An Insight into the Characteristics of 3D Printed Polymer Materials for Orthoses Applications: Experimental Study

Area of Science:

• Biomedical Engineering
• Materials Science
• Orthotics and Prosthetics

Background:

• Knee orthoses improve gait and alleviate pain in patients with knee abnormalities.
• Traditional plaster molding for orthoses is labor-intensive and time-consuming.
• 3D printing offers a promising alternative to traditional methods for custom orthosis fabrication.

Purpose of the Study:

• To investigate the mechanical, physical, and dimensional properties of five 3D printing materials (PLA, ABS, PETG, TPU, PP).
• To assess the suitability of these materials for fabricating knee orthoses.
• To provide data-driven recommendations for material selection in 3D printed knee orthosis design.

Main Methods:

• Characterization of 3D printing materials using tensile testing.
• Microscopic imaging with an Olympus microscope.
• Water absorption studies.
• Dimensional analysis using a coordinate measuring machine.

Main Results:

• Polylactic acid (PLA) exhibited the highest yield strength (25.98 MPa), tensile strength (30.89 MPa), and lowest shrinkage (0.46%).
• Polypropylene (PP) demonstrated the lowest water absorption (0.15%) and highest flexibility (407.99%) but posed fabrication challenges.
• Specific material recommendations were made for different knee orthosis components: PLA for frames, PLA/ABS for hinges, PP for padding, and TPU/PP for straps.

Conclusions:

• PLA is a strong candidate for the structural components of 3D printed knee orthoses due to its mechanical properties and low shrinkage.
• Material selection for 3D printed knee orthoses should consider a balance of mechanical strength, flexibility, water resistance, and fabricability.
• This research offers valuable insights for material selection in the development of effective and customized 3D printed knee orthoses.