Date of Award

5-1984

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Bioengineering

First Advisor

Dennis L. Powers

Second Advisor

William R. Krause

Third Advisor

David D. Mayle

Abstract

The increase in the incidence of loosening of the femoral component and resorption of the bone in the calcar region is a recognized problem following total hip arthroplasty ( THA) . It is suspected that various causes such as the heat of polymerization and monomer leakage from the bone cement, interruption of the blood supply to the upper femur, micromovement of the prosthesis, and wear debris may lead to bone resorption and loosening of the prosthesis. It is currently believed by many researchers that disuse atrophy caused by stress shielding of the upper femur after implantation of the femoral component is the primary cause of bone resorption in the calcar region. The purpose of this study was to evaluate the effectiveness of a prototype prosthesis, that incorporates a straight stem and pliable inserts, in decreasing the stress shielding effect. Five pairs of embalmed human cadaver femurs were used. One bone from each pair was first used to obtain the strain levels at clinically important locations at different loads for the intact bone. This was repeated after a commercially available prosthesis was implanted, and after the calcar collar was undermined to simulate calcar resorption. The testing was done using an Instron MaterialsTesting Machine to apply vertical static loads to the femurs that were placed onto a special mounting apparatus. This same test procedure was used for the five remaining femurs, except that the prototype prosthesis was used. The results obtained for the standard and prototype prostheses were compared. It was found that the strain levels in the proximal femur were not reduced as much from the intact bone strain levels, in a majority of the femurs, with the prototype prosthesis. The same general results were found after undermining the calcar collars. The proximal strain levels again showed less of a reduction from the intact bone strain levels in a majority of the cases. These results indicate that the prototype prosthesis reduced the stress shielding effect in the proximal femur.

Download

Share

COinS