The implant thread as a retention element in cortical bone: the effect of thread size and thread profile: a finite element study.

Assuming that high stress peaks in the bone can trigger bone resorption a screw-shaped bone implant should be given such a design that the peak stresses arising in the bone, as a result of a certain load, are minimized. Using idealized assumptions the aim of the study was to analyse the effect of variations of the size and the profile of the thread of an axially loaded, screw-shaped, bone implant upon the magnitude of the stress peaks in cortical bone. The investigation was performed by means of axisymmetric finite element analysis. It was found that the shape of the thread profile has a profound effect upon the magnitude of the stresses in the bone and that very small threads of a favourable profile can be quite effective.