A clinical morphologic study of the C2 pedicle and isthmus

Abstract

Purpose This anatomic, radiographic study investigated locational differences in the C2 pedicle and isthmus [pediculoisthmic component (PIC)] and characterized its narrowest section for clinical application in posterior C2 screw fixation. Methods Structures surrounding the transverse foramina of 30 dry C2s and 10 C3s were compared morphologically. Spinal CT scans of 32 Chinese adults were subjected to volume rendering and multiplanar reconstruction to identify the narrowest C2 PIC, and correlative parameters were measured and analyzed. Results Inferior C2 and C3 structures were morphologically similar. In superior view, the C2 superior facets lay on the transverse foramen and the upper portion between superior and inferior facets was flat (average mediolateral angle, 11.1°± 2.4°). In inferior view, the posteroinferomedial portion of the C2 transverse foramen displayed a partially tubular structure (average mediolateral angle of projection, 42.6°± 4.9°). Average height and width were 11.6 and 6.9 mm. The inner medullary cavity was elliptical and the middle site of endosteal diameter was 3.3 ± 1.9 mm.Medial internal cortical bone was significantly thicker than lateral bone (P \ 0.01). Conclusions The PIC is located between superior and inferior C2 facets. The superior flat area is the isthmus and the inferomedial area connecting the inferior facet and vertebral body is the pedicle. The pedicle is partially tubular and projects posteromedially to the transverse foramen. The narrowest PIC section is the narrowest point of the C2 pedicle. Considering its thin lateral cortical bone, medial and superior pedicle screw placement and preoperative CT reconstruction are recommended.

Detailed description of anatomy of the fracture line in hangman's injury: a retrospective observational study on motor vehicle accident victims

“…Several authors have described these anatomical peculiarities and tried to determine the precise location of the pedicle and pars of the C2 vertebra. 11,[13][14][15][16][17] In this study, we used Naderi criteria for identifying the pedicle and pars. Naderi et al believed that C2 isthmus (pars interarticularis) and the C2 pedicle are distinct structures.…”

Medially-shifted rather than high-riding vertebral arteries preclude safe pedicle screw insertion

“…Pedicles were assessed according to the previous report by Yuan [16]. First, the pedicle axis was determined along with the sagittal trajectory of the C2 PS (Fig.…”

Radiographic measurements of C-2 in patients with atlas assimilation

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