A morphometric study of variation in dens of second cervical vertebrae: corona dentis and its clinical implication

Monali Hiwarkar; Shalika Sharma; Prasad Anjali Krishna; Jolly Agarwal; Harsimran Jit Singh; M. Ramkumar

doi:10.18203/2320-6012.ijrms20252885

Authors

Monali Hiwarkar Department of Anatomy, All India Institute of Medical Sciences, Jammu, India
Shalika Sharma Department of Anatomy, All India Institute of Medical Sciences, Jammu, India
Prasad Anjali Krishna Department of Anatomy, Sri Krishna Medical College, Muzaffarpur, Bihar, India
Jolly Agarwal Department of Anatomy, Government Doon Medical College (GDMC), Dehradun, Uttarakhand, India
Harsimran Jit Singh Department of Anatomy, All India Institute of Medical Sciences, Jammu, India
M. Ramkumar Department of Anatomy, All India Institute of Medical Sciences, Jammu, India

DOI:

https://doi.org/10.18203/2320-6012.ijrms20252885

Keywords:

Corona dentis, Odontoid process, Axis vertebra, Morphometry, Anterior odontoid screw, Craniovertebral junction

Abstract

Background: Type-II odontoid fractures are often managed by anterior screw fixation, a technique that requires precise morphometric knowledge of the dens. The corona dentis, a bony spur at the odontoid apex, may artificially elongate measurements, leading to potential surgical complications if unrecognized.

Methods: Thirty dry human C2 vertebrae were studied using a digital vernier caliper. Morphometric parameters of the dens and vertebral body were recorded, including height, anteroposterior (AP) and mediolateral (ML) diameters, and dimensions of the corona dentis. Non-metric features such as dens tip shape, orientation, and transverse ligament groove morphology were assessed independently by two observers. Measurements were repeated to minimize intra-observer variability.

Results: Corona dentis was observed in 8 of 30 specimens (26.7%). The mean height of the dens without corona was 15.35±1.84 mm anteriorly and 15.65±1.70 mm posteriorly, whereas combined heights with corona averaged 18.95 mm and 19.25 mm, respectively. The corona itself measured 3.60±0.79 mm in height and 9.80±0.99 mm in width. The dens averaged 10.1±0.91 mm (AP) and 9.8±0.99 mm (ML). Non-metric analysis showed tapering tips in 40%, retroverted axes in 56.7%, and transverse-type ligament grooves in 60% of specimens.

Conclusions: The corona dentis is a relatively common anatomical variation that significantly increases apparent dens height. Failure to recognize this structure may result in overestimation of screw length during anterior odontoid fixation. Preoperative CT evaluation and careful apex identification are essential for safe surgical planning.

Metrics

Metrics Loading ...

References

Azad TD, Schiedo R, Ranganathan S, Ran KR, Jain A. Cervical spine injuries in elderly patients: Special considerations. In Seminars in Spine Surgery. WB Saunders. 2024;36(2):101104. DOI: https://doi.org/10.1016/j.semss.2024.101104

Monsalve T, Pais-Brito JL, Buikstra J. Osteobiographical Study of Tomás Carrasquilla. Bioarchaeol Int. 2025;9(1):10. DOI: https://doi.org/10.5744/bi.2024.0009

Adogwa O, Elsamadicy AA, Vuong V, Moreno JR, Cheng JS, Karikari IO, et al. Triple Injection Therapy Including Neuropathy, Musculopathy, and Enthesopathy Improved Non-specific Chronic Lower Back Pain After Post Surgery Syndrome. Neurosurgical Focus. 2017;42(3):A1-85.

Anderson LD, D'Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am. 1974;56(8):1663-74. DOI: https://doi.org/10.2106/00004623-197456080-00017

Müller EJ, Wick M, Russe O, Muhr G. Management of odontoid fractures in the elderly. Eur Spine J. 1999;8(5):360-5. DOI: https://doi.org/10.1007/s005860050188

Joaquim AF, Patel AA. Surgical treatment of type II odontoid fractures: anterior odontoid screw fixation or posterior cervical instrumentation? Neurosurg Focus. 2013;35(1):E5.

Detwiler KN, Loftus CM, Godersky JC, Menezes AH. Management of cervical spine injuries in patients with ankylosing spondylitis. J Neurosurg. 1990;72(2):210-5. DOI: https://doi.org/10.3171/jns.1990.72.2.0210

Collins I, Min WK. Anterior screw fixation of type II odontoid fractures in the elderly. J Trauma Acute Care Surg. 2008;65(5):1083-7. DOI: https://doi.org/10.1097/TA.0b013e3181848cbc

Börm W, Kast E, Richter HP, Mohr K. Anterior screw fixation in type II odontoid fractures: is there a difference in outcome between age groups? Neurosurgery. 2003;52(5):1089-94. DOI: https://doi.org/10.1227/01.NEU.0000057697.62046.16

Alonso F, Iwanaga J, Chapman JR, Oskouian RJ, Tubbs RS. The corona dentis: description of an anatomical variant with technical implications for anterior odontoid screw placement. World Neurosurg, 2017;104:132-5. DOI: https://doi.org/10.1016/j.wneu.2017.05.029

Calce SE, Kurki HK, Weston DA, Gould L. The relationship of age, activity, and body size on osteoarthritis in weight-bearing skeletal regions. Int J Paleopathol. 2018;22:45-53. DOI: https://doi.org/10.1016/j.ijpp.2018.04.001

Prameela MD, Prabhu LV, Murlimanju BV, Pai MM, Rai R, Kumar CG. Anatomical dimensions of the typical cervical vertebrae and their clinical implications. Eur J Anat. 2020;24(1):9-15.

Prathap Kumar J, Anupama K, Radhika PM, Komala N. Elongated odontoid process of axis vertebra. Int J Anat Res. 2014;2(3):594-6.

Singla M, Goel P, Ansari MS, Ravi KS, Khare S. Morphometric analysis of axis and its clinical significance-an anatomical study of Indian human axis vertebrae. J Clin Diagnostic Res. 2015;9(5):AC04.

Jain N, Verma R, Garga UC, Baruah BP, Jain SK, Bhaskar SN. CT and MR imaging of odontoid abnormalities: a pictorial review. Indian J Radiol Imaging. 2016;26(1):108-19. DOI: https://doi.org/10.4103/0971-3026.178358

Rehman AA, Turner RC, Lucke-Wold BP, Boo S. Successful treatment of symptomatic intracranial carotid artery stenosis using a 24-mm long bare metal coronary stent. World Neurosurg. 2017;102:693-e15. DOI: https://doi.org/10.1016/j.wneu.2017.04.018

Prathap Kumar J, Anupama K, Radhika PM, Komala N. Elongated odontoid process of axis vertebra. Int J Anat Res. 2014;2(3):594-6.

Jablonski NG, Chaplin G. The roles of vitamin D and cutaneous vitamin D production in human evolution and health. Int J Paleopathol. 2018;23:54-9. DOI: https://doi.org/10.1016/j.ijpp.2018.01.005

Prameela MD, Prabhu LV, Murlimanju BV, Pai MM, Rai R, Kumar CG. Anatomical dimensions of the typical cervical vertebrae and their clinical implications. Eur J Anat. 2020;24(1):9-15.

Wani NA, Qureshi UA, Jehangir M, Ahmad K, Hussain Z. Atypical MR lenticular signal change in infantile isovaleric acidemia. Indian J Radiol Imaging. 2016;26(01):131-4.

Singla M, Goel P, Ansari MS, Ravi KS, Khare S. Morphometric analysis of axis and its clinical significance-an anatomical study of Indian human axis vertebrae. J Clin Diagnost Res. 2015;9(5):AC04. DOI: https://doi.org/10.7860/JCDR/2015/13118.5931

Wani NA, Qureshi UA, Jehangir M, Ahmad K, Hussain Z. Atypical MR lenticular signal change in infantile isovaleric acidemia. Indian J Radiol Imaging. 2016;26(01):131-4. DOI: https://doi.org/10.4103/0971-3026.178362

Prameela MD, Prabhu LV, Murlimanju BV, Pai MM, Rai R, Kumar CG. Anatomical dimensions of the typical cervical vertebrae and their clinical implications. Eur J Anat. 2020;24(1):9-15.