Role of surgeon handedness in transpedicular screw insertion

Objective: The aim of this study was to determine the role surgeon handedness plays in transpedicular screw placement. Methods: The study included 269 pedicle screws inserted by two right-handed surgeons who stood on different sides of patients and used the free-hand technique. A parallel line was drawn to the endplate of the vertebrae on lateral radiograph. Measurement was made to observe the angle between the screw and the line parallel to the endplate. Angles were classified as cranial ‘+’ when the tip of the screw stood above the endplate line and as caudal ‘-’ when it stood below the endplate line. Angles of screws placed from the right side were compared to those placed from the left. Results: On the left side, 80 screws (58.4%) were classified as cranial and 82 screws (62.1%) on the right side were classified as caudal. The difference in orientation was statistically significant (p 0.0001). Conclusion: Surgeon handedness appears to have an influence over the orientation of pedicle screws. This may create problems for right-handed surgeons in the insertion of upper level screws from the left side and lower level screws from the right side. Based on this finding, it may be necessary to include ambiguity in handedness as a part of pedicle screw insertion training for spinal surgeons.