High-resolution MRI and micro-FE for the evaluation of changes in calcaneal bone mechanical properties in postmenopausal women after one year of idoxifene treatment

Introduction Current methods for the assessment of fracture risk in osteoporosis are primarily based on bone mineral density (BMD) measurements. The mechanical properties of bones, however, are not only related to its density, but also to its internal architecture and its tissue properties. A non-invasive measurement of bone mechanical properties that accounts for the in-vivo bone internal architecture would be of great value for improving the assessment of fracture risk and for the evaluation of the efficacy of drug treatments in osteoporotic patients. Accounting for bone architecture is a prerequisite for a better evaluation of cancellous bone mechanical properties. Recently, new microfinite element (μFE) techniques have been introduced to directly quantify cancellous bone mechanical properties as they relate to its trabecular architecture, which is accessed by high-resolution 3D magnetic resonance (MR) images (van Rietbergen et al., 1998). Recent studies demonstrated that such analyses can provide very detailed information about in-vivo bone anisotropic mechanical properties and can identify differences between osteopenic and healthy groups in cross sectional analyses (Newitt et al., 2001, 2001b). The purpose of this study was to investigate if μFE analyses based on in-vivo MR images can detect significant changes in cancellous bone mechanical properties during long-term longitudinal clinical studies that are aimed at evaluating the efficacy of drugs for the treatment of osteoporosis.