Effects of Different Loading Patterns on the Trabecular Bone Morphology of the Proximal Femur Using Adaptive Bone Remodeling

Abstract

In this study, the changes in the bone density of human femur model as a result of different loadings were investigated. The model initially consisted of a solid shell representing cortical bone encompassing a cubical network of interconnected rods representing trabecular bone. A computationally efficient program was developed that iteratively changed the structure of trabecular bone by keeping the local stress in the structure within a defined stress range. The stress was controlled by either enhancing existing beam elements or removing beams from the initial trabecular frame structure. Analyses were performed for two cases of homogenous isotropic and transversely isotropic beams.Trabecular bone structure was obtained for three load cases: walking, stair climbing and stumbling without falling. The results indicate that trabecular bone tissue material properties do not have a significant effect on the converged structure of trabecular bone. In addition, as the magnitude of the loads increase, the internal structure becomes denser in critical zones. Loading associated with the stumbling results in the highest density;whereas walking, considered as a routine daily activity, results in the least internal density in different regions. Furthermore, bone volume fraction at the critical regions of the converged structure is in good agreement with previously measured data obtained from combinations of dual X-ray absorptiometry (DXA) and computed tomography (CT). The results indicate that the converged bone architecture consisting of rods and plates are consistent with the natural bone morphology of the femur. The proposed model shows a promising means to understand the effects of different individual loading patterns on the bone density.

Bone fracture healing in mechanobiological modeling: A review of principles and methods

“…Therefore, the appropriate mechanical environment for bone formation in the healing process differs from that of normal bone formation. In the first few weeks of healing, the fracture site is usually fixed completely, while in the non-injured state, bone that is inactive for a long duration will be resorbed by osteoclast activities (Pivonka and Dunstan, 2012, Prendergast et al, 1997, McKibbin, 1978, Banijamali et al, 2015). In spite of mechanobiological regulations, Comiskey et al found a positive correlation between callus stiffening rate and strain, based on their meta-analysis data from multiple studies.…”

Curved Beam Computed Tomography based Structural Rigidity Analysis of Bones with Simulated Lytic Defect: A Comparative Study with Finite Element Analysis

“…Three dimensional (3D) models of the femurs were constructed using MATLAB (MathWorks Inc., Natick, MA, USA). The calcium-phosphate (Ca-P) density (ρ CHA ) of each pixel in the CT scan was calculated using the calibrating phantoms 18 (the pixels below 30 mg/ml were automatically removed), and a 3D model was constructed using mutually connected pixels 19 20 . Using the relationship ρ ash = 0.0633 + 0.887 ρ CHA 21 , the Ca-P densities were transformed to bone mineral density ( ρ ash ).…”

Guidelines for Topology Optimization as Concept Design Tool and Their Application for the Mechanical Design of the Inner Frame to Support an Ancient Bronze Statue

“…On the other hand, there are still some open issues evolving around TO. These issues are mainly concerned with the aesthetic problem [42]; additive manufacturing problems related to large overhanging members [43][44][45][46], the remodeling of the optimized structure due to poor shape geometry [47]; stress-related problems [48][49][50]; the application of manufacturing constraints [14]; the optimization of multi-scale and multi-material structures [16][17][18][19][20], etc.…”