Accuracy of Percutaneous Pedicle Screw Placement: Does Training Level Matter?

Study Design: In vitro human cadaveric surgical technique study.

Objective: To assess the accuracy of percutaneous pedicle screw placement in a human cadaveric model using standard fluoroscopic guidance technique, compared across varying levels of experience.

Summary Of Background Data: The current literature varies widely in the reported frequency of facet violation during placement of percutaneous pedicle screws. However, as of yet there are no studies examining the effect that training level has on accuracy of placement.

Materials And Methods: Four surgeons with differing levels of training (PGY-2, PGY-4, fellow, attending) were evaluated on their accuracy of percutaneous placement of screws in a uniform manner. Each of the 10 cadavers was instrumented from L1 to S1 bilaterally, for a total of 120 screws. Specimens were dissected to evaluate for facet and pedicle wall violations. These were then recorded and analyzed to evaluate for correlation among participating surgeons, laterality, spinal level, and cadaver body mass index.

Results: Of 120 screws placed, there were 35 total violations [26 superior articular facet violations (21.7%), 5 intra-articular facet joint violations (4.2%), and 4 pedicle breaches (3.3%)]. Among the trainees there was no difference in the likelihood of causing a violation (P=0.8863) but there was a difference when compared with the attending surgeon (P=0.0175). Laterality (P=0.1598), spinal level (P=0.3536), and body mass index (P=0.8547) did not correlate with the likelihood of a violation.

Conclusions: Surgeons of differing training levels are able to safely and accurately place lumbar pedicle screws in a percutaneous manner, with a low likelihood of facet and pedicle wall violations.