A biomechanical testing method to assess tissue adhesives for annulus closure

Area of Science:

• Biomaterials Science
• Biomechanics
• Orthopedic Research

Background:

• Low Back Pain (LBP) is a global health issue linked to intervertebral disc (IVD) degeneration.
• Annulus fibrosus (AF) tearing and nucleus pulposus (NP) herniation are key features of IVD degeneration.
• Current therapies for AF defects are limited and can increase reherniation risk.

Purpose of the Study:

• To develop and validate a biomechanical testing method for assessing bioadhesive performance in sealing AF tears.
• To evaluate two candidate bioadhesives: a tough hydrogel and a cyanoacrylate glue.

Main Methods:

• Quantified adhesion energy of a tough hydrogel adhesive using peel tests on bovine discs.
• Developed an experimental method to measure IVD burst pressure.
• Measured burst pressure of intact, injured (AF punctured), and bioadhesive-sealed IVDs.

Main Results:

• The tough hydrogel adhesive demonstrated strong adhesion energy (239 ± 49 J/m²).
• IVD burst pressure significantly decreased after injury (13.2 ± 3.8 MPa to 5.1 ± 1.5 MPa).
• The tough hydrogel adhesive restored burst pressure to levels comparable to intact discs (12.3 ± 4.5 MPa), while cyanoacrylate glue did not.

Conclusions:

• A novel biomechanical burst pressure method effectively assesses bioadhesives for AF tear sealing.
• A tough hydrogel adhesive shows promise for sealing AF injuries, restoring IVD structural integrity.
• This method offers a valuable tool for evaluating bioadhesives under high loading conditions before clinical application.