Expandable Intervertebral Cage for Narrow-Access Lordosis Adjustment
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Solution Overview
Problem
Current intervertebral cages face challenges in navigating narrow access pathways due to limited working space and the need to accommodate angular relationships between vertebral bodies, particularly for larger lordotic angles, while maintaining structural integrity and stability.
Innovation Solution
Expandable and angularly adjustable intervertebral cages manufactured using additive manufacturing techniques, such as selective laser melting, allowing for size and angle adjustments without external fixation, and featuring engineered cellular structures and internal expansion components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cage is designed with a larger size to maintain disc height and stabilize the spine, then the structural integrity and stability are improved, but the difficulty of insertion through narrow access pathways increases
Solution Approach 1:
The cage is divided into an insert portion and an expansion portion. The insert portion is designed with a smaller cross-sectional area to facilitate insertion through narrow access pathways, while the expansion portion is designed with a larger cross-sectional area to maintain disc height and provide structural stability after implantation. The two portions are connected by a hinge that allows relative movement between them.
Solution Approach 2:
The cage transitions from a static small-size configuration during insertion to a dynamic expanded configuration after implantation. The hinge connection allows the expansion portion to rotate relative to the insert portion, enabling the cage to adapt its size and shape based on the surgical stage (insertion vs. stabilization).
2Adaptability or versatility
If the cage is designed to accommodate larger lordotic angles, then the adaptability to angular relationships between vertebral bodies is improved, but the device complexity increases
Solution Approach 1:
The hinge connection enables the cage to dynamically adjust its angular orientation to accommodate different lordotic angles between vertebral bodies. The expansion portion can rotate relative to the insert portion, allowing the cage to adapt to the natural curvature of the spine without requiring multiple pre-configured angle options.
Solution Approach 2:
The cage changes its geometric parameters (angular orientation) through the hinge mechanism. By allowing relative rotation between the insert portion and expansion portion, the cage can achieve different lordotic angles to match the patient's specific spinal anatomy, rather than being fixed at a single angle.
3Adaptability or versatility
If the cage is designed with expandable features and angular adjustment capabilities, then the adaptability to patient-specific anatomy is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The cage is segmented into distinct portions (insert portion and expansion portion) connected by a hinge. This segmentation allows each portion to be manufactured with standard precision tolerances, while the assembly of these portions creates the expandable and angularly adjustable functionality, reducing the overall manufacturing precision requirements compared to a monolithic precision component.
Solution Approach 2:
The dynamic hinge connection provides angular adjustment capability through mechanical degrees of freedom rather than requiring precision-manufactured angular features. The hinge allows the expansion portion to rotate to different angles, providing adaptability without needing to manufacture each possible angle with high precision.
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
Facilitates easy insertion through narrow spaces, accommodates varying lordotic angles, maintains disc height, and stabilizes the spine by restoring sagittal balance, promoting fusion and minimizing mismatch with patient-specific bone qualities.
Implementation Method 1
Expandable and angularly adjustable intervertebral cages manufactured using additive manufacturing techniques, such as selective laser melting
Data Source
AI summary
The embodiments provide various interbody fusion spacers, or cages, for insertion between adjacent vertebrae. These intervertebral cages can restore and maintain intervertebral height of the spinal segment to be treated, and stabilize the spine by restoring sagittal balance and alignment. The cages may have a first, insertion configuration characterized by a reduced size at each of their insertion ends to facilitate insertion through a narrow access passage and into the intervertebral space. The cages may be expanded to a second, expanded size once implanted. In their second configuration, the cages are able to maintain the proper disc height and stabilize the spine by restoring sagittal balance and alignment. The intervertebral cages are configured to be able to adjust the angle of lordosis, and can accommodate larger lordotic angles in their second, expanded configuration. Further, these cages may promote fusion to further enhance spine stability by immobilizing the adjacent vertebral bodies.