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Effect of screw placement.
| Total number of screws (PCS) | Classification criteria for Gertzbein-Robbins | Excellent and good rate (%) | ||
|---|---|---|---|---|
| Class I | Level II and above | |||
| Group A | 142 | 136 | 6 | 95.77 |
| Group B | 138 | 123 | 15 | 89.13 |
| χ2 value | 4.4534 | |||
| P values | 0.0348 | |||
χ2 value and P value are the comparison of excellent and good rates between the 2 groups.
