 14 mm, respectively. Using Trajectory 3 with Entry point A, only 41, 64, and 87% had a pars length that measured ≥ 18, 16, and 14 mm, respectively.
Conclusions
Using an entry point 3-mm rostral to the inferior edge of the lateral mass and a trajectory directed toward the superior facet/pars junction, 99% of partes interarticularis in this study would tolerate a 14-mm screw without breach of the transverse foramen.
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Affiliation(s)
- Daniel J. Hoh
- 1Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Charles Y. Liu
- 1Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California; and
| | - Michael Y. Wang
- 2Department of Neurological Surgery, Miller School of Medicine, University of Miami, Florida
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Carazzo CA, Guirado VMDP, Meluzzi A, Liberti EA, Dias MRP, Fontes RBDV, Taricco MA. Características morfológicas da pars de C2 de humanos. COLUNA/COLUMNA 2009. [DOI: 10.1590/s1808-18512009000300008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJETIVO: avaliar a morfometria da pars da segunda vértebra cervical, verificar as variações existentes e predizer sua segurança para a colocação de parafusos por meio de uma abordagem cervical posterior. MÉTODOS: 58 vértebras foram obtidas para estudo anatômico (116 pars de C2) e foram medidas a altura e largura da pars, além do comprimento eixo-pedículo, largura e comprimento do pedículo, angulação sagital e medial. Todas as medidas foram separadas quanto aos seus lados direito e esquerdo; foi realizado o cálculo da média, variação, desvio padrão e a médica foi comparada com os estudos prévios. RESULTADOS: a largura média da pars de C2 foi de 9,5 mm; a altura, 9,5 mm; não houve diferença significativa entre os lados esquerdo e direito. O comprimento médio do pedículo foi de 10,5 mm; a medida média encontrada para o comprimento eixo-pedículo foi de 24,9 mm; a largura do pedículo foi de 2,8 mm. A angulação sagital encontrada foi de 19,6º e a horizontal foi de 28,5º. CONCLUSÕES: este estudo demonstra a viabilidade para a colocação de parafuso na pars de C2 em uma população caucasiana, destacando-se, porém, a grande variabilidade anatômica encontrada nas referidas medidas.
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