Expandable Corpectomy Spacer Locking for Bone Graft Delivery
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Solution Overview
Problem
Conventional vertebral body replacement implants face issues such as proximity to the dura and spinal cord due to lordosis/kyphosis, cumbersome screw installation, difficulty in safely removing and replacing components, and limited space for bone graft material delivery in expandable cages.
Innovation Solution
An expandable corpectomy spacer with a locking mechanism that allows for bone graft material delivery after expansion, featuring a single component that engages with a gear to splay open or disengage, and an insertion instrument for expanding or contracting the implant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional corpectomy cages are used with screws to secure endplates, then the implant can be secured to adjacent vertebrae, but the screws are cumbersome to install and make it difficult to safely remove and replace components
Solution Approach 1:
The patent removes the screw fastening system entirely from the implant design. The endplates are integrated directly into the cage structure without requiring separate screws for attachment, eliminating the cumbersome installation and removal process while maintaining structural integrity through the integrated design.
Solution Approach 2:
The endplates are merged with the cage body to form an integrated structure. This combination eliminates the need for separate fastening components (screws) and simplifies the overall assembly, making installation and removal more straightforward while ensuring the endplates remain securely attached during use.
2Quantity of substance
If expandable VBR cages are used, then the implant can be expanded to provide stabilization, but the space for packing bone graft materials is limited and delivery into the implant after expansion is restricted
Solution Approach 1:
The patent incorporates bone graft material into the implant before the expansion process. The graft material is pre-loaded into the cage structure in its compressed state, allowing sufficient quantity to be included without requiring post-expansion delivery mechanisms. This preliminary loading ensures adequate bone graft availability while maintaining the expandable functionality of the implant.
3Object-affected harmful factors
If the implant is expanded to provide greater stabilization, then the distance from the dura and spinal cord increases, but the expansion range is limited in current designs
Solution Approach 1:
The patent implements an expandable cage structure that can dynamically adjust its dimensions. The cage expands from a compressed insertion state to a larger stabilized state, allowing the implant to increase its distance from the dura and spinal cord as needed. This dynamic expansion capability provides greater control over the final position and stabilization effect while minimizing initial surgical complexity.
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 solution provides a secure, expandable implant that maintains distance from the dura and spinal cord, facilitates easy component removal and replacement, and allows for greater bone graft material delivery, enhancing surgical safety and efficacy.
Implementation Method 1
a threaded actuator disposed inside the outer ring
Implementation Method 2
a locking mechanism disposed in the outer ring and configured to removably engage with the gear
Data Source
AI summary
An implant assembly including an expandable vertebral body replacement implant. The implant assembly includes a right hand end and a left hand end configured to attach to a threaded actuator. An outer ring is configured to surround each of the right and left hand ends and the threaded actuator. The implant assembly may include removable endplates configured to engage vertebral bodies as interbody spacer or through a corpectomy. The implant assembly includes a locking mechanism to prevent collapse or movement the implant assembly after implantation. The locking mechanism automatically engage after removal of an inserter instrument from the implant assembly.