Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Anthropology

Supervisor

Dr. Andrew Nelson

2nd Supervisor

Dr. Joseph Eldon Molto

Joint Supervisor

Abstract

The purpose of this dissertation was to assess the value of micro-CT to palaeopathology for the non-destructive analysis of orbital and cranial porotic hyperostosis, common lesions observed in many archaeological skeletal collections. The objectives of this study were to: 1) identify palaeoepidemiological trends in the prevalence of porotic hyperostosis that may support differential diagnoses, 2) evaluate the reproducibility and reliability of two-dimensional (2D) and three-dimensional (3D) methods of micro-CT data collection for the quantitative analysis of bone microarchitecture, and 3) quantitatively evaluate orbital and cranial porotic hyperostosis to determine the value of micro-CT methods for understanding disease pathogenesis and improving the differential diagnosis of these lesions.

Sixty-six individuals obtained from four skeletal collections were assessed macroscopically using published methods of visual analysis as well as quantitatively using micro-CT methods. Structural indices used to quantify bone microarchitecture included bone volume density (BV/TV), specific bone surface (BS/BV), trabecular thickness (Tb.Th.), trabecular number (Tb.N.), and trabecular spacing (Tb.Sp.) (Hildebrand et al. 1999). The results of the visual analysis demonstrated an age-related trend in the prevalence of porotic hyperostosis, supporting previous hypotheses that this condition has an onset in childhood (e.g. Stuart-Macadam 1985).

The micro-CT results illustrated that the most reliable and reproducible method for quantifying bone microarchitecture was a 3D volume of interest (VOI) method that maximized VOI size. Three-dimensional methods using VOIs of a uniform size were recommended with caution, and 2D VOI methods did not provide consistent observer agreement.

The analysis of orbital porotic hyperostosis demonstrated significant changes (p < 0.05) to bone microarchitecture in the advanced stages of disease pathogenesis, but not in the early or healing stages. The results for cranial porotic hyperostosis demonstrated significant changes only in the light stage. These results suggest that orbits are differentially and more significantly affected than the cranial vault likely due to structural differences between the bones of the skull. Changes to bone microarchitecture included an overall loss of trabecular bone and an increase in thinned, gracile trabeculae. Considering these findings within the clinical literature a differential diagnosis that includes anaemic conditions was supported. The identified palaeoepidemiological context also supported this differential diagnosis. Overall, the application of 3D micro-CT methods is of significant value for elucidating the process of disease pathogenesis and supporting current differential diagnoses of porotic hyperostosis in archaeological skeletal remains.

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