Prediction of stress shielding around an orthopedic screw: using stress and strain energy density as mechanical stimuli.

Using finite element analysis, a parametric study was developed to compare stress and strain energy density (SED), in order to determine which stimuli might be better for predicting stress shielding in bone-screw models. Defined stimuli transfer parameters demonstrated that stress and SED (strong candidates for initiating the bone remodeling process) are transferred distinctively between an implant and bone. While small diameter angled threads increased transfer of both stimuli, reducing the screw's elastic modulus resulted in an increased transfer of stress; and unexpected decrease in SED, indicating that SED should be carefully examined in the context of future bone-screw models.