3D-Printed Plantar Orthoses and the Conditional Viability of Recycled PLA

Area of Science:

• Biomaterials Engineering
• Podiatric Biomechanics
• Additive Manufacturing

Background:

• Plantar orthoses are crucial in podiatric care for load redistribution and treating conditions like diabetic foot disease.
• Additive manufacturing (3D printing) enables customized orthoses by integrating digital design and fabrication.
• 3D-printed orthoses can mimic foot biomechanics, offering load redistribution, shock absorption, and gait stabilization.

Purpose of the Study:

• To review the conditional viability of recycled polylactic acid (rPLA) for 3D-printed plantar orthoses.
• To integrate direct clinical evidence with indirect technical data on rPLA's use in orthotics.
• To assess the environmental, economic, and technical aspects of using rPLA in custom orthotic devices.

Main Methods:

• Literature review integrating clinical evidence on orthotic function with material-level and process-level studies.
• Analysis of studies on extrusion-based 3D printing technologies for customized insoles and advanced structures.
• Evaluation of rPLA's properties, including viscosity, dimensional consistency, and mechanical reliability after reprocessing.

Main Results:

• Recycled PLA offers potential environmental and economic advantages for 3D-printed orthoses.
• Repeated thermomechanical reprocessing of rPLA can negatively impact material properties like viscosity and interlayer adhesion.
• Current 3D-printed orthosis developments predominantly use virgin materials, with limited use of recycled feedstocks.
• Evidence for rPLA in plantar orthoses is primarily indirect and technical, not directly clinical.

Conclusions:

• Recycled PLA is not yet a direct substitute for virgin PLA in plantar orthoses.
• The technical promise of rPLA is conditional, requiring feedstock traceability and process control.
• Clinical validation is essential to confirm the functional suitability and reliability of rPLA-based plantar orthoses.