COMPARISON OF UNIAXIAL AND TRIAXIAL ROSETTE GAUGES FOR STRAIN-MEASUREMENT IN THE FEMUR

A major problem of hip prostheses and other bone fixation devices is t hat they alter the stress distribution in the femur. This phenomenon i s named stress shielding, and derives from the bigger stiffness of the implant when compared to the bone. Strain gages are the most common t ool used in in vitro stress-shielding investigations. There is a lack of agreement in the literature about which gage type is to be preferre d (uniaxial grid, biaxial or triaxial rosette). Rosettes are required when complete information is needed. However, uniaxial gages can be ad vantageous because they reduce the number of measurement channels requ ired. The aim of this work is to verify if (and under which hypothesis ) uniaxial gages can replace triaxial rosettes.