Monitoring the strains on cadaveric femoral bones with titanium alloy prosthetic stems

Abstract

The present work involved the mechanical properties evaluation of cadaveric specimens with titanium prosthetic stems by monitoring the strains in a realistic simulated environment of human joint forces. The results of this work can be used to understand the behavior of bone tissue and improve the design of the hip implants, enhancing quality of life for patients suffering from diseases and injuries. The literature survey part of the research referenced multiple scientific fields crucial for its completion, including the historical context of THA, the evolution of contemporary THA, hip biomechanics, the mechanical properties and the behavior of bone tissue and biomaterials, additive manufacturing techniques for the construction of patient-specific implants, and the biomechanical sensors and optical techniques that provide strain distribution and displacement data for the implant-bone system. The experimental phase was divided into two main parts: designing and constructing a mechanical system capable of accurately replicating the forces acting on the hip joint, and the mechanical evaluation of two cadaver human femurs, one intact and one implanted with a titanium alloy prosthetic stem. A Digital Image Correlation (DIC) system was used to capture the strains of the cadaver specimens in two different planes. The intact femur reached the maximum load in all five attempts, exhibiting a linear behavior. The DIC results indicated that the highest strain concentrations are in the medial diaphysis and in the femoral neck. These results were consistent with other studies referenced in the theoretical part of this work. The implanted femur did not reach the maximum load because it was damaged by the polymerization of PMMA at the great trochanter. With only limited data collected, the implant-bone system showed linear behavior during the loading, a similar behavior that was detected for the intact femur, however, this data is insufficient so as to evaluate implant integrity. Future research should focus on improving both experimental design and methodology utilising the challenges and limitations encountered in this work.