Bone Screw Set Rotational Stability via Nested Screws
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Solution Overview
Problem
Current bone screw fixation methods for smaller bones, such as scaphoid fractures or pseudoarthrosis, fail to provide sufficient rotational stability while minimizing tissue disruption, as they require additional implants or transverse splints that can compromise blood supply and joint stability.
Innovation Solution
A bone screw set comprising a compression screw and a second screw with engaging means, such as threads or a longitudinal groove, that interact to prevent rotation between bone fragments, allowing for asymmetrical or non-rotationally symmetrical cross-sections without the need for transverse bores, ensuring rotational stability through self-tapping and radial expansion forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If transverse splints and additional implants are used to provide rotational stability, then rotational stability is improved, but tissue disruption and compromise of blood supply worsen
Solution Approach 1:
The patent combines two bone screws into a single integrated implant system where the second screw is inserted through the first screw. This merging of functions allows rotational stability to be achieved without adding separate transverse splints that would require additional tissue dissection and compromise blood supply.
Solution Approach 2:
The second bone screw is nested within the first bone screw, with the second screw passing through the longitudinal groove of the first screw. This nesting configuration provides rotational stability while minimizing the overall implant profile and avoiding the need for additional transverse bores that would disrupt tissue and blood supply.
2Stability of the object's composition
If multiple independent implants are used to achieve rotational stability, then rotational stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the functions of two separate bone screws into an integrated system where the second screw is inserted through the first screw. This combination provides rotational stability through the interacting screw geometry without requiring multiple independent implants, thereby reducing device complexity.
3Force
If compression screws with different thread pitches are used to achieve compression, then compression capability is improved, but manufacturing complexity increases
Solution Approach 1:
The first bone screw is divided into two functional segments: an external thread for engaging the bone and generating compression, and an internal thread within the longitudinal groove for receiving the second screw. This segmentation allows each thread type to be optimized independently, simplifying manufacturing while maintaining compression 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 set provides enhanced rotational stability and fixation of bone fragments, preventing twisting and promoting healing by allowing for a minimally invasive procedure with reduced tissue disruption and increased anchorage in the surrounding bone tissue.
Implementation Method 1
the first and the second bone screw have engaging means that interact with one another in order to prevent rotation of the second bone screw from the cross section of the first bone screw
Implementation Method 2
the interacting engagement means are formed by a thread of the second bone screw and a thread of the first bone screw that can be brought into engagement with it
Implementation Method 3
A self-tapping second screw that makes its own way when it is screwed in and thereby develops a fixing radial expansion force would be preferred
Implementation Method 4
the first bone screw is designed as a compression screw
Data Source
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AI summary
The invention relates to a bone screw set for fixing two bone fragments, especially for treating a scaphoid bone fracture or a scaphoid bone pesudoarthrosis, comprising a first bone screw (1) and at least one second bone screw (2). The first bone screw (1) is preferably embodied as a compression screw, and the first and second bone screws (1, 2) comprise interacting engagement means for fixing the second bone screw (2) in a position, in relation to the first bone screw (1), wherein at least part of the second bone screw protrudes from the cross-section of the first bone screw (1).