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Miao XZ, Xu Z, Zhu FK, Hu H, Liu Y, Yang JS, Yan ZJ, Deng ZL, Chu L, Shi L. Unilateral Biplanar Screw-Rod Fixation Technique for the Treatment of Odontoid Fractures in Patients with Atlantoaxial Bone or Vascular Abnormalities. World Neurosurg 2024; 186:e173-e180. [PMID: 38537785 DOI: 10.1016/j.wneu.2024.03.101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Accepted: 03/18/2024] [Indexed: 04/20/2024]
Abstract
OBJETIVE This study aims to introduce the unilateral biplanar screw-rod fixation (UBSF) technique (a hybrid fixation technique: 2 sets of atlantoaxial screws were placed on the same side), which serves as a salvage method for traditional posterior atlantoaxial fixation. To summarize the indications of this technique and to assess its safety, feasibility, and clinical effectiveness in the treatment of odontoid fractures. METHODS Patients with odontoid fractures were enrolled according to special criteria. Surgical duration and intraoperative blood loss were documented. Patients were followed up for a minimum of 12 months. X-ray and computerized tomography scans were conducted and reviewed at 1 day, and patients were asked to return for computerized tomography reviews at 3, 6, 9, and 12 months after surgery until fracture union. Recorded and compared the Neck Visual Analog Scale and Neck Disability Index presurgery and at 1 week and 12 months postsurgery. RESULTS Between January 2016 and December 2022, our study enrolled 7 patients who were diagnosed with odontoid fractures accompanied by atlantoaxial bone or vascular abnormalities. All 7 patients underwent successful UBSF surgery, and no neurovascular injuries were recorded during surgery. Fracture union was observed in all patients, and the Neck Visual Analog Scale and Neck Disability Index scores improved significantly at 1 week and 12 months postoperative (P < 0.01). CONCLUSIONS The UBSF technique has been demonstrated to be safe, feasible, and effective in treating odontoid fractures. In cases where the atlantoaxial bone or vascular structure exhibits abnormalities, it can function as a supplementary or alternative approach to the conventional posterior C1-2 fixation.
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Affiliation(s)
- Xi-Zi Miao
- Department of Orthopaedics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Zhou Xu
- Department of Orthopaedics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China; Department of Orthopaedics, The Ninth People's hospital of Chongqing, Chongqing, China
| | - Fu-Kuan Zhu
- Department of Orthopaedics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Hao Hu
- Department of Orthopaedics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Yu Liu
- Chongqing Medical and Pharmaceutical College, Chongqing, China
| | - Jun-Song Yang
- Department of Orthopaedics, Hong Hui Hospital of Xi'an, Xi'an, China
| | - Zheng-Jian Yan
- Department of Orthopaedics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China; Geriatric Clinical Research Center of Chongqing, Chongqing, China
| | - Zhong-Liang Deng
- Department of Orthopaedics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China; Geriatric Clinical Research Center of Chongqing, Chongqing, China
| | - Lei Chu
- Department of Orthopaedics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China; Geriatric Clinical Research Center of Chongqing, Chongqing, China
| | - Lei Shi
- Department of Orthopaedics, The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China; Geriatric Clinical Research Center of Chongqing, Chongqing, China.
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Ma Z, Zhang YN, Ma X, Chen C, Feng HY. Comparison of the clinical efficacy of unilateral and bilateral pedicle screw short-segment fixation and fusion in the treatment of atlantoaxial fracture-dislocation. Technol Health Care 2023; 31:1619-1629. [PMID: 36970926 PMCID: PMC10578255 DOI: 10.3233/thc-220721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 01/16/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Few studies have compared the clinical efficacy of unilateral and bilateral pedicle screw fixation and fusion in treating atlantoaxial fracture-dislocation. OBJECTIVE To compare the efficacy of unilateral and bilateral fixation and fusion for atlantoaxial fracture-dislocation and to explore the feasibility of the unilateral surgical procedure. METHODS Twenty-eight consecutive patients with atlantoaxial fracture-dislocation were included in the study from June 2013 to May 2018. They were divided into a unilateral fixation group and a bilateral fixation group (14 patients in each group with an average age of 43.6 ± 16.3 years and 51.8 ± 15.4 years, respectively). The unilateral group had a unilateral anatomical variation of the pedicle or vertebral artery, or traumatic pedicle destruction. All patients underwent atlantoaxial unilateral or bilateral pedicle screw fixation and fusion. Intraoperative blood loss and operation time were recorded. The visual analog scale (VAS) and Japanese Orthopedic Association (JOA) scoring systems were used to evaluate pre- and postoperative occipital-neck pain and neurological function. X-ray and computerized tomography (CT) were used to assess atlantoaxial stability, the implants' position, and bone graft fusion. RESULTS All patients were followed up for 39-71 months postoperatively. Intraoperatively, no spinal cord or vertebral artery injury was observed. At the last follow-up, occipital-neck pain and neurological function in the two groups were significantly improved (P< 0.05). The X-ray films and CT showed satisfactory atlantoaxial stability, implant position, and osseous fusion in all the patients at 6 months postoperatively. CONCLUSION Unilateral and bilateral pedicle screw fixation and fusion can restore atlantoaxial stability and improve occipital-neck pain and neurological function in patients with atlantoaxial fracture-dislocation. The unilateral surgical procedure can be a supplementary option for patients with unilateral abnormal atlantoaxial lesions.
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Affiliation(s)
- Zhuo Ma
- Department of Orthopedic Surgery, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, The Third Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Yan-Nan Zhang
- Department of Orthopedic Surgery, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, The Third Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Xun Ma
- Department of Orthopedic Surgery, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, The Third Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Chen Chen
- Department of Orthopedic Surgery, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, The Third Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
| | - Hao-Yu Feng
- Department of Orthopedic Surgery, Shanxi Bethune Hospital, Shanxi Academy of Medical Sciences, Tongji Shanxi Hospital, The Third Hospital of Shanxi Medical University, Taiyuan, Shanxi, China
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The morphological classification and clinical significance of atlas vertebral artery sulcus based on computed tomography three-dimensional reconstruction. Surg Radiol Anat 2023; 45:241-246. [PMID: 36715709 PMCID: PMC9981493 DOI: 10.1007/s00276-023-03079-x] [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: 07/13/2022] [Accepted: 01/06/2023] [Indexed: 01/31/2023]
Abstract
OBJECTIVE The purpose of this study was to research the morphological classification and clinical significance of vertebral artery sulcus on atlas based on CT three-dimensional reconstruction. METHODS Three-dimensional reconstruction images of 300 adult atlases were collected. A total of 600 atlas vertebral artery sulci were selected in this study. The parameters required for placement of C1 pedicle screw, including depth of grinding drilling (ao), width (cd), length ab), height (H), lateral wall thickness (L1), inner wall thickness (L2), medial angle (∠α), and the cephalad angle to the transverse plane of atlas pedicle (∠β), were measured. RESULTS CT three-dimensional reconstruction images showed that there were five types of atlas vertebral artery sulci: no process type (n = 494 cases, 82.33%), upper process type (n = 29, 4.83%), lower process type (n = 25, 4.17%), double process type (n = 19, 3.17%), and posterior ring type (33, 5.50%). One-way ANOVA tests showed that the five groups differed significantly in the parameter of ao, L2, H, ∠α and ∠β. One-way ANOVA with the LSD post hoc tests showed that the parameter ao of the group of no process type was less than that of the group of upper or lower process type (P < 0.05), and ao of the group of lower process or posterior ring type was less than that of the group of the upper type (P < 0.05). The parameter of ao of the male group was larger than that of the female group. CONCLUSION No process type of the atlas vertebral artery sulcus was the most common, and the medial angle and cephalad angle of the atlas pedicle in this type were the smallest. When pedicle screws are inserted, the above two angles should not be too large. Male's ao was larger than that of female's. All these findings should be considered to avoid the deviation of the nail track.
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Vakharia VN, Smith L, Tahir Z, Sparks R, Ourselin S, Tucker S, Thompson D. Occipitocervical instrumented fixation utilising patient-specific C2 3D-printed spinal screw trajectory guides in complex paediatric skeletal dysplasia. Childs Nerv Syst 2021; 37:2643-2650. [PMID: 34148128 DOI: 10.1007/s00381-021-05260-2] [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: 05/11/2021] [Accepted: 06/09/2021] [Indexed: 10/21/2022]
Abstract
PURPOSE Instability of the craniocervical junction in paediatric patients with skeletal dysplasia poses a unique set of challenges including anatomical abnormalities, poor bone quality, skeletal immaturity and associated general anaesthetic risks. Instrumented fixation provides optimal stabilisation and fusion rates. The small vertebrae make the placement of C2 pedicle screws technically demanding with low margins of error between the spinal canal and the vertebral artery. METHODS We describe a novel clinical strategy utilising 3D-printed spinal screw trajectory guides (3D-SSTG) for individually planned C2 pedicle and laminar screws. The technique is based on a pre-operative CT scan and does not require intraoperative CT imaging. This reduces the radiation burden to the patient and forgoes the associated time and cost. The time for model generation and sterilisation was < 24 h. RESULTS We describe two patients (3 and 6 years old) requiring occipitocervical instrumented fixation for cervical myelopathy secondary to Morquio syndrome with 3D-SSTGs. In the second case, bilateral laminar screw trajectories were also incorporated into the same guide due to the presence of high-riding vertebral arteries. Registration of the postoperative CT to the pre-operative imaging revealed that screws were optimally placed and accurately followed the predefined trajectory. CONCLUSION To our knowledge, we present the first clinical report of 3D-printed spinal screw trajectory guides at the craniocervical junction in paediatric patients with skeletal dysplasia. The novel combination of multiple trajectories within the same guide provides the intraoperative flexibility of potential bailout options. Future studies will better define the potential of this technology to optimise personalised non-standard screw trajectories.
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Affiliation(s)
- Vejay N Vakharia
- Department of Neurosurgery, Great Ormond Street Hospital, UCL Great Ormond Street Institute of Child Health, London, UK. .,Department of Neurosurgery, National Hospital for Neurology and Neurosurgery, UCL Institute of Neurology, Queen Square, London, WC1N 3BG, UK.
| | - Luke Smith
- Department of Neurosurgery, Great Ormond Street Hospital, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Zubair Tahir
- Department of Neurosurgery, Great Ormond Street Hospital, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Rachel Sparks
- School of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, King's College London, London, UK
| | - Sebastien Ourselin
- School of Biomedical Engineering and Imaging Sciences, St Thomas' Hospital, King's College London, London, UK
| | - Stewart Tucker
- Department of Neurosurgery, Great Ormond Street Hospital, UCL Great Ormond Street Institute of Child Health, London, UK
| | - Dominic Thompson
- Department of Neurosurgery, Great Ormond Street Hospital, UCL Great Ormond Street Institute of Child Health, London, UK
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Qiu F, Xu X, Ma X, Jiang W, Liu G, Fang Z, Lin Z. [Biomechanical stability evaluation of the fixation technique for crossed rods consisting of occipital plate and C 2 bilateral lamina screws]. ZHONGGUO XIU FU CHONG JIAN WAI KE ZA ZHI = ZHONGGUO XIUFU CHONGJIAN WAIKE ZAZHI = CHINESE JOURNAL OF REPARATIVE AND RECONSTRUCTIVE SURGERY 2020; 34:1545-1549. [PMID: 33319533 DOI: 10.7507/1002-1892.202005029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Objective To evaluate the stability of the fixation technique for the crossed rods consisting of occipital plate and C 2 bilateral lamina screws by biomechanical test. Methods Six fresh cervical specimens were harvested and established an atlantoaxial instability model. The models were fixed with parallel rods and crossed rods after occipital plate and C 2 bilateral laminae screws were implanted. The specimens were tested in the following sequence: atlantoaxial instability model (unstable model group), under parallel rods fixation (parallel fixation group), and under crossed rods fixation (cross fixation group). The range of motion (ROM) of the C 0-2 segments were measured in flexion-extension, left/right lateral bending, and left/right axial rotation. After the test, X-ray film was taken to observe the internal fixator position. Results The biomechanical test results showed that the ROMs in flexion-extension, left/right lateral bending, and left/right axial rotation were significantly lower in the cross fixation group and the parallel fixation group than in the unstable model group ( P<0.05). There was no significant difference between the cross fixation group and the parallel fixation group in flexion-extension and left/right lateral bending ( P>0.05). In the left/right axial rotation, the ROMs of the cross fixation group were significantly lower than those of the parallel fixation group ( P<0.05). After the test, the X-ray film showed the good internal fixator position. Conclusion The axial rotational stability of occipitocervical fusion can be further improved by crossed rods fixation when the occipital plate and C 2 bilateral lamina screws are used.
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Affiliation(s)
- Feng Qiu
- Department of Orthopaedics, Puning Overseas Chinese Hospital, Puning Guangdong, 515300, P.R.China
| | - Xilin Xu
- Department of Orthopaedics, Puning Overseas Chinese Hospital, Puning Guangdong, 515300, P.R.China
| | - Xiangyang Ma
- Department of Spinal Surgery, Orthopaedics Hospital, General Hospital of Southern Theatre Command, Guangzhou Guangdong, 510010, P.R.China
| | - Weicheng Jiang
- Department of Orthopaedics, Puning Overseas Chinese Hospital, Puning Guangdong, 515300, P.R.China
| | - Gengchao Liu
- Department of Orthopaedics, Puning Overseas Chinese Hospital, Puning Guangdong, 515300, P.R.China
| | - Zhouqun Fang
- Department of Orthopaedics, Puning Overseas Chinese Hospital, Puning Guangdong, 515300, P.R.China
| | - Zejiang Lin
- Department of Orthopaedics, Puning Overseas Chinese Hospital, Puning Guangdong, 515300, P.R.China
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Qiu F, Zou XB, Xu XL, Jiang WC, Liu GC, Ma XY. A biomechanical comparison of crossed and parallel rod configurations in atlantoaxial internal 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 2020; 30:576-584. [PMID: 33180193 DOI: 10.1007/s00586-020-06655-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 08/10/2020] [Accepted: 10/30/2020] [Indexed: 11/26/2022]
Abstract
BACKGROUND Posterior atlantoaxial fixation with screw rod forms an approximate "II" shape or "H" increasing transverse link for better stability. In order to improve stability and in consideration of difficult placement of transverse connecting rod, possibility of inadequate bone graft, some scholars have preliminarily researched biomechanics of a novel crossed rod as an approximate "X" configuration of screw rod. PURPOSE The aim of this study was to evaluate and compare the biomechanics of the crossed and parallel rod configurations in the screw rod system for posterior atlantoaxial fixation on a cadaveric model. METHODS Six fresh cervical specimens were used to complete the range of motion (ROM) testing by applying pure moments of ± 2.0 nm. Following intact state and under destabilization testing, screws were implanted. The specimens were then tested in the following sequence: Group BLS + PR (C2 bilateral laminar screws + parallel rod), Group BLS + CR (C2 bilateral laminar screws + crossed rod), LPRLS + PR (C2 left pedicle screw and right laminar screw + parallel rod), LPRLS + CR (C2 left pedicle screw and right laminar screw + crossed rod), BPS + PR (C2 bilateral pedicle screws + parallel rod) and BPS + CR (C2 bilateral pedicle screws + crossed rod). The ROM of the C1-2 segments was measured in flexion-extension, lateral bending and axial rotation. Six surgical constructs were compared between the groups and with intact condition, respectively. RESULTS The six fixed modes significantly increased stability compared with both the intact and destabilization group in flexion-extension, lateral bending and axial rotation (p < .05). In extension, BPS + CR and BLS + CR showed greater stability than BLS + PR (p < .05). During flexion, the six fixation methods showed no statistical significance (p > .05). In left lateral bending, stability of the other five screw rod fixation techniques significantly increased when compared with BLS + PR (p < .05). In the right lateral bending direction, the stability of BLS + PR was worse than that of BPS + CR and BPS + PR (p < .05). In the left axial rotation, stability of BLS + CR, LPRLS + CR and BPS + CR was greater than that of BLS + PR, LPRLS + PR and BPS + PR (p < .05). In the right axial rotation, the stability of BPS + CR and BLS + CR was greater than that of BLS + PR (p < .05). CONCLUSION The six investigated fixation methods provide sufficient biomechanical stability. The crossed rod configuration can further enhance the axial rotation stability of the screw rod system, which consists of C1 bilateral pedicle and C2 pedicle, or C2 lamina screws. The crossed rod can also improve the stability of the screw rod system made up of C1 bilateral pedicle and C2 lamina screws in lateral bending and extension. The crossed rod configuration is reliable and provides superior stability for clinical application.
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Affiliation(s)
- Feng Qiu
- Department of Orthopaedic, Puning Overseas Chinese Hospital, 515300, Puning, Jieyang, Guangdong, People's Republic of China
| | - Xiao-Bao Zou
- The First School of Clinical Medicine, Southern Medical University, No.1838 North of Guangzhou Road, 510515, Guangzhou, People's Republic of China
| | - Xi-Lin Xu
- Department of Orthopaedic, Puning Overseas Chinese Hospital, 515300, Puning, Jieyang, Guangdong, People's Republic of China
| | - Wei-Cheng Jiang
- Department of Orthopaedic, Puning Overseas Chinese Hospital, 515300, Puning, Jieyang, Guangdong, People's Republic of China
| | - Geng-Chao Liu
- Department of Orthopaedic, Puning Overseas Chinese Hospital, 515300, Puning, Jieyang, Guangdong, People's Republic of China
| | - Xiang-Yang Ma
- Department of Orthopedics, General Hospital of Southern Theatre Command of PLA, 111 Liuhua Road, 510010, Guangzhou, People's Republic of China.
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Chan AKH, Yusof MI, Abdullah MS. Computed Tomographic Morphometric Analysis of C1 and C2 for Lamina Cross Screw Placement in Malay Ethnicity. Asian Spine J 2020; 15:1-8. [PMID: 32252193 PMCID: PMC7904487 DOI: 10.31616/asj.2019.0242] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 11/02/2019] [Indexed: 12/04/2022] Open
Abstract
Study Design This is an observational study of computed tomography (CT) data. Purpose The C1 and C2 laminas in the Malaysian Malay population were analyzed for the feasibility of fitting 3.5-mm laminar screws in a cross configuration. Overview of Literature Morphometric analysis of the C1 and C2 laminas has been performed for various populations but not for the Malaysian Malay population. Methods A total of 330 CT cervical images were measured to establish the bicortical diameter of the C1 and C2 laminas as well as their height and length. The C1 posterior tubercle bicortical diameter and height were also determined from these images. All parameters were measured up to 0.1 mm, and statistical analysis was performed using IBM SPSS Statistics ver. 24.0 (IBM Corp., Armonk, NY, USA). An independent t -test and the Pearson chi-square test were used to determine the mean difference and screw acceptance. Results The means of the C1 lamina measurements were 5.79±1.19 mm in diameter, 9.76±1.51 mm in height, and 20.70±1.86 mm in length. The means of the measurements of the posterior tubercle were 7.20±1.88 mm in diameter and 10.51±1.68 mm in height. The means of the C2 lamina measurements were 5.74±1.31 mm in diameter, 11.76±1.69 mm in height, and 24.96±2.56 mm in length. Overall 65.5% of C1 and 80.3% of C2 laminas are able to accept 3.5-mm screws in a cross configuration. Screw acceptability is similar between the right and left sides (p>0.05). However, males have a higher screw acceptability compared with females (p<0.05), except for the C2 left lamina. Conclusions It is feasible to insert a 3.5-mm screw in a cross configuration in the C1 and C2 laminas of the Malaysian Malay population, especially in males. However, a CT scan should be performed prior to the operation to determine screw acceptability and to estimate screw sizes.
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Affiliation(s)
- Allan Kah Hay Chan
- Department of Orthopaedics, Hospital Universiti Sains Malaysia, Kota Bharu, Malaysia
| | - Mohd Imran Yusof
- Department of Orthopaedics, Hospital Universiti Sains Malaysia, Kota Bharu, Malaysia
| | - Mohd Shafie Abdullah
- Department of Radiology, Hospital Universiti Sains Malaysia, Kota Bharu, Malaysia
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Sangondimath G, Mallepally AR, Salimath S. Computed Tomography-Based Feasibility Study of C1 Posterior Arch Crisscrossing Screw Fixation. Asian Spine J 2020; 14:298-304. [PMID: 31906612 PMCID: PMC7280928 DOI: 10.31616/asj.2019.0199] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 08/19/2019] [Indexed: 12/02/2022] Open
Abstract
Study Design Retrospective radiographic analysis. Purpose Posterior fixation of C1 using screws is the most popular technique among the various methods for C1 stabilization, but it places the surrounding neurovascular structures at risk. Approximately 20% of the population has an anomalous groove for the vertebral artery; therefore, salvage methods are necessary. Therefore, we analyzed the feasibility of a newer C1 posterior arch crisscrossing screw fixation technique and studied its feasibility in the Indian population on the basis of the anatomy of the C1 posterior arch. Overview of Literature Multiple techniques have been described for C1–C2 fixation, such as wiring techniques, interlaminar clamps, transarticular screws, screw-plate/screw-rod system fixation, and hook-screw system fixation techniques, to provide rigid C1–C2 stability. However, although C1 fixation has evolved with time, it is not complication-free. Methods A 100 computed tomography (CT) scans of cervical spines with 1 mm slice thickness in the axial and sagittal sections obtained were randomly selected for the evaluation. Atlantoaxial anomalies due to trauma, deformities, infections, and tumors were excluded. All the images were measured for height of the posterior tubercle, width of the posterior arch, and length of the screw, and the screw projection angle was calculated. Demographic data were collected for all the subjects. Results Out of the 88 CT scans analyzed, the mean height of the posterior tubercle was 7.4 mm, wherein 84.09% exceeded 7 mm, and the width of the posterior tubercle was 5.4 mm, wherein 88.6% (n=78) had posterior arch width >3.5 mm. A total of 13.6% (n=12) vertebrae were not suitable for screw placement, whereas 75% (n=66) vertebrae could accommodate 3.5×15 mm or longer screws. The screw projection angles ranged from 11.2° to 35° on the right and from 15.6° to 38.2° on the left. Conclusions C1 posterior arch screw fixation is a feasible and safe method because it poses little risk of injury to the surrounding neurovascular structures.
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Affiliation(s)
| | | | - Suman Salimath
- Department of Spine Services, Indian Spinal Injuries Centre, New Delhi, India
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Cadena G, Duong HT, Liu JJ, Kim KD. Atlantoaxial fixation using C1 posterior arch screws: feasibility study, morphometric data, and biomechanical analysis. J Neurosurg Spine 2019; 30:314-322. [DOI: 10.3171/2018.8.spine18160] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 08/15/2018] [Indexed: 01/15/2023]
Abstract
OBJECTIVEC1–2 is a highly mobile complex that presents unique surgical challenges to achieving biomechanical rigidity and fusion. Posterior wiring methods have been largely replaced with segmental constructs using the C1 lateral mass, C1 pedicle, C2 pars, and C2 pedicle. Modifications to reduce surgical morbidity led to the development of C2 laminar screws. The C1 posterior arch has been utilized mostly as a salvage technique, but recent data indicate that this method provides significant rigidity in flexion-extension and axial rotation. The authors performed biomechanical testing of a C1 posterior arch screw (PAS)/C2 pars screw construct, collected morphometric data from a population of 150 CT scans, and performed a feasibility study of a freehand C1 PAS technique in 45 cadaveric specimens.METHODSCervical spine CT scans from 150 patients were analyzed to determine the average C1 posterior tubercle thickness and size of C1 posterior arches. Eight cadavers were used to compare biomechanical stability of intact specimens, C1 lateral mass/C2 pars screw, and C1 PAS/C2 pars screw constructs. Paired comparisons were made using repeated-measures ANOVA and Holm-Sidak tests. Forty-five cadaveric specimens were used to demonstrate the feasibility and safety of the C1 PAS freehand technique.RESULTSMorphometric data showed the average craniocaudal thickness of the C1 posterior tubercle was 12.3 ± 1.94 mm. Eight percent (12/150) of cases showed thin posterior tubercles or midline defects. Average posterior arch thickness was 6.1 ± 1.1 mm and right and left average posterior arch length was 28.7 mm ± 2.53 mm and 28.9 ± 2.29 mm, respectively. Biomechanical testing demonstrated C1 lateral mass/C2 pars and C1 PAS/C2 pars constructs significantly reduced motion in flexion-extension and axial rotation compared with intact specimens (p < 0.05). The C1 lateral mass/C2 pars screw construct provided significant rigidity in lateral bending (p < 0.05). There was no statistically significant difference between the two constructs in flexion-extension, lateral bending, or axial rotation. Of the C1 posterior arches, 91.3% were successfully cannulated using a freehand technique with a low incidence of cortical breach (4.4%).CONCLUSIONSThis biomechanical analysis indicates equivalent stability of the C1 PAS/C2 pars screw construct compared with a traditional C1 lateral mass/C2 pars screw construct. Both provide significant rigidity in flexion-extension and axial rotation. Feasibility testing in 45 cadaveric specimens indicates a high degree of accuracy with low incidence of cortical breach. These findings are supported by a separate radiographic morphometric analysis.
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Affiliation(s)
- Gilbert Cadena
- 1Department of Neurological Surgery, University of California, Irvine, Orange, California
| | - Huy T. Duong
- 2Department of Neurosurgery, Kaiser Foundation Medical Center, Sacramento, California
| | - Jonathan J. Liu
- 3Department of Neurosurgery, Advocate Lutheran General Hospital, Park Ridge, Illinois; and
| | - Kee D. Kim
- 4Department of Neurological Surgery, University of California, Davis, Sacramento, California
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Shi L, Shen K, Chu L, Yu KX, Yu QS, Deng R, Deng ZL. Biomechanical Study of Novel Unilateral Fixation Combining Unilateral Pedicle and Contralateral Translaminar Screws in the Subaxial Cervical Spine. World Neurosurg 2019; 121:e684-e690. [DOI: 10.1016/j.wneu.2018.09.191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2018] [Revised: 09/24/2018] [Accepted: 09/25/2018] [Indexed: 11/27/2022]
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Novel unilateral C1 double screw and ipsilateral C2 pedicle screw placement combined with contralateral laminar screw-rod fixation for atlantoaxial instability. 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 2018; 28:362-369. [PMID: 30539243 DOI: 10.1007/s00586-018-5853-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 12/06/2018] [Indexed: 10/27/2022]
Abstract
PURPOSE To investigate the anatomical and biomechanical feasibility of the unilateral C1 double screw [pedicle screw (PS) + lateral mass screw (LMS)] and ipsilateral C2 PS combined with contralateral C2 laminar screw (LS)-rod fixation for atlantoaxial instability by comparison with traditional posterior fixation methods. METHODS Fifteen sets of complete dry bony specimens of atlas were used for morphometric analysis. The working length, width and thickness of the C1 PSs and LMSs were manually measured. Ten fresh-frozen cervical spines (C0-C7) were used to complete the range of motion (ROM) testing in their intact condition, under destabilization and after stabilization by the following procedures: unilateral C1-C2 PS rod fixation (Group A), bilateral C1-C2 PS rod fixation (Group B), and unilateral C1 double screw and ipsilateral C2 PS combined with contralateral C2 LS rod fixation (Group C). RESULTS The working thickness of the C1 PS was ≤ 3.5 mm in only one (1/15 = 6.7%) specimen. The other parameters were > 3.5 mm in all specimens. In the ROM test, all fixation groups showed significantly reduced flexibility in all directions compared with both the intact and destabilization groups. Further, Groups B and C showed better stability in all directions than Group A. However, no significant differences were observed between Groups B and C. CONCLUSION The C1 unilateral lateral mass could mostly contain two screws(PS + LMS) with diameters ≤ 3.5 mm. The novel technique of unilateral C1 double screw and ipsilateral C2 PS combined with contralateral C2 LS rod fixation provided better stability than unilateral PS rod fixation and similar as bilateral PS rod fixation. Therefore, it is a feasible salvage method that provides a new insight into atlantoaxial instability. These slides can be retrieved under Electronic Supplementary Material.
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