Biomechanical Comparison of Three Methods of Stabilization of Tibial Tuberosity Fractures in Dogs: A Cadaveric Study

Introduction: Pin and tension band wire (PTBW) fixation has been the primary stabilization method described for tibial tuberosity avulsion fractures. Early implant removal has been recommended in very young dogs with substantial remaining growth to prevent premature physeal closure and subsequent tibial conformational abnormalities. In our experience hybrid external skeletal fixation (HESF) has yielded acceptable clinical outcomes while allowing for easy implant removal under sedation. The objective of this study is to compare the biomechanical properties of a hybrid construct to paired Kirschner’s wires and PTBW for the stabilization of tibial tuberosity fractures.

Materials and Methods: Tibias were harvested from 12 dog cadavers weighing 20 to 30 kg. An osteotomy was made through the base of the tibial tuberosity, which was subsequently repaired with either paired Kirschner’s wires, PTBW fixation, or HESF. A tensile load was applied to the tibial tuberosity until failure occurred. Mode of failure was described, and biomechanical parameters were compared between fixation groups.

Results: The PTBW fixation and HESF construct afforded greater stiffness and load at 3 mm of axial displacement compared with fixation with Kirschner’s wires alone. There was no significant difference in stiffness and load at 3 mm displacement between PTBW and HESF fixation. Failure occurred by bending and pullout of the wires for all fixations, preceded by untwisting of the figure-of-eight wire in PTWB specimens.

Discussion/Conclusion: A HESF may be an advantageous alternative to PTBW fixation for tibial tuberosity avulsion fracture stabilization in young dogs with substantial remaining growth potential.

Acknowledgment: Internal funding was provided.