Radiographic Evaluation of Cervical Spine Injuries

For this review, only pretreatment imaging studies were collected and analyzed. Lateral-view radiographs of the cervical spine were used to measure the C2/3 anterior translation and angulation according to the method described by Li et al. and Watanabe et al. (Fig. 1) [10 (link), 15 (link)]. The axial-plane CT scans, sagittal- and coronal-plane reconstructions, and three-dimensional reconstructions were used to look for the posterior vertebral wall (PVW) fracture of C2, which was defined as fracture lines propagating through the posterior wall of the vertebral body of C2 on one or two sides (Fig. 2) [7 (link), 9 (link)]. Magnetic resonance imaging (MRI) images acquired in some patients were used to determine if there were spinal cord signal changes, and if so, identify the location and range of the signal changes.Fig. 1

A schematic diagram showing that anterior translation of C2-3 is measured as the distance between lines drawn parallel to the posterior margins of the C3 and C2 bodies at the level of the disc space (a), and angulation of C2-3 is measured as the angle formed by lines drawn along the inferior endplate of the C2–C3 vertebrae (b)

Fig. 2

A schematic diagram showing the presence of the posterior vertebral wall (PVW) fracture of C2 on the right side (A) or two sides (B)

Since a significant anterior translation of C2/3 (≥ 3.5 mm) and/or angulation of C2/3 (≥ 11°) were accepted as radiographic evidence for segmental instability, we divided the translation of C2/3 into 50% (≥ 1.8 mm) and 100% (≥ 3.5 mm) of significant translation to help establish the threshold of parameters for neurological deficit, and we also divided the angulation of C2/3 into 50% (≥ 5.5°) and 100% (≥ 11°) of significant angulation [13 (link)]. Then, PVW fractures combined with a different degree of translation of C2/3, as causative factors of neurological deficit, and the presence of PVW fractures and ≥ 1.8 mm and 3.5 mm of C2/3 translation were recorded as PVW fractures combined with 50% and 100% of significant translation, respectively. Similarly, PVW fractures combined with a different degree of C2/3 angulation, as causative factors of neurological deficit, and the presence of PVW fracture and ≥ 5.5° and 11° of C2/3 angulation were recorded as PVW fractures combined with 50% and 100% of significant angulation, respectively.