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

随着人口老龄化，关节炎变得越来越普遍，加拿大关节炎联盟最近的报告表明，关节炎给加拿大人带来了330亿美元的负担，其中包括医疗费用和生产力损失。在30年内，预计每4个加拿大人中就有1人患有骨关节炎。当患者的骨关节炎出现症状并伴有功能丧失时，患者可以通过关节置换手术的形式进行手术干预，即用植入物代替关节。典型的骨关节炎，随着软骨退化，关节发生适应性变化。然而，由于对正常患者和骨关节炎患者之间的差异知之甚少，治疗受到阻碍，而且我们目前无法建立患者特异性骨质量模型，这使我们无法预测关节置换手术的成功。此外，外科医生目前无法考虑患者的骨质量来选择最佳的植入物类型，以最大限度地减少患者骨中的机械应力。高的内部骨应力可能导致小的骨折，导致植入物松动并最终失效。这就需要进行翻修手术，这将增加患者的风险，并需要延长住院时间。翻修手术的费用也比原来的关节置换手术高出3到5倍，这进一步增加了我们医疗系统的成本负担。本研究的目的是通过在高分辨率微ct扫描仪上观察骨样品的内部结构，并通过实验对骨样品施加力来开发和验证骨预测模型。骨的内部结构是复杂的，骨样本来自于接受肩关节置换手术的患者。在这项研究中，我们利用了这些原本会被丢弃的病人骨碎片，并在实验室中用外力对它们进行了测试。患者骨的力学测试对于提高我们对需要关节置换术或有骨折风险的患者骨质量受损的理解是必不可少的。虽然这项研究最初将在肩骨上进行，但最终的工作将转移到其他关节，如臀部和膝盖。最终，这项工作将提供新的方法来评估新开发的生物材料和可植入装置的机械性能，包括用于治疗骨关节炎的关节植入物。此外，这些新的骨骼患者特异性分析方法将导致新的诊断和预测工具的发展，外科医生可以使用这些工具来更好地了解单个患者的情况。这些进步有可能改善患者的手术结果。

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.