Adjustable Spinal Fusion Cage With Simplified Height Mechanism
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Solution Overview
Problem
Existing spinal fusion cages face challenges with complex height adjustment mechanisms, potential damage to vertebrae due to excessive force, and increased burden due to heavy and complicated surgical tools, leading to prolonged recovery times and inventory management issues.
Innovation Solution
A height-adjustable spinal fusion cage with a simplified mechanism using a first and second end plate, distal and proximal movable blocks, and an adjustment member that allows linear adjustment within a given range, supported by guide portions and removable portions to prevent excessive torque, reducing tool complexity and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a height adjustment mechanism is added to the spinal fusion cage, then the adaptability to different patient conditions is improved, but the device complexity increases
Solution Approach 1:
The cage is divided into multiple segments including a body, end plates, and height adjustment mechanisms at each end. Each end plate can be independently adjusted relative to the cage body through threaded rods and nuts, allowing incremental height changes without requiring a completely different cage design for each height requirement.
Solution Approach 2:
The cage transitions from a static fixed-height structure to a dynamic adjustable-height structure. The height adjustment mechanisms with threaded rods, nuts, and locking features enable the cage to change its height after insertion, adapting to different vertebral spacing requirements while maintaining structural integrity through the dynamic adjustment system.
2Adaptability or versatility
If a complex height adjustment mechanism is used, then the height adjustability is improved, but the surgical tool complexity and weight increase
Solution Approach 1:
The height adjustment function is extracted from the main cage body and implemented as separate, modular adjustment mechanisms at each end. This allows the adjustment functionality to be independently optimized and simplified, with each end plate having its own threaded rod and nut assembly that can be adjusted without affecting the other end, reducing overall system complexity.
Solution Approach 2:
The height adjustment mechanism is designed to be self-contained at each end of the cage, with each end plate having its own adjustment components. This self-service design allows surgeons to adjust one end independently without needing to manipulate the entire cage or use complex external tools, simplifying the surgical procedure and reducing tool requirements.
3Adaptability or versatility
If multiple cage sizes are maintained in inventory, then the adaptability to different patient conditions is improved, but the inventory management burden increases
Solution Approach 1:
A single cage design with height adjustment capabilities replaces the need for multiple fixed-size cage variants. The universal cage can be adjusted to different heights to accommodate various patient anatomies and surgical requirements, eliminating the need to maintain separate inventories of small, medium, and large cages while providing the same adaptability.
4Stability of the object's composition
If excessive force is applied during cage insertion, then the cage stability is improved, but the risk of vertebrae damage increases
Solution Approach 1:
The cage is pre-adjusted to the appropriate height and configuration before insertion, and the height adjustment mechanisms are pre-loaded with appropriate tension. This preliminary preparation ensures that the cage achieves stable positioning without requiring excessive force during insertion, as the adjustment mechanisms are already optimized for the specific surgical requirements.
Solution Approach 2:
The height adjustment mechanisms include locking features and tensioning systems that provide mechanical feedback during insertion. As the cage is inserted and the end plates contact the vertebral bodies, the adjustment mechanisms automatically engage and lock at the appropriate height, preventing over-compression and providing tactile feedback to the surgeon that the correct positioning has been achieved, thereby avoiding excessive force application.
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
Enables optimal height adjustment based on patient conditions, simplifies surgery by reducing tool complexity and weight, and minimizes inventory requirements, thereby shortening operation time and recovery periods.
Implementation Method 1
a threaded rod (110) extending in the proximal-distal direction and having threads formed on an outer surface thereof, and a nut (120) fitted to the threaded rod (110) and having an inner surface formed with inner threads engaged with the threads of the threaded rod (110)
Data Source
AI summary
The present invention relates to a spinal fusion cage which is inserted between vertebral bodies in a state where the cage has the lowest height, is height-adjustable in the inserted state, and can simplify a height adjustment mechanism, thus making it possible to replace cages having heights in a certain range by a single cage. Therefore, manufacturers can reduce product groups that need to be produced, and can also reduce product stock. Further, in contrast to the conventional cages having predetermined heights at regular intervals, the height of the inventive cage can be linearly adjusted according to the distance between the vertebral bodies of a patient, and thus a surgery can be performed using the cage adjusted to an optimum height according to the patient's condition.