When 9:00 AM - 10:30 AM Nov 03, 2006
Where 1670 CSE
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Fabrication, Mechanical Properties, and Microstructural Considerations for Bone Ingrowth in Load-bearing Hydroxyapatite Scaffolds


Amy Wagoner Johnson, University of Illinois at Urbana-Champaign

<img align ="left" src="http://www-s.mechse.uiuc.edu/media/uploads/faculty_photos/ajwj.jpg" /><p>There is an irrefutable need for better methods of bone defect repair than are currently available. Bone graft procedures are numerous and costly with 1.5 million procedures reported in 2004 and expenditures in the billions each year, demonstrating a real economic burden to society. The majority of bone graft procedures use either autograft or allograft. The likelihood of successful integration of the autograph is high; however, the cost associated with the bone harvest and the high rate of complications are compelling disadvantages. Allografts, on the other hand, increase the risk of disease transmission. HIV, for example, is transmittable through bone tissue. Finally, allografts and autografts represent a limited supply of material under the best of circumstances.<br />
In this seminar, I will present our work on hydroxyapatite (HA) scaffolds considered for load-bearing applications that spans from scaffold fabrication to mechanical properties after implantation. Specifically, I will describe results from a recent pilot study in which two important observations were made. First, the scaffolds exhibited a change in behavior from brittle to bone-like after intramuscular implantation. Second, scaffolds containing multi-scale porosity were significantly more osteoconductive in the presence of growth factor than those with a single pore size. Histology of deformed samples show that the natural bone arrested crack propagation in the scaffolds with multi-scale porosity and that osteointegration occurred at multiple lengthscales in these samples. We suggest that the ingrown bone and connective tissue allow for the transition from brittle to bone-like behavior. <br />
The results obtained from this research will lead to a framework in which the quality and function of an implant will be well characterized over time. In turn, this will guide clinicians in prescribing rehabilitation strategies for recovering patients with a range of load bearing bone defects.<p>

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