Biomechanical Analysis of Orthogonal Plating and Plate–Rod Combination in a Canine Tibial Fracture Gap Model

The aim of this study was to compare different secondary fixation methods in a canine tibial fracture gap model.Twelve paired tibiae from large-breed dogs were examined. The tibiae were classified into four groups using a random block design. Implant fixation methods included a single 3.5 mm locking plate (3.5 LP), a 3.5 LP with a single 2.8 mm intramedullary pin (3.5 LP/2.8 IM pin) and two 2.0 mm or 2.7 mm orthogonal locking plates (3.5/2.0 LP or 3.5/2.7 LP). The tibial constructs were non-destructively tested in four-point bending and torsion and tested to failure in craniocaudal or lateromedial bending.In the non-destructive tests, the 3.5/2.7 LP had higher torsional stiffness than the others (p < 0.001). In the destructive tests with the craniocaudal bending, the 3.5/2.7 LP had higher yield stiffness (vs. 3.5 LP, p = 0.002; vs. 3.5 LP/2.8 IM pin, p = 0.041; vs. 3.5/2.0 LP, p = 0.021) and bending moment (vs. 3.5 LP, p = 0.002; vs. 3.5 LP/2.8 IM pin, p = 0.017; vs. 3.5/2.0 LP, p = 0.038) than the others. In lateromedial bending, the 3.5 LP/2.8 IM pin had a higher yield angle than the other constructs (vs. 3.5/2.0 LP, p = 0.020; vs. 3.5/2.7 LP, p = 0.012).The orthogonal plating technique using the 3.5/2.7 LP was the strongest construct and may have a mechanical advantage over other secondary fixation methods tested.