The current effort focuses on developing a legform impactor subsystem to comply with the ISO standards. It is also the intention of this project to eliminate the necessity of using plastically deformable elements. This system is constructed with non-frangible knee elements and cylindrical segments representing the tibial and femoral components. Dynamic deformation of the legform subsystem is separated into isolated bending and shearing responses which can be directly measured. Bending is controlled by a clutch type mechanism which can be easily adjusted for calibration and certification purposes. The shearing characteristics of the legform are defined by viscoelastic elements which allow media/lateral translation of the lower leg segment relative to the upper leg. Bench testing has proven that this mechanism is a viable alternative to the current legform impactor designs which use frangible knee elements. Details concerning the design development,. calibration results and practical testing are included in this paper. (A)
Abstract