Artificial Intervertebral Joint with Gradient Elasticity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current spinal arthroplasty devices fail to effectively address degenerative changes, facet pain, and spondylolisthesis while maintaining natural spinal motion, often leading to further deterioration at adjacent levels.
Innovation Solution
An artificial intervertebral joint comprising arthroplasty subcomponents with spacers and retaining portions made from biocompatible materials, featuring varying moduli of elasticity and keels for stabilization, allowing limited motion while promoting bone ingrowth, and designed for insertion via posterior or anterior approaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spinal arthrodesis (spine fusion) is performed to eliminate motion at the affected level, then immediate symptoms are alleviated, but further deterioration of adjacent levels occurs over time
Solution Approach 1:
The prosthesis enables dynamic motion at the replaced intervertebral level through articulation between the upper and lower articulating surfaces, allowing flexion, extension, lateral bending, and axial rotation. This dynamic capability prevents the transfer of excessive motion stresses to adjacent levels that would occur with rigid fusion, thereby preventing adjacent level deterioration while providing reliable symptom relief.
Solution Approach 2:
The prosthesis utilizes materials with specific elastic moduli matched to bone density (higher modulus for endplates, lower modulus for core members) to optimize load distribution and stress transfer characteristics. This parameter optimization allows the prosthesis to maintain stability and provide symptom relief while preserving physiological motion at adjacent levels.
2Ease of operation
If an artificial disc is used to maintain motion at the joint, then patient mobility is preserved, but the device fails to address facet pain and spondylolisthesis effectively
Solution Approach 1:
The prosthesis performs multiple functions simultaneously: the articulating surfaces maintain spinal motion and reduce friction, the core members with varying moduli provide structural support and load distribution, the keels prevent spondylolisthesis through posterior engagement, and the overall design addresses facet pain by redistributing loads. This multi-functionality allows the device to preserve mobility while effectively treating facet pain and spondylolisthesis.
Solution Approach 2:
The prosthesis employs composite construction with core members of varying moduli (softer central portion, harder outer portions) and different materials (metal, ceramic, polymer combinations) to simultaneously achieve motion preservation through elastic deformation and reliable support for treating facet pain and spondylolisthesis through rigid structural elements.
3Reliability
If solid fusion is performed to eliminate motion, then immediate symptom relief is achieved, but device complexity increases and adjacent level deterioration is caused
Solution Approach 1:
The prosthesis is divided into functionally independent segments: upper endplate, lower endplate, and core members. This segmentation allows each component to be optimized for its specific function (load bearing, motion control, structural support) while simplifying the overall implantation procedure compared to complex fusion constructs, and provides reliable symptom relief through targeted functional optimization.
4Strength
If a rigid prosthesis is used to provide mechanical support, then structural stability is improved, but natural spinal motion and wear characteristics deteriorate
Solution Approach 1:
The prosthesis applies local quality differentiation through core members with varying moduli (softer central portion for motion and wear reduction, harder outer portions for structural support) and endplates with higher modulus for load bearing. This localized property optimization allows the prosthesis to provide necessary mechanical support while preserving natural spinal motion and reducing wear at critical articulating surfaces.
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 artificial intervertebral joint provides mechanical support, maintains natural spinal motion, and reduces wear debris, minimizing the risk of adjacent level deterioration and locking or dislocation, while allowing for a range of motions with variable centers of rotation.
Implementation Method 1
The spacer 51 may have a dual modulus of elasticity... The dual moduli of the spacer 51 allows the spacer 51 to be stiff in axial compression while still providing a dampening effect. Also, the dual moduli of the spacer 51 allows the spacer 51 to be soft enough to allow motion in flexion/extension, axial rotation, and lateral bending.
Implementation Method 2
Additionally, the superior keel may include a catch so as to help further secure the superior component to the superior vertebra 7a.
Data Source
Figure 1~2
Figure 3
Figure 4~6
AI summary
An artificial vertebral joint for interposition between a superior vertebra and an inferior vertebra comprises a pair of bilateral joint subcomponents. Each joint subcomponent includes a superior component including a superior vertebra engaging surface and an inferior component including an inferior vertebra engaging surface. Each joint subcomponent further includes a spacer extending between the superior component and the inferior component. The spacer includes a first modulus of elasticity and a second modulus of elasticity. The first modulus transitions to the second modulus with a gradient change.