Multi-lobe Artificial Spine Joint Asymmetric Articulation
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Solution Overview
Problem
Existing artificial inter-vertebral discs lack stability and accurately mimic natural spinal motion, leading to increased stress on surrounding tissues, instability, and accelerated degeneration of adjacent joints, particularly when multiple discs are replaced.
Innovation Solution
An artificial disc design featuring non-congruent articulating surfaces that allow for asymmetrical and coupled movement, utilizing projections and recesses to facilitate translational and rotational movement, ensuring the joint returns to a neutral position under compressive forces, thereby reducing tissue fatigue and instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ball in cup or ball in trough design is used, then the artificial joint can provide simple replacement structure, but the joint lacks stability and requires surrounding tissues to provide support
Solution Approach 1:
The patent employs asymmetric articulating surfaces where the upper vertebral body has a convex surface and the lower vertebral body has a concave surface, creating an asymmetric joint configuration. This asymmetry provides inherent stability by ensuring that gravitational and compressive forces naturally guide the joint back to a neutral position, eliminating the need for surrounding tissues to provide stabilizing support.
2Ease of operation
If symmetrical pivotal motion is allowed, then the joint can provide simple movement capability, but the motion does not match natural spinal kinematics and causes tissue stress
Solution Approach 1:
The patent implements dynamic motion characteristics by designing the asymmetric articulating surfaces to naturally guide the joint through physiologically accurate movement patterns. The surfaces are configured so that during flexion, the vertebrae translate and rotate in a coupled manner that mimics natural spinal kinematics, reducing stress on surrounding soft tissues while maintaining ease of movement.
Solution Approach 2:
The patent changes the geometric parameters of the articulating surfaces, specifically using non-uniform curvature and asymmetric profiles. These parameter changes enable the joint to reproduce the complex coupled translations and rotations of natural spinal motion, thereby reducing harmful stresses on surrounding tissues while preserving full range of motion.
3Ease of operation
If the joint is moved from neutral position, then the joint can provide range of motion, but the joint tends to continue moving in that direction and applies un-natural stress on surrounding tissues
Solution Approach 1:
The asymmetric articulating surfaces function as a mechanical counterweight system where the geometry of the convex and concave surfaces creates restorative forces. When the joint is displaced from neutral position, the asymmetric configuration generates forces that naturally push the joint back toward neutral, providing energetic stability without restricting the available range of motion.
Data Source
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AI summary
An artificial disc is provided which more closely matches the movement of the natural spine. The artificial disc uses one or more projections and corresponding recesses to provide a sliding articulation. The artificial joint is inherently stable in that compressive forces placed on the disc such as the weight placed upon the joint or the tension of surrounding tissues urges the joint towards a neutral position and not farther away from a neutral position