Table 4.
Pedicle screw placement accuracy grades according to the Gertzbein and Robbins classification system
| Number of screws | |||||
|---|---|---|---|---|---|
| Grade | A | B | C | D | E |
| L1 | 5 | 1 | 0 | 0 | 0 |
| L2 | 21 | 3 | 2 | 0 | 0 |
| L3 | 63 | 8 | 0 | 1 | 0 |
| L4 | 83 | 11 | 0 | 0 | 0 |
| L5 | 86 | 3 | 2 | 1 | 0 |
| S1 | 53 | 3 | 2 | 0 | 0 |
| Total | 311 | 29 | 6 | 2 | 0 |
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