TITLE:
Computational Simulations of Bone Remodeling under Natural Mechanical Loading or Muscle Malfunction Using Evolutionary Structural Optimization Method
AUTHORS:
Hadi Latifi, Yi Min Xie, Xiaodong Huang, Mehmet Bilgen
KEYWORDS:
Bone Remodeling; Computer Simulation; Finite Element Modeling; Evolutionary Structural Optimization; Wolff’s Law
JOURNAL NAME:
Engineering,
Vol.6 No.3,
March
7,
2014
ABSTRACT: Live bone inherently
responds to applied mechanical stimulus by altering its internal tissue composition
and ultimately biomechanical properties, structure and function. The final
formation may structurally appear inferior by design but complete by function.
To understand the loading response, this paper numerically investigated
structural remodeling of mature sheep femur using evolutionary structural optimization method (ESO). Femur images from
Computed Tomography scanner were used to determine the elastic modulus
variation and subsequently construct finite element model of the femur with
stiffest elasticity measured. Major muscle forces on dominant phases of healthy
sheep gait were imposed on the femur under static mode. ESO was applied to
progressively alter the remodeling of numerically simulated femur from its
initial to final design by iteratively removing elements with low strain energy
density (SED). The computations were repeated with two different mesh sizes to
test the convergence. The elements within the medullary canal had low SEDs and
therefore were removed during the optimization. The SEDs in the remaining
elements varied with angle around the circumference of the shaft. Those
elements with low SED were inefficient in supporting the load and thus
fundamentally explained how bone remodels itself with less stiff inferior
tissue to meet load demand. This was in line with the Wolff’s law of transformation
of bone. Tissue growth and remodeling process was found
to shape the sheep femur to a mechanically optimized structure and this was
initiated by SED in macro-scale according to traditional principle of Wolff’s
law.