M.L. Becker
Duke University,
United States
Keywords: 3D printing, medical devices
Summary:
Although work in resorbable polymers has been extensive, few materials have been utilized solely in FDA-approved orthopedic hardware and scaffolds. Materials explored along this path include polylactides, poly(ε-caprolactone) (PCL), and polycarbonates. Polylactides, including PLGA, have been found to resorb in 1-2 months (too early) and typically undergo rapid bulk degradation leading to a localized acidosis and inflammatory response. PCL is known to degrade very slowly, sometimes over years, thereby preventing tissue remodeling and vascularization. Most of these polymers rely on crystallinity for toughness and result in brittle materials that fracture at low strains or deformations. Additive manufacturing (AM), especially VAT photopolymerization, is one way to fabricate crosslinked networks. The range of bone defect types, fracture sites, and cases of multiple fractures makes AM uniquely situated for the fabrication of resorbable scaffolds for bone defect repair. However, more recent fumarate-based copolyesters crosslinked with ester containing thiols and ceramic composite fillers have greatly expanded both the mechanical properties and degradability of the resulting resins. Clinical success of 3D printed composite scaffolds will depend on fully degradable polymer networks that possess mechanical properties suitable for fixation and controlled degradation properties. However, until now, fully resorbable, 3D printable polymers suitable for load sharing and load bearing orthopaedic applications did not exist.