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      The dimensions of the posterior arch of C2 for instrumented screw fixation. A radiological study in the Spanish population Translated title: Dimensiones del arco posterior de C2 para el guiado de tornillos translaminares. Estudio radiológico en población española

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          Abstract

          Abstract Background To describe the feasibility of the posterior arch of C2 accepting two crossing screws in the Spanish population. Methods One hundred and fifty patients who underwent a routine neck CT scan for non-cervical pathology were enrolled. Submillimeter slices (thickness 0.7 mm) every 0.4 mm were performed with a 64 multi-detector CT scan, which allows isometric measurements. We measured the length and height of the cortical and cancellous (endomedullar) region of the lamina and the spinous process, inclination, maximal screw length and spinolaminar angle. Results The average (standard deviation) measurements of the lamina were: width of the left cortical 7.2 (1.5) mm, right cortical 6.9 (1.3) mm, width of the cancellous part of the left lamina 4.8 (1.5) mm, right side 4.6 (1.4) mm. The mean left cortical height was 13.0 (1.5) mm and 13.1 (1.6) mm for the right. The mean height of the cancellous part was 9.0 mm for both sides. The average measurements of the spinous process were: cortical length 15.7 (3.5) mm, endomedullar length 12.5 (3.9) mm; cortical height 11.9 (2.2) mm, endomedullar height 8.4 (2.1) mm; spinolaminar angle 49º (4); the maximum screw length 3.18 cm, and the inclination angle 143º. Conclusion A CT scan with submillimeter slices is necessary in order to avoid malpositioning of the screws. The outer cortical measurements are 2 to 4 mm bigger than the endomedullar ones. Taking into account the dimensions of the spinous process, 24% of the population would not be candidates for this crossing screw technique.

          Translated abstract

          Resumen Fundamento Describir la capacidad del arco posterior de C2 en población española para colocar dos tornillos cruzados translaminares. Método Se reclutaron 150 pacientes a los que se les realizó un escáner del cuello por patología no cervical. Para el estudio se utilizó un 64 multi-detector TAC realizando cortes submilimétricos (0,7 mm de grosor) cada 0,4 mm, permitiendo obtener medidas isométricas. Se midieron anchura y altura cortical y endomedular de la lámina y de la espinosa, inclinación de la lámina, máxima longitud de tornillo y ángulo espinolaminar. Resultados Las media (desviación estándar) de las medidas de la lámina fueron: anchura cortical izquierda 7.2 (1,5) mm, cortical derecho 6,9 (1,3) mm, anchura endomedular izquierda 4,8 (1,5) mm, derecha 4,6 (1,4) mm La altura media cortical izquierda fue 13,0 (1,5) mm y de 13,1 (1,6) mm para la derecha. La altura media endomedular fue de 9,0 mm en ambos lados. Las medidas medias de la espinosa fueron: longitud media cortical 15,7 (3,5) mm, longitud endomedular 12,5 (3,9) mm; altura cortical 11,9 (2,2) mm, altura endomedular de 8,4 (2,1) mm; ángulo espinolaminar 49º (4); la longitud máxima de tornillo 3,18 cm; y el ángulo de inclinación 143º. Conclusiones Para evitar la colocación errónea de los tornillos es necesario un estudio de TAC con cortes submilimétricos. La diferencia entre las medidas corticales y endomedulares oscila entre 2 y 4 mm. Teniendo en cuenta las dimensiones de la espinosa, un 24% de la población no sería candidato a esta técnica de tornillos cruzados translaminares.

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          Posterior C2 fixation using bilateral, crossing C2 laminar screws: case series and technical note.

          Rigid screw fixation of the axis, for either atlantoaxial fixation or for incorporation of C2 into subaxial cervical constructs, provides significant stability and excellent long-term fusion results but remains technically demanding due to the danger of injury to the vertebral artery. Anatomic variability of the foramen transversarium in the body of the axis can preclude safe transarticular C1-C2 screw placement in up to 20% of patients. Although more recent methods of C2 screw fixation with pedicle screws allow safer fixation in a higher number of patients, there remains a significant risk to the vertebral artery with C2 pedicle screw placement. The author describes a novel technique of C2 rigid screw fixation using bilateral, crossing C2 laminar screws, not previously reported in the literature, which does not place the vertebral artery at risk during C2 fixation. This technique has been successfully used by the author in cases of craniocervical and atlantoaxial fixation as well as for incorporation of C2 into subaxial fixations. The technique is illustrated, and the author's initial experience in treating 10 patients with crossing, bilateral C2 aminar screws for indications of trauma, neoplasm, pseudarthrosis, and degenerative disease is reviewed. The possible advantages of C2 fixation with C2 laminar screws are discussed.
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            Seven years of experience with C2 translaminar screw fixation: clinical series and review of the literature.

            C2 translaminar screws offer biomechanical stability similar to that of other C2 fixation methods but with minimal risk to neural and vascular structures. To report our experience with the technique since 2002 and to review the pertinent literature to advance the understanding of C2 translaminar screw fixation. Fifty-two consecutive adult patients with disorders requiring axis stabilization were treated with C2 translaminar screws by a single surgeon. All patients underwent preoperative computed tomography scans to confirm the feasibility of screw placement. Patients were followed up with serial flexion/extension radiographs and/or computed tomography scans. The average age in our series was 58.1 years. One hundred three C2 translaminar screws were placed (average length, 28.9 mm). No vascular or neurological injuries occurred. Of 41 patients with sufficient follow-up (average, 13.3 months) to evaluate fusion, 1 instrumentation failure/pseudoarthrosis was observed. Five patients (average age, 78.7 years) died of complications related to medical comorbidities. In the literature, 169 cases of C2 translaminar fixation have been reported, with a fusion rate of 95.3% and no vertebral artery injuries. In biomechanical studies, C2 translaminar screws perform similarly to C2 pedicle screws and may outperform C2 pars screws in intact spine models. With disrupted atlantoaxial ligaments, constructs with C2 translaminar screws may not resist lateral bending as well as those with other screws, although they have more stability than uninstrumented, intact spines. This study reports 103 C2 translaminar screws, the largest single-surgeon series to date. C2 translaminar screws are a technically feasible, low-risk option for C2 fixation, with a 97.6% fusion rate in this series. Copyright © 2011 by the Congress of Neurological Surgeons
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              Anatomic considerations for the placement of C2 laminar screws.

              Cadaveric study.
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                Author and article information

                Journal
                asisna
                Anales del Sistema Sanitario de Navarra
                Anales Sis San Navarra
                Gobierno de Navarra. Departamento de Salud (Pamplona, Navarra, Spain )
                1137-6627
                December 2020
                : 43
                : 3
                : 323-331
                Affiliations
                [2] Pamplona orgnameClínica Universidad de Navarra orgdiv1Orthopedic Surgery and Traumatology Department Spain
                [3] Pamplona orgnameClínica Universidad de Navarra orgdiv1Radiology Department Spain
                [4] Madrid Madrid orgnameUniversidad Autónoma de Madrid orgdiv1School of Medicine orgdiv2Department of Preventive Medicine and Public Health Spain
                [1] Pamplona orgnameComplejo Hospitalario de Navarra orgdiv1Orthopedic Surgery and Traumatology Department Spain
                Article
                S1137-66272020000300004 S1137-6627(20)04300300004
                10.23938/assn.0867
                890c34bb-4366-40e4-a536-6fd1ee806b24

                This work is licensed under a Creative Commons Attribution-NonCommercial 3.0 International License.

                History
                : 06 May 2020
                : 21 September 2019
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 27, Pages: 9
                Product

                SciELO Spain

                Categories
                Original Articles

                TAC multi-detector,Tornillos translaminares,C2 lamina,C2 spinous processes,Atlantoaxial fixation,C2 translaminar screw,Multi-detector CT scan,Lámina C2,Proceso espinoso C2,Fijación atlantoaxial

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