Using additive manufactured tooling in the fabrication of poly (L-lactide-co-glycolide) implants

Abstract

Rectification of defective bone structures due to trauma or deformation has benefited from the introduction of mostly rigid metal prostheses. However, the high stiffness of metal implants can cause stress shielding in bone restoration. In addition a second operation is required for the removal of the metal implants, screws, plates, and rods once the bone has healed. This paper discusses an adaptable solution where a customised implant is defined which is secured by adhesion and resorbable to enable tissue restoration without a second operation. This paper describes research on methods of creating customised structures from poly (L-lactide-co-glycolide) (PLGA). An existing 3D mandible model in stereolithography file format was used as the basis for this research which a rapid tooling approach is used to create a mould for sintering PLGA particles. The tooling was developed through a stl file of a mandible being imported into a NURBS-based CAD modeller. The modeller was used to create a 3D solid patch model for use as an implantable fracture fixation component. Based on the 3D patch, the tooling was designed and then fabricated by using Stereolitography. Granules of PLGA were placed inside the mould and heated under low pressure to produce the scaffolds with three different formulation of PLGA used in this study. Consolidation of the PLGA occurred under constant pressure with a sintering temperature of 73°C for 2.5hours. Mechanical testing was performed on samples and the results were comparable with conventional processing of PLGA. The geometrical shape of the fabricated PLGA implant resembles the desired fixation component and fits accurately to the fracture site. This work demonstrates that this approach is a viable route in fabricating customised PLGA structures for orthopaedic surgery.