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Publication Metadata only Posterior Rigid Instrumentation of C7: Surgical Considerations and Biomechanics at the Cervicothoracic Junction. A Review of the Literature(ELSEVIER SCIENCE INC, 2018) Bayoumi, Ahmed B.; Efe, Ibrahim E.; Berk, Selim; Kasper, Ekkehard M.; Toktas, Zafer Orkun; Konya, Deniz; Bahcesehir University; Free University of Berlin; Humboldt University of Berlin; Charite Universitatsmedizin Berlin; Harvard University; Harvard University Medical Affiliates; Beth Israel Deaconess Medical Center; Harvard Medical SchoolBACKGROUND: The cervicothoracic junction is a challenging anatomic transition in spine surgery. It is commonly affected by different types of diseases that may significantly impair stability in this region. The seventh cervical vertebra (C7) is an atypical cervical vertebra with unique anatomic features compared to subaxial cervical spine (C3 to C6). C7 has relatively broader laminae, larger pedicles, smaller lateral masses, and a long nonbifid spinous process. These features allow a variety of surgical methods for performing posterior rigid instrumentation in the form of different types of screws, such as lateral mass screws, pedicle screws, transfacet screws, and intralaminar screws. Many biomechanical studies on cadavers have evaluated and compared different types of implants at C7. METHODS: We reviewed PubMed/ Medlineby using specific combinations of keywords to summarize previously published articles that examined C7 posterior rigid instrumentation thoroughly in an experimental fashion on patients or cadavers with additional descriptive radiologic parameters for evaluation of the optimum surgical technique for each type. RESULTS: A total of 44 articles were reported, including 22 articles that discussed anatomic considerations (entry points, sagittal and axial trajectories, and features of screws) and another 22 articles that discussed the relevant biomechanical testing at this transitional region if C7 was directly involved in terms of receiving posterior rigid implants. CONCLUSIONS: C7 can accommodate different types of screws, which can provide additional benefits and risks based on availability of bony purchase, awareness of surgical technique, biomechanics, and anatomic considerations.Publication Metadata only Anterior transpedicular screw fixation of cervical spine: Is it safe? Morphological feasibility, technical properties, and accuracy of manual insertion(American Association of Neurological Surgeons, 2015) Köktekir, Ender; Toktaş, Zafer Orkun; Şeker, Aśkin N.; Akakin, Akin In; Konya, Deniz; Kilic, Turker D.; Köktekir, Ender, Department of Neurosurgery, Selçuk Üniversitesi, Selçuklu, Turkey; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Şeker, Aśkin N., Department of Neurosurgery, Marmara Üniversitesi, Istanbul, Turkey; Akakin, Akin In, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Kilic, Turker D., Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyOBJECT: Due to lack of construct stability of the current anterior cervical approaches, supplemental posterior cervical approaches are frequently employed. The use of an anterior-only approach with anterior transpedicular screws (ATPSs) has been proposed as a means of providing 3-column fixation. This study was designed to investigate the feasibility of anterior transpedicular screw (ATPS) fixation of cervical spine, to obtain the morphological measurements for technical prerequisites, and to evaluate the accuracy of the ATPS using fluoroscopy. METHODS: The study included both radiological and anatomical investigations. The radiological investigations were based on data from cervical spine CT scans performed in 65 patients. Technical prerequisites of ATPS were calculated using OsiriX for Mac OS. In the anatomical part of the study, 30 pedicles (C3-7) from 6 formalin-preserved cadavers were manually instrumented. Measurements obtained included pedicle width (PW), pedicle height (PH), pedicle transverse angle (PTA), distance of the entry point from the midline (DEPM), and distance of the entry point from the superior endplate (DEPSEP). The authors also analyzed screw position in the manually instrumented vertebrae. RESULTS: The mean PW and PH values showed a tendency to increase from C-3 to C-7 in both males and females. The means were significantly larger for both PW and PH in males than in females at all levels (p = 0.001). The overall mean PTA value was significantly lower at C-7 (p < 0.0001). The mean value for the distance of entry point from the midline (DEPM) represented a point at the contralateral side of the pedicle for every level except C-7. The mean DEPSEP values showed significant differences between all levels (p < 0.0001). Seven of the 30 screws were identified as breaching the pedicle (23.3%), these screw malplacements were seen at C-3 (3 screws), C-4 (2 screws), and C-5 (2 screws). CONCLUSIONS: The morphological measurements of this study demonstrated that ATPS fixation is feasible in selected cases. They indicate that ATPS insertion using a fluoroscopy-assisted pedicle axis view is safe at the C-6 and C-7 levels, but the results at the other levels did not prove the safety of this technique. © 2018 Elsevier B.V., All rights reserved.Publication Metadata only Posterior Rigid Instrumentation of C7: Surgical Considerations and Biomechanics at the Cervicothoracic Junction. A Review of the Literature(Elsevier Inc. [email protected], 2018) Bayoumi, Ahmed B.; Efe, Ibrahim Efecan; Berk, Selim; Kasper, Ekkehard Matthias; Toktaş, Zafer Orkun; Konya, Deniz; Bayoumi, Ahmed B., Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Efe, Ibrahim Efecan, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey, Department of Neurosurgery, Charité – Universitätsmedizin Berlin, Berlin, Germany; Berk, Selim, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Kasper, Ekkehard Matthias, Division of Neurosurgery, Harvard Medical School, Boston, United States; Toktaş, Zafer Orkun, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, Turkey; Konya, Deniz, Department of Neurosurgery, Bahçeşehir Üniversitesi, Istanbul, TurkeyBackground: The cervicothoracic junction is a challenging anatomic transition in spine surgery. It is commonly affected by different types of diseases that may significantly impair stability in this region. The seventh cervical vertebra (C7) is an atypical cervical vertebra with unique anatomic features compared to subaxial cervical spine (C3 to C6). C7 has relatively broader laminae, larger pedicles, smaller lateral masses, and a long nonbifid spinous process. These features allow a variety of surgical methods for performing posterior rigid instrumentation in the form of different types of screws, such as lateral mass screws, pedicle screws, transfacet screws, and intralaminar screws. Many biomechanical studies on cadavers have evaluated and compared different types of implants at C7. Methods: We reviewed PubMed/Medline by using specific combinations of keywords to summarize previously published articles that examined C7 posterior rigid instrumentation thoroughly in an experimental fashion on patients or cadavers with additional descriptive radiologic parameters for evaluation of the optimum surgical technique for each type. Results: A total of 44 articles were reported, including 22 articles that discussed anatomic considerations (entry points, sagittal and axial trajectories, and features of screws) and another 22 articles that discussed the relevant biomechanical testing at this transitional region if C7 was directly involved in terms of receiving posterior rigid implants. Conclusions: C7 can accommodate different types of screws, which can provide additional benefits and risks based on availability of bony purchase, awareness of surgical technique, biomechanics, and anatomic considerations. © 2018 Elsevier B.V., All rights reserved.