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

Abstract

To compare the stiffness and strength of three plate and rod fixation constructs applied to a feline tibial gap model. Ex vivo study. Thirty-three unpaired tibiae obtained from skeletally mature cats. 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. 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. 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. 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.