Fabrication, mechanical and in vivo performance of polycaprolactone/tricalcium phosphate composite scaffolds

This paper explores the use of selective laser sintering (SLS) for the generation of bone tissue engineering scaffolds from polycaprolactone (PCL) and PCL/tricalcium phosphate (TCP). Different scaffold designs are generated, and assessed from the point of view of manufacturability, porosity and mechanical performance. Large scaffold specimens are produced, with a preferred design, and are assessed through an in vivo study of the critical size bone defect in sheep tibia with subsequent microscopic, histological and mechanical evaluation. Further explorations are performed to generate scaffolds with increasing TCP content. Scaffold fabrication from PCL and PCL/TCP mixtures with up to 50 mass% TCP is shown to be possible. With increasing macroporosity the stiffness of the scaffolds is seen to drop; however, the stiffness can be increased by minor geometrical changes, such as the addition of a cage around the scaffold. In the animal study the selected scaffold for implantation did not perform as well as the TCP control in terms of new bone formation and the resulting mechanical performance of the defect area. A possible cause for this is presented.