Dimensional accuracy of 3D-printed surgical cutting guides after hospital sterilization: a comparative evaluation of ten MEX materials

Abstract

Background: Integrating 3D printing into orthopedic oncology enables the development of patient-specific cutting guides for specific anatomy. To preserve surgical precision, especially in tumor resections where the safety margins must balance minimization of recurrence with avoidance of excessive bone removal, it is critical to maintain the dimensional accuracy of these guides throughout all stages of fabrication, disinfection, cleaning, and sterilization.

Methods: Personalized cutting guides were 3D printed using ten filaments, and 3D scanned before and after sterilization. Two sterilization methods were used: autoclave and vaporized hydrogen peroxide. Dimensional deviations were assessed by comparing the reference STL model with the scanned models using metrics such as root mean square, standard deviation, Gaussian mean, and maximum error. Pearson correlation analysis was conducted to evaluate inter-sample variability and metric interdependence.

Results: PLA and PETG showed the best dimensional accuracy in the as-printed state with RMS values of 0.093 mm and 0.093 mm, respectively, and standard deviations below 0.092 mm. After hydrogen peroxide sterilization, PETG, PC, and PETG-CF kept a high accuracy, while PLA, PLA-HP, PA, and PA6-CF showed significant deformations. Autoclave sterilization determined severe deformation in most materials, with PC showing unexpectedly changes of the geometrical form, increasing in RMS error from 0.127 mm to 3.642 mm. In the as-printed state, maximum error remained below 0.29 mm for all materials, with PLA having the highest localized deviation (0.283 mm). After hydrogen peroxide sterilization, PETG, PC, and ABS maintained maximum error values lower than 0.27 mm, while PLA increased to 0.274 mm and PLA-HP to 0.268 mm. These values, although moderate, showed geometric changes that affect fit in anatomically constrained regions. Pearson correlation analysis showed that hydrogen peroxide sterilization altered the relationship between accuracy metrics of prints after manufacturing, weakening the correlation between RMS and Gaussian mean. This suggested increased unpredictability in deformation direction and highlighted less consistent deformation patterns.

Conclusions: Disinfection and sterilization processes were highly material-dependent, as expected. PETG, PC, and PETG-CF were the most stable materials for the 3D-printed surgical guides when using cold plasma sterilization. Materials like PLA, PLA-HP, and PA require caution due to their instability. Designers should take into account the deformation directionality loss post-sterilization and integrate fit allowances into surgical guide geometry.

Keywords: 3D printing; Dimensional accuracy; MEX; Orthopedic oncology; Sterilization; Surgical guides.

Fig. 1

X-ray images — a before and b after

Fig. 2

Surgical guide development workflow — a CT scans of the patient’s tibia; b point cloud import and guide design; c guide 3D printing using MEX; d sterilization; and e clinical use

Fig. 3

Surgical guide design using point cloud data — a point selection and b automatic surface reconstruction

Fig. 4

Tumor identification — a on the virtual model and b on the anatomical replica

Fig. 5

Build orientation for the surgical guide

Fig. 6

3D scanning process of the guides using MetroX 3D scanner

Fig. 7

CloudCompare process — a manual alignment using point pairs and b distance analysis of the PLA guide using the STL model as reference

Fig. 8

Correlation between Gaussian mean and RMS error for as-printed guides

Fig. 9

Sterilized guides

Fig. 10

Correlation between Gaussian mean and RMS error for plasma sterilized guides

Fig. 11

Max distance parameter for as-printed, autoclave and plasma sterilized guides

Fig. 12

Pearson correlation matrix between analyzed metrics — a as-printed guides and b plasma-sterilized guides