Date of Award

12-2011

Degree Name

MS in Biomedical Engineering

Department

Biomedical and General Engineering

Advisor

Scott Hazelwood

Abstract

ABSTRACT

SEASONAL AND ANATOMICAL VARIATION IN COMPACT BONE REMODELING IN THE ADULT SHEEP

Joseph Calcagno

In order to determine whether ovine compact bone is suitable for study of osteoporosis, the remodeling parameters of the untreated animal must be fully characterized. Ovine compact bone is an attractive large animal model due to its similarities in size and bone remodeling to humans. However hormonal, exercise, and dietary changes due to seasonal changes can cause treatment effects to be hidden or superimposed on existing changes in the bone. In order to determine if any seasonal or anatomical variation occurred in the compact bone remodeling, 28 skeletally mature Columbia-Rambouillet cross ewes underwent a sham ovariectomy, OVX, as part of a larger study. The animals were divided into 4 seasonal groups (autumn, winter, spring, and summer) of 7 sheep. Each group underwent surgery and was sacrificed 12 months post-op in their respective seasons. The radii and ulnae were harvested and processed for analysis. Each radius/ulna was divided into 6 anatomical locations (craniolateral, cranial, craniomedial, caudolateral, caudal, and caudomedial). Histomorphometric analysis of the bone volume to tissue volume ratio, the percent of tissue and material remodeling, the mean secondary osteonal radius, and the number of cement line interfaces were quantified. Quantitative microdensitometry analysis was performed to determine the density of each region with respect to an aluminum standard. 2-way repeated measures ANOVAs were performed to determine seasonal and anatomical differences as well as a possible interaction between season and anatomical sectors. Significant seasonal and anatomical differences as well as seasonality within sectors were observed in the remodeling parameters. With the seasonal and anatomical changes in the untreated animal, comparison to other models must ensure treatment and follow up times as well anatomical locations are similar. This research provides a baseline of seasonal and anatomical variations in compact bone remodeling for the untreated adult ovine.