PMC3927091_01
Periopertive CT findings for optimal intralaminar screw placement; (a) Preoperative mid-sagital CT showing severe C3-C6 spondylosis with central canal compromise. (b) Right parasagital CT showing the narrow C7 lateral mass (4.0 mm)-arrow versus the patients other levels (average 8 mm). (c) Axial CT through the C7 pedicle showing it to be narrow and small (4 mm). (d) Axial CT through the C7 lamina showing excellent anatomical characteristics for laminar screw placement: 6 mm laminar width and 30 mm laminar length. (e) Postoperative CT showing the C7 intralaminar screw placement, 3.5 x 24 mm Depuy Mountaineer. This screw is almost double the length placed in the lateral masses of the adjacent levels, 3.5 x 14 mm, and similar to that of what the pedicle screw would have held without the safety hazard, (Mountaineer, Depuy Spine, Johnson & Johnson, Raynham, MA)
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F1
Of note, the lateral masses of C7 were small (8 mm) compared with adjacent lateral masses (8 mm) [Figures 1 and 2]. Also concerning were the size of the C7 pedicle, 4 mm [Figure 1]. The C7 lamina was large (6 mm thick and 30 mm in length) [Figure 1].
3D and intraoperative C7 intralaminar screw placement. (a) Preoperative 3D dorsal, CT of the cervical spine showing the patients small lateral masses relative to adjacent levels. (b) Postoperative dorsal C3-6 lateral mass and C7 laminar screw construct. Screw placement was performed without difficulty using anatomical preoperative CT and intraoperative landmarks. No intraoperative fluoroscopy was required. (c) Intraoperative photographs showing placement of the C7 laminar screws and final construct. The rods were attached to the laminar screws with lateral offset connectors. All instrumentation used was Mountaineer, Depuy Spine, Johnson & Johnson, Raynham MA
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F2
Of note, the lateral masses of C7 were small (8 mm) compared with adjacent lateral masses (8 mm) [Figures 1 and 2]. C3-6 lateral masses held either a 12 or 14 x 3.5 mm screw. C7 intralaminar fixation was achieved by drilling two pilot holes (Midas Rex, Medtronic) with a 3 mm matchstick at the spinolaminar junction [Figure 2].