Spinal Fusion Cage Screw Adjustment With Built-In Torque Limit
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Solution Overview
Problem
Existing spinal fusion cages face challenges such as complex height adjustment mechanisms, risk of vertebral damage from excessive force, and increased burden due to heavy and complicated surgical tools, which complicate surgery and recovery.
Innovation Solution
A height-adjustable spinal fusion cage with a simplified mechanism, allowing linear adjustment to fit varying vertebral distances, and featuring a torque-limiting design to prevent excessive force, reducing tool complexity and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a vertical ratchet mechanism is used for height adjustment, then height adjustment function is achieved, but the structure becomes complicated and manufacturing becomes difficult
Solution Approach 1:
The cage is divided into a first body portion and a second body portion that can move relative to each other. The adjustment member includes a screw portion that engages with a threaded hole in the first body portion, allowing linear adjustment through simple rotational movement rather than complex mechanical linkages.
Solution Approach 2:
The patent replaces complex mechanical adjustment mechanisms (such as vertical ratchets) with a simpler screw-threaded adjustment system. The adjustment member with screw portion engages with a threaded hole, converting rotational motion to linear motion in a straightforward manner that is easier to manufacture and assemble.
2Adaptability or versatility
If excessive force is applied during vertebral body extension, then height adjustment is achieved, but vertebral damage may occur
Solution Approach 1:
The connection portion is designed with limited torque capability that is predetermined to be safe for vertebral bodies. This built-in mechanical limitation acts as a cushion against excessive forces, preventing damage before it can occur during the adjustment process.
Solution Approach 2:
The patent converts the potential harmful effect of excessive torque into a beneficial safety feature. The connection portion is specifically designed with limited torque capability that prevents over-tightening and vertebral damage, turning what could be a hazard into a protective mechanism.
3Object-affected harmful factors
If a torque limit handle is connected to the screwdriver, then vertebral damage is prevented, but the tool becomes complex and heavy
Solution Approach 1:
The torque limiting function is merged into the connection portion itself rather than being a separate tool attachment. The connection portion's inherent mechanical design provides torque limitation, eliminating the need for additional complex tool handles or attachments.
Solution Approach 2:
The connection portion is self-limiting in terms of torque capability. It automatically prevents excessive forces from being applied to the vertebral bodies through its own structural design, without requiring external control mechanisms or additional tools.
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 surgical fit, reduces inventory and production burden, minimizes surgical effort, and shortens operation and recovery time by simplifying height adjustment and tool design.
Implementation Method 1
an adjustment member (110) which is connected to the distal movable block (108) through the proximal movable block (106), and comprises a screw portion (214, 314, 414) that rotates within a movable block thread portion (202)
Data Source
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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.