Surgical Locking Screw With Variable Thread Diameter
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Solution Overview
Problem
Existing surgical locking screws for heel fractures often cause compression of bone parts, which can hinder the healing process, and lack effective mechanisms for secure fixation and prevention of loosening.
Innovation Solution
A surgical locking screw with an axially continuous external thread of constant pitch, a core diameter that remains constant in the distal section and increases in the proximal section, and a conical enveloping contour, which provides a secure locking mechanism without compression, ensuring rotational stability and preventing loosening through increased friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the external thread diameter increases towards the proximal end to provide a locking function, then the screw can be securely positioned and prevented from loosening, but this may cause compression of the bone parts
Solution Approach 1:
The external thread is designed with different characteristics in different axial sections: the distal section has a smaller, constant diameter for bone engagement without compression, while the proximal section has a larger diameter for locking. This local differentiation allows each section to perform its specific function optimally without causing harmful effects.
Solution Approach 2:
The external thread is divided into two distinct axial sections with different functional characteristics. The distal section engages the bone with a constant smaller diameter, while the proximal section provides locking with a larger diameter. This segmentation allows the screw to achieve both bone engagement and secure positioning without compression.
2Reliability
If the core diameter increases in the proximal section to provide a locking mechanism, then the screw can be securely fixed, but this increases friction and may hinder screwing-in
Solution Approach 1:
The core diameter is designed to be constant in the distal section to facilitate easy screwing-in, while increasing in the proximal section to provide secure locking. This local differentiation ensures that the screwing-in process is not hindered while still achieving reliable fixation.
3Reliability
If the external thread has a varying diameter to prevent loosening, then the screw can be securely positioned, but the thread pitch may cause compression of bone parts
Solution Approach 1:
The external thread is designed with a constant pitch throughout its length to prevent bone compression, while the diameter varies between sections to provide locking functionality. This local differentiation in diameter without varying the pitch allows the screw to achieve anti-loosening properties without causing harmful compression effects.
4Object-affected harmful factors
If the screw has a constant core diameter throughout, then bone compression is prevented, but the screw may lack a defined positioning mechanism
Solution Approach 1:
The core diameter is constant in the distal section to prevent bone compression, while the external thread diameter increases in the proximal section to provide a locking mechanism for defined positioning. This local differentiation allows the screw to maintain its core function of preventing compression while still achieving secure, defined positioning through the external thread geometry.
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 described locking screw enhances long-term healing by preventing bone compression and ensuring a secure, stable fixation of bone fragments, reducing the risk of screw loosening and facilitating easy implantation with minimal weakening of bone material.
Implementation Method 1
the increased friction of the thread tips located further outside prevents the screw from loosening itself
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a surgical locking screw for fastening bone parts in the event of a heel fracture, comprising a front end, a rear driving end having a drive for turning the locking screw, and an external thread, which has a constant thread pitch continuously over the axial extent of the external thread, wherein a major diameter of the external thread is constant in a first axial segment of the locking screw and increases with increasing distance from the front end in a second axial segment adjacent to the first axial segment in the direction of the rear end, wherein a minor diameter of the external thread is constant in the first and second axial segments, wherein the external thread extends, at least approximately, axially continuously over the entire axial extent of the locking screw, and wherein the minor diameter of the external thread extends over the entire axial extent of the external thread.