Design Parameter Optimization for HTPLA FDM Printed Cutting Guides in Orthopedic Surgery

3D printing enables high customization, and Fused Deposition Modelling (FDM) repre-sents a low-cost and accessible option increasingly adopted in medicine. In orthopedics, PLA patient-specific instruments (PSIs) enhance surgical precision and reproducibility, yet sterilization remains challenging for polymeric materials. Annealed HT-PLA im-proves thermal stability and mechanical performance, supporting its use for surgical cut-ting guides. This study investigates the dimensional behavior of pin holes, a key design feature in 3D printed cutting guides, with the aim of supporting proper dimensioning during the design phase. Response Surface Methodology (RSM) was applied to analyze how inner diameter and wall thickness change after annealing in HTPLA printed sam-ples. Results show that inner diameters decrease while wall thickness increases after thermal treatment. A quadratic model was developed, demonstrating that the final hole diameter depends on nominal diameter, wall thickness, and the square of the nominal diameter. These findings provide quantitative insight into the dimensional variations oc-curring during annealing and offer an initial reference for compensating shrinkage in the design of HTPLA cutting guides. These findings help establish preliminary design criteria to improve dimensional accuracy in 3D printed HTPLA PSIs, ensuring accurate hole siz-ing and stronger process robustness, ultimately supporting safer and more reliable surgi-cal application.