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The addition of information regarding obesity status to the forensic anthropological biological profile could significantly contribute to the identification of human skeletal remains since over 40% of the U.S. adult population is currently obese. This study examines the differences in talar shape and trabecular bone structure between obese and non‐obese individuals. A sample of 20 obese and 20 non‐obese divided evenly by sex was selected from the Texas State University Donated Skeletal Collection. Tali were imaged using x‐ray computed tomography (voxel size: 28–38.7 μm). Image stacks were processed to produce binary images as well as trabecular thickness and spacing maps. Landmark‐based geometric morphometric analyses were conducted to quantify shape variation. Shape coordinates were used to locate 100 geometrically homologous volumes of interest within each talus. Bone volume fraction, trabecular thickness, and trabecular spacing were extracted at each volume of interest. Within each sex, a one‐way ANCOVA was used to determine if significant differences exist between obese and non‐obese individuals in trabecular bone after controlling for age. The size of the talus as well as subtle aspects of shape were found to distinguish the sexes. The results further indicate that bone volume fraction significantly differs between obese and non‐obese males. In females, bone volume fraction is correlated with age but does not differ between obese and non‐obese. The study demonstrates that bone microstructure is a promising approach to estimating body mass or body mass index category but age effects diminish the potential for the talus to be used alone.

Analyses of bone microstructure based on single volumes of interest (VOIs) are limited in their ability to quantify variation in trabecular properties across a joint. Geometric morphometric methods can overcome these limitations by utilizing sliding semilandmarks to locate multiple VOIs within a trabecular structure. Variation in the placement of semilandmarks, however, may change collected bone parameter values. Here we quantify the effect of intraobserver error in delineating the articular surface on sliding semilandmark placement and sampled trabecular properties.Proximal tibiae of 12 individuals that are part of the Texas State University Donated Skeletal Collection were scanned using micro‐computed tomography at the Forensic Anthropology Center at Texas State. Original grey scale image stacks were converted to binary images, and surface models of the exterior bone surface were created. Medial condyles were trimmed from their full surface models three times over a period of weeks. Sliding semilandmarks (n=141) were distributed on the condyle surfaces and then slid to minimize the bending energy of the thin‐plate spline function relative to the updated Procrustes average. Each sliding semilandmark was then used to locate a single VOI just deep to the cortical shell. To investigate the effect of landmark placement on trabecular bone parameters, each VOI was moved 0.5–1.5 mm to one of 10 neighboring positions. Bone volume fraction (BV/TV) and trabecular thickness (Tb.Th) were calculated for each VOI at each of the 11 positions. VOIs that moved outside the trabecular structure were removed from further analyses. 10,000 randomized combinations of the 11 positions of each VOI were created and correlations between bootstrap samples were calculated.Sliding semilandmark placement differed by 0.27 mm on average. Landmarks most affected by intraobserver error were those placed along the edge of the condylar surface (mean = 0.38 mm), while those on the interior portion of the condyle were affected less (mean = 0.21 mm). Sampled BV/TV and Tb.Th vary with VOI position, although there is a strong correlation among the 11 sampled values for BV/TV (r=0.83) and Tb.Th (r=0.80). These results suggest that VOI positions calculated from sliding semilandmarks provide consistent information about bone microstructure even when VOI placement is forced to deviate beyond average variation in sliding landmark position.Support or Funding InformationThis work was supported in part by instrumentation funded by the NSF under grant NSF: MRI 1338044.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.