Presentation made to the Southern Biomedical Engineering Conference in Bethesda, MD 9.18.02. An assessment of the importance of micro-environmental variation on resulting stress and strains levels at the microarchitecture of bone.

1. Scaffold Optimization for Load Bearing Applications Rice University Department of Bioengineering Michael Liebschner, Ph.D. Matthew Wettergreen

3. Bone Replacement Material Autograft Allograft/Xenograft Synthetic Material Bone Tumor Joint Replacement Bony Fusion

5. Levels for Considerations in Tissue Engineering

6. Structural Levels to Consider Whole Bone Level Tissue Level

9. Ideal Scaffold Design?

10. Micro-Architectural Variations

12. FE Models Rhombitruncated Cuboctahedron Porosity – 91.4% #Elements – 35326 Truncated Octahedron Porosity – 91.55% #Elements – 30399 Truncated Hexahedron Porosity – 91.5% #Elements – 22651 Cancellous Bone Porosity – 91.5% #Elements – 246720

14. FEM Simulated Deformation Truncated Octahedron

15. Results

16. Results Elastic Modulus 5.01e 9 3.04e 8 3.37e 9 Truncated Octahedron 3.58e 8 4.51e 8 Ultimate Stress Peak Stress Peak Load Ultimate Strength Stiffness Cancellous Bone 2.65e 9 2.37e 9 Truncated Hexahedron 4.224e 12 1.49e 9 Rhombitruncated Cuboctahedron

20. Material Property Mismatch 520 pixels, ~5.0 mm 520 pixels, ~5.5 mm 520 pixels, ~5.0 mm Isotrain Isostress Displacement Stress Continuity Continuity Bone Mass _ + 0  200  MESr MESp MESm 3000  >4000  Atrophy Necrosis Hypertrophy Individual physiological usage 1000 

21. NEW BONE Cultured Scaffold Bioreactor Simulating In-Vivo Loads Stress-Strain Analysis In -Vitro Scaffold Engineering MicroCT Analysis of Tissue Growth Original Bone Scaffold AO Research Institute Manufacturing of Optimized Scaffolds

22. Scaffold-Bone Load Transfer During Scaffold Degradation Scaffold Bone Time Percent load bearing 100 0