QLS Seminar Series - Natalie Reznikov

Mapping of trabecular bone anisotropy in 3D: a tool to decipher the loading history of bones using microCT

Natalie Reznikov, McGill University
Tuesday April 25, 12-1pm
Zoom Link: https://mcgill.zoom.us/j/86855481591

Abstract: Trabecular bone anisotropy, describing preferential trabecular co-alignment, is a proxy for its long-term loading history. Trabecular anisotropy varies locally, thus rendering averaged calculations across an entire bone inutile. I will present a 3D trabecular anisotropy mapping method using vector fields where each vector reflects the extent of local co-alignment of the elementary units of surface. Such 3D vector fields were constructed and rendered independently by magnitude and by direction using micro-computed tomography of four presumably nonpathologic human calcanei and compared their anisotropy signature with pathologically loaded calcanei in club foot and calcaneonavicular ankylosis. In the nonpathologic calcaneus, a pattern of four anisotropy trajectories (bands) was consistently identified. Both pathologic specimens deviated from the nonpathologic pattern. The calcaneus in the congenitally disused club foot showed very low local anisotropy values and no stress trajectories. The ankylosed calcaneus showed lower anisotropy than the nonpathologic calcaneus, but not to the same extent as the club foot . The directionality of co-oriented stress trajectories was barely discernable in the ankylosed calcaneus as compared to nonpathologic calcaneus. The anisotropy signature of the nonpathologic calcaneus is consistent with a kinetic loading pattern attributable to walking. The loss of this kinetic loading results in an absent/vanishing anisotropy signature. Such 3D mapping adds new dimensions to quantitative bioimaging of bone and the understanding of skeletal adaptation.