Neudisc™ Anisotropic Synthetic Hydrogel For Nucleus Replacement

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Anthony T. Yeung M.D.


Address:
Pheonix
AZ

Ann Prewett Ph.D.


Address:
Cranbury
NJ

James Yue M.D.


Address:
New Haven
CT

Citation: A. T. Yeung, A. Prewett & J. Yue : Neudisc™ Anisotropic Synthetic Hydrogel For Nucleus Replacement . The Internet Journal of Minimally Invasive Spinal Technology. 2008 Supplement I - to IJMIST Vol 1 No 2

Abstract

Purpose: Nucleus replacement is a new and rapidly emerging surgical treatment that aims to reduce discogenic pain by restoring the function of a normal nucleus. This technology may provide a minimally invasive surgical alternative earlier in the degenerative cascade than total disc replacement and fusion. We will present the clinical findings, and preliminary results of a concurrent pilot study..
Method: The NeuDisc™ device is a biocompatible hydrogel implant currently under clinical investigation. NeuDisc™ is comprised of a hydrolyzed polyacrylonitrile hydrogel that is pre-formed, requires no mixing or polymerization steps at the time of surgical introduction ,and may be inserted through a 6 mm annulotomy. The implant has been subjected to extensive pre-clinical testing. Mechanical tests were performed to evaluate essential properties of the implant including resistance to fatigue and extrusion. Preclinical tests followed ISO 10993 guidelines and included both chronic and short term animal implantation tests. Confined and unconfined cyclic durability testing was conducted out to 30 million cycles in uni-axial and multi-axial loading schemes. Range of motion and extrusion testing was performed in cadavers. Test fluid was collected and examined for presence of wear particulate. A cadaveric study determined that because of its size and configuration, aided by specialized implantation instrumentation, the Neudisc™ is compatible for implantation using all established surgical portals that include posterior, postero-lateral, lateral, and anterior-lateral approaches. A lateral (ALPA) clinical pilot study and concurrent endoscopic postero-lateral study were subsequently initiated.
Findings: The hydrated elliptically shaped implant closely approximates the size and shape of the nuclear cavity. Chemical and mechanical properties of the implants were closely similar to controls following cyclic fatigue testing. Biocompatibility testing in accordance with ISO 10993 showed the materials to be non-toxic and well-tolerated by host tissues. Mechanical and biomechanical testing shows no evidence of device failure under loads and strains exceeding physiologic exposure. The presence of wear particulate was minimal to non-detectable. Preliminary concurrent clinical studies demonstrate significant improvement in VAS and Oswestry scores, and maintenance and improvement of disc height with re-hydration of the nucleus in post-operative MRIs. There were no extrusions.
Conclusion: Fatigue, wear and biocompatibility tests showed favorable results. Bench-top and biomechanical cadaveric tests on lumbar motion segments suggest that the NeuDisc™ implant may be a sutible nucleus replacement device. The size of the dehydrated implant makes it compatible for all standard surgical approaches, including posterior, postero-lateral, and lateral. The indications and potential of NeuDisc™ for discogenic pain and post-discectomy nucleus replacement may have a greater range of indications than total disc replacement.

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