Mobile Spinal Cage Preserving Kinematics
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Solution Overview
Problem
Current spinal fusion techniques, such as those used for degenerative disc disease, often result in unnatural motion patterns, increased degeneration of adjacent segments, and complications like spondylolysis and spondylolisthesis, while motion preservation solutions like disc arthroplasty are risky and only effective for a small percentage of patients.
Innovation Solution
A mobile cage system for posterior or lateral insertion into the intervertebral disc space, comprising a pair of caps with concave indentations and a nucleus, allowing for relative motion and preventing bone growth between the caps, thus providing support without the need for metal plates or pedicle screws, and allowing for bone ingrowth on the caps for stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spinal fusion techniques are used to treat degenerative disc disease, then stability and pain relief are achieved, but adjacent segment degeneration and unnatural motion patterns occur
Solution Approach 1:
The cage is designed with mobile features including a nucleus that can move relative to the caps, and the caps themselves can move relative to each other, allowing the implant to dynamically adapt to physiological spinal motion rather than rigidly fixing the segment. This dynamic design maintains stability while preserving natural motion patterns and reducing stress on adjacent segments
Solution Approach 2:
The cage is divided into multiple functional components (caps and nucleus) that can move independently relative to each other. This segmentation allows each component to perform its specific function while collectively providing stability, enabling the system to maintain support without preventing physiological motion
2Strength
If rigid cages are used for spinal fusion, then structural support is provided, but the need for additional fixation hardware (pedicle screws, metal rods) increases device complexity
Solution Approach 1:
The mobile cage combines multiple functions into a single implant structure that provides both structural support and motion preservation capabilities. The caps and nucleus work together as an integrated system that eliminates the need for separate fixation hardware while maintaining adequate structural support for spinal stability
3Ease of operation
If motion preservation solutions like disc arthroplasty are used, then natural spinal motion is maintained, but surgical risk increases and applicability is limited to small percentage of patients
Solution Approach 1:
The implant provides motion preservation specifically at the treated intervertebral disc space while maintaining stability through the cap-vertebrae connections. This localized approach allows natural motion to be preserved where needed without compromising overall spinal stability, making it applicable to a broader patient population than full disc arthroplasty
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 mobile cage system preserves spinal motion kinematics, reduces the risk of adjacent segment degeneration, and simplifies surgical procedures by eliminating the need for bone grafts and fusion, thereby offering a safer and more effective alternative to traditional spinal fusion methods.
Implementation Method 1
at least a portion of the first cap outer surface and at least a portion of the second cap outer surface are porous
Data Source
Figure 1~4
Figure 5A~5E
Figure 6A~8B
AI summary
A mobile cage system for restoring motion kinematics of the spine featuring a pair of opposing caps that form a cavity and a nucleus disposed in the cavity. The system allows for motion of the caps relative to the nucleus. The mobile cage system provides sufficient support so as to eliminate the need for incorporation of a metal plate or rod and pedicle screws that may be used for spinal fusions. The mobile cage system of the present invention also prevents vertical collapse of the vertebrae and complete bone fusion, and the mobile cage system helps preserve intervertebral motion of the spine.