Figure 1.

Bone stress injuries (BSI) cause porosity and reduced localized mechanical properties. A) Tomographic image of a posteromedial tibial cortex BSI (broken circle) in a 22-year-old female distance runner, acquired using high-resolution peripheral quantitative computed tomography (voxel resolution = 61 μm). Note the presence of undermineralized callus bridging the periosteal surface at the injury site (arrows). B) 3D map showing regions of porosity in red. The majority of the tibial cortex has limited porosity, including the newly formed undermineralized callus. However, there is prevalent porosity at the BSI site (large arrow) and branching medially and laterally along the original periosteal layer of bone (small arrows). C) Finite element model of the stress distribution in response to axial compressive loading. Stresses are concentrated on the regions of the BSI (large arrow) and the immature undermineralized callus (small arrows).