Interface Performance Enhancement in 3D-Printed Biphasic Scaffolds with Interlocking Hourglass Geometry.

Area of Science:

• Biomedical Engineering
• Regenerative Medicine
• Materials Science

Background:

• Ginglymus joints (e.g., knee, elbow, TMJ) experience unidirectional shear and orthogonal compression.
• Biphasic scaffolds for joint repair must withstand these complex biomechanical loads.
• Existing scaffold designs may not adequately address the specific mechanical demands of hinge joints.

Purpose of the Study:

• To computationally design and empirically evaluate a 3D-printed biphasic scaffold with enhanced biomechanical performance for ginglymus joints.
• To introduce a novel sinusoidal hourglass tube geometry to improve shear stress support and orthogonal compression resistance.
• To assess the scaffold's performance under various loading conditions compared to a standard crosshatch design.

Main Methods:

• Computational modeling was used to design a 3D-printed polylactic acid (PLA) hourglass scaffold.
• The scaffold interface was infilled with hydrogels (agarose or pentenoate-modified hyaluronic acid, polyethylene glycol diacrylate, and devitalized cartilage).
• Biphasic constructs and the hourglass architecture alone were tested under shear and compression using empirical and in silico methods.

Main Results:

• The PHA-PEGDA-DVC hydrogel-infilled scaffold achieved ultimate interface shear stresses up to 51 ± 7 kPa, outperforming the crosshatch control.
• The hourglass architecture alone demonstrated a 39% higher ultimate compressive stress (6.9 ± 1.8 MPa) in the 3-direction compared to the crosshatch design.
• Computational modeling indicated geometry-dependent shear load transfer, supporting the hourglass design's effectiveness.

Conclusions:

• The 3D-printed hourglass biphasic scaffold design significantly enhances biomechanical performance under shear and compression relevant to ginglymus joints.
• This novel geometry offers improved load transfer at the hydrogel-substrate interface and superior compressive strength.
• The enhanced hourglass design holds promise for future applications in regenerating tissues within hinge joints.