Mechanical Modelling
Finite element (FE) modelling allows parametric study of factors affecting the mechanical stability of implants. Such models allow mechanical stresses and strains to be sampled in each material and at interfaces. Many modern hip components are uncemented and anchored by press fit. The application of contact analysis at interfaces allows predicitons of bone ingrowth to be made. The reaction of the skeleton by remodelling can also be studied by relating local mechanical stimuli to changes in local bone density. Modern software allows patient-specific variations to be incorporated by mapping bone geometry and density from CT scan data. Micro-CT models also allow press-fit to be studied at the scale of the trabeculae comprising the cancellous bone. Comparison with experimental data, particularly in-house cadaveric studies are used to validate FE models. Analytical modelling is also used to understand load transfer in hip implantations from first principles.
Publications:
Rothstock, S., Uhlenbrock, A., Bishop, N., Laird, L., Nassutt, R., Morlock, M., Influence of interface condition and implant design on bone remodelling and failure risk for the resurfaced femoral head, J Biomech. 44(9):1646-1653, 2011
Bishop, N.E., Burton, A., Maheson, M., Morlock, M.M., Biomechanics of short hip endoprostheses - The risk of bone failure increases with decreasing implant size, Clinical Biomechanics 25 (7): 666-674 Aug 2010
Bishop-et-al, Risk of Bone Failure in Short Femoral Hip Components, ORS, New Orleans-2010-poster
S. Rothstock, A. Uhlenbrock, N. Bishop , M. Morlock, Primary stability of uncemented femoral resurfacing implants for varying interface parameters and material formulations during walking and stair climbing, J Biomech. 2010 Feb 10;43(3):521-6. Epub 2009 Nov 12
Bishop, N., Morlock, M., The Influence of bone quality and implant size / position on the risk of bone failure in short femoral hip implants, 6. Jahrestagung der DGfB Münster 2009, poster PA48
A. Gebert, J. Peters, N. E. Bishop, F. Westphal, and M. M. Morlock,Influence of press-fit parameters on the primary stability of uncemented femoral resurfacing implants, Med.Eng Phys. 31 (1):160-164, 2009
Bishop-et-al, The Effects of Stumbling on Press Fit Acetabular Cups, DGfB-München-2003-poster
Bishop-et-al, Die Effekte des Stolperns auf Presssitz-Hüftpfannen, DGfB-München-2003-ger poster
