Effect of sterilization on 3D printed patient-specific surgical guides

Abstract

Background The current workflow for the design and production of patient-specific surgical guides at the Elisabeth-TweeSteden hospital is out-sourced to external companies, making it a time-consuming and costly task. In order to minimize the production time and expenses, the design and fabrication of these guides could be implemented into the hospital’s workflow using an in-house available 3D printer. Compared to the current gold standard for the production of patient-specific surgical guides, a different printing technique and 3D print material will be used. Therefore, it should be determined whether these are suitable for the production of the guides. Moreover, the 3D printed models must be compatible with the in-house sterilization method in order to ensure quality and reliability. The aim of this thesis was to investigate the effect of the in-house available sterilization method on the mechanical, dimensional, and sterility properties of a novel biocompatible 3D printing material. Methods and results BioMed Clear resin specimens were tested according to the ISO standards for mechanical testing of plastics. Overall, steam sterilization changed the mechanical properties of the material, making it stronger and stiffer but more brittle, as compared to unsterilized specimens. The dimensional tests indicated that sterilization resulted in a dimensional change, up to 0.12 mm, which mostly occurred in the small crevices of the model. The deviations of the dimensions of the resulting 3D printed model compared to the digital 3D model were roughly less than 0.3 mm, which is comparable to the accuracy of the gold standard material, polyamide 12. Sterility tests showed that sterilization of the 3D printed models is indeed mandatory for the guides to be used intraoperatively. Also, the Central Sterile Services Department of the hospital is able to deliver sterile medical devices that can be stored for a minimum of four weeks at the sterile storage room. Conclusion With the feasibility confirmed for the hospital to be able to design and produce patient-specific surgical guides in-house, it is necessary to stress that the hospital must meet the Medical Device Regulations by complying with an appropriate quality management system, documenting the manufacturing process, evaluating the performance, and reviewing the experiences from clinical use.