Expandable Intervertebral Cage With Self-Locking Lordosis Adjustment
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Solution Overview
Problem
Current expandable intervertebral cages face challenges with complex structures, risk of accidental collapse, and inability to adapt to the patient's lordosis angle, often requiring complex expansion mechanisms and limited access due to bony and nervous structures.
Innovation Solution
A minimally invasive, shallow-designed intervertebral cage that can be inserted through a small opening and expanded to double in height, featuring a self-locking mechanism with interconnected drive shafts and nuts for stability, allowing adjustment to the patient's lordosis angle and providing a large interior space for bone graft insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cage is designed to be shallow for minimally invasive insertion, then the insertion access is improved, but the expansion mechanism becomes more complex
Solution Approach 1:
The expansion mechanism is nested within the base and stage structures. The drive shafts and nuts are contained within the base, allowing the cage to expand from a shallow compressed state to a taller expanded state without requiring external expansion components that would increase the initial insertion profile.
Solution Approach 2:
The cage transitions from a static shallow configuration during insertion to a dynamic expanded configuration after placement. The expansion mechanism allows the cage to change its height and shape dynamically, adapting from a compact insertion form to a stable expanded form that provides the necessary structural support.
2Device complexity
If the cage structure is simplified, then the device complexity is reduced, but the risk of accidental collapse increases
Solution Approach 1:
The self-locking mechanism is designed with inherent safety features that prevent accidental collapse. The interconnected drive shafts and nuts create a mechanically locked state that maintains cage expansion without requiring continuous external force or complex active control systems.
Solution Approach 2:
The expansion and locking functions are merged into a single integrated mechanism. The drive shafts and nuts work together to simultaneously achieve cage expansion and self-locking, eliminating the need for separate complex locking systems while maintaining structural reliability.
3Device complexity
If the cage cannot adapt to lordosis angle, then the device complexity is reduced, but the adaptability to patient anatomy decreases
Solution Approach 1:
The cage incorporates dynamic adjustment capabilities that allow it to adapt to different lordosis angles. The expansion mechanism can be operated to achieve both height expansion and angular orientation adjustment, enabling the cage to conform to the patient's specific spinal anatomy without requiring multiple pre-configured device variants.
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 cage maintains mechanical stability, prevents accidental collapse, and allows for precise adjustment to the patient's anatomy, facilitating effective fusion and correction of lordosis while minimizing surgical invasiveness.
Implementation Method 1
a first thread (16) arranged on an outer surface of the bushing (21) and second thread (17) arranged on an outer surface of the shaft (20)
Implementation Method 2
a first nut (18) placed on the first thread (16) and the second nut (19) placed on the second thread (17)
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The present disclosure relates to an expandable intervertebral cage (1) comprising a base (2) with a circumferential side wall (7) extending in a first direction (z) and a first bone interaction surface (5) and a stage (3) comprising a second bone in-teraction surface (6) arranged essentially opposite to the first bone interaction surface (5) with respect to the expandable intervertebral cage (1). An expansion mechanism (4) serves for adjusting the position of the second bone interaction surface (6) of the stage (3) with respect to the first bone interaction surface (5) of the base (2) at least in the first direction (z). The expansion mechanism (4) is thereby arranged at least partially within the circumferential side wall (7) of the base (2).