Biomechanical comparison of three locking plate constructs for stabilization of a femoral segmental defect model in cats

This study biomechanically evaluated three titanium locking plate constructs for stabilizing a segmental defect model that simulated a comminuted femoral shaft fracture in cats. Four groups were formed: G1 - single locking plate; G2 - plate-rod construct; G3 - dual plate in an orthogonal configuration; and G4 - intact bone. G1 used 16-hole locking plate with bicortical screws placed in holes 1, 3, 7, 10, 14, and 16. In G2, an intramedullary pin was included, with monocortical screws in the same positions. In G3, screws were placed as in G1, except that monocortical screws were used in holes 7 and 10. Additionally, an 8-hole plate was applied in orthogonal configuration, with monocortical screws placed in holes 1, 3, 6, and 8. All constructs underwent cyclic eccentric axial compression, followed by destructive testing, except G4, which was tested only destructively. During cyclic testing, stiffness did not differ between G2 and G3, while G1 exhibited lower stiffness. Deformation measured with Gauge 1 (16-hole plate) was greatest in G1, with no significant difference between G2 and G3. Deformation measured with Gauge 2 (intramedullary pin and orthogonal plate) was greater in G2 than in G3. In destructive testing, stiffness did not differ between G1 and G2, or between G2 and G3. Maximum force and displacement did not differ among Groups 1, 2 and 3. Group 4 differ from other groups for these variables. In conclusion, both the locking plate-rod construct and the dual titanium locking plate demonstrated similar stiffness, but locking plate-rod configuration exhibited greater deformation.