Vertebral Insert Anchoring Nucleus Disc Implant
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Solution Overview
Problem
Nucleus disc replacement devices face challenges in maintaining position within the annulus of a spinal disc due to the soft and pliable materials used, which can lead to expulsion through existing fissures or openings, especially in degenerated annulus conditions.
Innovation Solution
The development of a vertebral body insert device with a bone-engaging portion and a mating portion that interacts with a nucleus disc replacement implant to prevent expulsion, featuring configurations such as threaded shanks, wire extensions, or ring-shaped members to securely anchor the implant within the annulus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If soft and pliable biopolymer materials (hydrogel) are used to closely mimic the native nucleus, then the device can elastically deform during normal activities and allow motion, but the device can potentially squeeze out of the opening(s) formed in the annulus and used to introduce the NDR
Solution Approach 1:
The NDR device is nested within a containment structure that includes an outer containment wall and an inner containment wall. The inner containment wall is positioned within the outer containment wall, creating a nested configuration that provides multiple barriers to prevent device expulsion while allowing the soft biopolymer material to deform elastically.
Solution Approach 2:
The containment walls are designed as flexible structures that can deform with the soft biopolymer material while maintaining the containment function. The flexible shell structure allows motion and elastic deformation of the NDR device while preventing expulsion through the annular opening.
2Reliability
If the containment wall of the NDR is designed to fit within the annulus, then the device can be contained, but the degenerated annulus has existing fissures or will develop fissures in which the NDR device can expulse over time
Solution Approach 1:
The dual containment wall structure is designed beforehand to account for potential annular fissures and degeneration. The inner and outer containment walls work together to provide redundant containment, cushioning against the risk of expulsion through existing or future fissures in the degenerated annulus.
Solution Approach 2:
The containment structure uses composite design with an outer containment wall and an inner containment wall made of different structural configurations. This composite approach provides enhanced reliability and resistance to expulsion through fissures compared to a single-wall structure.
3Reliability
If a TDR procedure is performed to replace all disc tissue, then a stable replacement device can be implanted, but the procedure is more time consuming and poses more risk and loses functionality of surrounding structures
Solution Approach 1:
The invention extracts only the nucleus portion of the disc for replacement, leaving the annulus intact. This selective extraction approach maintains the functionality of surrounding structures and reduces surgical complexity compared to total disc replacement, while the dual containment wall structure provides the necessary stability for the replaced nucleus.
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 solution effectively prevents the expulsion of nucleus disc replacement implants by providing a mechanical interlock with the insert device, ensuring stable positioning and maintaining the disc space height, thus mimicking the natural nucleus's load-bearing and motion functions.
Implementation Method 1
One such material is called hydrogel, which expands as it absorbs water. The device is placed into the nucleus cavity of the disc and hydrates to expand and fill the cavity.
Implementation Method 2
The shank can be threaded for mating to bone
Implementation Method 3
The device is flexible or compressible and by this means, allows motion, much like a natural disc nucleus. In particular, the device can elastically deform during normal activities (axial loading, flexion, extension).
Data Source
AI summary
Methods and devices are provided for replacing a nucleus of a spinal disc, and in particular for preventing nucleus disc replacement expulsion. The nucleus of a spinal disc can be removed from the annulus by forming a small opening in the annulus. Once the nucleus is removed, one or more insert devices can be implanted within the annulus of a spinal disc and they can be mated to one or both endplates of the adjacent vertebrae. The insert(s) is configured to interact with a nucleus disc replacement implant to prevent expulsion of the implant from the annulus.