Development of a novel minimally invasive scaffold system for spinal disc repair

Abstract

Debilitating chronic back pain caused by severe spinal disc degeneration leads to loss of mobility, affecting quality of life, a significant loss of productivity for the employee and the employer. Currently available surgical intervention options, such as spinal fusion and total disc replacement, seeking only to alleviate pain, are not only invasive, but fail to address the underlying biological causes of spinal disc degeneration, or restore normal physiological spinal motion. Recently proposed tissue engineering approaches focus on stopping and reversing the degenerative cascade, which has a promising regenerative effect, though not without significant challenges before a clinical application is made available, including tumourigenesis risks and proof of efficacy. A minimally invasive nucleus pulposus replacement option, which preserves the competent annulus fibrosis, while replacing the removed degenerated nucleus tissue with a prosthesis, provides an alternative for early disc degeneration, though most commercially available types are at clinical trial stages. There is an opportunity for developing a minimally invasive nucleus pulposus replacement type spinal implant system that restores disc biomechanics and addresses biological degenerative causes. This body of work details the design, development, fabrication, prototyping, verification and validation of this novel implant system. The implant system consisted of a configuration of scaffold and hydrogel interpenetrating polymer network composite delivered minimally invasively via a cannula system, after the nucleus pulposus is removed in a nucleotomy with a set of specialised tools. Implantation of the novel prosthesis was shown to be successful in various spinal disc models, in meeting identified design and functional requirements, including biomechanical loading, resistance to expulsion and radiopacity