1. MECHANICAL STRENGTH EVOLUTION OF A RECONSTRUCTED FEMUR DURING FOLLOW-UP Taddei F. *, Martelli S. *, Montanari L. *, Greco V. *, Leardini A. §, Viceconti M. *, Manfrini M. # * Laboratorio di Tecnologia Medica § Laboratorio di Analisi del Movimento # Muscoloskeletal Oncology Department

2. LTM-IOR © 2006 Date of operation: 06/2001 Clinical case 10 years old child –Osteosarcoma at the distal left femoral dyaphisis –Operated in July 2001 –The tumor did not interest sourrounding blood vessels and nerves The patient was eligible for limb salvage surgery Reconstruction of the distal femur with a massive allograft in conjunction with a vascularised fibula autograft

3. LTM-IOR © 2006 Follow-up controls 1 month7 months 13 months 29 months 36 months 44 months Pre-op

4. LTM-IOR © 2006 FEM generation AMIRA v. 4.0 (Amiravis Inc, USA) HyperMesh v. 7.0 (HyperWorks Inc., USA) BONEMAT_V2 Taddei F, et al.. Med Eng Phys. 2004 Jan;26(1):61-9. Segmentation Automatic mesh generation 10-node tetrahedra Convergence test Material mapping

5. LTM-IOR © 2006 FEM in-vitro validation Comparison with experimentally measured strains on 5 cadaveric femurs Taddei F, et al..J. Biomech. 2005, e-pub ahead of print Schileo E., et al, poster #67, EORS 2006

6. LTM-IOR © 2006 Boundary conditions Model - motion registration

7. LTM-IOR © 2006 Boundary condition MS model: –9 bone segments –6 joints: hip (ball and socket) knee (hinge) ankle (hinge) –108 landmarks –84 muscles * Static optimisation algorithm ** *Kepple T.M. et al., J Biomech. 1998, 31, 77-80. **Friederich J.A. et al, J Biomech. 1990, 23(1), 91-5. **Crowninshield R.D. et al.,J Biomech, 1981,14, 793-801.

8. LTM-IOR © 2006 Follow-up study

9. LTM-IOR © 2006 Results Von Mises stress (Mpa) Tumour lesion

10. LTM-IOR © 2006 Results Risk of fracture definition RF=  1 /  yield *  yield = 1.02% ** *Taylor D, Nat Mater 2003; 2(3):133-4. *Bayraktar HH, et. al, J Biomech 2004; 37(1):27-35. **Currey JD, J Biomech. 2004 Apr;37(4):549-56.

11. LTM-IOR © 2006 Results Risk of fracture

12. LTM-IOR © 2006 Results Risk of fracture

13. LTM-IOR © 2006 Results Deformed shape

14. LTM-IOR © 2006 Results Von Mises stress (MPa)

15. LTM-IOR © 2006 Results Risk of fracture

16. LTM-IOR © 2006 Results Mineral density femoral neck

17. LTM-IOR © 2006 Results Risk of fracture

18. LTM-IOR © 2006 Results Von Mises stress (MPa)

19. Thank you!