Rapid prototyping of scaphoid and lunate bones

In this study, a novel rapid prototyping technology was used to fabricate scaphoid and lunate bone prostheses, two carpal bones that are prone to avascular necrosis. Carpal prostheses were fabricated with an Envisiontec Perfactory SXGA stereolithography system using Envisiontec eShell 200 photocurable polymer. Fabrication was guided using 3-D models, which were generated using Mimics software (Materialise NV, Leuven, Belgium) from patient computer tomography data. The prostheses were fabricated in a layer-by-layer manner; approximately 50-microm thick layers were observed in the prostheses. Hardness and Young's modulus values of polymerized eShell 200 material were 93.8 +/- 7.25 MPa and 3050 +/- 90 MPa, respectively. The minimum compressive force required for fracture was 1360 N for the scaphoid prosthesis and 1248 N for the lunate prosthesis. Polymerized Envisiontec eShell material exhibited high human neonatal epidermal keratinocyte cell viability rate in an MTT assay. The results of this study indicate that small bone prostheses fabricated by stereolithography using eShell 200 polymer may have suitable geometry, mechanical properties, and cytocompatibility properties for in vivo use.