Abstract 7

MECHANICAL PROPERTIES OF THE MIDSHAFT AND FEMORAL NECK FOLLOWING ESTROGEN DEFICIENCY

Chapman J; Rajaratnam R; Tan S; Payten C; Neil M; Walsh, WR

Orthopaedic Research Laboratory, Prince of Wales Hospital, University of New South Wales, Sydney, Australia

Purpose: The increased burden of osteoporotic related fractures to the healthcare system worldwide is without question. Bagi [1] have reported changes in the femoral neck up to 12 weeks following removal of the ovaries in the rodent model. The current study examined the medium and long-term effects of estrogen deficiency in the ovariectomised rodent model. Methods: Forty female Sprague Dawley rats were ovariectomised or sham operated at 10 weeks. Equal group were killed at 6 and 12 months following surgery (n=20). Anthropometric measurements, bone mineral density and mechanical properties of the mid shaft femurs and femoral necks were performed. Data was analyzed with a 2-way analysis of variance. Results: Significant endosteal expansion at 12 months in the OVX group compared to shams (p<0.05) was found. Moment of inertia increased with time but did not differ. Bone mineral density decreased with time and was significantly different compared to Shams (p<0.05) but did not differ at 6 and 12 months. Stiffness and ultimate load decreased at 6 and 12 months in the OVX animals compared to shams. Femoral neck stiffness increased between 6 and 12 months in both groups but did not differ. A significant decrease in the ultimate load of the femoral neck was observed at 12 months between groups. Conclusions: Similar to Bagi, we observed changes in the geometric and mechanical properties of the femur at 6 and 12 months compared to shams. The properties cortical bone is reasonable to consider along with changes in the neck when examining therapies related to bone loss following estrogen deficiency.

Return to Listing of 2004 Abstracts
View Listing of 2005 Abstracts