Design of Bone Scaffolds Structures for Rapid Prototyping with Increased Strength and Osteoconductivity

Abstract

Abstract.The geometry of bone scaffolds plays a crucial role in bone tissue regeneration. This architecture, especially pore size and shape, determines the mechanical strength of the scaffold. A number of previous workers have indicated the parameters which are believed to be the main stimulus in the adaptive bone remodelling process. An ideal bone manufacturing system would deliver bone morphogenetic proteins (BMP) and provide adequate mechanical properties. The aim of this study was to design a highly osteoconductive and mechanically strong bone regeneration scaffold which can be successfully manufactured. Three porous architectures of scaffold were designed using Solid Edge TM 3D solid modelling software. The equivalent trabecular structure model consisted of repeatable unit cells arranged in layers to fill the chosen scaffold volume. The three different unit cell structures examined include cubic, triangular, and hexagonal polyhedral. Designed scaffold's pores were varied in this study to 120, 340 and 600 m. This range was selected to meet one of the requirements of the scaffold design -the macropores must be at least 100 m in diameter, so the cells can penetrate and proliferate within the structure. The strengths of each scaffold were determined using ANSYS TM finite element software. Trabecular scaffold designs were analysed independently and in connection with simulated cortical bone in order to investigate their stress-strain response. As well as providing useful information on strengths developed from these topologies, the models developed indicated geometric constraints in order to tailor scaffolds to specific patient needs.

Scaffold microarchitecture determines internal bone directional growth structure: A numerical study

“…Therefore, using directional porosity, we may modulate both the rate and internal microarchitecture of new bone tissue formation. Lipowiecki and Brabazon (2010) also agree that geometrical scaffold architecture has important consequences in bone regeneration, and also suggest preferential zones of bone regeneration around scaffold struts, where higher stresses are found. This may also be linked with the experimental observation that mesenchymal stem cells tend to differentiate to bone-like cells (osteoblasts) with increasing stiffness of the substrate, which also favours migration (Pavlin et al, 2001;Di Palma et al, 2005;Ignatius et al, 2005;Engler et al, 2006;Tang et al, 2006;Lewandowska-Szumiel et al, 2007).…”

Effect of scaffold architecture and BMP-2/BMP-7 delivery on in vitro bone regeneration

“…5). Most of the studies in the literature investigating the effect of fiber organization involving RP techniques focused on the dependence of structural and mechanical properties of the scaffolds in relation with fiber organization and pore properties [31,32]. In a recent study from Melchels et al [33], the effect of pore architecture on the behavior of immortalised bone marrow derived MSCs was studied by using P(D,L/LA)based scaffolds produced by stereolithography and salt leaching leading to scaffolds with highly oriented and random pores, respectively.…”

Permeability of rapid prototyped artificial bone scaffold structures

“…Structures produced by rapid prototyping techniques, allow for control of pore size, porosity, and geometry. These structures have previously been tested by the authors and confirmed to be suitable to withstand the mechanical loading requirements of bone scaffolds . These structure types provide a high stiffness and, at the same time, a high level of porosity and large pore size which would be considered advantageous for achieving a high level of permeability.…”

“…These structures have previously been tested by the authors and confirmed to be suitable to withstand the mechanical loading requirements of bone scaffolds. 26,27 These structure types provide a high stiffness and, at the same time, a high level of porosity and large pore size which would be considered advantageous for achieving a high level of permeability. The aim of this work therefore was to investigate the use of SLA and 3DP rapid prototyping methods for the production of predefined, previously stresstested, cubic, and hexagonal synthetic bone scaffold designs with a view to optimizing these for permeability.…”