Autoclave sterilization of an in-house 3D-printed polylactic acid piece: biological safety and heat-induced deformation.

AIMS: Fused filament fabrication 3D printing with polylactic acid filaments is the most widely used method to generate biomodels at hospitals throughout the world. The main limitation of this manufacturing system is related to the biomodels' temperature sensitivity, which all but prevents them to be sterilized using conventional methods. The purpose of this study is to define an autoclave temperature-resistant FFF-PLA 3D printing protocol to print 3D fractures biomodels during preoperative planning. METHODS AND RESULTS: Six different printing protocols were established, each with a different infill percentage. Ten distal radius biomodels were printed with each protocol and each biomodel was subject to 3D scanning. The biomodels were subsequently autoclave-sterilized at 134 °C and subjected to a new scanning process, which was followed by a calculation of changes in area, volume and deformity using the Hausdorff-Besicovitch method. Finally, 192 polylactic acid models were produced using the printing protocol offering the greatest resistance and were contaminated with 31 common nosocomial pathogens to evaluate the effectiveness of sterilizing the model printed using the said protocol. Sterilization resulted in a mean deformation of the biomodel of 0.14 mm, a maximum deformity of 0.75 mm, and a 1% area and a 3.6% volume reduction. Sterilization of the pieces printed using the analyzed protocol was 100% effective. CONCLUSIONS: The analyzed 3D printing protocol may be applied with any FFF-PLA 3D printer, it is safe and does not significantly alter the morphology of biomodels. These results indicate that 3D printing is associated with significant advantages for health centers as it increases their autonomy, allowing them to easily produce 3D biomodels that can be used for the treatment of fractures.

Security of 3D-printed polylactide acid piece sterilization in the operating room: a sterility test.

INTRODUCTION: 3D-printing technology has become very popular the last 10 years, and their advantages have been widely proved. However, its safety in the operating room after sterilization has not been evaluated. Thus, the use of 3D printing is still questioned. The aim of this work is to evaluate the security of polylactic acid (PLA) to print surgical models after its sterilization. MATERIALS AND METHODS: One hundred and eighty-six PLA plates and 6 negative controls without microorganisms were seeded. After 10 days of culture, the PLA plates were randomized into three groups: A, B, and C. Group A underwent a sterilization process using an autoclave program at 134 °C. Group B was seeded in different culture media and group C was used to make crystal violet stains on the biofilms formed on the PLA. Mechanical properties of PLA after autoclave sterilization including, the breaking load, deformation and breaking load per surface were calculated. RESULTS: Hundred percent of the group B showed monomicrobial growth. Stains performed on group C PLA showed biofilms in all PLA pieces. After sterilization, no pathogen growth was observed in group A during the culture observation period showing 100% sterilization effectiveness. A filling percentage of 5% obtained a breaking load of 6.36 MPa, and its elastic limit occurred after an elongation of 167.4%. A 10% infill was mechanically safe. CONCLUSIONS: Autoclave sterilization of PLA-printed pieces is safe for the patient and mechanically strong for the surgeon. This is the first 3D-printing protocol described and evaluated to implement 3D-printing technology safely in the operating room. SIGNIFICANCE AND IMPACT OF STUDY: This is the first 3D-printing protocol described to print and sterilize 3D biomodels using an autoclave showing its biological safety and its mechanical resistance.