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Journal of Craniovertebral Junction and Spine
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ORIGINAL ARTICLE
Year : 2016  |  Volume : 7  |  Issue : 4  |  Page : 201-203  

Is the existence of cervical rib an advantage for C7 posterior stabilization?


1 Department of Neurosurgery, Firat University, School of Medicine, Elazig, Turkey
2 Department of Radiology, Firat University, School of Medicine, Elazig, Turkey

Date of Web Publication2-Nov-2016

Correspondence Address:
Sait Ozturk
Firat Universitesi Hastanesi, Beyin Cerrahisi Klinigi, 23119, Elazig
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0974-8237.193269

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   Abstract 

Background and Aim: Defining a new screwing method for C7 posterior stabilization in case of a cervical rib existence aimed in this report.
Materials and Methods: Ten adult patients, five of which without cervical rib (Group 1) and the other five of which (Group 2) with cervical rib that has been chosen from the radiology archive. Axial, sagittal, coronal sections of cervical computed tomography and three dimensional images were obtained. Lateral mass sizes of all cases were measured and compared between two groups. The relationship between cervical rib and lateral mass was identified in Group 2.
Results: The mean length, width, and height of lateral masses were measured respectively, as 5.4, 17.6, and 12.7 mm in Group 1. The measurement of Group 2 (with cervical rib) revealed the mean length of 20.7, the width of 20.4, and the height of 15.9 mm. When both groups were compared, there were no significant differences between the width and height of the lateral masses. However, axial measurements of Group 2 revealed a remarkable and significant length for screwing.
Conclusion: In patients with cervical rib, directing lateral mass screw toward cervical rib conjoint can present a simple and reliable alternative method in C7 posterior stabilization process.

Keywords: C7; cervical rib; posterior stabilization; screwing.


How to cite this article:
Ozturk S, Yildirim H, Kaplan M. Is the existence of cervical rib an advantage for C7 posterior stabilization?. J Craniovert Jun Spine 2016;7:201-3

How to cite this URL:
Ozturk S, Yildirim H, Kaplan M. Is the existence of cervical rib an advantage for C7 posterior stabilization?. J Craniovert Jun Spine [serial online] 2016 [cited 2018 Nov 19];7:201-3. Available from: http://www.jcvjs.com/text.asp?2016/7/4/201/193269


   Introduction Top


Evaluation of pathological condition together with normal anatomy plays a key role in surgical planning. A favorable radiological anatomy analysis can present distinctive surgical options. Cervical vertebra injuries have a significant place in neurosurgical practice. In inferior cervical injury cases, complications are experienced during surgical treatment due to anatomical structure of C7.[1] In addition, complication rate in posterior stabilization of C7 is relatively higher.[2] In this study, we discussed on a new anatomical model for C7 posterior screwing. About 0.2%–8% of the population has cervical rib in C7.[3],[4],[5],[6] We have evaluated anatomical structure of cervical rib and lateral mass conjoint on radiological images of patients having cervical rib. This anatomical feature compared with the images of patients without cervical rib. Moreover, in the light of findings that we obtained, we discussed on a new alternative method aimed at screwing for C7 in cases with cervical rib.


   Materials and Methods Top


In this study, 10 adult patients, 5 of which without cervical rib (Group 1), and the other 5 of which (Group 2) with cervical rib that has been chosen randomly from the radiology archive. While choosing both groups, the presence of vertebral foramina in C7 was regarded. Images of computed tomography were obtained by Toshiba® Aquilion (Tokyo Japan, 2007) which is a device with multiple slices and 64 detectors. Besides the axial, sagittal, and coronal sections, the three dimensional (3D) reconstruction images were prepared. 2D and 3D images were performed in Vitria 2 workstation (Toshiba®), and measurements were performed on the basis of both 2D and 3D images (Kv 120, mA 150, scanning time: 5.439 sn). Lateral mass sizes of both groups were observed anatomically. The relationship between cervical rib and lateral mass was identified in the Group 2. The measurements were performed in an axial, sagittal, and coronal plane in both groups. The values obtained were noted and compared. The differences between both groups were interpreted by taking into consideration the values obtained.


   Results Top


The mean length (anteroposterior or axial), the mean width (mediolateral or coronal), the height (vertical) of lateral masses were measured respectively, approximately, 5.4 mm (from point A to B), 17.6 mm (from point C to D), and 12.7 mm (from point E to F) in Group 1 [Table 1] and [Figure 1]. In the Group 2, cervical ribs were making joint with C7 and closely adjacent to the lateral mass of C7, leading toward a posterior side. In axial plane, a line was identified extending from the median point of lateral mass toward cervical rib. Mean length (A1B1) was measured as 20.7 mm [Table 1] and [Figure 2]. Besides, the mean width and the mean height of those were measured respectively as: 20.4 mm (from point C1 to D1) and 15.9 mm (from point E1 to F1) [Table 1] and [Figure 2]. When both groups were compared, there were no significant differences between the mean width and the height of the lateral masses. As for the cervical rib lateral mass conjoint, it was determined that it has an anatomical relationship which significantly increases the length.
Table 1: Measurements of length, width, and height of C7 in both groups

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Figure 1: Three-dimensional-computed tomography reconstruction of C7 in Group 1 whom without cervical rib. (a) Axial image of C7. The mean distance between point A and B is 5.4 mm. (b) 45° supero-coronal image of C7. The mean distance from point C to D is 17.6 mm. (c) Coronal image of C7. The mean distance between point E and F is 12.7 mm

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Figure 2: Three-dimensional-computed tomography reconstruction of C7 in Group 2 whom with cervical rib. (a) Axial image of C7. The mean distance between point A1 and B1 is 20.7 mm. (b) 45° supero-coronal image of C7. The mean distance from point C1 to D1 is 20.4 mm. (c) Coronal image of C7. The mean distance between point E1 and F1 is 15.9 mm

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   Discussion Top


Lateral mass screwing method for cervical vertebra establishes a common practice of spinal surgery in cervical posterior fixation. However, C7 has the characteristics of both cervical and thoracic vertebrae. The lateral mass screwing method is problematic for C7, having thin and short lateral masses. For these reasons, various stabilization methods were reported for C7 stabilization. The transpedicular screwing method is mostly recommended. However, transpedicular screwing is technically harder. It has a high risk of causing neural or vascular injury by the screw driven out of pedicle.[7],[8],[9] Hence, alternative methods as transfacet and intralaminar screwing reported.[8],[10],[11]

The presence of cervical rib is a remarkable anatomical variation for C7. Two significant criteria are identified for cervical rib: First, cervical rib must make joint with C7, and it must not fuse with C7 vertebra. It is called prolonged transverse process if it fuses. Second, the rib must not originate from the transverse process of the first thoracic vertebra.[12] Patients with cervical rib provide the optimal conditions for that diagnosis.

In the Group 2, the measurements we have taken in the axial, sagittal, and coronal plane from C7 lateral mass to cervical rib indicate that this zone provides sufficient volume for lateral mass screwing method. The mean length (A1B1 line), the mean width (C1D1 line), the mean height (E1F1 line) of patients with cervical rib were measured respectively at 20.7 mm, 20.4 mm, and 15.9 mm [Figure 2]a,[Figure 2]b,[Figure 2]c. We consider that these measurements are sufficient to replace lateral mass screw when lateral masses of the other cervical vertebrae are taken into account.[9] The distinction in the patients with cervical rib is remarkable when compared with the cases without cervical rib having normal C7. When the screw is directed toward cervical rib conjoint, reliable zone also will be provided. As observed in Group 2, screw must be directed a bit more toward lateral side, unlike the methods used for lateral mass screwing [Figure 3].
Figure 3: Illustration of posterior C7 stabilization by lateral mass screw in case with cervical rib. (a) Screwing virtually on the image of three-dimensional-computed tomography, (b) charcoal image of screwing

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Cervical ribs may have different anatomical configurations. For this reason, the lateral mass and cervical rib conjoint must be calculated, and the direction of the screw must be adjusted separately for each case. In addition, the standard values for cervical rib lateral mass conjoint have not been defined in the cases with cervical rib. In the cases with cervical rib, that the lateral mass morphology of C7 and the relationship of it with cervical rib being reported after it is inspected in a large population, will contribute significantly to clinical practice.

As a consequence, in patients with cervical rib, directing lateral mass screw toward cervical rib conjoint can present a simple and reliable alternative method in C7 posterior stabilization process. However, this report should be supported with further biomechanical studies.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest

 
   References Top

1.
Kast E, Mohr K, Richter HP, Börm W. Complications of transpedicular screw fixation in the cervical spine. Eur Spine J 2006;15:327 34.  Back to cited text no. 1
    
2.
Bozkus H, Ames CP, Chamberlain RH, Nottmeier EW, Sonntag VK, Papadopoulos SM, et al. Biomechanical analysis of rigid stabilization techniques for three column injury in the lower cervical spine. Spine (Phila Pa 1976) 2005;30:915 22.  Back to cited text no. 2
    
3.
Brewin J, Hill M, Ellis H. The prevalence of cervical ribs in a London population. Clin Anat 2009;22:331 6.  Back to cited text no. 3
    
4.
Gulekon IN, Barut C, Turgut HB. The cervical rib in Anatolian population. Gazi Med J 1999;10:149 52.  Back to cited text no. 4
    
5.
Gupta A, Gupta DP, Saxena DK, Gupta RP. Cervical rib: It’s prevalence in Indian population around Lucknow (UP). J Anat Soc India 2012;61:189 91.  Back to cited text no. 5
    
6.
Walden MJ, Adin ME, Visagan R, Viertel VG, Intrapiromkul J, Maluf F, et al. Cervical ribs: Identification on MRI and clinical relevance. Clin Imaging 2013;37:938 41.  Back to cited text no. 6
    
7.
Barrey C, Cotton F, Jund J, Mertens P, Perrin G. Transpedicular screwing of the seventh cervical vertebra: Anatomical considerations and surgical technique. Surg Radiol Anat 2003;25:354 60.  Back to cited text no. 7
    
8.
Lu S, Xu YQ, Lu WW, Ni GX, Li YB, Shi JH, et al. A novel patient specific navigational template for cervical pedicle screw placement. Spine (Phila Pa 1976) 2009;34:E959 66.  Back to cited text no. 8
    
9.
Tessitore E, El Hassani Y, Schaller K. How I do it: Cervical lateral mass screw fixation. Acta Neurochir (Wien) 2011;153:1695 9.  Back to cited text no. 9
    
10.
Horn EM, Reyes PM, Baek S, Senoglu M, Theodore N, Sonntag VK, et al. Biomechanics of C7 transfacet screw fixation. J Neurosurg Spine 2009;11:338 43.  Back to cited text no. 10
    
11.
Jang SH, Hong JT, Kim IS, Yeo IS, Son BC, Lee SW. C7 posterior fixation using intralaminar screws: Early clinical and radiographic outcome. J Korean Neurosurg Soc 2010;48:129 33.  Back to cited text no. 11
    
12.
Viertel VG, Intrapiromkul J, Maluf F, Patel NV, Zheng W, Alluwaimi F, et al. Cervical ribs: A common variant overlooked in CT imaging. AJNR Am J Neuroradiol 2012;33:2191 4.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]
 
 
    Tables

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