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Dynamically Crystalizing Liquid‐Crystal Elastomers for an Expandable Endplate‐Conforming Interbody Fusion Cage
Author(s) -
Volpe Ross H.,
Mistry Devesh,
Patel Vikas V.,
Patel Ravi R.,
Yakacki Christopher M.
Publication year - 2020
Publication title -
advanced healthcare materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.288
H-Index - 90
eISSN - 2192-2659
pISSN - 2192-2640
DOI - 10.1002/adhm.201901136
Subject(s) - materials science , fusion , elastomer , cage , composite material , spinal fusion , modulus , biomedical engineering , fabrication , structural engineering , surgery , medicine , philosophy , linguistics , alternative medicine , pathology , engineering
Degenerative disc disease (DDD) is the leading cause of low back pain and radiating leg pain. DDD is commonly treated surgically using spinal fusion techniques, but in many cases failure occurs due to insufficient immobilization of the vertebrae during fusion. The fabrication and demonstration of a 3D‐printed semi‐crystalline liquid crystal elastomer (LCE) spinal fusion cage that addresses these challenges in particular subsidence are described. During implantation of the fusion cage, the LCE is rubbery and capable of deforming around and conforming to delicate anatomy. In the hours following implantation, the device crystallizes into a rigid, structural material with the modulus increasing tenfold from 8 to 80 MPa. In the crystalline regime, a 3D‐printed prototype device is capable of enduring 1 million cycles of physiologic compressive loading with minimal creep‐induced ratcheting. Effects of LCE molecular architecture on the rate and magnitude of modulus increase, material processability, and mechanical properties are explored. This fundamental characterization informs a proof‐of‐concept device—the first bulk 3D printed LCE demonstrated to date. Moreover, the novel deployment strategy represents an exciting new paradigm of spinal fusion cages, which addresses real clinical challenges in expandable interbody fusion cages.