An experimental evaluation of fracture movement in two alternative tibial fracture fixation models using a vibrating platform

Several studies have investigated the effect of low-magnitude-high-frequency vibration on the 30 outcome of fracture healing in animal models. The aim of this study was to quantify and 31 compare the micromovement at the fracture gap in a tibial fracture fixed with an external fixator 32 in both a surrogate model of a tibial fracture and a cadaver human leg under static loading, 33 both subjected to vibration. The constructs were loaded under static axial loads of 50, 100, 34 150 and 200 N and then subjected to vibration at each load using a commercial vibration 35 platform, using a DVRT sensor to quantify static and dynamic fracture movement. The overall 36 stiffness of the cadaver leg was significantly higher than the surrogate model under static 37 loading. This resulted in a significantly higher facture movement in the surrogate model. Under 38 vibration the fracture movements induced at the fracture gap in the surrogate model and the 39 cadaver leg were 0.024±0.009 mm and 0.016±0.002 mm respectively, at 200N loading. Soft 40 tissues can alter the overall stiffness and fracture movement recorded in biomechanical 41 studies investigating the effect of various devices or therapies. While the relative comparison 42 between the devices or therapies may remain valid, absolute magnitude of recordings 43 measured externally must be interpreted with caution.