Modular Nucleus Pulposus Prosthesis for Spinal Motion Preservation
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Solution Overview
Problem
Current spinal disc prostheses have limitations in long-term effectiveness, often leading to degeneration of adjacent natural disc parts and increased loading on facet joints, resulting in short-term relief with potential for long-term deterioration and complications such as osteoarthritis and foraminal stenosis.
Innovation Solution
A spinal disc endoprosthesis with 'yin-yang' shaped segments made of biocompatible materials, designed to mimic the natural disc's motion and stiffness, allowing for secure implantation and integration with the vertebral body, reducing the need for mechanical hinges and promoting bone growth, while maintaining natural spinal biomechanics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current spinal disc prostheses are used to replace degenerated discs, then short-term relief from symptoms is achieved, but long-term effectiveness deteriorates due to degeneration of adjacent natural disc parts and increased loading on facet joints
Solution Approach 1:
The prosthesis is divided into three distinct segments: an upper plate, a lower plate, and a nucleus pulposus implant positioned between them. This segmentation allows each component to perform its specific function - the plates provide structural support and motion control while the nucleus implant restores disc height and distributes loads, thereby preventing adjacent segment degeneration and improving long-term effectiveness
Solution Approach 2:
The nucleus pulposus implant is nested within the space created by the upper and lower plates. The plates are positioned against the vertebral bodies and the nucleus implant is inserted into the intervertebral space between them, creating a nested configuration that restores natural disc anatomy and biomechanics, reducing harmful loads on adjacent segments
2Stability of the object's composition
If spinal fusion procedures are performed to treat disc degeneration, then stability is improved, but motion is lost and adjacent segment degeneration accelerates
Solution Approach 1:
The prosthesis incorporates a nucleus pulposus implant made of viscoelastic material that dynamically responds to compressive and tensile loads, allowing the spinal segment to maintain physiological motion while the plates provide stable anchoring to the vertebral bodies, thus achieving both stability and motion preservation
Solution Approach 2:
The nucleus implant is designed to change its physical parameters - becoming more rigid under compression and more flexible under tension - to mimic natural disc behavior. This parameter change allows the prosthesis to provide stability when needed while maintaining motion capability, preventing adjacent segment degeneration
3Ease of operation
If mechanical hinges are used in disc prostheses to maintain motion, then spinal mobility is preserved, but device complexity increases and bone growth is inhibited
Solution Approach 1:
The prosthesis replaces complex mechanical hinge systems with a simpler configuration of plates and a viscoelastic nucleus implant. The motion control is achieved through the material properties and geometric configuration of the nucleus implant rather than mechanical hinges, reducing device complexity while maintaining spinal mobility and promoting bone growth
4Object-generated harmful factors
If the nucleus pulposus is removed during discectomy, then herniated disc symptoms are relieved, but disc height is lost and adjacent vertebrae put pressure on spinal nerves
Solution Approach 1:
The nucleus pulposus implant is pre-formed with the appropriate size and shape to maintain disc height. During surgery, after removal of the herniated nucleus material, the implant is inserted into the prepared space, preliminarily restoring disc height and preventing vertebral collapse before the patient leaves the operating room, thereby avoiding nerve compression
Data Source
AI summary
At least two substantially identical generally mirror image complimentary disc segments combined to form a generally discoid endoprosthetic disc and associated tools and methods for replacing the intervertebral disc. Complimentary disc segments include outer circumferential walls roughly equal to a semi-circle aligned along concave-convex inner wall inner walls forming an “s”- shaped common border to provide a generally symmetrical discoid congruent structure which is positioned within the annulus of a spinal disc section. Disc segments may include structures to support, position and secure the segments to one another intradiscally. Surgical tools include structures for inserting and aligning disc members together. Also disclosed is a system and method for replacing the nucleus pulposus using the surgical tools adapted for placement and alignment of the disc.