C2 Synchondrosal Injuries: A Case Report and Anatomic Review

Abstract

Developmental succession in the pediatric patient requires special consideration in post-traumatic assessment. An understanding of the sequential development of this region and common patterns of injury can provide an accurate initial assessment before proceeding to further management and prognostic evaluation. Primarily, this article focuses on the synchondrosal development of C2 and its role in the craniocervical junction, as well as its common patterns of injury. This article presents two sample cases and offers a review of treatment options with added prognostic factors.

Keywords: axis fracture; cervical trauma; craniocervical junction; magnetic resonance imaging; synchondrosis.

Figure 1. Sagittal T2-weighted (A) and STIR (B) MR imaging of the cervical spine demonstrates anterior subluxation of the dens with surrounding fluid (blue arrows). There is mild indentation of the ventral thecal sac secondary to truncated posterior longitudinal ligament (orange arrows). Widening of the posterior atlantoaxial space with associated hyperintensity is also noted (green arrows).

STIR - short tau inversion recovery, MR - magnetic resonance

Figure 2. Sagittal T2-weighted (A) and STIR (B) MR images show abnormal hyperintensity with associated anterior tilting of the dens (blue arrows) consistent with odontocentral synchondrosal injury. Associated craniocervical junction posterior element injury involving the posterior atlantoaxial ligament (green arrows) and C1-C2 interspinous ligament (orange arrows) hyperintensity.

STIR - short tau inversion recovery, MR - magnetic resonance

Figure 3. Coronal CT image demonstrates a normal developing C2 vertebra in a two-year-old (A). The os odontoideum has not yet ossified, but the apicodental synchondrosis is appreciable. The odontocentral is the other midline synchondrosis. The remaining odontoneural and neurocentral synchondroses are symmetric. Coronal CT image depicts adult C2 vertebra (B) on coronal axis for comparison. Note apical ossification and complete vertebral fusion.

CT - computed tomography

Figure 4. Coronal CT (A) shows calcified os terminale with unfused apicodental synchondrosis. Remaining synchondroses also incompletely fused, as expected for age. Coronal CT image (B) demonstrates a theoretical type 1 fracture through bilateral ondontoneural and midline odontocentral synchondroses (white line). Coronal CT image (C) demonstrates a theoretical type 2F fracture through bilateral neurocentral and midline odontocentral synchondroses (white line). Coronal CT image (D) demonstrates theoretical type 3 fracture through bilateral neurocentral and odontoneural synchondroses (white lines). Coronal CT image (E) demonstrates a theoretical type 4 fracture through either odontoneural synchondrosis with or without adjacent injury to bordering odontocentral or neurocentral synchondrosis. Provided image depicts left odontoneural (thick, solid line) and possible injury to adjacent odontocentral (thin, solid line) or neurocentral (dashed line) synchondroses.

CT - computed tomography