Dynamic-mechanical properties of a novel composite intervertebral disc prosthesis

Area of Science:

• Biomaterials Science
• Orthopedic Engineering
• Polymer Chemistry

Background:

• Current intervertebral disc (IVD) prostheses often fail due to mechanical property mismatches with spinal segments.
• Developing IVD replacements with appropriate biological, mechanical, and transport properties remains a significant challenge.

Purpose of the Study:

• To engineer a novel poly(2-hydroxyethyl methacrylate)/poly(methyl methacrylate) (PHEMA/PMMA) semi-interpenetrating polymer network (s-IPN) composite hydrogel reinforced with poly(ethylene terephthalate) (PET) fibers.
• To investigate the static and dynamic mechanical properties of the developed composite IVD prostheses.

Main Methods:

• Utilized filament winding and moulding technologies to fabricate composite IVD prostheses mimicking natural IVD structure.
• Conducted compressive properties analysis, including static and dynamic mechanical testing.
• Performed fatigue testing for ten million cycles in a physiological solution.

Main Results:

• The composite IVD prostheses exhibited a J-shaped stress-strain curve, characteristic of natural IVDs.
• Compressive modulus ranged from 84 to 120 MPa, with stress exceeding 10 MPa, aligning with natural lumbar IVD values.
• No failure was observed during a ten-million-cycle fatigue test, indicating excellent durability.

Conclusions:

• The developed PHEMA/PMMA/PET composite hydrogel s-IPN exhibits promising mechanical properties for IVD replacement.
• The fabrication method successfully replicated the complex structure of natural IVDs.
• The composite IVD prostheses demonstrate suitable viscoelastic properties and superior fatigue resistance for potential clinical application.