Effect of Screw Insertion Angle and Speed on the Incidence of Transcortical Fracture Development in a Canine Tibial Diaphyseal Model

Introduction: Transcortical fractures (TCF) are a potential complication with self-tapping screws (STS). The goal of the current study was to compare TCF rates at varied screw insertion angles (SIA) and at varied screw insertion speeds (SIS) using a tibial diaphyseal model.

Materials and Methods: Fifty-five cadaveric tibiae were randomly assigned to 1 of 5 groups. Each tibia was mounted in a custom jig and pilot holes were drilled using a drill press. Tibiae were rotated about the long axis to the appropriate SIA. 3.5 mm locking STSs were inserted with a drill press or a handheld screwdriver based on group assignment. Orthogonal radiographs were evaluated for TCFs. Chi-squared analyses were performed to evaluate differences in the frequency of TCF between groups.

Results: In Group A (0°/650 RPM), a 0% TCF rate was observed (n = 0/78). Group B (5°/650 RPM) had a 3.75% TCF rate (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). Significant differences in TCF rates were observed between Groups A and C (= 8.407, p = 0.004) and between Groups A and E (= 12.888, p ≤ 0.001).

Discussion/Conclusion: A significant increase in TCF rate was observed in groups where screws were power inserted at 10° and when inserted at increased speed. Hand insertion of screws was associated with a reduced TCF rate. The results of the study suggest increased SIA and SIS are predisposing factors in TCF development.

Acknowledgments: Movora kindly supplied the orthopaedic implants.

Publication History

Article published online:
11 September 2023