Bone Screw Internal Extendable Tang Fixation
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Solution Overview
Problem
Conventional bone screws tend to loosen over time due to expansion of the hole or rotation out of the screw, necessitating a solution for secure fixation after insertion.
Innovation Solution
A bone screw with an internal extendable tang system that deploys tangs at an angle after insertion, utilizing a driver to convert rotational motion into linear motion to extend tangs from the screw body, providing enhanced resistance to rotation and optional removability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional screws are used for bone fixation, then the insertion process is simple, but the screw loosens over time due to hole expansion or rotation
Solution Approach 1:
The screw transitions from a static structure to a dynamic one by deploying tangs after insertion. The tangs are initially concealed within the screw body and are pushed out through guide surfaces by a driver, transforming the screw from a simple threaded fastener to an active fixation device that engages bone tissue mechanically
Solution Approach 2:
The fixation function is divided into two independent components: the threaded screw body for insertion and the deployable tangs for anchoring. This segmentation allows the screw to perform insertion through threading while the tangs provide separate anti-rotation and anti-loosening functionality
2Reliability
If tangs are extended to prevent rotation, then rotational resistance improves, but the insertion process becomes more complex
Solution Approach 1:
The tangs are pre-positioned within the screw body in a concealed state, ready for deployment but not interfering with the insertion process. The driver mechanism is pre-configured to push the tangs out through guide surfaces after the screw is threaded into place, separating the insertion and anchoring operations
3Reliability
If the tang system is made permanent for secure fixation, then fixation reliability improves, but removability is lost
Solution Approach 1:
The tang system is designed to be dynamically adjustable between deployed and retracted states. A driver can push the tangs out through guide surfaces for secure fixation, and a modified driver with a threaded rod can pull the tangs back into the screw body for removal, allowing the same system to provide both permanent fixation and removable capability
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 bone screw effectively secures itself within the bone by extending tangs at an angle, preventing rotation and allowing for secure fixation, while being optionally removable through a modified driver mechanism.
Implementation Method 1
A driver allows the user to control the different steps of insertion, including converting rotational motion of a knob into linear motion of a rod
Data Source
AI summary
The bone screw with internal extendable is a bone screw with an internal, extendable tang. The tang—part of a tang system—is concealed within the body of the screw until after placement. After the screw is threaded into the bone, the internal tang system is pushed out of the bone screw body, forcing one or more tangs to extend out of the body and into the bone. A driver allows the user to control the different steps of insertion, including converting rotational motion of a knob into linear motion of a rod, the rod moving through the screw body to force the tang to exit the bone screw body. The one or more tangs preferably exit the bone screw body at a tang exit portal formed by one or more tang exit guide surfaces.