Multi-Directional Mechanical Testing of Bone using CT-Compatible Loading Mechanisms

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Arthritis is becoming more prevalent with the aging population, and recent reports from the Arthritis Alliance of Canada indicate that arthritis is a $33 Billion burden on Canadians, which includes healthcare expenses and lost productivity. Within 30 years, 1 in 4 Canadians is expected to have osteoarthritis. When a patient's osteoarthritis becomes symptomatic and associated with functional loss, then patients can benefit from surgical intervention in the form of a joint replacement surgery, in which the joint is replaced with implants. Typically with osteoarthritis, the joint undergoes adaptive changes as the cartilage degrades. However, treatment is hampered because differences between normal and osteoarthritic patients are poorly understood, and our current inability to model patient-specific bone quality prevents us from being able to predict the success of a joint replacement surgery. Also, surgeons are currently not able to consider the patient's bone quality to select an optimal implant type that minimizes mechanical stresses in the patient's bone. High internal bone stresses may lead to small fractures that progress to cause loosening of implants and eventual failure. This then necessitates a revision surgery, which places the patient at increased risk and requires prolonged hospital stay. Revision surgeries also cost 3 to 5 times more than the original joint replacement surgery, which further increases the cost burden on our healthcare system. The purpose of this research is to develop and validate bone predictive models by experimentally applying forces to bone samples while viewing their internal structure in a high resolution micro-CT scanner. The internal structure of bone is a complex Bone samples are acquired from patients who undergo shoulder replacement surgery. In this research, we utilize these patient bone fragments that would otherwise be discarded, and we test them with applied forces in the laboratory. Mechanical testing of patient bone is essential to improve our understanding of compromised bone quality in patients requiring joint replacements, or who are at risk of fracture. While this research will initially be conducted in shoulder bone, the resulting work will be transferrable to other joints like hips and knees. Ultimately, this work will provide new methods to assess mechanical performance of newly developed biomaterials and implantable devices, including joint implants used in the treatment of osteoarthritis. Additionally, these new bone patient-specific analysis methods will lead to the development of new diagnostic and predictive tools that surgeons can use to better understand the case of the individual patient. These advancements have to potential to improve surgical outcomes for patients.