Spinal Prosthesis Design for Facet Joint Protection
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Solution Overview
Problem
Current artificial disc prostheses exacerbate facet joint degeneration due to increased load and motion, leading to reduced pain-free intervals and clinical success in treating degenerative spine disease, as they fail to replicate natural spinal motion and distribute stress effectively.
Innovation Solution
The development of orthopedic prostheses that replicate physiological movement, limit rotational movement, and distract facet joints to reduce aberrant contact, along with unique attachment methods and designs that minimize stress on facet joints, such as spring-loaded and keel-based systems, to maintain spinal mobility and slow facet joint degeneration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If artificial disc prosthesis are used to replace degenerated discs, then spinal mobility is preserved, but facet joint degeneration accelerates due to increased load and motion
Solution Approach 1:
The prosthesis employs different materials and structural properties in different regions: the central disc portion uses mobile materials to preserve spinal motion, while the peripheral regions incorporate stress-shielding features and facet joint distractions to protect against degeneration. The asymmetric design provides localized stress distribution that mimics natural disc function while protecting facet joints.
Solution Approach 2:
The prosthesis incorporates dynamic elements including mobile disc portions that allow controlled motion, spring-loaded mechanisms that adapt to loading conditions, and adjustable facet joint distractions that respond to movement. This dynamic design enables the prosthesis to preserve spinal mobility while adapting to reduce facet joint stress during various motion states.
2Object-affected harmful factors
If complete immobilization and bony fusion are performed, then pain from degenerative disc disease is relieved, but the load on adjacent spinal segments increases and accelerates their degeneration
Solution Approach 1:
The prosthesis divides the spinal segment into functionally independent portions: a mobile central disc portion that maintains motion, and peripheral stress-shielding regions that protect adjacent segments. This segmentation allows pain relief at the treated level while preserving motion and reducing load transmission to adjacent segments, preventing the cascade of degeneration that occurs with complete fusion.
Solution Approach 2:
The prosthesis acts as an intermediary structure between adjacent spinal segments, providing stress-shielding features and facet joint distractions that mediate the mechanical interaction. This intermediary design relieves pain at the treated level while protecting adjacent segments from excessive load, preventing the need for extension of fusion to neighboring levels.
3Ease of operation
If artificial disc prosthesis increase rotational freedom, then spinal motion is restored, but facet joint stress increases leading to faster joint degeneration
Solution Approach 1:
The prosthesis provides localized rotational freedom in the central disc region while constraining or distracting the peripheral facet joints. The asymmetric design allows motion where needed while applying stress-shielding features and facet joint distractions at locations where motion would increase stress, creating local quality variations that balance motion restoration with stress reduction.
Solution Approach 2:
The prosthesis incorporates dynamic facet joint distractions that adjust to motion conditions, and spring-loaded mechanisms that modulate stress transmission. These dynamic features allow the prosthesis to restore spinal motion while adaptively reducing facet joint stress during various motion states, preventing the accelerated degeneration that occurs with rigid rotational freedom.
Data Source
AI summary
A mobile device is adapted to at least partially replace the motion characteristics of a natural inter-vertebral disc positioned in a disc space. In an embodiment, a receptacle is coupled to the bearing surface. The receptacle is adapted to accept an implantable material without the removal of the bearing surface, wherein the implantable material contacts the abutment surface of each of the vertebral bodies adjacent to the disc space and leads to fusion and immobilization of two vertebral bodies adjacent the disc space.