The Use of Pedicle Screw-Rod System for the Posterior Fixation in Cervico-Thoracic Junction

Abstract

Objective : In cervico-thoracic junction (CTJ), the use of strong fixation device such as pedicle screw-rod system is often required. Purpose of this study is to analyze the anatomical features of C7 and T1 pedicles related to screw insertion and to evaluate the safety of pedicle screw insertion at these levels. Methods : Nineteen patients underwent posterior CTJ fixation with C7 and/or T1 included in fixation levels. Seventeen patients had tumorous conditions and two with post-laminectomy kyphosis. The anatomical features were analyzed for C7 and T1 pedicles in 19 patients using computerized tomography (CT). Pedicle screw and rod fixation system was used in 16 patients. Pedicle violation by screws was evaluated with postoperative CT scan. Results :The mean values of the width, height, stable depth, safety angle, transverse angle, and sagittal angle of C7 pedicles were 6.9 ± 1.34 mm, 8.23 ± 1.18 mm, 30.93 ± 4.65 mm, 26.42 ± 7.91 degrees, 25.9 ± 4.83 degrees, and 10.6 ± 3.39 degrees. At T1 pedicles, anatomic parameters were similar to those of C7. The pedicle violation revealed that 64.1% showed grade I violation and 35.9% showed grade II violation, overall. As for C7 pedicle screw insertion, grade I was 61.5% and grade II 38.5%. At T1 level, grade I was 65.0% and grade II 35.0%. There was no significant difference in violation rate between the whole group, C7, and T1 group. Conclusion : C7 pedicles can withstand pedicle screw insertion. C7 pedicle and T1 pedicle are anatomically very similar. With the use of adequate fluoroscopic oblique view, pedicle screw can be safely inserted at C7 and T1 levels.

Impact of dynamic alignment, motion, and center of rotation on myelopathy grade and regional disability in cervical spondylotic myelopathy

“…58 It is no wonder that this transition zone where the lordotic cervical spine blends to the kyphotic curvature of the thoracic spine is a structurally critical area that is susceptible to many kinds of insults. 13,49 Furthermore, Cho et al found that lower cervical laminae are thinner and weaker compared with upper thoracic vertebrae, again demonstrating another anatomical point of inflection that can be exploited by traumatic or repetitive motion. 13,43 Within the surgical literature for CSM, fusions ending at C-7 raise concern about instability and adjacentsegment disease; 26,31 our findings that listhesis at the CTJ correlates with a worse mJOA score in CSM suggest that stability between C-7 and T-1 is related to myelopathy severity.…”

C7 intra-laminar screws for complex cervicothoracic spine surgery—a case series

“…Original Study C7 intra-laminar screws for complex cervicothoracic spine surgery-a case series similar results obtained with thoracic pedicle screw fixation (2)(3)(4). Of note, C7 has been successfully used as an anchor point using its lateral masses (5) and pedicles (6,7), although in many patients the lateral mass of C7 may be small, and pedicle fixation can be technically demanding and require a wide exposure. Higher level cervical pedicle screw fixation has been well described but is also technically challenging with greater consequences of pedicle breaches (8).…”

Easy method to simplify “freehand” subaxial cervical pedicle screw insertion

“…[ 16 17 18 ] According to the anthropometric data the “safest” vertebrae for SCPS are C6 and C7, due to the larger diameter of pedicles,[ 1 3 11 16 17 18 19 ] besides, more than 95% of C7 vertebrae do not contain a vertebral artery. [ 20 ] “Most dangerous” vertebrae for SCPS are C3–C5, the risk of neurovascular injury is much higher due to smaller diameter and steep slope of axis of the pedicle. [ 1 3 11 16 17 18 19 ] In general, the method of SCPS insertion is recommended for application by experienced surgeons.…”