Spinal Prosthesis Flexure Limiter with Pre-Shaped Bends
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Solution Overview
Problem
Existing spinal prostheses fail to effectively limit excessive flexure in the spine, leading to undesired anatomy, loss of mobility, and pain due to conditions like spinal stenosis and spondylosis, which cause the vertebrae to misalign and pinch the spinal cord or nerves.
Innovation Solution
A spinal prosthesis with a flexure limiting member, comprising slim elongate members with pre-shaped bends and attachment elements, is designed to restrict angular movement between articulating members, specifically limiting omnidirectional flexure about the lateral-medial axis, using biocompatible materials like stainless steel, titanium, or compliant elastomeric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spinal prosthesis allows omnidirectional flexure to maintain mobility, then patient mobility is improved, but excessive flexure causes vertebrae misalignment and pinching of spinal cord or nerves
Solution Approach 1:
The flexure limiting member changes the flexure parameter by introducing a mechanical constraint that limits the angular distance of movement between articulating members. The pre-shaped bends in the elongate member create a geometric constraint that allows flexure within a safe range while blocking excessive movement that would cause misalignment and nerve pinching.
Solution Approach 2:
The flexure limiting member acts as an intermediary element between the first and second articulating members. This intermediate component mediates the interaction between the articulating members by providing a controlled flexure path through its pre-shaped bends, allowing movement while preventing harmful excessive flexure.
2Reliability
If the flexure limiting member uses pre-shaped bends to limit angular movement, then excessive flexure is restricted, but the device complexity increases
Solution Approach 1:
The flexure limiting member is segmented into multiple functional portions: slim elongate members with pre-shaped bends, attachment elements at ends, and integration points with articulating members. This segmentation allows each component to perform its specific function while maintaining overall simplicity.
Solution Approach 2:
The flexure limiting member utilizes pre-shaped bends and curved geometries in the elongate members to create the flexure limitation function. The curvature of the bends provides the mechanical constraint needed to limit angular movement without requiring complex active control mechanisms.
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 flexure limiting member effectively reduces excessive spinal movement, enhancing stability and reducing pain by limiting the angular distance and velocity of articulating members, thereby addressing the misalignment issues caused by degenerative spinal conditions.
Implementation Method 1
The flexure limiting member may include one or more slim elongate members. The flexure limiting member may be pre-shaped with one or more bends. For example, the flexure limiting member may have at least one first curved portion and a second curved portion, curved opposite to the at least one first curved portion and joined thereto at an inflection point.
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Apparatus including a first spinal prosthetic member that may articulate with a second spinal prosthetic member, the first and second spinal prosthetic members flexing relative to one another about a lateral-medial axis corresponding to a lateral-medial axis of a body, and a flexure limiting member attached to the first and second spinal prosthetic members that limits flexure about the lateral-medial axis.