Stereolithographic models for biomechanical testing

Area of Science:

• Biomedical Engineering
• Orthopedic Surgery
• Materials Science

Background:

• Cadaveric bone variability and limited availability pose challenges for implant stability testing.
• Existing artificial bone models may lack customization for specific research needs.
• Stereolithography (SLA) offers custom bone geometries but has a lower Young's modulus, potentially impacting biomechanical outcomes.

Purpose of the Study:

• To evaluate implant stability and cortical strains in SLA-made tibiae compared to stiffer artificial bone models.
• To determine if adjusting cortical thickness in SLA models can compensate for a lower Young's modulus.
• To assess the suitability of SLA tibiae as a biomechanical testing model for knee surgery.

Main Methods:

• Tibial trays were cemented into both SLA and composite artificial bone models.
• Cyclic loading was applied to the cemented trays.
• Cortical strain and tibial tray migration (permanent and cyclic) were measured.
• Analysis included the effect of material stiffness and cortical thickness on strain distribution.

Main Results:

• Tray migration in SLA models (13-28 µm permanent, 58-85 µm cyclic) fell within the range observed in composite models (4-62 µm permanent, 51-105 µm cyclic).
• Distal cortical strains showed an inverse relationship with both material stiffness and cortical thickness.
• SLA tibiae demonstrated comparable implant stability and biomechanical responses to other artificial bone models.

Conclusions:

• Stereolithography (SLA) tibiae represent a valid and promising model for the biomechanical assessment of novel knee surgery techniques.
• SLA models provide a customizable and reproducible alternative to cadaveric bone for implant research.
• The findings support the favorable comparison of SLA tibiae with previously used artificial bone models in biomechanical studies.