Computational Simulations of Bone Remodeling under Natural Mechanical Loading or Muscle Malfunction Using Evolutionary Structural Optimization Method

摘要

style="text-align:justify;">ntLive bone inherentlynresponds to applied mechanical stimulus by altering its internal tissue compositionnand ultimately biomechanical properties, structure and function. The finalnformation may structurally appear inferior by design but complete by function.nTo understand the loading response, this paper numerically investigatednstructural remodeling of mature sheep femur using evolutionary structural optimization method (ESO). Femur images fromnComputed Tomography scanner were used to determine the elastic modulusnvariation and subsequently construct finite element model of the femur withnstiffest elasticity measured. Major muscle forces on dominant phases of healthynsheep gait were imposed on the femur under static mode. ESO was applied tonprogressively alter the remodeling of numerically simulated femur from itsninitial to final design by iteratively removing elements with low strain energyndensity (SED). The computations were repeated with two different mesh sizes tontest the convergence. The elements within the medullary canal had low SEDs andntherefore were removed during the optimization. The SEDs in the remainingnelements varied with angle around the circumference of the shaft. Thosenelements with low SED were inefficient in supporting the load and thusnfundamentally explained how bone remodels itself with less stiff inferiorntissue to meet load demand. This was in line with the Wolff’s law of transformationnof bone. Tissue growth and remodeling process was foundnto shape the sheep femur to a mechanically optimized structure and this wasninitiated by SED in macro-scale according to traditional principle of Wolff’snlaw.n