Utilizing Micro Computed Tomography Data to Produce Implantable Scaffolds for Orthopedic Tissue Engineering

Abstract

Tissue engineering requires a three dimensional porous matrix that provides mechanical support and a template for new tissue growth, as well as allowing vascularization for nutrient delivery and waste product removal. Multiple methods exist for producing porous tissue engineering scaffolds from biocompatible materials. The combination of high resolution imaging systems and rapid prototyping techniques, however, has opened the door to producing scaffolds whose pore structures can match that of the tissue being repaired. A micro computed tomography scanner was used to scan trabecular bone samples from adult male canines, producing three dimensional bone models. These data sets were exported to a computer aided drawing program, where further customization of the data was performed. Additional features were added to the trabecular bone-like pore structure to allow the attachment of strain gauges to the scaffold, as well as achieve an anatomical fit with the intended surgical implant site. The customized scaffolds, made of polybutylene terephthalate (PBT), were produced using a fused deposition modeler. Morphological analysis, mechanical testing and degradation studies were performed to compare the trabecular-like scaffolds, to those with conventionally-designed pore structures. Morphological analysis revealed that the trabecular-like scaffolds matched the bone samples from which they were made in porosity only, requiring an improvement in modeler resolution to better match bone properties such as connectivity density and trabecular number. Mechanical testing showed that the trabecular-like scaffolds and simple pore structured scaffolds possessed a compressive stiffness within the range reported for human trabecular bone, with the trabecular-like scaffolds having a greater compressive stiffness than the complex pore structured scaffolds originally produced to duplicate trabecular bone. Degradation studies show that the mechanical properties and morphology of porous scaffolds made of PBT remained constant after three months soaking in a 37°C saline solution.