Mechanical strength across metastatic lesions in trabecular bone: The interplay of microstructure and composition

Pathological bone fractures are a prevalent complication associated with metastatic cancer. However, the fragility associated with bone metastasis exhibits distinct characteristics that are not adequately addressed by current fracture risk assessment systems, which are primarily designed for osteoporosis. To understand how metastasis impairs trabecular bone strength, we experimentally measured mechanical strain across osteolytic and osteoblastic metastatic lesions under axial compression using mechanical testing coupled with micro-computed tomography (micro-CT) and digital volume correlation (DVC) method. We then attempted to evaluate the correlation between this mechanical strain and various parameters, including bone microstructure, bone mineral density, and bone fat-water concentration with the presence of trabecular bone, as assessed through high-resolution micro-CT and magnetic resonance imaging (MRI). This proof-of-concept study demonstrates a workflow that integrates mechanical testing and medical imaging data, enabling the potential to develop a quantitative correlation between local bone strength and the microstructural and compositional parameters measurable through medical imaging techniques. This innovative approach is helpful for identifying key factors influencing mechanical strength of metastatic bones and provides valuable insights for the development of new fracture risk assessment protocols for cancer patients.