Spinal Implant Rolling Contact Core Flexure Motion
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Solution Overview
Problem
Current spinal fusion treatments often fail to provide long-term relief for back pain and can lead to degeneration in adjacent spinal segments due to restricted motion and increased stress on adjacent discs and facet joints, while existing intervertebral disc prostheses typically only allow motion in one or two axes, limiting natural spinal movement.
Innovation Solution
A spinal implant with rolling-contact cores and flexures that allow for motion in three axes (flexion-extension, lateral extension/bending, and axial rotation), mimicking the natural kinematics and kinetics of a healthy spine, reducing stress on diseased segments and maintaining the health of adjacent spinal structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If spinal fusion is performed to stabilize the spine and relieve back pain, then stability and pain relief are improved, but motion in the spinal segment is restricted and stress on adjacent spinal segments increases leading to degeneration
Solution Approach 1:
The spinal implant uses dynamic flexures instead of rigid fusion structures, allowing the implant to adapt its stiffness and motion characteristics based on the applied loads. The flexures enable controlled motion in multiple directions while maintaining stability, resolving the contradiction between spinal stability and ease of operation (motion).
Solution Approach 2:
The implant changes the mechanical parameters of the spinal segment by introducing compliant flexures that can deform elastically under load. This transforms the rigid stability of fusion into a dynamic stability that permits physiological motion, thereby improving both spinal stability and maintaining spinal motion simultaneously.
2Ease of operation
If existing intervertebral disc prostheses are used to maintain motion, then motion in one or two axes is preserved, but natural three-axis spinal movement is limited
Solution Approach 1:
The implant adds a third dimension of motion capability by incorporating flexures that enable rotation about three orthogonal axes (x, y, and z axes). This transforms the limited one or two-axis motion of existing prostheses into comprehensive three-axis spinal movement, improving adaptability and versatility while maintaining ease of operation.
Solution Approach 2:
The flexure-based structure serves multiple functions simultaneously: it allows flexion-extension, lateral bending, and axial rotation, making the implant universally applicable to restore natural spinal kinematics in all directions, thereby enhancing the range of motion while preserving ease of operation.
3Object-affected harmful factors
If spinal fusion restricts motion to provide stability, then pain relief is improved, but adjacent spinal segments undergo increased stress and degeneration
Solution Approach 1:
The implant extracts the destabilizing element (degenerate disc) while preserving the stabilizing function through compliant flexures. By removing only the diseased disc and replacing it with a motion-preserving prosthesis rather than performing fusion, the implant relieves back pain while preventing the transmission of excessive stresses to adjacent segments, thereby protecting adjacent segment health.
Solution Approach 2:
The implant converts the harmful lack of support from disc degeneration into a beneficial motion-preserving structure. The flexures are designed to be compliant under physiological loads, transforming the potential harm of instability into a beneficial dynamic support system that protects adjacent segments while relieving pain.
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 spinal implant restores natural spinal movement, reducing muscle fatigue and pain by allowing motion similar to a healthy spine, while minimizing the risk of degeneration in adjacent segments and maintaining effective range of motion for muscles and tendons.
Implementation Method 1
a first rolling-contact core that is operably coupled to the first vertebra. The rolling-contact core includes a convex surface having a first axis, the convex surface providing a rolling motion in a first direction to the vertebra coupled to the rolling-contact core relative to a second vertebra
Implementation Method 2
At least one flexure optionally connected to the first rolling-contact core constrains, at least in part, the rolling motion of the first rolling-contact core
Data Source
AI summary
A spinal implant includes a first rolling-contact core operably coupled to a first vertebra, said first rolling-contact core having a first convex surface having a first axis, said first convex surface configured to provide a first rolling motion in a first direction to said first vertebra relative to a second vertebra. At least one flexure is connected to said first rolling-contact core, said flexure configured to constrain said first rolling motion.