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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 9  |  Issue : 2  |  Page : 59-62

Morphometric study of uncinate process of cervical vertebra and its surgical importance


1 Postgraduate Student, Department of Anatomy, Mysore Medical College and Research Institute, Mysore, Karnataka, India
2 Professor and Head, Principal, Department of Anatomy, Mysore Medical College and Research Institute, Mysore, Karnataka, India

Date of Submission01-Jun-2019
Date of Decision25-Jul-2019
Date of Acceptance18-Nov-2019
Date of Web Publication10-Sep-2020

Correspondence Address:
P Durga
Department of Anatomy, Mysore Medical College and Research Institute, Mysore, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/NJCA.NJCA_4_20

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  Abstract 


Introduction: Uncinate process (UP) is a projection on the posterolateral margins of the superior surface of the body of the cervical vertebra. They are involved in the uncovertabral (Luschka's) joints, with intervertebral foramen in between, which is related to vertebral artery and spinal nerve roots. Osteophytes of UP cause narrowing of intervertebral foramen, resulting in cervical spondylotic radiculopathy. Objectives: (1) To measure the morphometric parameters of UP of the cervical vertebra. (2) To classify the cervical vertebra on the basis of the encroachment of UP on the adjacent intervertebral foramen. Materials and Methods: One hundred dry cervical vertebrae were obtained from regions in and around Mysore, Karnataka, India. Measurements were taken using digital Vernier calipers. Results: Mean average values of the parameters are: width – 3.389 ± 0.83 mm (right), 3.389 ± 0.86 mm (left); length – 10.42 ± 1.46 mm (right), 10.64 ± 1.88 mm (left); and height – 5.32 ± 1.36 mm (right), 5.21 ± 1.16 mm (left). Classification of UP according to its encroachment on intervertebral foramen which is traversed by neurovascular structures, which may be compressed. Conclusion: Comparing the results of te present study with previous studies in different regions will help neurosurgeons to determine the boundaries of UP and allow adequate decompression of neural elements with reduced risk of neurovascular structures during anterior decompression of the spine.

Keywords: Cervical vertebra, osteophyte, uncinate process


How to cite this article:
Durga P, Dakshayani K R. Morphometric study of uncinate process of cervical vertebra and its surgical importance. Natl J Clin Anat 2020;9:59-62

How to cite this URL:
Durga P, Dakshayani K R. Morphometric study of uncinate process of cervical vertebra and its surgical importance. Natl J Clin Anat [serial online] 2020 [cited 2020 Dec 1];9:59-62. Available from: http://www.njca.info/text.asp?2020/9/2/59/294748




  Introduction Top


The superior discal surface of the cervical vertebra is saddle-shaped, formed by flange-like lips, uncinate processes (UPs), which arise from most of the lateral circumference of the upper margin of the vertebral body. UPs are rudimentary at birth and are usually found on the third to seventh cervical vertebra in the adult. The UPs on the vertebra below articulate with the corresponding bevelled surfaces on the inferior aspect of the vertebra above. Whether uncovertebral joints are synovial joints has proved controversial since their description by von Luschka in 1858; the demonstration of synoviocytes in the lateral joint capsule tissue of the elderly uncovertebral joints suggest that they should be regarded as synovial joints.[1] The main cause of cervical spondylotic radiculopathy and myelopathy is the projection of osteophytes from the UP, leading to narrowing of the intervertebral foramina.[2] Vertebral artery injury is a catastrophic complication that can occur during anterior decompression of the cervical foramen.[3] Comparison of the morphometric measurements of the cervical UP reduces risk to neurovascular structures in anterior cervical spine surgery and helps in improving adequate decompression of the neural elements.

Aim

(1) To measure the morphometric parameters of UP of the cervical vertebra. (2) To classify cervical vertebra on the basis of the encroachment of UP on the adjacent intervertebral foramen.


  Materials and Methods Top


For the study, 100 dry cervical vertebrae from human cadavers of both sexes were obtained from regions in and around Mysore, Karnataka, India, from May 2017 to December 2017. Bones with visible osseous pathologies such as tumors, deformities, fractures, and trauma were excluded. Morphometric parameters of UP of the cervical vertebra were measured using digital caliper. The length was measured as the anteroposterior distance of UP [Figure 1]. The height of the UP was measured as the distance between the tip of the process and the superior surface of the vertebra [Figure 2]. The width was measured as the distance between the medial and lateral margins of the UP at its base [Figure 3]. Data were tabulated and reported as mean ± standard deviation.
Figure 1: The length was measured as the anteroposterior distance of uncinate process

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Figure 2: The height of the uncinate process was measured as the distance between the tip of the process and the superior surface of the vertebra

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Figure 3: The width was measured as the distance between the medial and lateral margins of the uncinate process at its base

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  Results Top


Mean average values of the parameters are: width – 3.389 ± 0.83 mm (right), 3.389 ± 0.86 mm (left); length – 10.42 ± 1.46 mm (right), 10.64 ± 1.88 mm (left); height – 5.32 ± 1.36 mm (right); 5.21 ± 1.16 mm (left). All these values are tabulated in [Table 1]. [Table 2]: Type 1 (no encroachment on intervertebral foramen) [Figure 4] – 82%; Type 2 (inclined and encroached on intervertebral foramen) [Figure 5] – 12%; Type 3 (not inclined, but large enough to encroach on intervertebral foramen) [Figure 6] – 6%.
Table 1: Mean value of studied parameters

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Table 2: Classification of cervical vertebra according to the encroachment of uncinate process over intervertebral foramen

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Figure 4: No encroachment on adjacent intervertebral foramen

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Figure 5: Inclined to encroach on adjacent intervertebral foramen

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Figure 6: Not inclined; but large enough to encroach on adjacent intervertebral foramen

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  Discussion Top


The vertebral body is a composite of the annular epiphyses and the mass of bone between them. All secondary centers unite with the rest of the vertebra at approximately 25 years of age.[4] Osteophytes (bony spurs) may form from the compact cortical bone on the anterior and lateral surfaces of the bodies. Although individual variations occur, these changes appear in most individuals from 20 years onward.[1]

Knowledge of the width of the UP is also important when decompressing nerve roots posterolaterally. An increase in the width of the UP due to osteophyte formation in the UP may result in intervertebral foraminal stenosis and neural compression.[5] In the present study, the width ranged from 2.2 to 4.6 mm with a mean of 3.4 mm; the length ranged from 8.3 to 14.6 mm with a mean of 10.5 mm. The height and width of the UP may be considered as the entrance to the spinal nerve and vertebral artery for decompression of the intervertebral foramen anterolaterally. The UP is an important bone landmark that becomes larger and flatter as individuals get older, losing its sharp and bony characteristics.[5] In the present study, the height ranged from 3.2 to 6.9 mm with a mean of 5.3 mm. The results of the present study were compared with previous studies [Table 3]. The results of the present study showed great variations from previous studies from Southeast Asian, European, and American regions.
Table 3: Comparison of present study with previous studies

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Use of computed tomographic images for the measurements showed better results since the alignment of the vertebra in a single individual was not disturbed, compared to the studies on dry bones (obtained from different individuals).[5]

The main cause of cervical spondylotic radiculopathy is that osteophytes project from the UP, which results in narrowing of the intervertebral foramina.[2] Hence, in the present study, the UP was classified into three types based on their relation to the intervertebral foramen according to the Bergman's comprehensive encyclopedia of anatomic variations.[10] In 12% of vertebrae, the UP was inclined toward the intervertebral foramen, and in 6% of vertebrae, the UP was not inclined but was large enough to encroach into the intervertebral foramen [Figure 5] and [Figure 6].

Limitations

A study was done on dry bones. Hence, bones of various levels were not from a single individual; gender and age could not be taken into account.


  Conclusion Top


This study shows regional variations in the morphometric parameters of UP of cervical vertebra. Thus, it will help neurosurgeons in determining the boundaries of UP and allowing adequate decompression of neural elements with reduced risk of neurovascular structures during anterior decompression of the spine.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Standring S. Gray's Anatomy. 41st ed. London; Elsevier Publishers: 2008. p. 721.  Back to cited text no. 1
    
2.
Lu J, Ebraheim NA, Yang H, Skie M, Yeasting RA. Cervical uncinate process: An anatomic study for anterior decompression of the cervical spine. Surg Radiol Anat 1998;20:249-52.  Back to cited text no. 2
    
3.
Park MS, Moon SH, Kim TH, Oh JK, Jung JK, Kim HJ, et al. Surgical anatomy of the uncinate process and transverse foramen determined by computed tomography. Global Spine J 2015;5:383-90.  Back to cited text no. 3
    
4.
Zhu YH, Cheng KL, Zhong Z, Li YQ, Zhu QS. Morphologic evaluation of Chinese cervical endplate and uncinate process by three-dimensional computed tomography reconstructions for helping design cervical disc prosthesis. Journal of the Chinese Medical Association, 2016;79:500-6. Available from: https://doi.org/10.1016/j.jcma.2016.04.003  Back to cited text no. 4
    
5.
Güvençer M, Naderi S, Men S, Sayhan S, Tetik S. Morphometric evaluation of the uncinate process and its importance in surgical approaches to the cervical spine: A cadaveric study. Singapore Med J 2016;57:570-7.  Back to cited text no. 5
    
6.
Zhu YH, Cheng KL, Zhong Z, Li YQ, Zhu QS. Morphologic evaluation of Chinese cervical endplate and uncinate process by three-dimensional computed tomography reconstructions for helping design cervical disc prosthesis. J Chin Med Assoc 2016;79:500-6.  Back to cited text no. 6
    
7.
Lee TH, Kim SJ, Chung IH. Morphometrical study of uncinate processes and vertebral body of cervical spine. J Korean Neurosurg Soc 2012;51:247-52.  Back to cited text no. 7
    
8.
Kocabiyik N, Ercikti N, Tunali S. Morphometric analysis of the uncinate processes of the cervical vertebrae. Folia Morphol (Warsz) 2017;76:440-5.  Back to cited text no. 8
    
9.
Tubbs RS, Rompala OJ, Verma K, Mortazavi MM, Benninger B, Loukas M, et al. Analysis of the uncinate processes of the cervical spine: An anatomical study. J Neurosurg Spine 2012;16:402-7.  Back to cited text no. 9
    
10.
Tubbs RS. Bergman's Comprehensive Encyclopedia of Anatomic Variations. United States: John Wiley & Sons; 2016.  Back to cited text no. 10
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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