Intervertebral Disc Prosthesis with Spherical Bearing and Elastic Member

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Solution Overview

Problem

Current intervertebral disc prosthetics are large, making anterior insertion challenging and do not accurately mimic the restricted movements of natural discs, particularly in terms of axial rotation and lateral bending.

Innovation Solution

A smaller intervertebral disc prosthesis with a left and right component, each featuring a spherical bearing surface and elastic members that allow for significant flexion/extension while restricting axial rotation and lateral bending, facilitating posterior insertion and mimicking natural disc movement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If current intervertebral disc prosthetic devices are designed with large size, then they provide sufficient structural support and bearing capacity, but they require anterior insertion approach which presents surgical challenges near the aorta and vena cava

Engineering Contradiction:

Improveprosthesis sizeVSAvoidinsertion difficulty

Core Design Contradiction:

Volume of moving objectVSEase of operation

Solution Approach 1:

The prosthesis is divided into separate superior and inferior endplate components that can be inserted independently through a posterior approach, avoiding the need for a single large anterior insertion while maintaining structural integrity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The insertion approach is inverted from the conventional anterior approach to a posterior approach, allowing smaller component-wise insertion while achieving the same structural support function

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If the prosthesis allows significant axial rotation and lateral bending, then it increases mobility, but it does not accurately mimic the restricted movements of natural discs

Engineering Contradiction:

Improvemovement freedomVSAvoidmimicry of natural disc function

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The bearing surfaces are designed with specific geometric properties (spherical superior surface, concave inferior surface) that create different degrees of freedom in different directions, allowing significant flexion/extension while restricting axial rotation and lateral bending to mimic natural disc behavior

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Spherical and concave bearing surfaces are used to create a joint geometry that naturally permits flexion/extension movement while limiting rotation and lateral bending, accurately replicating the kinematics of natural intervertebral discs

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Device complexity

If a single bearing surface is used between endplates, then the structure is simple, but it cannot provide both significant flexion/extension and restricted axial rotation and lateral bending

Engineering Contradiction:

Improvebearing surface configurationVSAvoidmovement control

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The bearing surface is segmented into multiple distinct surfaces (spherical superior bearing surface, concave inferior bearing surface) that work together to provide differential movement control in different directions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The spherical and concave bearing surfaces create a ball-and-socket-like joint that inherently provides significant rotational freedom for flexion/extension while geometrically constraining axial rotation and lateral bending

Inventive Principle:

Principle #14Spheroidality (Curvature)

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 prosthesis enables effective posterior insertion and mimics natural disc movement, providing significant flexion/extension while limiting axial rotation and lateral bending, thus addressing the challenges of current prosthetic designs.

Implementation Method 1

a left elastic member positioned between the left superior endplate and the left bearing surface

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8556973B2Intervertebral disc prosthesis having multiple bearing surfaces

Publication Date: 2013.10.15 DEPUY SYNTHES PROD INC

AI summary

An intervertebral disc prosthesis comprises a left prosthesis component and a symmetric right prosthesis component positioned in an intervertebral space. Each prosthesis component includes a superior vertebra facing surface, an inferior vertebra facing surface, and a substantially spherical bearing surface. The bearing surface is positioned between the superior vertebra facing surface and the inferior vertebra facing surface. The superior vertebra facing surface is provided on a superior endplate and the inferior vertebra facing surface is provided on an inferior endplate. The superior endplate is operable to rotate relative to the inferior endplate upon the bearing surface. Each prosthesis component further comprises an elastic member positioned between an endplate and the bearing surface. The elastic member may be substantially cylindrical with a plurality of resilient ribs. Flexion/extension, lateral bending, and torsional movement are allowed by a combination of endplate rotation upon the bearing surface and compression of the elastic member.