抄録
This paper addressed issues related to the initial stability of stem fixation after implantation of the cementless shaft type hip stem. The study investigated whether a plate is useful to obtain initial fixation between the stem and bone tissue. The specimen was a characteristic stem with a proximal plate. Two type finite element models were constructed for the computer simulation. Stress distribution and micromotion in the movable plate stem model was compared to that in the fixed-plate stem model. Boundary and initial conditions were (i) Rigid contact of the distal end of the model femur with the rigid base. (ii) Walking load of 1800 N was applied to the proximal top of the stem. (iii) Muscle force was pulled from the greater trochanter of the femur. As a result, it was found that the representative von Mises stress in a movable plate stem model was lower than that of the fixed-plate stem model. The movable plate is useful to avoid excessive stress concentration and loosening. We judged that the slight mobility of a plate was useful for primary stem fixation.
