Personalised bone tissue engineering scaffold with controlled architecture using fractal tool paths in layered manufacturing

The scaffolds for bone tissue engineering should consider the functional requirements such as the external shape of the replacement, porosity for vessel and nutrient conduit, and stiffness in order to avoid stress shielding and to stimulate growth of the new tissue. Layered manufacturing (LM) has shown great promise in fabricating such porous bone scaffold. The present work proposes a biomimetic design and LM of patient- and site-specific controlled porosity scaffolds for optimised mechanical properties for repair and regeneration of bone. Correlation models between porosity and modulus for bone, and known biomaterials processable by LM are used to estimate the site-specific porosity requirements in the scaffold model. A novel method for generating a tool path using space-filling fractal curves eliminates representation difficulties associated with LM of porous objects. A representative study of a hydroxyapatite scaffold for a cortical bone defect site in human femur is presented to illustrate the methodology. © 2009 Taylor & Francis.