Additively Manufactured Patient-Specific Trabecular Bone Imitations in Anatomical Bone Models for Preoperative...

Additively manufactured (3D-printed) anatomical bone models are used for medical education and surgical training. Manufacturing of patient-specific anatomies and rare pathologies has improved rapidly in the recent past, enabling training opportunities that were previously restricted to limitedly available anatomic specimens. However, the imitation of patient-specific trabecular bone in additively manufactured bone models remains complex and thus inadequately addressed.

Test specimens in the form of Gyroid and Voronoi lattice cubes were manufactured via fused filament fabrication (FFF)-printing at varying densities with polylactide, polylactide /carbon fiber composite and polyamide /glass fiber composite filaments, and submerged in gelatin. Additionally, trabecular bone test cubes were removed from bovine femoral specimens, and the bone mineral density (BMD) was assessed utilizing quantitative computed-tomography (QCT). Subsequently, haptic drill resistance of all test cubes was evaluated by four orthopedic and trauma surgeons, and the mechanical drill resistance was assessed using a load frame.

Multiple polymer lattice structures and material configurations were evaluated by the surgeons as suitable to mimic actual trabecular bone (Likert ratings between 2.60 and 3.00). Regression analyses of the surgeons' evaluations of both the trabecular bone (R² = 0.82) and the polymer lattice cubes (0.66 ≤ R² ≤ 0.89) enabled the extraction of practical manufacturing parameters linking them with patient-specific BMD.

The imitation of trabecular bone models via FFF-printing is feasible and could substantially enhance the haptic feedback in additively manufactured anatomical bone models. Applying the presented manufacturing framework enables the cost- and time-efficient production of patient-specific anatomical models to enhance preoperative planning and surgical training.