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. 2013 Jan 10;8(1):e53580. doi: 10.1371/journal.pone.0053580

Figure 5. Illustration of grades of ATPS positions in cervical pedicle.

Figure 5

Grade 1: Screw positioned at the center of the pedicle. Grade 2: Less than one-third of the screw cross-section (≤1.2 mm with a 3.5-mm diameter screw) penetrating the cortex. Grade 3: Between one-third and one-half of the screw cross-section penetrating the cortex (or deviation <2 mm). Grade 4: More than one-half of the screw cross-section penetrating the cortex (or deviation ≥2 mm). Grade 5: Deviation equal or greater than the screw diameter.