Proximal Femoral Strain Distribution

Abstract

Comparison of intact femur, intramedullary and extramedullary prostheses. The strain distribution in the proximal femora was measured in vitro using strain gauges. Strains were recorded in the intact femora and then after insertion of intramedullary and extramedullary prostheses. After insertion of intramedullary prosthesis, the strain pattern was reversed compared with that in the intact femora. Extramedullary prosthesis showed similar strain pattern like intact femora but lower at almost all levels. These results suggest that unphysiological strain distribution of intramedullary prostheses may be the cause of aseptic loosening and extramedullary designs must be kept in mind.