Expandable Interbody Implant With In-Situ Screw-Linkage Expansion
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Solution Overview
Problem
Current intervertebral fusion devices for spinal surgery involve lengthy operations, risk of nerve injury, and hip pain due to bone graft harvesting, and require complex distraction techniques.
Innovation Solution
An expandable interbody device with a drive block, linkage block, endplates, and linkages that allow for controlled expansion and fixation between vertebrae, providing stability and immobilization through rotational movement of the drive screw, enabling minimal nerve retraction and bone fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bone graft harvesting is used for intervertebral fusion, then bone fixation is achieved, but operation time increases and risk of nerve injury increases
Solution Approach 1:
The expandable interbody device is pre-formed with bone graft material integrated into its structure before implantation. The device is inserted in a compressed state and then expanded within the disc space, eliminating the need for separate bone graft harvesting and preparation steps. This preliminary preparation of bone graft integration resolves the contradiction by achieving reliable bone fixation without the time-consuming harvesting procedure.
Solution Approach 2:
The invention combines the interbody device structure with bone graft material into a single integrated implant. The bone graft is incorporated within the device body, merging the structural support function with the bone fusion function. This consolidation eliminates multiple surgical steps (device insertion followed by separate bone graft placement) and reduces operation time while maintaining fixation reliability.
2Reliability
If traditional bone graft harvesting is used for intervertebral fusion, then bone fixation is achieved, but risk of nerve injury increases
Solution Approach 1:
The bone graft material is pre-integrated into the device structure before implantation, eliminating the need for separate harvesting procedures that require extensive surgical exposure and manipulation near neural structures. This preliminary preparation reduces the time the surgical field is exposed and minimizes handling near nerves, thereby reducing nerve injury risk while ensuring reliable bone fixation through the pre-loaded graft material.
Solution Approach 2:
The device is designed to be inserted in a compressed, low-profile state that minimizes surgical exposure and retraction of neural structures. The segmented expansion mechanism allows the device to gradually increase in size within the protected disc space, avoiding the need for prolonged exposure of neural elements during graft harvesting and placement, thus reducing nerve injury risk.
3Volume of moving object
If distraction device is used to enlarge disc space, then vertebral bodies are separated, but device complexity increases
Solution Approach 1:
The invention merges the disc space enlargement function with the interbody device itself. The device incorporates an expandable mechanism that allows it to increase in volume from a compressed insertion state to an expanded functional state within the disc space. This integration eliminates the need for a separate distraction device, reducing overall system complexity while achieving the required disc space enlargement for proper vertebral separation and device function.
Solution Approach 2:
The interbody device features a dynamic expandable structure that transitions from a compressed low-profile configuration during insertion to an expanded configuration after implantation. This dynamic capability allows the single device to perform both the distraction function (enlarging disc space) and the interbody fusion function, eliminating the need for separate static distraction and fusion devices and thereby reducing overall device complexity.
4Object-affected harmful factors
If minimal retraction is used for device implantation, then nerve injury risk is reduced, but disc space enlargement becomes difficult
Solution Approach 1:
The device is segmented into a compressed insertion configuration and an expanded functional configuration. During implantation, the compressed low-profile state minimizes the required disc space and reduces the need for neural retraction. After placement, the device expands to its full functional volume within the disc space, achieving adequate vertebral separation and disc space enlargement without requiring extensive initial retraction, thus protecting neural structures.
Solution Approach 2:
The device employs a dynamic expansion mechanism that allows it to transition from a compact insertion state to a voluminous functional state after implantation. This dynamic capability enables the surgeon to implant the device with minimal retraction of neural structures, then expand the device in-situ to achieve the necessary disc space enlargement and vertebral separation, thereby reducing nerve injury risk while still achieving adequate disc space volume.
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 stable spinal fusion with reduced operation time and risk of nerve injury by allowing controlled expansion and fixation between vertebrae, minimizing tissue disruption and enhancing bone growth.
Implementation Method 1
The drive screw is rotatably coupled at least partially in the drive block opening or linkage block opening and is threadingly disposed within the other of the linkage block opening or the drive block opening. Rotation of the drive screw causes movement of the linkage block relative to the drive block
Implementation Method 2
At least one linkage rotatably couples the linkage block to the first endplate, and at least one other linkage rotatably couples the linkage block to the second endplate. Rotation of the drive screw causes movement of the linkage block relative to the drive block and movement of the first endplate relative to the second endplate
Implementation Method 3
The first endplate optionally includes a first endplate engagement arrangement. The second endplate optionally includes a second endplate engagement arrangement. The first and/or second endplate engagement arrangements can be optionally mechanically and slidably engaged to the block engagement arrangement. The engagement of the first and/or second endplate engagement arrangements with the block engagement arrangement optionally at least partially guides movement of the first endplate and/or the second endplate relative to at least one of the drive block or linkage block during rotation of the drive screw
Data Source
AI summary
An expandable interbody device used as a prosthesis during spinal surgery. The expandable interbody device is configured to be inserted into the space between spinal disks to provide stability. The expandable interbody device includes a drive block, a linkage block, a drive screw, a first endplate, a second endplate, and at least two linkages. Rotation of the drive screw causes movement of the linkage block relative to the drive block and/or movement of the first endplate relative to the second endplate.