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Müller JU, Nowak S, Matthes M, Pillich DT, Schroeder HWS, Müller J. Biomechanical comparison of two different compression screws for the treatment of odontoid fractures in human dens axis specimen. Clin Biomech (Bristol, Avon) 2024; 111:106162. [PMID: 38159327 DOI: 10.1016/j.clinbiomech.2023.106162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2023] [Revised: 12/13/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
BACKGROUND Lag screw osteosynthesis for odontoid fractures has a high rate of pseudoarthrosis, especially in elderly patients. Besides biomechanical properties of the different screw types, insufficient fragment compression or unnoticed screw stripping may be the main causing factors for this adverse event. The aim of the study was to compare two screws in clinical use with different design principles in terms of compression force and stability against screw stripping. METHODS Twelve human cadaveric C2 vertebral bodies were considered. Bone density was determined. The specimens were matched according to bone density and randomly assigned to two experimental groups. An odontoid fracture was induced, which were fixed either with a 3.5 mm standard compression screw or with a 5 mm sleeve nut screw. Both screws are certified for the treatment of odontoid fractures. The bone samples were fixed in a measuring device. The screwdriver was driven mechanically. The tests were analyzed for peak interfragmentary compression and screw-in torque with a frequency of 20 Hz. FINDINGS The maximum fragment compression was significantly higher with screw with sleeve nut at 346.13(SD ±72.35) N compared with classic compression screw at 162.68(SD ±114.13) N (p = 0.025). Screw stripping occurred significantly earlier in classic compression screw at 255.5(SD ±192.0)° rotation after reaching maximum compression than in screw with sleeve nut at 1005.2(SD ±341.1)° (p = 0.0039). INTERPRETATION Screw with sleeve nut achieves greater fragment compression and is more robust to screw stripping compared to classic compression screw. Whether the better biomechanical properties lead to a reduction of pseudoarthrosis has to be proven in clinical studies.
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Affiliation(s)
- Jan-Uwe Müller
- Department of Neurosurgery, University Medicine, Greifswald, Germany.
| | - Stephan Nowak
- Department of Neurosurgery, University Medicine, Greifswald, Germany
| | - Marc Matthes
- Department of Neurosurgery, University Medicine, Greifswald, Germany
| | | | | | - Jonas Müller
- Department of Neurosurgery, University Medicine, Greifswald, Germany
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Ai Y, Alemayehu DG, Mao G, Liang Y, Cao R, Hu J, Yang Y, Ren Z. Feasibility of Two-Screw Anterior Fixation for Odontoid Fractures in a Chinese Population: A Morphometric Study Based on Computed Tomography. Clin Orthop Surg 2023; 15:983-988. [PMID: 38045572 PMCID: PMC10689213 DOI: 10.4055/cios23094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 07/03/2023] [Accepted: 07/26/2023] [Indexed: 12/05/2023] Open
Abstract
Background To evaluate the feasibility of treating odontoid fractures in the Chinese population with two cortical screws based on computed tomography (CT) scans and describe a new measurement strategy to guide screw insertion in treating these fractures. Methods A retrospective review of cervical computed tomographic scans of 128 patients (aged 18-76 years; men, 55 [43.0%]) was performed. The minimum external transverse diameter (METD), minimum external anteroposterior diameter (MEAD), maximum screw length (MSL), and screw projection back angle (SPBA) of the odontoid process were measured on coronal and sagittal CT images. Results The mean values of METD and MEAD were 10.0 ± 1.1 mm and 12.0 ± 1.0 mm, respectively, in men and 9.2 ± 1.0 mm and 11.0 ± 1.0 mm, respectively, in women. Both measurements were significantly higher in men (p < 0.001). In total, 87 individuals (68%) had METD > 9.0 mm that could accommodate two 3.5-mm cortical screws. The mean MSL value and SPBA range were 34.4 ± 2.9 mm and 13.5°-24.2°, respectively, with no statistically significant difference between men and women. Conclusions The insertion of two 3.5-mm cortical screws was possible for anterior fixation of odontoid fractures in 87 patients (68%) in our study, and there was a statistically significant difference between men and women.
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Affiliation(s)
- Yixiang Ai
- Department of Orthopedics, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Dereje Gobena Alemayehu
- Department of Orthopedics, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Genwen Mao
- Department of Orthopedics, The Second Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | | | - Ran Cao
- Xi’an Jiaotong University, Xi’an, China
| | - Jiale Hu
- Xi’an Jiaotong University, Xi’an, China
| | - Yimin Yang
- Department of Orthopedics, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
| | - Zhiwei Ren
- Department of Orthopedics, The First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
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Uthman A, Salman B, Shams Aldeen H, Marei H, Al-Bayati SF, Al-Rawi NH. Morphometric analysis of odontoid process among Arab population: a retrospective cone beam CT study. PeerJ 2023; 11:e15411. [PMID: 37250724 PMCID: PMC10215736 DOI: 10.7717/peerj.15411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 04/23/2023] [Indexed: 05/31/2023] Open
Abstract
Objective This study aims to evaluate the feasibility of using cone beam computed tomography (CBCT) scans to assess the odontoid process diameter in the Arab population and to determine whether one or two cortical screws can be used for treating odontoid fractures. Methods The odontoid process of 142 individuals aged 12-75 years, including 72 males (mean age: 35.5) and 70 females (mean age: 36.2), were analyzed using CBCT scans. The sagittal and coronal CBCT views were used to evaluate the antero-posterior (AP) and transverse diameters of the odontoid process. Results Males had substantially bigger transverse and AP diameters of the odontoid process than females (p < 0.05 & P < 0.01 respectively). Among the sample, 97 individuals (67.4%) had external transverse diameter (METD) of less than 9 mm which is slightly bigger than that of Indians and 48 individuals (31.83%) had enough room for two 3.5 mm or two 2.7 mm screws as their METD was more than 9 mm like that of Greek and Turkish. Age had no significant impact on the morphometric measurements of the odontoid process. Conclusion More than sixty percent of the sample had METDs of less than 9 millimeters, indicating that a single 4.5-mm Herbert screw may be suggested for fixing fractured odontoid processes in the Arab population.
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Affiliation(s)
- Asmaa Uthman
- Department of Diagnostic and Surgical Dental Sciences, College of Dental Medicine, Gulf Medical University, Ajman-Al-Jurf, Ajman, United Arab Emirates
| | - Basheer Salman
- Department of Oral and Craniofacial Health Sciences, College of Dental Medicine, Sharjah, United Arab Emirates
| | - Hawraa Shams Aldeen
- Department of Oral and Craniofacial Health Sciences, College of Dental Medicine, Sharjah, United Arab Emirates
| | - Hesham Marei
- Department of Diagnostic and Surgical Dental Sciences, College of Dental Medicine, Gulf Medical University, Ajman-Al-Jurf, Ajman, United Arab Emirates
| | - Sura F. Al-Bayati
- Department of Diagnostic and Surgical Dental Sciences, College of Dental Medicine, Gulf Medical University, Ajman-Al-Jurf, Ajman, United Arab Emirates
| | - Natheer H. Al-Rawi
- Department of Oral and Craniofacial Health Sciences, College of Dental Medicine, Sharjah, United Arab Emirates
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Muacevic A, Adler JR, Chaiyamoon A, Glynn RM, Jenkins S, Graham RA, Johal J, Gardner B, Iwanaga J, Dumont AS, Tubbs RS. Classifications of Odontoid Process Fractures: A Systematic Review and Proposal of a New Simplified Classification System Based on Embryology. Cureus 2022; 14:e32520. [PMID: 36654633 PMCID: PMC9838683 DOI: 10.7759/cureus.32520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2022] [Indexed: 12/15/2022] Open
Abstract
Odontoid fractures are the most common cervical spine fractures in the elderly. Although many classification systems have been developed for them, the ambiguity in various definitions can potentially lead to misunderstandings. This paper aims to review the terminologies and current classification systems of odontoid fractures and propose a new, simplified anatomical classification. Given the descriptive variability of odontoid fractures in current classifications, we systematically reviewed the literature using PRISMA guidelines querying the National Library of Medicine PubMed database. The initial literature search yielded 175 publications. A total of seven reports met the inclusion criteria and were ultimately included for a full review. The classification systems previously used to categorize fractures of the odontoid process often need to be more transparent, imprecise, and incongruous. To simplify them, a new embryologically accurate system is proposed. A new embryological and anatomically-based system, combining the former systems' specific attributes, allows a more straightforward and adaptable classification of odontoid fractures.
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Acharya S, Kumar M, Ghosh JD, Adsul N, Chahal RS, Kalra KL. Morphometric parameters of the odontoid process of C2 vertebrae, in Indian population, a CT evaluation. Surg Neurol Int 2021; 12:494. [PMID: 34754544 PMCID: PMC8571391 DOI: 10.25259/sni_417_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: 04/26/2021] [Accepted: 08/30/2021] [Indexed: 11/29/2022] Open
Abstract
Background: Osteosynthesis of odontoid fractures, especially for type II odontoid fractures, is often achieved by the placement of screws. Here, utilizing CT, we evaluated the normal anatomy of the odontoid process in an Indian population to determine whether one or two screws could be anatomically accommodated to achieve fixation. Methods: CT-based morphometric parameters of the odontoid process were assessed in 200 normal Indian patients (2018–2020). Results: Of 200 patients, 127 were male, and 73 were female. The mean minimum external transverse diameter (METD) was 8.80 mm (range 6.1–11.9 mm). Six (3%) patients had a minimum internal transverse diameter (TD) of >8.0 mm that would allow for the insertion of two 3.5-mm cortical screws without tapping, while 10 (5%) patients had TDs of <7.4 mm; none had diameters of <5.5 mm. The mean length of the implant was 36.45 mm in females and 36.89 mm in males, and the mean angle of screw insertion was 60.34° in females and 60.53° in males. Conclusion: About two-thirds (59%) of the 200 subjects in our study had a METD of <9 mm, indicating the impracticality for introducing second screws for odontoid fixation.
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Affiliation(s)
- Shankar Acharya
- Department of Ortho-Spine Surgery, Sir Ganga Ram Hospital, New Delhi, India
| | - Manoj Kumar
- Department of Ortho-Spine Surgery, Sir Ganga Ram Hospital, New Delhi, India
| | - Jay Deep Ghosh
- Department of Spine Surgery, Apollo Hospital, Guwahati, Assam, India
| | - Nitin Adsul
- Department of Ortho-Spine Surgery, Sir Ganga Ram Hospital, New Delhi, India
| | - R S Chahal
- Department of Ortho-Spine Surgery, Sir Ganga Ram Hospital, New Delhi, India
| | - K L Kalra
- Department of Ortho-Spine Surgery, Sir Ganga Ram Hospital, New Delhi, India
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Moscolo F, Meneghelli P, Boaro A, Impusino A, Locatelli F, Chioffi F, Sala F. The use of Grauer classification in the management of type II odontoid fracture in elderly: Prognostic factors and outcome analysis in a single centre patient series. J Clin Neurosci 2021; 89:26-32. [PMID: 34119278 DOI: 10.1016/j.jocn.2021.04.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 04/08/2021] [Accepted: 04/17/2021] [Indexed: 10/21/2022]
Abstract
OBJECTIVE To evaluate the results of Type II odontoid fractures management in the elderly, according to the Grauer classification. METHODS Consecutive patients with type II odontoid fracture, age > 65 years and follow-up longer than 3 months were included. Fracture management was proposed according to Grauer classification. Peri-surgical risk factors, NDI, VAS and rate of fusion were evaluated according to the treatment modality and compared between conservative and surgical groups. RESULTS Thirty-four patients were considered eligible for the study; 2 patients showed a Type IIa fracture, 30 patients a type IIb, and 2 patients a type IIc. Type IIa patients underwent conservative treatment that resulted in failure. A conservative management was adopted in 9 cases with type IIb due to patient preference or anaesthesiologic reasons with a treatment success at 6 months of 11%. Trans-odontoid stabilization was adopted in 21 type IIb cases with an evidence of bony or fibrous union at 6 months of 95% and a median NDI of 20%. A posterior approach was reserved for 2 type IIc fracture patients and in 6 cases as rescue surgery (bony union at 6 months of 100%; median NDI 37%). Higher Lakshmanan grade, gap and displacement of the fracture were found as significant risk factor for fracture non-union (p < 0.05). CONCLUSIONS The surgical group presented better clinical and radiological outcome and the anterior approach proved to achieve the best results in type IIb fractures. The presence of osteoporosis and fracture spatial features should be duly considered in the decision-making process.
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Affiliation(s)
- Fabio Moscolo
- Institute of Neurosurgery, Department of Neuroscience, Verona University and City Hospital, Verona, Italy
| | - Pietro Meneghelli
- Institute of Neurosurgery, Department of Neuroscience, Verona University and City Hospital, Verona, Italy.
| | - Alessandro Boaro
- Institute of Neurosurgery, Department of Neuroscience, Verona University and City Hospital, Verona, Italy
| | - Antonio Impusino
- Institute of Neurosurgery, Department of Neuroscience, Verona University and City Hospital, Verona, Italy; Division of Neurosurgery, Department of Neuroscience, Trieste University Hospital, Trieste, Italy
| | - Francesca Locatelli
- Unit of Epidemiology and Medical Statistics, Department of Diagnostic and Public Health, University of Verona, Verona, Italy
| | - Franco Chioffi
- Division of Neurosurgery, Department of Neuroscience, Padua University Hospital, Padua, Italy
| | - Francesco Sala
- Institute of Neurosurgery, Department of Neuroscience, Verona University and City Hospital, Verona, Italy
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Müller JU, Müller J, Marx S, Matthes M, Nowak S, Schroeder HWS, Pillich DT. Biomechanical comparison of three different compression screws for treatment of odontoid fractures evaluation of a new screw design. Clin Biomech (Bristol, Avon) 2020; 77:105049. [PMID: 32497928 DOI: 10.1016/j.clinbiomech.2020.105049] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 05/12/2020] [Accepted: 05/15/2020] [Indexed: 02/07/2023]
Abstract
BACKGROUND Lag screw osteosynthesis in odontoid fractures shows a high rate of pseudarthrosis. Biomechanical properties may play a role with insufficient fragment compression or unnoticed screw stripping. A biomechanical comparison of different constructed lag-screws was carried out and the biomechanical properties determined. METHODS Two identical compression screws with different pilot holes (1.25 and 2.5 mm), a double-threaded screw and one sleeve-nut-screw were tested on artificial bone (Sawbone, densities 10-30pcf). Fragment compression and torque were continuously measured using thin-film force sensors (Flexiforce A201, Tekscan) and torque sensors (PCE-TM 80, PCE GmbH). FINDINGS The lowest compression reached the double-threaded screw. Compression and sleeve-nut-screw achieved 214-298% and 325-546%, respectively, of the compression force of double-threaded-screw, depending on the test material. The pilot hole optimization led to a significant improvement in compression only in the densest test material. Screw stripping took place significantly later with increasing density of the test material on all screws. In compression screws this was done at a screw rotation of 180-270°, in sleeve nut screw at 270-720° and in double-threaded screws at 300-600° after reaching the maximum compression. INTERPRETATION Double-threaded screw is robust against screw stripping, but achieves only low fragment compression. The classic compression screws achieve better compression, but are sensitive to screw stripping. Sleeve-nut screw is superior in compression and as robust as double-threaded screw against screw stripping. Whether the better biomechanical properties lead to a reduction in pseudarthrosis must be proven in clinical trials.
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Affiliation(s)
- Jan-Uwe Müller
- Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany.
| | - Jonas Müller
- Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
| | - Sascha Marx
- Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
| | - Marc Matthes
- Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
| | - Stephan Nowak
- Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
| | | | - Dirk Thomas Pillich
- Department of Neurosurgery, University Medicine Greifswald, Greifswald, Germany
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Patil ND, Essam M, Ragab RK, Elsaghir H. Computerized Tomography-Based Morphometric Analysis of Odontoid in 100 Egyptian Patients. Int J Spine Surg 2020; 14:59-65. [PMID: 32128304 DOI: 10.14444/7008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background There is still no consensus in the literature regarding the use of 1 screw or 2 screws. A number of studies have proved ethnic variations in the morphometry of the odontoid. There is no literature on the morphometry of odontoid in Egyptian patients. Methods Computerized tomography (CT) scans of the head and cervical spine of 100 healthy (no evidence of cervical spine fracture) patients of Egyptian origin were studied. Measurements were performed using Horos software, which allowed exact morphometric measurements to be taken at a specific angle in the axial, coronal, and sagittal planes. Results The mean age was 48.57 ± 15.39 years (range, 18-79 years; 56 male and 44 female patients). The mean radiologically calculated screw length and the mean radiologically calculated screw insertion angle were 38.21 ± 2.2 mm and 55.7° ± 3.84°, respectively. The mean anteroposterior and transverse diameter of the odontoid at the waist in the axial cut were 11.02 ± 1.05 mm and 8.92 ± 0.93 mm, respectively. A total of 54% and 6% of the study sample had the transverse waist diameter of the odontoid in the axial cut below 9 mm and 7.4 mm, respectively. A total of 48% of the male and 61% of the female patients had their transverse diameter of the odontoid at the waist below 9 mm. There was a statistically significant difference in all the measurements of the odontoid between the male and female patients except in the anteroposterior diameter of the base of odontoid (P = .06) in the axial cut, and the radiologically calculated screw insertion angle (P = .57). The mean distance between the apex of the odontoid and the screw exit was 1.8 ± 0.75 mm (range, 0-3 mm). Conclusions CT-based morphometric analysis of the odontoid is necessary before using 2-screw fixation technique. Single 4.5-mm Herbert screws could be used in all Egyptian patients without the need for CT-based morphometric analysis of the odontoid. The posterior screw can violate the posterior wall of the odontoid, with a reduced fracture hold and a chance of injuring the thecal sac.
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Affiliation(s)
- Nirmal D Patil
- Department of Spine Surgery, El-Hadra Orthopedic Hospital, Alexandria, Egypt
| | - Mohammad Essam
- Department of Spine Surgery, El-Hadra Orthopedic Hospital, Alexandria, Egypt
| | - Raafat Kamal Ragab
- Department of Spine Surgery, El-Hadra Orthopedic Hospital, Alexandria, Egypt
| | - Hesham Elsaghir
- Department of Spine Surgery, El-Hadra Orthopedic Hospital, Alexandria, Egypt
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Sunar M, Kapakin S. Morphometric Evaluation of Craniocervical Junction by Magnetic Resonance Imaging Method. Asian J Neurosurg 2019; 14:702-709. [PMID: 31497088 PMCID: PMC6703074 DOI: 10.4103/ajns.ajns_293_17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Purpose: Morphometric evaluation of the craniocervical region using magnetic resonance imaging method in humans and determination of the reference values that could be used in various clinics were the aims of this study. Materials and Methods: In our study, 306 (95 males and 211 females) individuals who met the necessary criteria for anatomical structure were included and taken measurements afterward. Sagittal T1- and T2-weighted images were determined as a section thickness of 3 mm, an interval of 10 mm, a matrix of 352 × 224, a field of view of 170–240 mm, and a number of excitations of 4. Measurements of anatomical structures in the craniocervical region were taken via these images. Results: Statistically significant differences were found among the findings of male and female individuals such as height of dens axis, anteroposterior distance of the dens axis (APDDA), anterosuperior distance of the dens axis (ASDDA), sagittal diameter of the foramen magnum (SDFM), total cervical vertebra length (TCVL), distance of spatium retropharyngeum, Pavlov ratio, and the ratio between sagittal diameter of canalis vertebralis (SDCV) to the APDDA. Dens axis height showed a positive correlation with ASDDA and TCVL, and a negative correlation was found between the APDDA and the spatium retropharyngeum. Conclusion: Age- and sex-related changes in the measurements of anatomical regions reveal that an increase and a decrease in the various parameters reveal that these are the normal changes presumably determined by the functional and physical demands varying on the columna vertebralis.
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Affiliation(s)
- Mukadder Sunar
- Department of Anatomy, Faculty of Medicine, Erzincan University, Erzincan, Turkey
| | - Samet Kapakin
- Department of Anatomy, Faculty of Medicine, Atatürk Univesity, Erzurum, Turkey
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Chen D, Chen CH, Tang L, Wang K, Li YZ, Phan K, Wu AM. Three-dimensional reconstructions in spine and screw trajectory simulation on 3D digital images: a step by step approach by using Mimics software. JOURNAL OF SPINE SURGERY 2017; 3:650-656. [PMID: 29354744 DOI: 10.21037/jss.2017.10.09] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
There is a rapidly increasing amount of literature outlining the use of three-dimensional (3D) reconstruction and printing technologies in recent years. However, precise instructive articles which describe step-by-step methods of reconstructing 3D images from computed tomography (CT) or magnetic resonance imaging (MRI) remain limited. To address these issues, this article describes a detailed protocol which will allow the reader to easily perform the 3D reconstruction in their future research, to allow investigation of the appropriate surgical anatomy and allow innovative designs of novel screw fixation techniques or pre-operative surgical planning.
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Affiliation(s)
- Dong Chen
- Department of Spine Surgery, Digital Orthopedic Institute, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Second Medical College of Wenzhou Medical University, Zhejiang Spine Surgery Center, Wenzhou 325027, China
| | - Chun-Hui Chen
- Department of Spine Surgery, Digital Orthopedic Institute, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Second Medical College of Wenzhou Medical University, Zhejiang Spine Surgery Center, Wenzhou 325027, China
| | - Li Tang
- Department of Spine Surgery, Digital Orthopedic Institute, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Second Medical College of Wenzhou Medical University, Zhejiang Spine Surgery Center, Wenzhou 325027, China
| | - Kai Wang
- Department of Spine Surgery, Digital Orthopedic Institute, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Second Medical College of Wenzhou Medical University, Zhejiang Spine Surgery Center, Wenzhou 325027, China
| | - Yu-Zhe Li
- Department of Spine Surgery, Digital Orthopedic Institute, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Second Medical College of Wenzhou Medical University, Zhejiang Spine Surgery Center, Wenzhou 325027, China
| | - Kevin Phan
- NeuroSpine Surgery Research Group (NSURG), Prince of Wales Private Hospital, University of New South Wales, Sydney, Australia
| | - Ai-Min Wu
- Department of Spine Surgery, Digital Orthopedic Institute, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Second Medical College of Wenzhou Medical University, Zhejiang Spine Surgery Center, Wenzhou 325027, China
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11
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Iyer S, Hurlbert RJ, Albert TJ. Management of Odontoid Fractures in the Elderly: A Review of the Literature and an Evidence-Based Treatment Algorithm. Neurosurgery 2017; 82:419-430. [DOI: 10.1093/neuros/nyx546] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/01/2017] [Indexed: 11/12/2022] Open
Abstract
Abstract
Odontoid fractures are the most common fracture of the axis and the most common cervical spine fracture in patients over 65. Despite their frequency, there is considerable ambiguity regarding optimal management strategies for these fractures in the elderly. Poor bone health and medical comorbidities contribute to increased surgical risk in this population; however, nonoperative management is associated with a risk of nonunion or fibrous union. We provide a review of the existing literature and discuss the classification and evaluation of odontoid fractures. The merits of operative vs nonoperative management, fibrous union, and the choice of operative approach in elderly patients are discussed. A treatment algorithm is presented based on the available literature. We believe that type I and type III odontoid fractures can be managed in a collar in most cases. Type II fractures with any additonal risk factors for nonunion (displacement, comminution, etc) should be considered for surgical management. However, the risks of surgery in an elderly population must be carefully considered on a case-by-case basis. In a frail elderly patient, a fibrous nonunion with close follow-up is an acceptable outcome. If operative management is chosen, a posterior approach is should be chosen when fracture- or patient-related factors make an anterior approach challenging. The high levels of morbidity and mortality associated with odontoid fractures should encourage all providers to pursue medical co-management and optimization of bone health following diagnosis.
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Affiliation(s)
- Sravisht Iyer
- Department of Orthopedic Surgery, Hospital for Special Surgery, New York, New York
| | - R John Hurlbert
- Spine Program, Department of Surgery, University of Arizona—College of Medicine, Tuscon, Arizona
| | - Todd J Albert
- Department of Orthopedic Surgery, Hospital for Special Surgery, New York, New York
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12
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Gehweiler D, Wähnert D, Meier N, Spruit M, Raschke MJ, Richards RG, Noser H, Kamer L. Computational anatomy of the dens axis evaluated by quantitative computed tomography: Implications for anterior screw fixation. J Orthop Res 2017; 35:2154-2163. [PMID: 28054384 DOI: 10.1002/jor.23512] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 12/20/2016] [Indexed: 02/04/2023]
Abstract
The surgical fracture fixation of the odontoid process (dens) of the second cervical vertebra (C2/axis) is a challenging procedure, particularly in elderly patients affected by bone loss, and includes screw positioning close to vital structures. The aim of this study was to provide an extended anatomical knowledge of C2, the bone mass distribution and bone loss, and to understand the implications for anterior screw fixation. One hundred and twenty standard clinical quantitative computed tomography (QCT) scans of the intact cervical spine from 60 female and 60 male European patients, aged 18-90 years, were used to compute a three-dimensional statistical model and an averaged bone mass model of C2. Shape and size variability was assessed via principal component analysis (PCA), bone mass distribution by thresholding and via virtual core drilling, and the screw placement via virtual positioning of screw templates. Principal component analysis (PCA) revealed a highly variable anatomy of the dens with size as the predominant variation according to the first principal component (PC) whereas shape changes were primarily described by the remaining PCs. The bone mass distribution demonstrated a characteristic 3D pattern, and remained unchanged in the presence of bone loss. Virtual screw positioning of two 3.5 mm dens screws with a 1 mm safety zone was possible in 81.7% in a standard, parallel position and in additional 15.8% in a twisted position. The approach permitted a more detailed anatomical assessment of the dens axis. Combined with a preoperative QCT it may further improve the diagnostic procedure of odontoid fractures. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2154-2163, 2017.
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Affiliation(s)
- Dominic Gehweiler
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland.,Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Münster, Germany
| | - Dirk Wähnert
- Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Münster, Germany
| | - Norbert Meier
- Department of Clinical Radiology, University Hospital Münster, Münster, Germany
| | - Maarten Spruit
- Department of Orthopedic Surgery, Sint Maartenskliniek, Nijmegen, The Netherlands
| | - Michael Johannes Raschke
- Department of Trauma, Hand and Reconstructive Surgery, University Hospital Münster, Münster, Germany
| | | | - Hansrudi Noser
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
| | - Lukas Kamer
- AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland
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Wu AM, Jin HM, Lin ZK, Chi YL, Wang XY. Percutaneous anterior C1/2 transarticular screw fixation: salvage of failed percutaneous odontoid screw fixation for odontoid fracture. J Orthop Surg Res 2017; 12:141. [PMID: 28962628 PMCID: PMC5622415 DOI: 10.1186/s13018-017-0640-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Accepted: 09/17/2017] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The objective of this study is to investigate the outcomes and safety of using percutaneous anterior C1/2 transarticular screw fixation as a salvage technique for odontoid fracture if percutaneous odontoid screw fixation fails. METHODS Fifteen in 108 odontoid fracture patients (planned to be treated by percutaneous anterior odontoid screw fixation) were failed to introduce satisfactory odontoid screw trajectory. To salvage this problem, we chose the percutaneous anterior C1/2 transarticular screw fixation technique in treatment of these patients. The visual analogue score (VAS) of neck pain and Neck Disability Index (NDI) of all patients were scored at pre-operation, 3 months after operation, and final follow-up. Additional, technique-related complications were recorded and collected. RESULTS Percutaneous C1/2 transarticular screw fixation was performed successfully in all 15 patients whose odontoid screw fixation failed. No technique-related complications (such as nerve injury, spinal cord injury, and esophageal injury) occurred. The VAS of neck pain and NDI score improved significantly (P = 0.000) after operation, and no significant differences were found when compared to 93 non-salvage patients who successfully performed the percutaneous anterior odontoid screw fixation. No screw loose or breakage occurred, all of the odontoid fractures achieve radiographic fusion, bony fusion bridge could be observed at the C1/2 lateral articular facet on 9/15 patients. CONCLUSIONS We suggest that percutaneous anterior C1/2 transarticular screw fixation is a good alternative salvage technique if percutaneous odontoid screw fixation failed, and it is a minimally invasive, feasible, and safe technique.
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Affiliation(s)
- Ai-Min Wu
- Department of Spine Surgery, Zhejiang Spine Surgery Center, Orthopaedic Hospital, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, 109# XueYuan Western Road, Wenzhou, Zhejiang 325027 China
| | - Hai-Ming Jin
- Department of Spine Surgery, Zhejiang Spine Surgery Center, Orthopaedic Hospital, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, 109# XueYuan Western Road, Wenzhou, Zhejiang 325027 China
| | - Zhong-Ke Lin
- Department of Spine Surgery, Zhejiang Spine Surgery Center, Orthopaedic Hospital, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, 109# XueYuan Western Road, Wenzhou, Zhejiang 325027 China
| | - Yong-Long Chi
- Department of Spine Surgery, Zhejiang Spine Surgery Center, Orthopaedic Hospital, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, 109# XueYuan Western Road, Wenzhou, Zhejiang 325027 China
| | - Xiang-Yang Wang
- Department of Spine Surgery, Zhejiang Spine Surgery Center, Orthopaedic Hospital, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, 109# XueYuan Western Road, Wenzhou, Zhejiang 325027 China
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Johal J, Fisahn C, Burgess B, Loukas M, Chapman J, Oskouian RJ, Tubbs RS. The Dens: A Review of its Diverse Nomenclature and a Recommended Simplified Terminology. Cureus 2017; 9:e981. [PMID: 28229029 PMCID: PMC5315575 DOI: 10.7759/cureus.981] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Pathology of the dens, such as fractures, demands precise terminology so that communication between physicians are succinct, diagnoses are accurate, and treatment strategies exact. This review aims to summarize the various terms used to describe the parts of the dens and recommend the ideal terminology. Using standard search engines, English language publications were searched for the many terms used to describe parts of the dens. A multitude of terms was identified with many demonstrating overlaps. Terms identified included apex, tip, apicodental, subdental, dentocentral and odontocentral junctions, peg, waist, base, neck, shaft, shoulder, and stem. Exact terminology is necessary when diagnosing or treating patients with pathology of or near the dens. The authors suggest simplified terminology for describing the parts of the dens that can be used in the future in order to be unequivocal and to avoid confusion when classifying and communicating fractures through its parts.
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Affiliation(s)
- Jaspreet Johal
- Department of Anatomical Sciences, St. George's University School of Medicine, Grenada, West Indies
| | - Christian Fisahn
- Orthopedic Surgery, Swedish Neuroscience Institute ; Department of Trauma Surgery, BG University Hospital Bergmannsheil, Bochum, Germany
| | | | - Marios Loukas
- Department of Anatomical Sciences, St. George's University School of Medicine, Grenada, West Indies
| | - Jens Chapman
- Orthopedics Spine Surgery, Swedish Neuroscience Institute
| | - Rod J Oskouian
- Neurosurgery, Complex Spine, Swedish Neuroscience Institute
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Abstract
STUDY DESIGN Retrospective, cross-sectional study. OBJECTIVE To evaluate the feasibility of two screws anterior fixation of the odontoid process among Arab adults. SUMMARY OF BACKGROUND DATA Anterior screw fixation is the treatment of choice for type II odontoid fractures. In order to perform the procedure safely, the diameter of the odontoid process should be wide enough to allow for the placement of one or two screws. METHODS A retrospective review of 156 computed tomography scans of the cervical spine was done. The included patients were Arabs, adults (at least 18 years old), and had no evidence of upper cervical spine trauma, deformity, infection, tumor, or surgery. The minimum external transverse diameter (METD), minimum internal transverse diameter (MITD), minimum external anteroposterior diameter (MEAD), and minimum internal anteroposterior diameter (MIAD) of the odontoid process were measured. A P value of ≤0.05 was considered as the cutoff level of statistical significance. RESULTS Our study included 94 (60.3%) males and 62 (39.7%) females. The mean age of the subjects was 37.8 ± 16.9 years (range 18-85). The mean values of the METD, MITD, MEAD, and MIAD were 8.7 ± 1.0 mm, 6.0 ± 1.1 mm, 10.3 ± 1.0 mm, and 7.4 ± 1.1 mm, respectively. Men had larger diameters compared to women. This was statistically significant for METD (P = 0.035) and MEAD (P < 0.001). The METD was <9.0 mm in 95 (60.9%) subjects, while the MITD was <8.0 mm in 153 (98.1%) subjects. These findings were not significantly different between males and females. CONCLUSION Two screws anterior fixation of type II odontoid fracture is not feasible among the majority of Arabs. LEVEL OF EVIDENCE 3.
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Wu AM, Wang W, Xu H, Lin ZK, Yang XD, Wang XY, Xu HZ, Chi YL. A novel computed method to reconstruct the bilateral digital interarticular channel of atlas and its use on the anterior upper cervical screw fixation. PeerJ 2016; 4:e1737. [PMID: 26925345 PMCID: PMC4768695 DOI: 10.7717/peerj.1737] [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: 06/19/2015] [Accepted: 02/03/2016] [Indexed: 11/21/2022] Open
Abstract
Purpose. To investigate a novel computed method to reconstruct the bilateral digital interarticular channel of atlas and its potential use on the anterior upper cervical screw fixation. Methods. We have used the reverse engineering software (image-processing software and computer-aided design software) to create the approximate and optimal digital interarticular channel of atlas for 60 participants. Angles of channels, diameters of inscribed circles, long and short axes of ellipses were measured and recorded, and gender-specific analysis was also performed. Results. The channels provided sufficient space for one or two screws, and the parameters of channels are described. While the channels of females were smaller than that of males, no significant difference of angles between males and females were observed. Conclusion. Our study demonstrates the radiological features of approximate digital interarticular channels, optimal digital interarticular channels of atlas, and provides the reference trajectory of anterior transarticular screws and anterior occiput-to-axis screws. Additionally, we provide a protocol that can help make a pre-operative plan for accurate placement of anterior transarticular screws and anterior occiput-to-axis screws.
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Affiliation(s)
- Ai-Min Wu
- Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, The Key Orthopaedic Laboratory of Zhejiang Province , Wenzhou, Zhejiang , China
| | - Wenhai Wang
- Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, The Key Orthopaedic Laboratory of Zhejiang Province , Wenzhou, Zhejiang , China
| | - Hui Xu
- Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, The Key Orthopaedic Laboratory of Zhejiang Province , Wenzhou, Zhejiang , China
| | - Zhong-Ke Lin
- Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, The Key Orthopaedic Laboratory of Zhejiang Province , Wenzhou, Zhejiang , China
| | - Xin-Dong Yang
- Department of Anatomy, Wenzhou Medical University , Wenzhou , China
| | - Xiang-Yang Wang
- Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, The Key Orthopaedic Laboratory of Zhejiang Province , Wenzhou, Zhejiang , China
| | - Hua-Zi Xu
- Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, The Key Orthopaedic Laboratory of Zhejiang Province , Wenzhou, Zhejiang , China
| | - Yong-Long Chi
- Department of Spinal Surgery, Second Affiliated Hospital of Wenzhou Medical University, The Key Orthopaedic Laboratory of Zhejiang Province , Wenzhou, Zhejiang , China
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Amaral CABD, Nakagawa ET, Ferreira LT, Franco JS, Pires RES, Cavallari F, Labronici PJ. ONE OR TWO SCREWS IN THE FRACTURE OF THE ODONTOID PROCESS? EVALUATION USING COMPUTED TOMOGRAPHY. COLUNA/COLUMNA 2015. [DOI: 10.1590/s1808-185120151403147309] [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
Objective:To evaluate the bone area of the odontoid process through computed tomography and its relation with the area of one and two screws in the male and female subjects.Methods:188 CT scans of adults were analyzed. The isthmus area was selected and the transverse diameter was measured at 1.2 mm from the base of odontoid.Results:After placement of a screw, the odontoid area remains with 82% of free bone for both men and women. With two screws, 45.6% of women, had a free bone area of the odontoid process between 50% and 75% and 54.4% were above 75%. 26.6% men had percentage from 50% to 75% of free bone area and 73.4% above 75% (p=0.07). After the placement of two screws, the bone area was, in average, 77.3% in men and 75.4% in women. Using the Student t-test, the differences between the average of percentage of free bone area in men and women are significantly lower in women (p=0.0012).Conclusion:The pre-operative planning through CT can help to choose the number of screws in the odontoid process. The choice should be particularly careful when using two screws in women.
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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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Wu AM, Wang S, Weng WQ, Shao ZX, Yang XD, Wang JS, Xu HZ, Chi YL. The radiological feature of anterior occiput-to-axis screw fixation as it guides the screw trajectory on 3D printed models: a feasibility study on 3D images and 3D printed models. Medicine (Baltimore) 2014; 93:e242. [PMID: 25526447 PMCID: PMC4603117 DOI: 10.1097/md.0000000000000242] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Anterior occiput-to-axis screw fixation is more suitable than a posterior approach for some patients with a history of posterior surgery. The complex osseous anatomy between the occiput and the axis causes a high risk of injury to neurological and vascular structures, and it is important to have an accurate screw trajectory to guide anterior occiput-to-axis screw fixation. Thirty computed tomography (CT) scans of upper cervical spines were obtained for three-dimensional (3D) reconstruction. Cylinders (1.75 mm radius) were drawn to simulate the trajectory of an anterior occiput-to-axis screw. The imitation screw was adjusted to 4 different angles and measured, as were the values of the maximized anteroposterior width and the left-right width of the occiput (C0) to the C1 and C1 to C2 joints. Then, the 3D models were printed, and an angle guide device was used to introduce the screws into the 3D models referring to the angles calculated from the 3D images. We found the screw angle ranged from α1 (left: 4.99±4.59°; right: 4.28±5.45°) to α2 (left: 20.22±3.61°; right: 19.63±4.94°); on the lateral view, the screw angle ranged from β1 (left: 13.13±4.93°; right: 11.82±5.64°) to β2 (left: 34.86±6.00°; right: 35.01±5.77°). No statistically significant difference was found between the data of the left and right sides. On the 3D printed models, all of the anterior occiput-to-axis screws were successfully introduced, and none of them penetrated outside of the cortex; the mean α4 was 12.00±4.11 (left) and 12.25±4.05 (right), and the mean β4 was 23.44±4.21 (left) and 22.75±4.41 (right). No significant difference was found between α4 and β4 on the 3D printed models and α3 and β3 calculated from the 3D digital images of the left and right sides. Aided with the angle guide device, we could achieve an optimal screw trajectory for anterior occiput-to-axis screw fixation on 3D printed C0 to C2 models.
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Affiliation(s)
- Ai-Min Wu
- From the Department of Orthopaedics, Second Affiliated Hospital of Wenzhou Medical University, Zhejiang Spinal Research Center, Wenzhou, Zhejiang, People's Republic of China (A-MW, SW, W-QW, Z-XS, J-SW, H-ZX, Y-LC); and Department of Anatomy, Wenzhou Medical University, Wenzhou, Zhejiang, People's Republic of China (X-DY)
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