Objective: To assess the incidence of transcortical fracture (TCF) development based on screw insertion angle and screw insertion speed.
Study design: Cadaveric experimental study.
Sample population: Sixty-six canine tibiae.
Methods: Sixty-six cadaveric tibiae were randomly assigned to one of six groups that varied based on screw insertion angle relative to the pilot hole (0, 5, or 10°) and screw insertion speed (650 or 1350 revolutions per minute [rpm]). Each tibia was mounted in a custom jig. Locking self-tapping screws (3.5 mm) were inserted at varying speeds and insertion angles, based on group assignment. Orthogonal radiographs were evaluated for TCFs. Fisher's exact tests with a Bonferroni correction were performed to evaluate differences in the frequency of TCF between groups.
Results: In Group A (0°/650 rpm: control), a 0% TCF rate was observed (n = 0/80). Group B (5°/650 rpm) had a 3.75% TCF rate (n = 3/80). Group C (10°/650 rpm) had a 12.5% TCF rate (n = 10/80). Group D (10°/hand insertion) had a 3.75% TCF rate (n = 3/80). Group E (10°/1350 rpm) had a 17.5% TCF rate (n = 14/80). Group F (0°/1350 rpm) had a 0% TCF rate (n = 0/80). Groups C and E had the highest TCF rates with a difference in TCF rates observed between the control group and Group C (p = .001) and between the control group and Group E (p < .001).
Conclusion: Increased screw insertion angle and insertion speed appear to be predisposing factors for TCF development in cadaveric bone.
Clinical significance: Ensuring screw insertion is coaxial with the pilot hole and using slower screw insertion speeds may help reduce the risk of TCF development.
© 2023 American College of Veterinary Surgeons.