Biomechanical Comparison of Single-, Double-, and Triple-Screw Fixation for Tibial Eminence Fractures: A Skeletally Immature Porcine Cadaveric Study

Abstract

This study uses a porcine cadaveric model to biomechanically compare the single-, double-, and triple-screw fixation techniques for tibial eminence fractures. Eighty porcine tibiae were divided into eight groups (n = 10 each): intact control, pull-out suture fixation, one 4.0-mm half-threaded screw, one 4.0-mm full-threaded screw, one 4.5-mm screw, two 4.0-mm parallel screws, two 4.0-mm divergent screws, and three 4.0-mm screws. Standardized fractures were created and fixed according to each protocol. The specimens underwent cyclic followed by load-to-failure testing. Maximum failure load and cyclic displacement were compared. The intact specimens demonstrated significantly higher ultimate load (1059.44 ± 311.84 N) than all fixation groups (p < 0.001). Among the fixation methods, the three-screw configuration withstood the highest load (442.10 ± 123.42 N), followed by the two-screw divergent (392.26 ± 47.63 N) and two-screw parallel (329.33 ± 56.30 N) configurations. The two-screw divergent configuration provided significantly greater strength than the parallel orientation (p < 0.050). Full-threaded screws demonstrated significantly less cyclic displacement (1.05 ± 0.49 mm) than half-threaded screws (2.21 ± 0.49 mm, p < 0.001). The pull-out suture showed significantly greater displacement (3.25 ± 1.07 mm) than all screw fixations (p < 0.050), yet achieved a comparable ultimate failure load (397.82 ± 126.35 N), indicating that the primary advantage of screw fixation lies in cyclic stability rather than ultimate strength. Although three-screw fixation yielded the highest absolute failure load, the two-screw divergent configuration offered comparable strength (p = 0.571), representing a practical alternative. Screw number, orientation, and thread design significantly influence fixation stability in tibial eminence fractures.