Micromotions and Strains of Cementless Femoral Prostheses

Summary

Using cadaver femurs, strains on the femoral surface and micromotions between stem and bone were measured.

Stress shielding in the proximal medial region after stem insertion was apt to be stronger with a collarless stem than with a collared stem.

It was considered important to obtain a close proximal fit in order to minimize micromotion in the proximal region of the stem. Distal fixation, however, did not exert any influence on micromotion in the proximal region. With a collared stem, micromotion in the proximal region was largest in proximal-loose and distal-fit. The collarless stem had generally smaller micromotion regardless of proximal and distal fixation. Therefore, it was considered more favorable to use a collarless stem to obtain proximal fixation of the stem.