The Internal Trabecular Bone Structure of the Odontoid Process of the Axis: A Retrospective Single-Center Comparative Study in Patients Following Cervical Trauma

Abstract

Background

Odontoid C2 fractures account for 9 to 15% of adult cervical spine fractures. The aim of this study is to report the incidence of a previously described Y-shaped trabecular bone structure (TBS) in the odontoid process in a larger sample of patients with a computed tomography (CT) scan following a cervical trauma to investigate if its absence can increase the risk of odontoid process fracture of the axis.

Methods

A retrospective review of 245 patients who underwent a CT scan for cervical spine injury was performed during a 12-month period between May 2020 and May 2021.

Results

The presence of a Y-shaped TBS at the odontocentral synchondrosis level was observed in 165 patients (67.3%) included in this study. Eighteen patients (7.3%) had an odontoid type II C2 fracture. A Y-shaped TBS at the odontocentral synchondrosis level was observed in 8 (44.4%) of these 18 patients. The presence of a Y-shaped TBS at the odontocentral synchondrosis level was statistically more frequently observed in patients without an odontoid process fracture (69.2 vs. 30.8%) compared with patients who developed an odontoid process fracture (44.4 vs. 55.6%) after a cervical trauma (p = 0.03).

Conclusion

This study highlights the crucial role of the Y-shaped TBS in the biomechanics of the C1–C2 joint and its significant clinical relevance in odontoid fractures of the axis.

Keywords

odontoid process - cervical anatomy - axis - biomechanics - computed tomography scan

Publication History

Received: 08 August 2022

Accepted: 14 October 2022

Accepted Manuscript online:
17 October 2022

Article published online:
09 June 2025

• References

• 1 Maak TG, Grauer JN. The contemporary treatment of odontoid injuries. Spine 2006; 31 (11, Suppl): S53-S60 , discussion S61
• 2 Montemurro N, Santoro G, Marani W, Petrella G. Posttraumatic synchronous double acute epidural hematomas: two craniotomies, single skin incision. Surg Neurol Int 2020; 11: 435
• 3 Vaccaro AR, Kepler CK, Kopjar B. et al. Functional and quality-of-life outcomes in geriatric patients with type-II dens fracture. J Bone Joint Surg Am 2013; 95 (08) 729-735
• 4 Joestl J, Lang NW, Tiefenboeck TM, Hajdu S, Platzer P. Management and outcome of dens fracture nonunions in geriatric patients. J Bone Joint Surg Am 2016; 98 (03) 193-198
• 5 Sarode DP, Demetriades AK. Surgical versus nonsurgical management for type II odontoid fractures in the elderly population: a systematic review. Spine J 2018; 18 (10) 1921-1933
• 6 Anderson LD, D'Alonzo RT. Fractures of the odontoid process of the axis. J Bone Joint Surg Am 1974; 56 (08) 1663-1674
• 7 Wagner SC, Schroeder GD, Kepler CK. et al. Controversies in the management of geriatric odontoid fractures. J Orthop Trauma 2017; 31 (Suppl. 04) S44-S48
• 8 Fehlings MG, Tetreault L, Nater A. et al. The aging of the global population: the changing epidemiology of disease and spinal disorders. Neurosurgery 2015; 77 (Suppl. 04) S1-S5
• 9 Magerl F, Seemann P. Stable posterior fusion of the atlas and axis by transarticular screw fixation. In: Society C.S.R., editor. Cervical Spine. New York, NY: Springer-Verlag; 1986: 322-327
• 10 Harms J, Melcher RP. Posterior C1-C2 fusion with polyaxial screw and rod fixation. Spine 2001; 26 (22) 2467-2471
• 11 Singh M, Nagrath AR, Maini PS. Changes in trabecular pattern of the upper end of the femur as an index of osteoporosis. J Bone Joint Surg Am 1970; 52 (03) 457-467
• 12 Amling M, Hahn M, Wening VJ, Grote HJ, Delling G. The microarchitecture of the axis as the predisposing factor for fracture of the base of the odontoid process. A histomorphometric analysis of twenty-two autopsy specimens. J Bone Joint Surg Am 1994; 76 (12) 1840-1846
• 13 Montemurro N, Perrini P, Mangini V, Galli M, Papini A. The Y-shaped trabecular bone structure in the odontoid process of the axis: a CT scan study in 54 healthy subjects and biomechanical considerations. J Neurosurg Spine 2019; 1: 1-8
• 14 Vernon H, Mior S. The Neck Disability Index: a study of reliability and validity. J Manipulative Physiol Ther 1991; 14 (07) 409-415
• 15 Schuld C, Franz S, Brüggemann K. et al; EMSCI study group. International standards for neurological classification of spinal cord injury: impact of the revised worksheet (revision 02/13) on classification performance. J Spinal Cord Med 2016; 39 (05) 504-512
• 16 Heggeness MH, Doherty BJ. The trabecular anatomy of the axis. Spine 1993; 18 (14) 1945-1949
• 17 Gehweiler D, Wähnert D, Meier N. et al. Computational anatomy of the dens axis evaluated by quantitative computed tomography: implications for anterior screw fixation. J Orthop Res 2017; 35 (10) 2154-2163
• 18 Amling M, Pösl M, Wening VJ, Ritzel H, Hahn M, Delling G. Structural heterogeneity within the axis: the main cause in the etiology of dens fractures. A histomorphometric analysis of 37 normal and osteoporotic autopsy cases. J Neurosurg 1995; 83 (02) 330-335
• 19 Kulkarni AG, Shah SM, Marwah RA, Hanagandi PB, Talwar IR. CT based evaluation of odontoid morphology in the Indian population. Indian J Orthop 2013; 47 (03) 250-254
• 20 Naderi S, Arman C, Güvençer M. et al. An anatomical study of the C-2 pedicle. J Neurosurg Spine 2004; 1 (03) 306-310
• 21 Perrini P, Montemurro N. Congenital absence of a cervical spine pedicle. Neurol India 2016; 64 (01) 189-190
• 22 Korres DS, Lazaretos J, Papailiou J. et al. Morphometric analysis of the odontoid process: using computed tomography—in the Greek population. Eur J Orthop Surg Traumatol 2016; 26 (02) 119-125
• 23 Schaffler MB, Alson MD, Heller JG, Garfin SR. Morphology of the dens. A quantitative study. Spine 1992; 17 (07) 738-743
• 24 Sabuncuoglu H, Ozdogan S, Karadag D, Kaynak ET. Congenital hypoplasia of the posterior arch of the atlas: case report and extensive review of the literature. Turk Neurosurg 2011; 21 (01) 97-103
• 25 Teo EC, Paul JP, Evans JH, Ng HW. Biomechanical study of C2 (Axis) fracture: effect of restraint. Ann Acad Med Singap 2001; 30 (06) 582-587
• 26 Shen Y, Miao J, Li C. et al. A meta-analysis of the fusion rate from surgical treatment for odontoid factures: anterior odontoid screw versus posterior C1-C2 arthrodesis. Eur Spine J 2015; 24 (08) 1649-1657
• 27 Fiumara E, Tumbiolo S, Lombardo MC. et al. Type II odontoid fracture: a case series highlighting the treatment strategies. Acta Neurochir Suppl (Wien) 2019; 125: 317-324
• 28 Konieczny MR, Gstrein A, Müller EJ. Treatment of dens fractures with posterior transarticular fixation. JBJS Essential Surg Tech 2014; 4 (02) e10
• 29 Campanelli M, Kattner KA, Stroink A, Gupta K, West S. Posterior C1-C2 transarticular screw fixation in the treatment of displaced type II odontoid fractures in the geriatric population: review of seven cases. Surg Neurol 1999; 51 (06) 596-600 , discussion 600–601
• 30 Polli FM, Miscusi M, Forcato S, Raco A. Atlantoaxial anterior transarticular screw fixation: a case series and reappraisal of the technique. Spine J 2015; 15 (01) 185-193
• 31 Sonone S, Dahapute AA, Waghchoure C. et al. Anatomic considerations of anterior transarticular screw fixation for atlantoaxial instability. Asian Spine J 2019; 13 (06) 890-894
• 32 Lodin J, Hejčl A, Bolcha M, Sameš M, Vachata P. Utility of Hounsfield units in predicting fusion rates of patients undergoing anterior odontoid screw fixation following Anderson d'Alonzo type II and shallow type III fractures. J Neurosurg Sci 2023; 67 (03) 331-339
• 33 Goel A. Vertical facetal instability: is it the point of genesis of spinal spondylotic disease?. J Craniovertebr Junction Spine 2015; 6 (02) 47-48
• 34 Goel A. Artificial atlantoaxial joint: is it a possible option?. J Craniovertebr Junction Spine 2015; 6 (04) 147-148
• 35 Goel A. Letter to the Editor. Artificial atlantoaxial joint. J Neurosurg Spine 2018; 29 (06) 729-731
• 36 Goel A. Artificial atlantoaxial and subaxial facetal joint: proposal of models. J Craniovertebr Junction Spine 2022; 13 (02) 107-109
• 37 Joaquim AF, Patel AA. Surgical treatment of type II odontoid fractures: anterior odontoid screw fixation or posterior cervical instrumented fusion?. Neurosurg Focus 2015; 38 (04) E11
• 38 Hanigan WC, Powell FC, Elwood PW, Henderson JP. Odontoid fractures in elderly patients. J Neurosurg 1993; 78 (01) 32-35
• 39 Vaccaro AR, Lambrechts MJ, Karamian BA. et al; AO Spine Upper Cervical Injury Classification International Members. Global validation of the AO Spine Upper Cervical Injury Classification. Spine 2022; 47 (22) 1541-1548
• 40 Montemurro N, Scerrati A, Ricciardi L, Trevisi G. The exoscope in neurosurgery: an overview of the current literature of intraoperative use in brain and spine surgery. J Clin Med 2021; 11 (01) 223
• 41 Schroeder GD, Canseco JA, Patel PD. et al; AO Spine Cervical Classification Validation Group. Establishing the injury severity of subaxial cervical spine trauma: validating the hierarchical nature of the AO Spine Subaxial Cervical Spine Injury Classification System. Spine 2021; 46 (10) 649-657
• 42 O'Brien Sr WT, Shen P, Lee P. The dens: normal development, developmental variants and anomalies, and traumatic injuries. J Clin Imaging Sci 2015; 5: 38
• 43 Lambrechts MJ, Schroeder GD, Karamian BA. et al; AO Spine Upper Cervical Injury Classification International Members, AO Spine Upper Cervical Injury Classification International Members. Effect of surgical experience and spine subspecialty on the reliability of the AO Spine Upper Cervical Injury Classification System. J Neurosurg Spine 2022; 19: 1-11
• 44 Mishra R, Narayanan MDK, Umana GE, Montemurro N, Chaurasia B, Deora H. Virtual reality in neurosurgery: beyond neurosurgical planning. Int J Environ Res Public Health 2022; 19 (03) 1719