Osteogenesis induced by bimorph polyvinylidene fluoride films

The first callus formation induced by piezoelectric polyvinylidene fluoride (PVDF) film has been reported in 1976 by Susuki. Nevertheless, the mechanism of action of induced osteogenesis remains still mysterious. So, the study of the influence of the nature of the stress exerted onto the piezoelectric film has been undertaken.For this purpose, the osteogenic power of two kinds of piezoelectric PVDF films has been followed:- monomorph PVDF films sensitive to all stresses,- bimorph PVDF films only sensitive to bending stresses.PVDF films of various thicknesses - 175 μ, 250 μ, 450 μ-were implanted on a series of white new-zealand mature male rabbits. Each PVDF film was implanted round the right femoral diaphysis and a reference PVDF film round the controlateral femur. Osteogenesis was controlled by X rays and quantitative analysis of alkaline phosphatases in the blood. With bimorph films, a greatest amount of callus and an important remodelling of the cortical bone were observed. The new osteons are perpendicular to the cortical osteons, their orientation being probably governed by the lines of equal potential. The very promising behavior of these bimorph piezoelectric films, might announce a new generation of osteogen material.