Ex vivo biomechanical evaluation of 2.4 mm LCP plate rod constructs versus 2.7 mm LCP applied to the feline tibia.

Objective: To compare the stiffness and strength of three plate and rod fixation constructs applied to a feline tibial gap model.

Study design: Ex vivo study.

Sample population: Thirty-three unpaired tibiae obtained from skeletally mature cats.

Methods: The tibiae were randomly divided into three groups. The following implants were then applied to the feline tibiae prior to the creation of a 10 mm diaphyseal gap. Group 1: 2.4 mm locking compression plate (LCP) and 1.0 mm intramedullary pin (IMP). Group 2: 2.4 mm LCP and 1.6 mm IMP. Group 3: 2.7 mm LCP. Subsequently, each specimen was tested for torsion, axial compression, and axial load until construct failure. Student's t-tests were used to compare the torsional and axial stiffness, yield load, and maximum axial force.

Results: Group 2 had higher axial stiffness than group 3 (p = .013). Group 1 showed a lower maximum axial force and yield point than groups 2 and 3 (p < .01; p < .05, respectively). There were no among-group differences in torsional stiffness.

Conclusion: Constructs with a 2.4 mm LCP and 1.6 mm IMP provided the strongest and most rigid constructs in a feline tibia gap model.

Clinical significance: A plate-rod construct combining a 2.4 mm LCP and a 1.6 mm IMP is appropriate for achieving high implant stiffness and resisting maximum axial force in treatment of tibial fractures in cats.