X. Wound and Fracture tai ng Stress Analysis of Internal Fracture Fixation of Long Bones

Progress Using mathematical models, we are investigating the influence of plate fixation on the internal stresses in long bones subjected to all known in vivo loading modes . The variables we are studying include : plate geometry, plate/bone fixity, and screw tightness. The mathematical models are based upon the finite element technique . The models will be subjected to all physiological loading modes, i .e., axial, bending and torsion loads . Plate geometry is studied by designating either stainless steel or titanium in the finite element model . Coulomb friction is used to vary the amount of plate/to bone and screw to plate fixity . Screw tightness will be varied from zero to the maximum value found in the literature from clinical studies . Idealized in vitro bone models have been made from magnesium and phenolic tubing . These will have fixation plates and strain gauges attached and be subjected to the same loads as for the mathematical models.