Percutaneous Nuclear Prosthesis with Expandable Fiber Ring
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Solution Overview
Problem
Existing methods for replacing the nucleus pulposus with artificial spinal discs face issues such as inadequate access, sealing, and material durability, leading to leakage, subsidence, and migration, and fail to restore disc space height and maintain spinal stability.
Innovation Solution
A percutaneously deployable intervertebral disc implant made of a hollow ring-like synthetic fiber graft filled with a curable elastomer, featuring a one-way valve to prevent leakage and an expandable design that maintains disc height and stability, with a buffer zone for inward deformation to reduce stress on vertebral end plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hard materials are used in the implant, then structural strength is improved, but deformability and compressibility deteriorate
Solution Approach 1:
The implant uses a composite structure combining a resilient elastomeric material for the main body with a separate compressible annular portion. This composite approach allows the elastomeric material to provide structural strength while the compressible portion provides deformability and compressibility, resolving the contradiction between strength and adaptability.
Solution Approach 2:
The implant is divided into functionally distinct segments: a resilient elastomeric material portion that provides structural support and an separate compressible annular portion that provides deformability. This segmentation allows each part to optimize its specific function without compromising the other, enabling both strength and compressibility.
2Reliability
If a non-compressible center bearing portion is used, then resistance to migration is improved, but risk of subsidence increases
Solution Approach 1:
The implant features local quality differentiation with a compressible annular portion at the periphery and a resilient elastomeric material in the center. The peripheral compressible portion accommodates vertebral end plate deformation to prevent subsidence, while the central resilient portion provides migration resistance, allowing each region to have optimized properties for its specific function.
3Adaptability or versatility
If the annulus fibrosus is damaged, then disc replacement is necessary, but device functionality deteriorates with damaged annulus
Solution Approach 1:
The implant includes a flexible compressible annular portion that can adapt to the damaged annulus fibrosus condition. This flexible annular structure provides structural support and stability even when the native annulus is compromised, allowing the device to function effectively in patients with annular damage who would otherwise be poor candidates for disc replacement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implant provides durable, long-lasting spinal support, maintains disc space height, and reduces degenerative processes by stabilizing the spinal segment while preserving normal motion, thus alleviating pain and preventing further instability.
Implementation Method 1
filled with a curable elastomer
Implementation Method 2
a one-way valve to allow elastomer to be injected into the graft while preventing backflow
Implementation Method 3
an expandable design that maintains disc height and stability
Implementation Method 4
Various techniques have been proposed for disc space distraction, including mechanical and hydrostatic techniques
Implementation Method 5
an interior cavity that allows inward deformation of the elastomer within the ring-like fiber graft
Implementation Method 6
The cured elastomer within the fiber graft provides torsional and compression stability. Thus, regardless of how loads are applied, the vectors of forces are substantially redirected centrally toward the interior cavity.
Data Source
AI summary
A prosthesis for implantation in a de-nucleated intervertebral disc includes a fiber ring-like layer which encloses a polymeric layer to create an annular space. The annular space is inflatable with an in-situ curable liquid polymer and forms an interior cavity. The annular space may be expanded uniformly or differentially to be tailored to the needs of a particular vertebral segment and to achieve optimal disc space width and angle, thereby stabilizing the segment while preserving normal motion of the vertebral segment. The interior cavity provides a void that allows inward deformation of the implant during weight bearing activities and bending. The prosthesis can be elastically deformed through axial elongation to a reduced profile to load into a delivery cannula using pulling techniques.