Browsing by Author "Dr. Ola L.A. Harrysson, Committee Chair"

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    Custom Design and Manufacturing of Canine Knee Implants
    (2003-12-02) Jajal, Ketankumar R; Dr. Denis R. Cormier, Committee Co-Chair; Dr. Denis Marcellin-Little, Committee Member; Dr. Simon Roe, Committee Member; Dr. Ola L.A. Harrysson, Committee Chair
    Arthritis is a very common joint disease. Knee and hip arthritis are increasing in humans and as the final treatment joints are replaced by implants. With more younger and active patients suffering from arthritis, a need has arisen to increase longevity by using customized implants. However, to obtain authorization for implantation of such prosthesis extensive trials are required. Arthritis is also very common in canines. One in every four dogs and cats are likely to develop arthritis before the end of their lives. Hip implants are commercially available for canines but due to large variations in sizes, knee (stifle) implants are not available. To conduct the clinical trials for the newly developed custom implant for humans and provide a new treatment for arthritis in canines, a custom design and manufacturing of knee implants for dogs is proposed herewith. The proposed custom design of implant has become possible with the advancement in medical imaging, bio-modeling, mass customization, reverse engineering, rapid prototyping, rapid tooling, and advanced CAD modeling. In this research, CT scan data was converted into CAD model and using advanced CAD modeling functions a patient specific canine knee implant was designed. A new process for manufacturing custom implants is also proposed. With the introduction of Electron Beam Melting (EBM) process, direct fabrication of fully dense components is now possible. The designed custom canine knee implants were manufactured in biocompatible Titanium alloy (Ti6Al4V) using EBM technology. This research introduces a complete process of designing and manufacturing of, firsts of its kind, custom canine knee implants.
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    Mesh Structures with Tailored Properties and Applications in Hip Stems.
    (2009-04-09) Cansizoglu, Omer; Dr. Denis Cormier, Committee Member; Dr. Afsaneh Rabiei, Committee Member; Dr. Ola L.A. Harrysson, Committee Chair; Dr. Denis J MArcellin-Little, Committee Co-Chair; Dr. Harvey A. West, Committee Member
    The purpose of the research has been to develop mesh structures with tailored properties for hip stems. Stress shielding is one of the crucial problems with current hip implants due to the modulus mismatch between the bone and the hip stem. Solid titanium or cobalt-chromium stems are changing the natural stress patterns in the femur. Stresses are transferred through the hip stem and are concentrated more at the distal end of the stem, which weakens the top portion of the femur and overloads the distal portion of the femur. Stress shielding in the long term may result in implant failure due to bone loss, which is costly and painful for the patient. Naturally, biomaterials have tailored structures that display optimal behaviors under tensile, bending and other applied loads. Bones are also tailored to the loading conditions and show stress patterns accordingly. This thesis reports on the development of new hip implants where the mechanical properties of the stems are tailored to match the bone’s properties using open cell structures and mesh structures. Solid free form fabrication techniques are used in this thesis to manufacture parts in the Electron Beam Melting (EBM) by Arcam AB, Sweden. This processing method offers a unique way of making hip stems with mesh and solid sections together in one build. Different designs of hip stems have been manufactured and tested. Their affects on the bones have been analyzed and demonstrated using the Finite Element Analysis (ABAQUS). Hip implants were tested on cadaver bones to measure the difference between mesh stems and solid commercial hip stems. This thesis also includes studies about the mesh quality under different processing conditions, and the applications of structural optimization.