Articulating Expandable Intervertebral Implant for Narrow Access
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Solution Overview
Problem
Current intervertebral cages face challenges in navigating narrow access pathways to the intervertebral space due to limited working space and the need to accommodate the angular relationship of vertebral bodies, particularly for larger lordotic angles, leading to improper fitting and potential dislodgment or migration.
Innovation Solution
An expandable intervertebral implant with an articulating mechanism that allows for angular adjustment and expansion in two perpendicular directions, manufactured using additive manufacturing to eliminate connection seams and facilitate customization for patient-specific needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cage size is increased to restore disc height and maintain spinal alignment, then the mechanical strength and structural integrity are improved, but the ability to pass through the narrow access pathway is worsened
Solution Approach 1:
The cage is divided into multiple expandable segments or struts that can be collapsed into a compact configuration for insertion through narrow pathways, then expanded to the full size needed for mechanical support. This segmentation allows the cage to transition from a small insertable form to a large load-bearing structure.
Solution Approach 2:
The cage components are designed to nest within each other in a collapsed state, similar to nested dolls, allowing the entire structure to be compressed to a small size for insertion. After placement in the intervertebral space, the nested components are deployed outward to achieve the required mechanical strength and disc height restoration.
2Adaptability or versatility
If the cage is designed to accommodate larger lordotic angles, then the adaptability to angular constraints is improved, but the device complexity increases
Solution Approach 1:
The cage incorporates dynamic articulating mechanisms such as pivoting struts or adjustable links that can change their relative angles to match different lordotic configurations. This dynamic capability allows the rigid cage structure to adapt to varying spinal curvatures without requiring multiple fixed-angle designs, thereby managing complexity through controlled movement rather than multiple static configurations.
Solution Approach 2:
The cage design allows for adjustment of geometric parameters such as strut angles, link lengths, or joint configurations to accommodate different lordotic angles. By making these parameters adjustable rather than fixed, the cage can be customized for various spinal anatomies without fundamentally changing the overall device architecture, thus managing complexity through parameter variation.
3Ease of operation
If the cage is made expandable to overcome insertion constraints, then the ease of insertion is improved, but the device complexity increases
Solution Approach 1:
The cage is pre-assembled in a collapsed or compressed configuration that maintains its structural integrity while reducing its dimensions for insertion. The expansion mechanism is pre-positioned and ready for activation once the cage is in place, eliminating the need for complex assembly steps after insertion. This preliminary preparation simplifies the insertion process while managing overall device complexity.
Solution Approach 2:
The cage incorporates self-expanding mechanisms such as spring-loaded struts, shape memory alloys, or hydraulic actuators that automatically expand the cage to its functional size after insertion. This self-service capability eliminates the need for external manipulation or complex manual expansion procedures, thereby improving ease of insertion while keeping the expansion mechanism integrated and relatively simple.
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3A~3B
AI summary
An intervertebral implant is configured to be implanted in an intervertebral space in a first initial configuration. Subsequently, an actuator is configured to be driven in an actuation direction such that the actuator urges the implant to expand along a first expansion direction. Once the implant has been fully expanded along the first expansion direction, the actuator is configured to be further driven in the actuation direction so as to expand the implant in a second expansion direction that is perpendicular to the first expansion direction.