Accuracy of cervical pedicle screw placement using a patient-specific template guide system and risk factor analysis for screw perforation: CT-based evaluation of 437 screws.

PURPOSE

Cervical pedicle screws (CPS) inserted with template-guided systems (TGS) have a low perforation rate. However, only a few case studies have been reported, and the risk factors for perforation remain unknown. This study aimed to evaluate the accuracy of CPS placement using TGS in a large case series and analyze the risk factors for CPS perforation.

METHODS

This was a retrospective clinical evaluation of prospectively enrolled patients. Eighty consecutive patients who underwent CPS insertion using TGS were included in the study. Overall, 437 CPS were inserted using TGS. Computed tomography was used to evaluate CPS positions and radiographic parameters of CPS and vertebrae. Furthermore, comparisons of patient background factors and radiographic parameters were performed between the perforated and non-perforated screw groups.

RESULTS

A total of 413 (94.5%) screws were completely inside the pedicle, 22 (5.0%) screws deviated by < 2 mm, and 2 (0.5%) screws deviated by > 2 mm and < 4 mm. Therefore, 435 (99.5%) screws were considered clinically acceptable. The perforation rate was the highest in C4 (12.5%). No neurovascular injury was observed. In comparisons between the perforated screw group and the non-perforated screw group, low height, low weight, low BMI, female sex, fellow surgeon, and narrow pedicle were considered as risk factors for CPS perforation using TGS.

CONCLUSION

CPS placement using the TGS showed very high clinical accuracy. Body size, sex, surgeon's experience, and pedicle width may affect the accuracy of CPS placement using TGS.