Expandable Interbody Device With Nested Cage Control Assembly
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Solution Overview
Problem
Current spinal interbody devices often require large access ports for implantation, limiting the size of tools and implants that can be used, and existing expandable devices lack efficient mechanisms for controlled expansion and contraction to accommodate varying patient needs.
Innovation Solution
The development of an expandable interbody device with superior and inferior shells and a control assembly that allows for controlled expansion or contraction through a mechanism involving interlocking cages and an adjustment screw, enabling precise adjustment and stability, and the use of porous materials for bone growth promotion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional non-expandable interbodies are used, then structural integrity is maintained, but the access port size must be large limiting minimally invasive approaches
Solution Approach 1:
The interbody device is divided into multiple segments including superior and inferior shells with internal control assemblies. These segmented components allow the device to be collapsed into a smaller configuration for insertion through limited access ports, then expanded to provide full structural support once positioned in the intervertebral space.
Solution Approach 2:
The control assembly is nested within the interbody device structure, with the adjustment mechanism housed inside the shells. This nesting allows the control system to be contained within the compact form factor required for minimally invasive insertion while still providing the capability for post-insertion expansion.
2Ease of operation
If expandable interbodies are used to reduce access port size, then minimally invasive implantation is enabled, but control over expansion and contraction becomes complex
Solution Approach 1:
The control assembly serves multiple functions: it controls expansion of the interbody device, maintains the expanded position, and enables contraction if needed. This multi-functionality is achieved through a unified adjustment mechanism that integrates these operations, simplifying the control process despite the device's expandable capabilities.
Solution Approach 2:
The interbody device transitions from a static design to a dynamic system that can change its configuration. The adjustment mechanism allows the device to be expanded from a collapsed insertion state to an expanded functional state, and potentially contracted again, providing dynamic adaptability while maintaining operational simplicity through intuitive control.
3Adaptability or versatility
If the interbody is made adjustable to fit specific patient anatomy, then adaptability is improved, but the device structure becomes more complex
Solution Approach 1:
The interbody device is designed with predetermined expansion increments and structural features that accommodate common anatomical variations. The control mechanism is pre-configured to provide specific expansion steps, allowing adaptation to different patient anatomies without requiring complex real-time calculations or adjustments, thus balancing adaptability with structural simplicity.
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 device allows for minimally invasive implantation with adjustable size to fit specific patient anatomy, promoting bone growth and providing structural integrity and stability through controlled expansion and contraction mechanisms.
Implementation Method 1
The adjustment screw is configured to engage with the proximal and distal cages. Rotation of the adjustment screw causes the distal cage to move longitudinally relative to the proximal cage
Implementation Method 2
The proximal cage comprises a pair of superior lateral projections and a pair of inferior lateral projections respectively configured to engage with the pairs of proximally angled channels of the superior and inferior shells. Similarly, the distal cage has a pair of superior lateral projections and a pair of inferior lateral projections respectively configured to engage with the pairs of distally angled channels of the superior and inferior shells. Rotation of the adjustment screw causes the distal cage to move longitudinally relative to the proximal cage, which in turn causes the interbody to expand or contract in a direction transverse to the longitudinal axis.
Data Source
AI summary
The present disclosure relates to expandable interbodies that include superior and inferior shells and a control assembly positioned between and inside of the shells, the control assembly including nested cages operably connected to each other with an adjustment screw. Rotation of the adjustment screw translates the cages relative to each other, which in turn causes the shells to open or expand.