Researchers studied 633 screws placed in 383 patients. The screws were graded as completely within the bone (Type I), less than half the diameter of the screw violating the surrounding cortex (Type II) and a clear violation of transverse foramen or spinal canal (Type III).
For Types I and II, there was 98.8 percent accuracy for the 154 transarticular screws, 98.5 percent accuracy for the 63 laminar screws, 100 percent accuracy for the 77 short pars screws and 94.6 percent accuracy for 509 screws that were viewed on a postoperative CT scan. Eight screws were unacceptably placed.
The mean measurements of pedicle height, axial width and laminar width were 8.1, 5.8 and 5.7 mm, respectively. Male patients experienced larger measurements than female patients in all categories.
Read the abstract about posterior screw placement at C2.
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