School of Engineering and Materials Science
Research Student Awards
PhD Thesis: Characterization of femoral prostheses using refined holographic interferometric techniques
Author: SABERI, Rezmin
Supervisor(s): Julia Shelton
The total hip replacement has evolved slowly over the last thirty years. Total hip arthroplasty restores pain-free mobility to patients with diseased or damaged hips. The concept has been refined, but not significantly changed over the years. Design alterations have been judged by the clinical outcomes, five to ten years after clinical trials have been initiated. This lack of early, predictive assessment has delayed progress. Short-term, experimental tests are required to predict the long-term clinical outcomes, before total hip replacements are implanted into patients.
Holographic interferometry is a full-field, non-contact, displacement sensitive technique suitable for determining the deformation of the femur. The technique enables out-of-plane surface displacements to be determined along the length of the femur. Holographic interferometry has been validated as a tool for the analysis of hip prostheses, implanted into both model and cadaveric femora. A useful term, namely curvature, derived from the displacement data, has been shown to be sensitive to the properties of different cadaveric femora and to reveal differences between different implant designs.
Intact and implanted femora, with a range of four prosthesis designs, were compared using quantitative holographic interferometry. Different designs of femoral prosthesis cause measurable changes in the deformation of the femoral surface. The differences in design and in deformation were correlated to clinical outcomes and were found to explain some of the clinical results.
The use of digital holographic interferometry has been explored to automate the technique for more rapid analysis of femoral deformations. It has been shown that digital holography can be used to record small objects. Future developments will allow the recording of larger objects, like the human femur. The digital technique will then permit direct access of femoral surface deformations in both static and dynamic loading scenarios.